WorldWideScience

Sample records for age-0 lake trout

  1. Effectiveness of a refuge for Lake Trout in Western Lake Superior II: Simulation of future performance

    Science.gov (United States)

    Akins, Andrea L; Hansen, Michael J.; Seider, Michael J.

    2015-01-01

    Historically, Lake Superior supported one of the largest and most diverse Lake Trout Salvelinus namaycush fisheries in the Laurentian Great Lakes, but Lake Trout stocks collapsed due to excessive fishery exploitation and predation by Sea Lampreys Petromyzon marinus. Lake Trout stocking, Sea Lamprey control, and fishery regulations, including a refuge encompassing Gull Island Shoal (Apostle Islands region), were used to enable recovery of Lake Trout stocks that used this historically important spawning shoal. Our objective was to determine whether future sustainability of Lake Trout stocks will depend on the presence of the Gull Island Shoal Refuge. We constructed a stochastic age-structured simulation model to assess the effect of maintaining the refuge as a harvest management tool versus removing the refuge. In general, median abundances of age-4, age-4 and older (age-4+), and age-8+ fish collapsed at lower instantaneous fishing mortality rates (F) when the refuge was removed than when the refuge was maintained. With the refuge in place, the F that resulted in collapse depended on the rate of movement into and out of the refuge. Too many fish stayed in the refuge when movement was low (0–2%), and too many fish became vulnerable to fishing when movement was high (≥22%); thus, the refuge was more effective at intermediate rates of movement (10–11%). With the refuge in place, extinction did not occur at any simulated level of F, whereas refuge removal led to extinction at all combinations of commercial F and recreational F. Our results indicate that the Lake Trout population would be sustained by the refuge at all simulated F-values, whereas removal of the refuge would risk population collapse at much lower F (0.700–0.744). Therefore, the Gull Island Shoal Refuge is needed to sustain the Lake Trout population in eastern Wisconsin waters of Lake Superior.

  2. Lake trout rehabilitation in Lake Erie: a case history

    Science.gov (United States)

    Cornelius, Floyd C.; Muth, Kenneth M.; Kenyon, Roger

    1995-01-01

    Native lake trout (Salvelinus namaycush) once thrived in the deep waters of eastern Lake Erie. The impact of nearly 70 years of unregulated exploitation and over 100 years of progressively severe cultural eutrophication resulted in the elimination of lake trout stocks by 1950. Early attempts to restore lake trout by stocking were unsuccessful in establishing a self-sustaining population. In the early 1980s, New York's Department of Environmental Conservation, Pennsylvania's Fish and Boat Commission, and the U.S. Fish and Wildlife Service entered into a cooperative program to rehabilitate lake trout in the eastern basin of Lake Erie. After 11 years of stocking selected strains of lake trout in U.S. waters, followed by effective sea lamprey control, lake trout appear to be successfully recolonizing their native habitat. Adult stocks have built up significantly and are expanding their range in the lake. Preliminary investigations suggest that lake trout reproductive habitat is still adequate for natural reproduction, but natural recruitment has not been documented. Future assessments will be directed toward evaluation of spawning success and tracking age-class cohorts as they move through the fishery.

  3. Use of cover habitat by bull trout Salvelinus confluentus and lake trout Salvelinus namaycush in a laboratory environment

    Science.gov (United States)

    Meeuwig, Michael H.; Guy, Christopher S.; Fredenberg, Wade A.

    2011-01-01

    Lacustrine-adfluvial bull trout, Salvelinus confluentus, migrate from spawning and rearing streams to lacustrine environments as early as age 0. Within lacustrine environments, cover habitat pro- vides refuge from potential predators and is a resource that is competed for if limiting. Competitive inter- actions between bull trout and other species could result in bull trout being displaced from cover habitat, and bull trout may lack evolutionary adaptations to compete with introduced species, such as lake trout, Salvelinus namaycush. A laboratory experiment was performed to examine habitat use and interactions for cover by juvenile (i.e., habitat, with bull trout using cover and bottom habitats more than lake trout. Habitat selection ratios indicated that bull trout avoided water column habitat in the presence of lake trout and that lake trout avoided bottom habitat. Intraspecific and interspecific agonistic interactions were infrequent, but approximately 10 times greater for intraspecific inter- actions between lake trout. Results from this study provide little evidence that juvenile bull trout and lake trout compete for cover, and that species-specific differences in habitat use and selection likely result in habitat partitioning between these species.

  4. Radio-transmitted electromyogram signals as indicators of swimming speed in lake trout and brown trout

    DEFF Research Database (Denmark)

    Thorstad, E.B.; Økland, F.; Koed, Anders

    2000-01-01

    Swimming speed and average electromyogram (EMG) pulse intervals were highly correlated in individual lake trout Salvelinus namaycush (r(2)=0.52-0.89) and brown trout Salmo trutta (r(2)=0.45-0.96). High correlations were found also for pooled data in both lake trout (r(2)=0.90) and brown trout...... of the Ema stock (r(2)=0.96) and Laerdal stock (r(2)=0.96). The linear relationship between swimming speed and average EMG pulse intervals differed significantly among lake trout and the brown trout stocks. This successful calibration of EMGs to swimming speed opens the possibility of recording swimming...... speed of free swimming lake trout and brown trout in situ. EMGs can also be calibrated to oxygen consumption to record energy expenditure. (C) 2000 The Fisheries Society of the British Isles...

  5. Lake trout (Salvelinus namaycush) suppression for bull trout (Salvelinus confluentus) recovery in Flathead Lake, Montana, North America

    Science.gov (United States)

    Hansen, Michael J.; Hansen, Barry S; Beauchamp, David A.

    2016-01-01

    Non-native lake trout Salvelinus namaycush displaced native bull trout Salvelinus confluentus in Flathead Lake, Montana, USA, after 1984, when Mysis diluviana became abundant following its introduction in upstream lakes in 1968–1976. We developed a simulation model to determine the fishing mortality rate on lake trout that would enable bull trout recovery. Model simulations indicated that suppression of adult lake trout by 75% from current abundance would reduce predation on bull trout by 90%. Current removals of lake trout through incentivized fishing contests has not been sufficient to suppress lake trout abundance estimated by mark-recapture or indexed by stratified-random gill netting. In contrast, size structure, body condition, mortality, and maturity are changing consistent with a density-dependent reduction in lake trout abundance. Population modeling indicated total fishing effort would need to increase 3-fold to reduce adult lake trout population density by 75%. We conclude that increased fishing effort would suppress lake trout population density and predation on juvenile bull trout, and thereby enable higher abundance of adult bull trout in Flathead Lake and its tributaries.

  6. Demographic characteristics of an adfluvial bull trout population in Lake Pend Oreille, Idaho

    Science.gov (United States)

    McCubbins, Jonathan L; Hansen, Michael J.; DosSantos, Joseph M; Dux, Andrew M

    2016-01-01

    Introductions of nonnative species, habitat loss, and stream fragmentation have caused the Bull Trout Salvelinus confluentus to decline throughout much of its native distribution. Consequently, in June 1998, the Bull Trout was listed under the U.S. Endangered Species Act as threatened. The Bull Trout has existed in Lake Pend Oreille and its surrounding tributaries since the last ice age, and the lake once supported a world-renowned Bull Trout fishery. To quantify the current status of the Bull Trout population in Lake Pend Oreille, Idaho, we compared the mean age, growth, maturity, and abundance with reports in a study conducted one decade earlier. Abundance was estimated by mark–recapture for Bull Trout caught in trap nets and gill nets set in Lake Pend Oreille during ongoing suppression netting of Lake Trout S. namaycushin 2007–2008. Bull Trout sampled in 2006–2008 were used to estimate age structure, survival, growth, and maturity. Estimated Bull Trout abundance was similar to that estimated one decade earlier in Lake Pend Oreille. Bull Trout residing in Lake Pend Oreille between 2006 and 2008 were between ages 4 and 14 years; their growth was fastest between ages 1 and 2 and slowed thereafter. Male and female Bull Trout matured at a similar age, but females grew faster than males, thereby maturing at a larger size. Our findings suggest that management has effectively addressed current threats to increase the likelihood of long-term persistence of the Bull Trout population in Lake Pend Oreille.

  7. Lake trout in northern Lake Huron spawn on submerged drumlins

    Science.gov (United States)

    Riley, Stephen C.; Binder, Thomas; Wattrus, Nigel J.; Faust, Matthew D.; Janssen, John; Menzies, John; Marsden, J. Ellen; Ebener, Mark P.; Bronte, Charles R.; He, Ji X.; Tucker, Taaja R.; Hansen, Michael J.; Thompson, Henry T.; Muir, Andrew M.; Krueger, Charles C.

    2014-01-01

    Recent observations of spawning lake trout Salvelinus namaycush near Drummond Island in northern Lake Huron indicate that lake trout use drumlins, landforms created in subglacial environments by the action of ice sheets, as a primary spawning habitat. From these observations, we generated a hypothesis that may in part explain locations chosen by lake trout for spawning. Most salmonines spawn in streams where they rely on streamflows to sort and clean sediments to create good spawning habitat. Flows sufficient to sort larger sediment sizes are generally lacking in lakes, but some glacial bedforms contain large pockets of sorted sediments that can provide the interstitial spaces necessary for lake trout egg incubation, particularly if these bedforms are situated such that lake currents can penetrate these sediments. We hypothesize that sediment inclusions from glacial scavenging and sediment sorting that occurred during the creation of bedforms such as drumlins, end moraines, and eskers create suitable conditions for lake trout egg incubation, particularly where these bedforms interact with lake currents to remove fine sediments. Further, these bedforms may provide high-quality lake trout spawning habitat at many locations in the Great Lakes and may be especially important along the southern edge of the range of the species. A better understanding of the role of glacially-derived bedforms in the creation of lake trout spawning habitat may help develop powerful predictors of lake trout spawning locations, provide insight into the evolution of unique spawning behaviors by lake trout, and aid in lake trout restoration in the Great Lakes.

  8. Contrasting PCB bioaccumulation patterns among Lake Huron lake trout reflect basin-specific ecology.

    Science.gov (United States)

    Paterson, Gordon; Ryder, Mark; Drouillard, Ken G; Haffner, G Douglas

    2016-01-01

    This study collected multiple age classes of lake trout from Lake Huron's Main Basin, Georgian Bay, and North Channel regions to compare and contrast top predator polychlorinated biphenyl (PCB) bioaccumulation patterns in separate compartments of the same ecosystem. Sum PCB concentrations were highest for Main Basin (260 ± 24.9 ng g(-1) wet wt) fish, followed by Georgian Bay (74.6 ± 16.2 ng g(-1) ) and North Channel (42.0 ± 3.3 ng g(-1)) fish. Discriminant functions analysis of lake trout PCB profiles and stable carbon (δ(13)C) and nitrogen (δ(15)N) isotope values clearly distinguished fish by location, indicating high degrees of basin fidelity throughout their lifetimes in addition to highly contrasting PCB bioaccumulation profiles. These unique profiles were not attributable to significant differences in lake trout lipid contents (p = 0.856) or trophic position (δ(15)N; p = 0.334), with rainbow smelt representing the primary prey across the basins. Furthermore, significant differences were observed among the basins for the relationships between PCB biomagnification factors and hydrophobicity. An empirical model for predicting PCB biomagnification in Lake Huron lake trout indicated that basin-specific population growth rates and prey abundances were significant for explaining these contrasting patterns of PCB bioaccumulation. The results of the present study are fundamental for understanding the role of ecology in legacy persistent organic pollutant (POP) bioaccumulation. Specifically, ecosystem characteristics such as prey abundances, foraging ecology, and ultimately consumer growth can regulate the variability of legacy POP bioaccumulation as observed within and among a wide range of freshwater ecosystems. © 2015 SETAC.

  9. Sanctuaries for lake trout in the Great Lakes

    Science.gov (United States)

    Stanley, Jon G.; Eshenroder, Randy L.; Hartman, Wilbur L.

    1987-01-01

    Populations of lake trout, severely depleted in Lake Superior and virtually extirpated from the other Great Lakes because of sea lamprey predation and intense fishing, are now maintained by annual plantings of hatchery-reared fish in Lakes Michigan, Huron, and Ontario and parts of Lake Superior. The extensive coastal areas of the Great Lakes and proximity to large populations resulted in fishing pressure on planted lake trout heavy enough to push annual mortality associated with sport and commercial fisheries well above the critical level needed to reestablish self-sustaining stocks. The interagency, international program for rehabilitating lake trout includes controlling sea lamprey abundance, stocking hatchery-reared lake trout, managing the catch, and establishing sanctuaries where harvest is prohibited. Three lake trout sanctuaries have been established in Lake Michigan: the Fox Island Sanctuary of 121, 500 ha, in the Chippewa-Ottawa Treaty fishing zone in the northern region of the lake; the Milwaukee Reef Sanctuary of 160, 000 ha in midlake, in boundary waters of Michigan and Wisconsin; and Julian's Reef Sanctuary of 6, 500 ha, in Illinois waters. In northern Lake Huron, Drummond Island Sanctuary of 55, 000 ha is two thirds in Indian treaty-ceded waters in Michigan and one third in Ontario waters of Canada. A second sanctuary, Six Fathom Bank-Yankee Reef Sanctuary, in central Lake Huron contains 168, 000 ha. Sanctuary status for the Canadian areas remains to be approved by the Provincial government. In Lake Superior, sanctuaries protect the spawning grounds of Gull Island Shoal (70, 000 ha) and Devils Island Shoal (44, 000 ha) in Wisconsin's Apostle Island area. These seven sanctuaries, established by the several States and agreed upon by the States, Indian tribes, the U.S. Department of the Interior, and the Province of Ontario, contribute toward solving an interjurisdictional fishery problem.

  10. From top to bottom: Do Lake Trout diversify along a depth gradient in Great Bear Lake, NT, Canada?

    Science.gov (United States)

    Chavarie, Louise; Howland, Kimberly L; Harris, Les N; Hansen, Michael J; Harford, William J; Gallagher, Colin P; Baillie, Shauna M; Malley, Brendan; Tonn, William M; Muir, Andrew M; Krueger, Charles C

    2018-01-01

    Depth is usually considered the main driver of Lake Trout intraspecific diversity across lakes in North America. Given that Great Bear Lake is one of the largest and deepest freshwater systems in North America, we predicted that Lake Trout intraspecific diversity to be organized along a depth axis within this system. Thus, we investigated whether a deep-water morph of Lake Trout co-existed with four shallow-water morphs previously described in Great Bear Lake. Morphology, neutral genetic variation, isotopic niches, and life-history traits of Lake Trout across depths (0-150 m) were compared among morphs. Due to the propensity of Lake Trout with high levels of morphological diversity to occupy multiple habitat niches, a novel multivariate grouping method using a suite of composite variables was applied in addition to two other commonly used grouping methods to classify individuals. Depth alone did not explain Lake Trout diversity in Great Bear Lake; a distinct fifth deep-water morph was not found. Rather, Lake Trout diversity followed an ecological continuum, with some evidence for adaptation to local conditions in deep-water habitat. Overall, trout caught from deep-water showed low levels of genetic and phenotypic differentiation from shallow-water trout, and displayed higher lipid content (C:N ratio) and occupied a higher trophic level that suggested an potential increase of piscivory (including cannibalism) than the previously described four morphs. Why phenotypic divergence between shallow- and deep-water Lake Trout was low is unknown, especially when the potential for phenotypic variation should be high in deep and large Great Bear Lake. Given that variation in complexity of freshwater environments has dramatic consequences for divergence, variation in the complexity in Great Bear Lake (i.e., shallow being more complex than deep), may explain the observed dichotomy in the expression of intraspecific phenotypic diversity between shallow- vs. deep-water habitats

  11. From top to bottom: Do Lake Trout diversify along a depth gradient in Great Bear Lake, NT, Canada?

    Science.gov (United States)

    Chavarie, Louise; Howland, Kimberly L.; Harris, Les N.; Hansen, Michael J.; Harford, William J.; Gallagher, Colin P.; Baillie, Shauna M.; Malley, Brendan; Tonn, William M.; Muir, Andrew M.; Krueger, Charles C.

    2018-01-01

    Depth is usually considered the main driver of Lake Trout intraspecific diversity across lakes in North America. Given that Great Bear Lake is one of the largest and deepest freshwater systems in North America, we predicted that Lake Trout intraspecific diversity to be organized along a depth axis within this system. Thus, we investigated whether a deep-water morph of Lake Trout co-existed with four shallow-water morphs previously described in Great Bear Lake. Morphology, neutral genetic variation, isotopic niches, and life-history traits of Lake Trout across depths (0–150 m) were compared among morphs. Due to the propensity of Lake Trout with high levels of morphological diversity to occupy multiple habitat niches, a novel multivariate grouping method using a suite of composite variables was applied in addition to two other commonly used grouping methods to classify individuals. Depth alone did not explain Lake Trout diversity in Great Bear Lake; a distinct fifth deep-water morph was not found. Rather, Lake Trout diversity followed an ecological continuum, with some evidence for adaptation to local conditions in deep-water habitat. Overall, trout caught from deep-water showed low levels of genetic and phenotypic differentiation from shallow-water trout, and displayed higher lipid content (C:N ratio) and occupied a higher trophic level that suggested an potential increase of piscivory (including cannibalism) than the previously described four morphs. Why phenotypic divergence between shallow- and deep-water Lake Trout was low is unknown, especially when the potential for phenotypic variation should be high in deep and large Great Bear Lake. Given that variation in complexity of freshwater environments has dramatic consequences for divergence, variation in the complexity in Great Bear Lake (i.e., shallow being more complex than deep), may explain the observed dichotomy in the expression of intraspecific phenotypic diversity between shallow- vs. deep-water habitats

  12. First evidence of successful natural reproduction by planted lake trout in Lake Huron

    Science.gov (United States)

    Nester, Robert T.; Poe, Thomas P.

    1984-01-01

    Twenty-two lake trout (Salvelinus namaycush) swim-up fry, 24-27 mm long, were captured with emergent fry traps and a tow net in northwestern Lake Huron on a small nearshore reef off Alpena, Michigan, between May 10 and June 1, 1982. These catches represent the first evidence of successful production of swim-up fry by planted, hatchery-reared lake trout in Lake Huron since the lake trout rehabilitation program began in 1973.

  13. Effects of lake trout refuges on lake whitefish and cisco in the Apostle Islands Region of Lake Superior

    Science.gov (United States)

    Zuccarino-Crowe , Chiara M.; Taylor, William W.; Hansen, Michael J.; Seider, Michael J.; Krueger, Charles C.

    2016-01-01

    Lake trout refuges in the Apostle Islands region of Lake Superior are analogous to the concept of marine protected areas. These refuges, established specifically for lake trout (Salvelinus namaycush) and closed to most forms of recreational and commercial fishing, were implicated as one of several management actions leading to successful rehabilitation of Lake Superior lake trout. To investigate the potential significance of Gull Island Shoal and Devils Island Shoal refuges for populations of not only lake trout but also other fish species, relative abundances of lake trout, lake whitefish (Coregonus clupeaformis), and cisco (Coregonus artedi) were compared between areas sampled inside versus outside of refuge boundaries. During 1982–2010, lake trout relative abundance was higher and increased faster inside the refuges, where lake trout fishing was prohibited, than outside the refuges. Over the same period, lake whitefish relative abundance increased faster inside than outside the refuges. Both evaluations provided clear evidence that refuges protected these species. In contrast, trends in relative abundance of cisco, a prey item of lake trout, did not differ significantly between areas inside and outside the refuges. This result did not suggest indirect or cascading refuge effects due to changes in predator levels. Overall, this study highlights the potential of species-specific refuges to benefit other fish species beyond those that were the refuges' original target. Improved understanding of refuge effects on multiple species of Great Lakes fishes can be valuable for developing rationales for refuge establishment and predicting associated fish community-level effects.

  14. Genetic diversity of wild and hatchery lake trout populations: Relevance for management and restoration in the Great Lakes

    Science.gov (United States)

    Page, K.S.; Scribner, K.T.; Burnham-Curtis, M.

    2004-01-01

    The biological diversity of lake trout Salvelinus namaycush in the upper Great Lakes was historically high, consisting of many recognizable morphological types and discrete spawning populations. During the 1950s and 1960s, lake trout populations were extirpated from much of the Great Lakes primarily as a result of overfishing and predation by the parasitic sea lamprey Petromyzon marinus. Investigations of how genetic diversity is partitioned among remnant wild lake trout populations and hatchery broodstocks have been advocated to guide lake trout management and conservation planning. Using microsatellite genetic markers, we estimated measures of genetic diversity and the apportionment of genetic variance among 6 hatchery broodstocks and 10 wild populations representing three morphotypes (lean, humper, and siscowet). Analyses revealed that different hatchery broodstocks and wild populations contributed disproportionally to the total levels of genetic diversity. The genetic affinities of hatchery lake trout reflected the lake basins of origin of the wild source populations. The variance in allele frequency over all sampled extant wild populations was apportioned primarily on the basis of morphotype (??MT = 0.029) and secondarily among geographically dispersed populations within each morphotype (??ST = 0.024). The findings suggest that the genetic divergence reflected in recognized morphotypes and the associated ecological and physiological specialization occurred prior to the partitioning of large proglacial lakes into the Great Lakes or as a consequence of higher contemporary levels of gene flow within than among morphotypes. Information on the relative contributions of different broodstocks to total gene diversity within the regional hatchery program can be used to prioritize the broodstocks to be retained and to guide future stocking strategies. The findings highlight the importance of ecological and phenotypic diversity in Great Lakes fish communities and

  15. Exposure-related effects of Zequanox on juvenile lake sturgeon (Acipenser fulvescens) and lake trout (Salvelinus namaycush)

    Science.gov (United States)

    Luoma, James A.; Severson, Todd J.; Wise, Jeremy K.; Barbour, Matthew

    2018-01-01

    The environmental fate, persistence, and non-target animal impacts of traditional molluscicides for zebra, Dreissena polymorpha, and quagga, D. bugensis, mussel control led to the development of the biomolluscicide Zequanox. Although previous research has demonstrated the specificity of Zequanox, one study indicated sensitivity of salmonids and lake sturgeon, Acipenser fulvescens, following non-label compliant exposures to Zequanox. This study was conducted to evaluate sublethal and lethal impacts of Zequanox exposure on juvenile lake sturgeon and lake trout, Salvelinus namaycush, following applications that were conducted in a manner consistent with the Zequanox product label. Fish were exposed to 50 or 100 mg/L of Zequanox as active ingredient for 8 h and then held for 33 d to evaluate latent impacts. No acute mortality was observed in either species; however, significant latent mortality (P < 0.01, df = 9; 46.2%) was observed in lake trout that were exposed to the highest dose of Zequanox. Statistically significant (P < 0.03, df = 9), but biologically minimal differences were observed in the weight (range 20.17 to 21.49 g) of surviving lake sturgeon at the termination of the 33 d post-exposure observation period. Statistically significant (P < 0.05, df = 9) and biologically considerable differences were observed in the weight (range 6.19 to 9.55 g) of surviving lake trout at the termination of the 33 d post-exposure observation period. Histologic evaluation of lake trout gastrointestinal tracts suggests that the mode of action in lake trout is different from the mode of action that induces zebra and quagga mussel mortality. Further research could determine the sensitivity of other salmonid species to Zequanox and determine if native fish will avoid Zequanox treated water.

  16. Visual observations of historical lake trout spawning grounds in western Lake Huron

    Science.gov (United States)

    Nester, Robert T.; Poe, Thomas P.

    1987-01-01

    Direct underwater video observations were made of the bottom substrates at 12 spawning grounds formerly used by lake trout Salvelinus namaycush in western Lake Huron to evaluate their present suitability for successful reproduction by lake trout. Nine locations examined north of Saginaw Bay in the northwestern end of the lake are thought to provide the best spawning habitat. The substrate at these sites consisted of angular rough cobble and rubble with relatively deep interstitial spaces (a?Y 0.5 m), small amounts of fine sediments, and little or no periphytic growth. Conditions at the three other sampling locations south of Saginaw Bay seemed much less suitable for successful reproduction based on the reduced area of high-quality substrate, shallow interstitial spaces, high infiltration of fine sediments, and greater periphytic growth.

  17. Sexual difference in PCB concentrations of lake trout (Salvelinus namaycush) from Lake Ontario

    Science.gov (United States)

    Madenjian, Charles P.; Keir, Michael J.; Whittle, D. Michael; Noguchi, George E.

    2010-01-01

    We determined polychlorinated biphenyl (PCB) concentrations in 61 female lake trout (Salvelinus namaycush) and 71 male lake trout from Lake Ontario (Ontario, Canada and New York, United States). To estimate the expected change in PCB concentration due to spawning, PCB concentrations in gonads and in somatic tissue of lake trout were also determined. In addition, bioenergetics modeling was applied to investigate whether gross growth efficiency (GGE) differed between the sexes. Results showed that, on average, males were 22% higher in PCB concentration than females in Lake Ontario. Results from the PCB determinations of the gonads and somatic tissues revealed that shedding of the gametes led to 3% and 14% increases in PCB concentration for males and females, respectively. Therefore, shedding of the gametes could not explain the higher PCB concentration in male lake trout. According to the bioenergetics modeling results, GGE of males was about 2% higher than adult female GGE, on average. Thus, bioenergetics modeling could not explain the higher PCB concentrations exhibited by the males. Nevertheless, a sexual difference in GGE remained a plausible explanation for the sexual difference in PCB concentrations of the lake trout.

  18. Net trophic transfer efficiencies of polychlorinated biphenyl congeners to lake trout (Salvelinus namaycush) from its prey

    Science.gov (United States)

    Madenjian, Charles P.; David, Solomon R.; Rediske, Richard R.; O’Keefe, James P.

    2012-01-01

    Lake trout (Salvelinus namaycush) were fed bloater (Coregonus hoyi) in eight laboratory tanks over a 135-d experiment. At the start of the experiment, four to nine fish in each tank were sacrificed, and the concentrations of 75 polychlorinated biphenyl (PCB) congeners within these fish were determined. Polychlorinated biphenyl congener concentrations were also determined in the 10 lake trout remaining in each of the eight tanks at the end of the experiment as well as in the bloater fed to the lake trout. Each lake trout was weighed at the start and the end of the experiment, and the amount of food eaten by the lake trout was recorded. Using these measurements, net trophic transfer efficiency (γ) from the bloater to the lake trout in each of the eight tanks was calculated for each of the 75 congeners. Results showed that γ did not vary significantly with the degree of chlorination of the PCB congeners, and γ averaged 0.66 across all congeners. However,γ did show a slight, but significant, decrease as logKOW increased from 6.0 to 8.2. Activity level of the lake trout did not have a significant effect on γ.

  19. Egg fatty acid composition from lake trout fed two Lake Michigan prey fish species.

    Science.gov (United States)

    Honeyfield, D.C.; Fitzsimons, J.D.; Tillitt, D.E.; Brown, S.B.

    2009-01-01

    We previously demonstrated that there were significant differences in the egg thiamine content in lake trout Salvelinus namaycush fed two Lake Michigan prey fish (alewife Alosa pseudoharengus and bloater Coregonus hoyi). Lake trout fed alewives produced eggs low in thiamine, but it was unknown whether the consumption of alewives affected other nutritionally important components. In this study we investigated the fatty acid composition of lake trout eggs when females were fed diets that resulted in different egg thiamine concentrations. For 2 years, adult lake trout were fed diets consisting of four combinations of captured alewives and bloaters (100% alewives; 65% alewives, 35% bloaters; 35% alewives, 65% bloaters; and 100% bloaters). The alewife fatty acid profile had higher concentrations of arachidonic acid and total omega-6 fatty acids than the bloater profile. The concentrations of four fatty acids (cis-13, 16-docosadienoic, eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids) were higher in bloaters than in alewives. Although six fatty acid components were higher in lake trout eggs in 2001 than in 2000 and eight fatty acids were lower, diet had no effect on any fatty acid concentration measured in lake trout eggs in this study. Based on these results, it appears that egg fatty acid concentrations differ between years but that the egg fatty acid profile does not reflect the alewife-bloater mix in the diet of adults. The essential fatty acid content of lake trout eggs from females fed alewives and bloaters appears to be physiologically regulated and adequate to meet the requirements of developing embryos.

  20. Dynamics of individual growth in a recovering population of lake trout (Salvelinus namaycush)

    Science.gov (United States)

    Fabrizio, Mary C.; Dorazio, Robert M.; Schram, Stephen T.

    2001-01-01

    In 1976, the Wisconsin Department of Natural Resources established a refuge for a nearly depleted population of lake trout (Salvelinus namaycush) at Gull Island Shoal, Lake Superior. The refuge was intended to reduce fishing mortality by protecting adult lake trout. We examined the growth dynamics of these lake trout during the period of recovery by comparing estimates of ndividual growth before and after the refuge was established. Our estimates are based on an annual mark-recapture survey conducted at the spawning area since 1969. We developed a model that allowed mean growth rates to differ among individuals of different sizes and that accommodated variation in growth rates of individuals of the same size. Likelihood ratio tests were used to determine if the mean growth increments of lake trout changed ater the refuge was established. Our results suggest that growth of mature lake trout (particularly wild fish) decreased significantly in the postrefuge period. This decreased growth may have been associated with a reduction in food availability. We also observed reductions in growth as wild fish grew older and larger, which suggests that the growth of these fish may be adequately approximated by a von Bertalanffy growth model if it becomes possible to obtain accurate ages.

  1. Evidence that lake trout served as a buffer against sea lamprey predation on burbot in Lake Erie

    Science.gov (United States)

    Stapanian, M.A.; Madenjian, C.P.

    2007-01-01

    The population of burbot Lota lota in Lake Erie recovered during 1986–2003, mainly because of the control of sea lamprey Petromyzon marinus, which began in 1986. Burbot populations continued to grow during 1996–1998, when sea lamprey control was substantially reduced. We calculated mortality parameters for burbot in Lake Erie by estimating age at capture for 2,793 burbot caught in annual gill-net surveys of eastern Lake Erie from 1994 to 2003. Based on catch-curve analysis, annual mortality in Lake Erie during 1994–2003 was estimated as 33%. Annual mortality of the 1992 year-class of burbot was estimated as 30%. The mortality of burbot during the years of reduced sea lamprey control was not different from that during the 3 years preceding reduced control and was significantly lower than that during the entire portion of the time series in which full sea lamprey control was conducted. These results suggest that the reduction in sea lamprey control did not lead to increased burbot mortality. The catch per gill-net lift of large burbot (total length > 600 mm), the size preferred by sea lampreys, was lower than that of adult lake trout Salvelinus namaycush (age 5 and older; total length > 700 mm) before lampricide application was reduced. Although adult lake trout populations declined, the abundance of large burbot did not change during the period of reduced lampricide application. These results support a hypothesis that a healthy population of adult lake trout can serve as a buffer species, acting to reduce predation of burbot by sea lampreys when sea lamprey populations increase. Burbot attained sexual maturity at a relatively early age (3 or 4 years) and a total length (approximately 500 mm) that was smaller than the preferred prey size for sea lampreys. These characteristics and the buffering effect of the lake trout population enabled growth of the burbot population during the brief period when lamprey control was reduced.

  2. Lake Michigan lake trout PCB model forecast post audit

    Science.gov (United States)

    Scenario forecasts for total PCBs in Lake Michigan (LM) lake trout were conducted using the linked LM2-Toxics and LM Food Chain models, supported by a suite of additional LM models. Efforts were conducted under the Lake Michigan Mass Balance Study and the post audit represents th...

  3. Contaminant trends in lake trout and walleye from the Laurentian Great Lakes

    Science.gov (United States)

    DeVault, David S.; Hesselberg, Robert J.; Rodgers, Paul W.; Feist, Timothy J.

    1996-01-01

    Trends in PCBs, DDT, and other contaminants have been monitored in Great Lakes lake trout and walleye since the 1970s using composite samples of whole fish. Dramatic declines have been observed in concentrations of PCB, ΣDDT, dieldrin, and oxychlordane, with declines initially following first order loss kinetics. Mean PCB concentrations in Lake Michigan lake trout increased from 13 μg/g in 1972 to 23 μg/g in 1974, then declined to 2.6 μg/g by 1986. Between 1986 and 1992 there was little change in concentration, with 3.5 μg/g observed in 1992. ΣDDT in Lake Michigan trout followed a similar trend, decreasing from 19.2 μg/g in 1970 to 1.1 μg/g in 1986, and 1.2 μg/g in 1992. Similar trends were observed for PCBs and ΣDDT in lake trout from Lakes Superior, Huron and Ontario. Concentrations of both PCB and ΣDDT in Lake Erie walleye declined between 1977 and 1982, after which concentrations were relatively constant through 1990. When originally implemented it was assumed that trends in the mean contaminant concentrations in open-lake fish would serve as cost effective surrogates to trends in the water column. While water column data are still extremely limited it appears that for PCBs in lakes Michigan and Superior, trends in lake trout do reasonably mimic those in the water column over the long term. Hypotheses to explain the trends in contaminant concentrations are briefly reviewed. The original first order loss kinetics used to describe the initial decline do not explain the more recent leveling off of contaminant concentrations. Recent theories have examined the possibilities of multiple contaminant pools. We suggest another hypothesis, that changes in the food web may have resulted in increased bioaccumulation. However, a preliminary exploration of this hypothesis using a change point analysis was inconclusive.

  4. Use of a seismic air gun to reduce survival of nonnative lake trout embryos: A tool for conservation?

    Science.gov (United States)

    Cox, B.S.; Dux, A.M.; Quist, M.C.; Guy, C.S.

    2012-01-01

    The detrimental impacts of nonnative lake trout Salvelinus namaycush in the western USA have prompted natural resource management agencies in several states to implement lake trout suppression programs. Currently, these programs rely on mechanical removal methods (i.e., gill nets, trap nets, and angling) to capture subadult and adult lake trout. We conducted a study to explore the potential for using high-intensity sound from a relatively small (655.5 cm3 [40 in3]) seismic air gun to reduce survival of lake trout embryos. Lake trout embryos at multiple stages of development were exposed to a single discharge of the seismic air gun at two depths (5 and 15 m) and at two distances from the air gun (0.1 and 2.7 m). Control groups for each developmental stage, distance, and depth were treated identically except that the air gun was not discharged. Mortality in lake trout embryos treated at 0.1 m from the air gun was 100% at 74 daily temperature units in degrees Celsius (TU°C) at both depths. Median mortality in lake trout embryos treated at 0.1 m from the air gun at 207 TU°C (93%) and 267 °C (78%) appeared to be higher than that of controls (49% and 48%, respectively) at 15-m depth. Among the four lake trout developmental stages, exposure to the air gun at 0.1 m resulted in acute mortality up to 60% greater than that of controls. Mortality at a distance of 2.7 m did not appear to differ from that of controls at any developmental stage or at either depth. Our results indicate that seismic air guns have potential as an alternative tool for controlling nonnative lake trout, but further investigation is warranted.

  5. Polychlorinated biphenyl reduction in lake trout by irradiation and broiling

    International Nuclear Information System (INIS)

    Cichy, R.F.; Zabik, M.E.; Weaver, C.M.

    1979-01-01

    The Great Lakes Environmental contaminants surveys (1974-1975) have concluded that excessive concentrations of polychlorinated biphenyls (PCBs) are present in a specific species of lake trout (Salvelinus namaycush). Over 30 ppM of PCBs have been detected in the edible fillet of this fat trout. The objective of this study was to determine the effect of gamma irradiation combined with broiling on the levels of PCBs in lake trout fillets

  6. Lake trout demographics in relation to burbot and coregonine populations in the Algonquin Highlands, Ontario

    Science.gov (United States)

    Carl, L.M.

    2008-01-01

    The objective of the study was to test the hypothesis that lake trout populations change in relation to cisco, lake whitefish, round whitefish and burbot populations in lakes in the Algonquin Highlands region of Ontario. Lake trout population change is greatest where cisco and lake whitefish are present. Lake trout populations in lakes without either coregonine tend to have small adults and many juveniles. Where cisco or lake whitefish are present, adult lake trout are large, juvenile abundance is low, and the stock-recruit relationship appears to be uncoupled likely due to a larval bottleneck. Lake trout populations in these lakes may be sensitive to overfishing and recruitment failure. Lake trout populations do not appear to change in relation to round whitefish. There appears to be an indirect positive change on juvenile lake trout abundance through reductions in the density of benthic coregonines in the presence of large, hypolimnetic burbot. ?? 2007 Springer Science+Business Media B.V.

  7. Evidence of sound production by spawning lake trout (Salvelinus namaycush) in lakes Huron and Champlain

    Science.gov (United States)

    Johnson, Nicholas S.; Higgs, Dennis; Binder, Thomas R.; Marsden, J. Ellen; Buchinger, Tyler John; Brege, Linnea; Bruning, Tyler; Farha, Steve A.; Krueger, Charles C.

    2018-01-01

    Two sounds associated with spawning lake trout (Salvelinus namaycush) in lakes Huron and Champlain were characterized by comparing sound recordings to behavioral data collected using acoustic telemetry and video. These sounds were named growls and snaps, and were heard on lake trout spawning reefs, but not on a non-spawning reef, and were more common at night than during the day. Growls also occurred more often during the spawning period than the pre-spawning period, while the trend for snaps was reversed. In a laboratory flume, sounds occurred when male lake trout were displaying spawning behaviors; growls when males were quivering and parallel swimming, and snaps when males moved their jaw. Combining our results with the observation of possible sound production by spawning splake (Salvelinus fontinalis × Salvelinus namaycush hybrid), provides rare evidence for spawning-related sound production by a salmonid, or any other fish in the superorder Protacanthopterygii. Further characterization of these sounds could be useful for lake trout assessment, restoration, and control.

  8. The reproduction of lake trout in southern Lake Superior

    Science.gov (United States)

    Eschmeyer, Paul H.

    1955-01-01

    The principal spawning grounds of lake trout (Salvelinus namaycush namaycush) in United States waters of southern Lake Superior are on rocky shoals at depths of less than 20 fathoms. Most spawning occurs in October and early November. Of the mature fish collected on or near the spawning grounds, 60 to 69 percent were males. Among mature fish the average length of females was greater than that of males; few males less than 24 inches or females less than 26 inches in total length were caught. Recoveries of lake trout tagged on the spawning grounds showed that some males remained in the immediate area for a period of several weeks during the spawning season. Marked fish showed a tendency to return during later years to spawning grounds on which they had been tagged, even though many of them ranged long distances between spawning seasons.

  9. Review of potential interactions between stocked rainbow trout and listed Snake River sockeye salmon in Pettit Lake Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Teuscher, D.

    1996-05-01

    The objective of this study was to determine if hatchery rainbow trout compete with or prey on juvenile Snake River sockeye salmon Oncorhynchus nerka in Pettit Lake, Idaho. In 1995, a total of 8,570 age-0 sockeye and 4,000 hatchery rainbow trout were released in Pettit Lake. After releasing the fish, gillnets were set in the pelagic and littoral zones to collected diet and spatial distribution data. Interactions were assessed monthly from June 1995 through March 1996. Competition for food was discounted based on extremely low diet overlap results observed throughout the sample period. Conversely, predation interactions were more significant. A total of 119 rainbow trout stomachs were analyzed, two contained O. nerka. The predation was limited to one sample period, but when extrapolated to the whole rainbow trout populations results in significant losses. Total consumption of O. nerka by rainbow trout ranged from an estimated 10 to 23% of initial stocking numbers. Predation results contradict earlier findings that stocked rainbow trout do not prey on wild kokanee or sockeye in the Sawtooth Lakes. The contradiction may be explained by a combination of poorly adapted hatchery sockeye and a littoral release site that forced spatial overlap that was not occurring in the wild populations. Releasing sockeye in the pelagic zone may have reduced or eliminated predation losses to rainbow trout.

  10. Review of potential interactions between stocked rainbow trout and listed Snake River sockeye salmon in Pettit Lake Idaho

    International Nuclear Information System (INIS)

    Teuscher, D.

    1996-01-01

    The objective of this study was to determine if hatchery rainbow trout compete with or prey on juvenile Snake River sockeye salmon Oncorhynchus nerka in Pettit Lake, Idaho. In 1995, a total of 8,570 age-0 sockeye and 4,000 hatchery rainbow trout were released in Pettit Lake. After releasing the fish, gillnets were set in the pelagic and littoral zones to collected diet and spatial distribution data. Interactions were assessed monthly from June 1995 through March 1996. Competition for food was discounted based on extremely low diet overlap results observed throughout the sample period. Conversely, predation interactions were more significant. A total of 119 rainbow trout stomachs were analyzed, two contained O. nerka. The predation was limited to one sample period, but when extrapolated to the whole rainbow trout populations results in significant losses. Total consumption of O. nerka by rainbow trout ranged from an estimated 10 to 23% of initial stocking numbers. Predation results contradict earlier findings that stocked rainbow trout do not prey on wild kokanee or sockeye in the Sawtooth Lakes. The contradiction may be explained by a combination of poorly adapted hatchery sockeye and a littoral release site that forced spatial overlap that was not occurring in the wild populations. Releasing sockeye in the pelagic zone may have reduced or eliminated predation losses to rainbow trout

  11. Age dependence of the accumulation of organochlorine pollutants in brown trout (Salmo trutta) from a remote high mountain lake (Redo, Pyrenees)

    International Nuclear Information System (INIS)

    Vives, I.; Grimalt, J.O.; Ventura, M.; Catalan, J.; Rosseland, B.O.

    2005-01-01

    Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were examined in the muscle of brown trout (Salmo trutta) from a high mountain lake located in the Pyrenees (Catalonia, Spain) that was used as a model of these lacustrine environments. Results indicate that fish age is the main factor of variability among specimens in this population that is subjected to atmospheric inputs of the organochlorine compounds (OC). Increases of 2- and 20-fold between fish aged 1 year and 15 years old are found. The observed pattern cannot be explained in terms of fish size, condition factor, or muscle lipid content. Higher molecular weight compounds (higher lipophilicity) are better correlated with fish age than low molecular weight compounds. A transformation from 4,4'-DDT to 4,4'-DDE occurs in fish after ingestion; this results in amplified age-dependent signals, especially in male specimens. In contrast, PCB congener no. 180 has lower age dependence than the general OC group, which could be due to its high hydrophobicity (log K ow > 7). In any case, selective accumulation of hydrophobic compounds is already observed among younger fish (age, 1 year). Due to this effect, the relative OC composition does not reflect the main OC pollutants in the lake waters. - Trout in high mountain lakes display age-dependent accumulation of certain organochlorine pollutants

  12. Age dependence of the accumulation of organochlorine pollutants in brown trout (Salmo trutta) from a remote high mountain lake (Redo, Pyrenees)

    Energy Technology Data Exchange (ETDEWEB)

    Vives, I. [Department of Environmental Chemistry, Institute of Chemical and Environmental Research (CSIC), Jordi Girona 18, 08034-Barcelona, Catalonia (Spain); Grimalt, J.O. [Department of Environmental Chemistry, Institute of Chemical and Environmental Research (CSIC), Jordi Girona 18, 08034-Barcelona, Catalonia (Spain)]. E-mail: jgoqam@cid.csic.es; Ventura, M. [Limnology Group (CSIC-UB), Centre for Advanced Studies of Blanes (CEAB-CSIC), Acces Cala St. Francesc, 14, Blanes 17300, Catalonia (Spain); Catalan, J. [Limnology Group (CSIC-UB), Centre for Advanced Studies of Blanes (CEAB-CSIC), Acces Cala St. Francesc, 14, Blanes 17300, Catalonia (Spain); Rosseland, B.O. [Norwegian Institute for Water Research (NIVA), P.O.B. 173 Kjelsaas, N-0411 Oslo (Norway); Institute for Biology and Nature Conservation, The Agricultural University of Norway (NLH) (Norway)

    2005-01-01

    Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were examined in the muscle of brown trout (Salmo trutta) from a high mountain lake located in the Pyrenees (Catalonia, Spain) that was used as a model of these lacustrine environments. Results indicate that fish age is the main factor of variability among specimens in this population that is subjected to atmospheric inputs of the organochlorine compounds (OC). Increases of 2- and 20-fold between fish aged 1 year and 15 years old are found. The observed pattern cannot be explained in terms of fish size, condition factor, or muscle lipid content. Higher molecular weight compounds (higher lipophilicity) are better correlated with fish age than low molecular weight compounds. A transformation from 4,4'-DDT to 4,4'-DDE occurs in fish after ingestion; this results in amplified age-dependent signals, especially in male specimens. In contrast, PCB congener no. 180 has lower age dependence than the general OC group, which could be due to its high hydrophobicity (log K{sub ow} > 7). In any case, selective accumulation of hydrophobic compounds is already observed among younger fish (age, 1 year). Due to this effect, the relative OC composition does not reflect the main OC pollutants in the lake waters. - Trout in high mountain lakes display age-dependent accumulation of certain organochlorine pollutants.

  13. Lake Michigan lake trout PCB model forecast post audit (oral presentation)

    Science.gov (United States)

    Scenario forecasts for total PCBs in Lake Michigan (LM) lake trout were conducted using the linked LM2-Toxics and LM Food Chain models, supported by a suite of additional LM models. Efforts were conducted under the Lake Michigan Mass Balance Study and the post audit represents an...

  14. New insight into the spawning behavior of lake trout, Salvelinus namaycush, from a recovering population in the Laurentian Great Lakes

    Science.gov (United States)

    Binder, Thomas R.; Thompson, Henry T.; Muir, Andrew M.; Riley, Stephen C.; Marsden, J. Ellen; Bronte, Charles R.; Krueger, Charles C.

    2015-01-01

    Spawning behavior of lake trout, Salvelinus namaycush, is poorly understood, relative to stream-dwelling salmonines. Underwater video records of spawning in a recovering population from the Drummond Island Refuge (Lake Huron) represent the first reported direct observations of lake trout spawning in the Laurentian Great Lakes. These observations provide new insight into lake trout spawning behavior and expand the current conceptual model. Lake trout spawning consisted of at least four distinct behaviors: hovering, traveling, sinking, and gamete release. Hovering is a new courtship behavior that has not been previously described. The apparent concentration of hovering near the margin of the spawning grounds suggests that courtship and mate selection might be isolated from the spawning act (i.e., traveling, sinking, and gamete release). Moreover, we interpret jockeying for position displayed by males during traveling as a unique form of male-male competition that likely evolved in concert with the switch from redd-building to itinerant spawning in lake trout. Unlike previous models, which suggested that intra-sexual competition and mate selection do not occur in lake trout, our model includes both and is therefore consistent with evolutionary theory, given that the sex ratio on spawning grounds is skewed heavily towards males. The model presented in this paper is intended as a working hypothesis, and further revision may become necessary as we gain a more complete understanding of lake trout spawning behavior.

  15. Successional change in the Lake Superior fish community: population trends in ciscoes, rainbow smelt, and lake trout, 1958-2008

    Science.gov (United States)

    Gorman, Owen T.

    2012-01-01

    The Lake Superior fish community underwent massive changes in the second half of the 20th century. Those changes are largely reflected in changes in abundance of the adults of principal prey species, the ciscoes (Coregonus spp.), the invasive rainbow smelt (Osmerus mordax), and the principal predator, lake trout (Salvelinus namaycush). To better understand changes in species abundances, a comprehensive series of gillnet and bottom trawl data collected from 1958 to 2008 were examined. In the late 1950s/early 1960s, smelt abundance was at its maximum, wild lake trout was at its minimum, and an abundance of hatchery lake trout was increasing rapidly. The bloater (Coregonus hoyi) was the prevalent cisco in the lake; abundance was more than 300% greater than the next most abundant cisco, shortjaw cisco (C. zenithicus), followed by kiyi (C. kiyi) and lake cisco (C. artedi). By the mid-1960s, abundance of hatchery lake trout was nearing maximum, smelt abundance was beginning to decline, and abundances of all ciscoes declined, but especially that of shortjaw cisco and kiyi. By the late 1970s, recovery of wild lake trout stocks was well underway and abundances of hatchery lake trout and smelt were declining and the ciscoes were reaching their nadir. During 1980–1990, the fish community underwent a dramatic shift in organization and structure. The rapid increase in abundance of wild lake trout, concurrent with a rapid decline in hatchery lake trout, signaled the impending recovery. Rainbow smelt abundance dropped precipitously and within four years, lake cisco and bloater populations rebounded on the heels of a series of strong recruitment events. Kiyi populations showed signs of recovery by 1989, and shortjaw by 2000, though well below historic maximum abundances. High abundance of adult smelt prior to 1980 appears to be the only factor linked to recruitment failure in the ciscoes. Life history traits of the cisco species were examined to better understand their different

  16. Effect of rearing density on poststocking survival of lake trout in Lake Ontario

    Science.gov (United States)

    Elrod, Joseph H.; Ostergaard, David E.; Schneider, Clifford P.

    1989-01-01

    Six paired lots of yearling lake trout (Salvelinus namaycush) reared at densities of 41,000 and 51,000 fish per raceway during their last 9 months in the hatchery were stocked in Lake Ontario. Poststocking survival of the high-density (HD) and low-density (LD) fish was not different for the 1982 year-class. However, for the 1983 year-class, mean survival was significantly different between HD and LD fish (P Mean survival of HD fish was only 76% that of LD fish (P Mean size at stocking was not different for HD and LD fish of the 1982 year-class, but for the 1983 year-class, the LD fish were 6% longer and 22% heavier than the HD fish. Mean lengths and weights of LD and HD fish were not different in samples collected in Lake Ontario at age 2 and older. Size at stocking was not likely the factor that caused the difference in survival. Rather, the rearing conditions (probably water exchange rate in relation to number of fish in the raceway) that resulted in slower growth of the HD fish of the 1983 year-class also caused them to be poorer physiologically than the LD fish. The number of yearling lake trout per rearing unit that will result in maximum contribution to populations in the Great Lakes after stocking may be lower than the rearing densities customarily used at some hatcheries.

  17. Seasonal Variations in Relative Weight of Lake Trout (Salvelinus namaycush), Kokanee Salmon (Oncorhynchus nerka), Rainbow Trout (Onocorhynchus mykiss), and Brown Trout (Salmo trutta) in Blue Mesa Reservoir, Colorado

    OpenAIRE

    Midas, Madeline; Williams, Asia; Cooper, Cindy; Courtney, Michael

    2013-01-01

    Blue Mesa Reservoir is the largest body of water in Colorado and is located on the western slope of the Rocky Mountains at an elevation of 7520 feet. Blue Mesa Reservoir contains recreationally important populations of lake trout (Salvelinus namaycush), kokanee salmon (Oncorhynchus nerka), rainbow trout (Onocorhynchus mykiss), and brown trout (Salmo trutta). A management challenge in recent years has been the overpopulation of lake trout, which has led to a steep decline in abundance of kokan...

  18. Do predators influence the distribution of age-0 kokanee in a Colorado Reservoir?

    Science.gov (United States)

    Hardiman, J.M.; Johnson, B.M.; Martinez, P.J.

    2004-01-01

    Seasonal changes in reservoir conditions such as productivity, light, and temperature create spatiotemporal variation in habitat that may segregate or aggregate predators and prey, producing implications for the distribution, growth, and survival of fishes. We used hydroacoustics to document the diel vertical distribution of age-0 kokanee Oncorhynchus nerka relative to environmental gradients at Blue Mesa Reservoir, Colorado, during May-August of 2002. Temperature, light, and zooplankton density profiles were examined relative to foraging conditions for kokanee and their primary predator, lake trout Salvelinus namaycush. Age-0 kokanee displayed large diel vertical migrations in May despite the lack of an energetic advantage before reservoir stratification. Age-0 kokanee minimized near-surface foraging at this time, perhaps to avoid predation by visual predators, such as lake trout, in the well-lit surface waters. Strong reservoir stratification in midsummer appeared to provide a thermal refuge from lake trout that the kokanee exploited. By August vertical migrations were shallow and most kokanee remained in the epilimnion throughout the day. Although the energetic implications of the late-summer strategy are unclear, it appears that kokanee were responding to changes in their predator environment. A robust model for kokanee diel vertical migration across a range of systems should include a predator avoidance component.

  19. The food of the lake trout (Cristivomer namaycush namaycush) and of the lawyer (Lota maculosa) of Lake Michigan

    Science.gov (United States)

    Van Oosten, John; Deason, Hilary J.

    1938-01-01

    This paper reports on a qualitative and quantitative analysis of the contents of 4,979 lake trout stomachs (593 examined in 1930 and 1,253 collected in 1931 from southern Lake Michigan, 1,446 from northern Lake Michigan and 1,687 from Green Bay in 1932), and of a total of 1,528 lawyer stomachs (172 examined in 1930 and 734 collected in 1931 from southern Lake Michigan, 612 from northern Lake Michigan and 10 from Green Bay in 1932). The food of the trout consisted of 98 per cent by volume of fish of which Cottidae and Coregonidae were the principal constituents. Cottidae were dominant in southern Lake Michigan (72 per cent by volume), Coregonidae in northern Lake Michigan (51 per cent) but the lake shiner, Notropis atherinides, was most important in Green Bay in the spring of the year (64 per cent). The lawyer food consisted of 74 per cent by volume of fish and 26 per cent invertebrates. Dominant items were Cottidae (76 per cent by volume) in southern Lake Michigan, Coregonidae (51 per cent) and Pontoporeia (37 per cent) in northern Lake Michigan, and Percopsis (34 per cent) and Mysis (26 per cent) in Green Bay. Data are also presented on the frequency of occurrence (number of stomachs) of the food items and its variation with the sizes of the trout and lawyers, depths of water, seasons, and localities; on the number of individual fish of each species destroyed by the trout and lawyers; and on the calculated volume of the food fishes preceding digestion. The lake trout and lawyer are competitors for the same food, are both predators of the commercially important Coregonidae, and the lawyer through its consumption of invertebrates is a food competitor of the Coregonidae.

  20. Laboratory estimation of net trophic transfer efficiencies of PCB congeners to lake trout (Salvelinus namaycush) from its prey

    Science.gov (United States)

    Madenjian, Charles P.; Rediske, Richard R.; O'Keefe, James P.; David, Solomon R.

    2014-01-01

    A technique for laboratory estimation of net trophic transfer efficiency (γ) of polychlorinated biphenyl (PCB) congeners to piscivorous fish from their prey is described herein. During a 135-day laboratory experiment, we fed bloater (Coregonus hoyi) that had been caught in Lake Michigan to lake trout (Salvelinus namaycush) kept in eight laboratory tanks. Bloater is a natural prey for lake trout. In four of the tanks, a relatively high flow rate was used to ensure relatively high activity by the lake trout, whereas a low flow rate was used in the other four tanks, allowing for low lake trout activity. On a tank-by-tank basis, the amount of food eaten by the lake trout on each day of the experiment was recorded. Each lake trout was weighed at the start and end of the experiment. Four to nine lake trout from each of the eight tanks were sacrificed at the start of the experiment, and all 10 lake trout remaining in each of the tanks were euthanized at the end of the experiment. We determined concentrations of 75 PCB congeners in the lake trout at the start of the experiment, in the lake trout at the end of the experiment, and in bloaters fed to the lake trout during the experiment. Based on these measurements, γ was calculated for each of 75 PCB congeners in each of the eight tanks. Mean γ was calculated for each of the 75 PCB congeners for both active and inactive lake trout. Because the experiment was replicated in eight tanks, the standard error about mean γ could be estimated. Results from this type of experiment are useful in risk assessment models to predict future risk to humans and wildlife eating contaminated fish under various scenarios of environmental contamination.

  1. Evolution and origin of sympatric shallow-water morphotypes of Lake Trout, Salvelinus namaycush, in Canada's Great Bear Lake.

    Science.gov (United States)

    Harris, L N; Chavarie, L; Bajno, R; Howland, K L; Wiley, S H; Tonn, W M; Taylor, E B

    2015-01-01

    Range expansion in north-temperate fishes subsequent to the retreat of the Wisconsinan glaciers has resulted in the rapid colonization of previously unexploited, heterogeneous habitats and, in many situations, secondary contact among conspecific lineages that were once previously isolated. Such ecological opportunity coupled with reduced competition likely promoted morphological and genetic differentiation within and among post-glacial fish populations. Discrete morphological forms existing in sympatry, for example, have now been described in many species, yet few studies have directly assessed the association between morphological and genetic variation. Morphotypes of Lake Trout, Salvelinus namaycush, are found in several large-lake systems including Great Bear Lake (GBL), Northwest Territories, Canada, where several shallow-water forms are known. Here, we assess microsatellite and mitochondrial DNA variation among four morphotypes of Lake Trout from the five distinct arms of GBL, and also from locations outside of this system to evaluate several hypotheses concerning the evolution of morphological variation in this species. Our data indicate that morphotypes of Lake Trout from GBL are genetically differentiated from one another, yet the morphotypes are still genetically more similar to one another compared with populations from outside of this system. Furthermore, our data suggest that Lake Trout colonized GBL following dispersal from a single glacial refugium (the Mississippian) and support an intra-lake model of divergence. Overall, our study provides insights into the origins of morphological and genetic variation in post-glacial populations of fishes and provides benchmarks important for monitoring Lake Trout biodiversity in a region thought to be disproportionately susceptible to impacts from climate change.

  2. Lake trout otolith chronologies as multidecadal indicators of high-latitude freshwater ecosystems

    Science.gov (United States)

    Black, B.A.; Von Biela, V.R.; Zimmerman, C.E.; Brown, Randy J.

    2013-01-01

    High-latitude ecosystems are among the most vulnerable to long-term climate change, yet continuous, multidecadal indicators by which to gauge effects on biology are scarce, especially in freshwater environments. To address this issue, dendrochronology (tree-ring analysis) techniques were applied to growth-increment widths in otoliths from lake trout (Salvelinus namaycush) from the Chandler Lake system, Alaska (68.23°N, 152.70°W). All otoliths were collected in 1987 and exhibited highly synchronous patterns in growth-increment width. Increments were dated, the widths were measured, and age-related growth declines were removed using standard dendrochronology techniques. The detrended time series were averaged to generate an annually resolved chronology, which continuously spanned 1964–1984. The chronology positively and linearly correlated with August air temperature over the 22-year interval (p fish metabolic rate or lake productivity. Given the broad distribution of lake trout within North America, this study suggests that otolith chronologies could be used to examine responses between freshwater ecosystems and environmental variability across a range of temporal and spatial scales.

  3. Effects of increased discharge on spawning and age-0 recruitment of rainbow trout in the Colorado River at Lees Ferry, Arizona

    Science.gov (United States)

    Avery, Luke A.; Korman, Josh; Persons, William R.

    2015-01-01

    Negative interactions of Rainbow Trout Oncorhynchus mykiss with endangered Humpback Chub Gila cypha pose challenges to the operation of Glen Canyon Dam (GCD) to manage for both species in the Colorado River. Operations to enhance the Rainbow Trout tailwater fishery may lead to an increase in downstream movement of the trout to areas where they are likely to interact with Humpback Chub. We evaluated the effects of dam operations on age-0 Rainbow Trout in the tailwater fishery to inform managers about how GCD operations could benefit a tailwater fishery for Rainbow Trout; although this could affect a Humpback Chub population farther downstream. A near year-long increase in discharge at GCD in 2011 enabled us to evaluate whether high and stable flows led to increased spawning and production of age-0 Rainbow Trout compared with other years. Rainbow Trout spawning was monitored by fitting a model to observed redd counts to estimate the number of redds created over a spawning season. Data collected during electrofishing trips in July–September and November were used to acquire age-0 trout population and mortality rate estimates. We found that high and stable flows in 2011 resulted in 3,062 redds (1.7 times the mean of all survey years) and a population estimate of 686,000 age-0 Rainbow Trout (second highest on record). Despite high initial abundance, mortality remained low through the year (0.0043%/d) resulting in significant recruitment with a record high November population estimate of 214,000 age-0 Rainbow Trout. Recent monitoring indicates this recruitment event was followed by an increase in downstream migration, which may lead to increased interactions with downstream populations of Humpback Chub. Consequently, while our results indicate that manipulating flow at GCD can be used to manage Rainbow Trout spawning and recruitment, fisheries managers should use flow manipulation in moderation to minimize downstream migration in order to reduce negative

  4. DECLINE AND EXTINCTION OF LAKE TROUT IN THE GREAT LAKES: CAN BIOLOGICAL INDICATORS HELP DIAGNOSE CAUSES, IDENTIFY REMEDIAL ACTIONS, AND PREDICT FUTURE CONDITIONS?

    Science.gov (United States)

    The lake trout, Salvelinus namaycush, is the predominant top predator native fish species of the Great Lakes. Lake trout are valued for commercial and recreational use in addition to their ecological importance. In the last half of the 20th century, population declines lead to vi...

  5. Tissue contaminants and associated transcriptional response in trout liver from high elevation lakes of Washington

    Science.gov (United States)

    Moran, P.W.; Aluru, N.; Black, R.W.; Vijayan, M.M.

    2007-01-01

    The consistent cold temperatures and large amount of precipitation in the Olympic and Cascade ranges of Washington State are thought to enhance atmospheric deposition of contaminants. However, little is known about contaminant levels in organisms residing in these remote high elevation lakes. We measured total mercury and 28 organochlorine compounds in trout collected from 14 remote lakes in the Olympic, Mt. Rainer, and North Cascades National Parks. Mercury was detected in trout from all lakes sampled (15 to 262 ??g/kg ww), while two organochlorines, total polychlorinated biphenyls (tPCB) and dichlorodiphenyldichloroethylene (DDE), were also detected in these fish tissues (<25 ??g/kg ww). In sediments, organochlorine levels were below detection, while median total and methyl mercury were 30.4 and 0.34 ??g/ kg dry weight (ww), respectively. Using fish from two lakes, representing different contaminant loading levels (Wilcox lake: high; Skymo lake: low), we examined transcriptional response in the liver using a custom-made low-density targeted rainbow trout cDNA microarray. We detected significant differences in liver transcriptional response, including significant changes in metabolic, endocrine, and immune-related genes, in fish collected from Wilcox Lake compared to Skymo Lake. Overall, our results suggest that local urban areas contribute to the observed contaminant patterns in these high elevation lakes, while the transcriptional changes point to a biological response associated with exposure to these contaminants in fish. Specifically, the gene expression pattern leads us to hypothesize a role for mercury in disrupting the metabolic and reproductive pathways in fish from high elevation lakes in western Washington. ?? 2007 American Chemical Society.

  6. Lake Roosevelt Rainbow Trout : Habitat/Passage Improvement Project Annual Report 2000.

    Energy Technology Data Exchange (ETDEWEB)

    Sear, Sheri

    2001-02-01

    Lake Franklin D. Roosevelt was created with the completion of the Grand Coulee Dam in 1942. The lake stretches 151 miles up-stream to the International border between the United States and Canada at the 49th parallel. Increased recreational use, subsistence and sport fishing has resulted in intense interest and possible exploitation of the resources within the lake. Previous studies of the lake and its fishery have been limited. Early studies indicate that natural reproduction within the lake and tributaries are not sufficient to support a rainbow trout (Onchoryhnchus mykiss) fishery (Scholz et. al., 1988). These studies indicate that the rainbow trout population may be limited by lack of suitable habitat for spawning and rearing (Scholz et. al., 1988). The initial phase of this project (Phase I, baseline data collection- 1990-91) was directed at the assessment of limiting factors such as quality and quantity of available spawning gravel, identification of passage barriers, and assessment of other limiting factors. Population estimates were conducted using the Seber/LeCren removal/depletion method. After the initial assessment of stream parameters, several streams were selected for habitat/passage improvement projects (Phase II, implementation-1992-96). At the completion of project habitat improvements, the final phase (Phase III, monitoring) began. This phase will assess changes and gauge the success achieved through the improvements. The objective of the project is to correct passage barriers and improve habitat conditions of selected tributaries to Lake Roosevelt for adfluvial rainbow trout that utilize tributary streams for spawning and rearing. Streams with restorable habitats were selected for improvements. Completion of improvement efforts should increase the adfluvial rainbow trout contribution to the resident fishery in Lake Roosevelt. Three co-operating agencies, the Confederated Tribes of the Colville Reservation (CCT), the Spokane Tribe of Indians (STI

  7. Lake Roosevelt Rainbow Trout : Habitat/Passage Improvement Project Annual Report 1999.

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Charles D.

    2000-02-01

    Lake Franklin D. Roosevelt was created with the completion of the Grand Coulee Dam in 1942. The lake stretches 151 miles up-stream to the International border between the United States and Canada at the 49th parallel. Increased recreational use, subsistence and sport fishing has resulted in intense interest and possible exploitation of the resources within the lake. Previous studies of the lake and its fishery have been limited. Early studies indicate that natural reproduction within the lake and tributaries are not sufficient to support a rainbow trout (Onchoryhnchus mykiss) fishery (Scholz et. al., 1988). These studies indicate that the rainbow trout population may be limited by lack of suitable habitat for spawning and rearing (Scholz et. al., 1988). The initial phase of this project (Phase I, baseline data collection- 1990-91) was directed at the assessment of limiting factors such as quality and quantity of available spawning gravel, identification of passage barriers, and assessment of other limiting factors. Population estimates were conducted using the Seber/LeCren removal/depletion method. After the initial assessment of stream parameters, several streams were selected for habitat/passage improvement projects (Phase II, implementation-1992-96). At the completion of project habitat improvements, the final phase (Phase III, monitoring) began. This phase will assess changes and gauge the success achieved through the improvements. The objective of the project is to correct passage barriers and improve habitat conditions of selected tributaries to Lake Roosevelt for adfluvial rainbow trout that utilize tributary streams for spawning and rearing. Streams with restorable habitats were selected for improvements. Completion of improvement efforts should increase the adfluvial rainbow trout contribution to the resident fishery in Lake Roosevelt. Three co-operating agencies, the Confederated Tribes of the Colville Reservation (CCT), the Spokane Tribe of Indians (STI

  8. Estimation of waste generated by the production of rainbow trout in Lake Tota, Colombia

    Directory of Open Access Journals (Sweden)

    Nixon Hernán Torres-Barrera

    2017-05-01

    Full Text Available In this study, the total waste from the production of rainbow trout, Oncorhynchus mykiss ( Wa l b a u m (Salmoniformes: Salmonidae in Lake Tota freshwater ecosystem, located in the Department of Boyacá, Colombia, and its potential impact on the lake was estimated. This economic activity has been carried out intensively since 2005 using submerged cages in the lake. With data obtained from the National Authority for Aquaculture and Fisheries (Aunap, the Autonomous Regional Corporation of Boyacá (Corpoboyacá, and the Chamber of Commerce of Sogamoso, fish farmers, their geographical location on the lake, production by these farms were identified, and with this information the amount of waste produced, including the amounts of nitrogen and phosphorus generated in this process was calculated. The results indicate that the lake is polluted due to intensive trout production. It is recommended to improve or modify trout production methods that will minimize water pollution.

  9. Comparison of three nonlinear models to describe long-term tag shedding by lake trout

    Science.gov (United States)

    Fabrizio, Mary C.; Swanson, Bruce L.; Schram, Stephen T.; Hoff, Michael H.

    1996-01-01

    We estimated long-term tag-shedding rates for lake trout Salvelinus namaycush using two existing models and a model we developed to account for the observed permanence of some tags. Because tag design changed over the course of the study, we examined tag-shedding rates for three types of numbered anchor tags (Floy tags FD-67, FD-67C, and FD-68BC) and an unprinted anchor tag (FD-67F). Lake trout from the Gull Island Shoal region, Lake Superior, were double-tagged, and subsequent recaptures were monitored in annual surveys conducted from 1974 to 1992. We modeled tag-shedding rates, using time at liberty and probabilities of tag shedding estimated from fish released in 1974 and 1978–1983 and later recaptured. Long-term shedding of numbered anchor tags in lake trout was best described by a nonlinear model with two parameters: an instantaneous tag-shedding rate and a constant representing the proportion of tags that were never shed. Although our estimates of annual shedding rates varied with tag type (0.300 for FD-67, 0.441 for FD-67C, and 0.656 for FD-68BC), differences were not significant. About 36% of tags remained permanently affixed to the fish. Of the numbered tags that were shed (about 64%), two mechanisms contributed to tag loss: disintegration and dislodgment. Tags from about 11% of recaptured fish had disintegrated, but most tags were dislodged. Unprinted tags were shed at a significant but low rate immediately after release, but the long-term, annual shedding rate of these tags was only 0.013. Compared with unprinted tags, numbered tags dislodged at higher annual rates; we hypothesized that this was due to the greater frictional drag associated with the larger cross-sectional area of numbered tags.

  10. Accumulation of lead (Pb) in brown trout (Salmo trutta) from a lake downstream a former shooting range.

    Science.gov (United States)

    Mariussen, Espen; Heier, Lene Sørlie; Teien, Hans Christian; Pettersen, Marit Nandrup; Holth, Tor Fredrik; Salbu, Brit; Rosseland, Bjørn Olav

    2017-01-01

    An environmental survey was performed in Lake Kyrtjønn, a small lake within an abandoned shooting range in the south of Norway. In Lake Kyrtjønn the total water concentrations of Pb (14µg/L), Cu (6.1µg/L) and Sb (1.3µg/L) were elevated compared to the nearby reference Lake Stitjønn, where the total concentrations of Pb, Cu and Sb were 0.76, 1.8 and 0.12µg/L, respectively. Brown trout (Salmo trutta) from Lake Kyrtjønn had very high levels of Pb in bone (104mg/kg w.w.), kidney (161mg/kg w.w.) and the gills (137mg/kg d.w), and a strong inhibition of the ALA-D enzyme activity were observed in the blood (24% of control). Dry fertilized brown trout eggs were placed in the small outlet streams from Lake Kyrtjønn and the reference lake for 6 months, and the concentrations of Pb and Cu in eggs from the Lake Kyrtjønn stream were significantly higher than in eggs from the reference. More than 90% of Pb accumulated in the egg shell, whereas more than 80% of the Cu and Zn accumulated in the egg interior. Pb in the lake sediments was elevated in the upper 2-5cm layer (410-2700mg/kg d.w), and was predominantly associated with redox sensitive fractions (e.g., organic materials, hydroxides) indicating low potential mobility and bioavailability of the deposited Pb. Only minor amounts of Cu and Sb were deposited in the sediments. The present work showed that the adult brown trout, as well as fertilized eggs and alevins, may be subjected to increased stress due to chronic exposure to Pb, whereas exposure to Cu, Zn and Sb were of less importance. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Analysis of strontium-90 in the bones of brown trout (Salmo trutta) from Lake Ontario

    International Nuclear Information System (INIS)

    Manos, C.G. Jr.; Kinney, R.M.; Lisk, D.J.

    1993-01-01

    Radionuclides such as Sr-90, mainly from liquid effluent releases from nuclear power generating facilities, can contaminate water and biota. Lake Ontario ultimately receives the outflow from each of the other Great Lakes. In the work reported, brown trout (Salmo trutta) were captured from Lake Ontario and their entire skeletal bone material analyzed for Sr-90. They showed an average concentration of Sr-90 approximately four times greater than control brown trout captured from nearby Cayuga Lake in Central New York State which has no nuclear generating facilities. The results are discussed considering fallout and hydrographic considerations. (author)

  12. Mitochondrial DNA variation in brood stocks of the lake trout

    International Nuclear Information System (INIS)

    Grewe, P.M.; Hebert, P.D.N.

    1986-01-01

    Efforts are in progress to restore lake trout populations in the Great Lakes from hatchery stocks. In most cases, plantings include a variety of brood stocks that originated from different portions of the Great Lakes. Members of the various stocks can be differentially fin clipped to permit comparison of their survival success, but this does not allow assessment of their reproductive capability in the wild. Assessment of reproductive success requires the existence of genetic markers between brook stocks which will ideally persist over many generations. Efforts to identify allozyme differences between brood stocks have met with little success. The present investigation has employed an alternative technique to identify genetic markers--the restriction analysis of mitochondrial DNA. Mitochondiral DNA analysis of 7 lake trout brood stocks has revealed the existence of 10 mitochondrial clones falling into 3 major groups. The results indicate that mt-DNA markers have great potential for brood stock management. Genetic variability in the nuclear genome of each stock can be maintained by utilizing a large number of male parents, while restricting female parents to members of a single mitochondrial clone. Genetically marked fry could then be produced with only minor shifts in hatchery management

  13. Brook trout (Salvelinus fontinalis extinction in small boreal lakes revealed by ephippia pigmentation: a preliminary analysis

    Directory of Open Access Journals (Sweden)

    Alexandre Bérubé Tellier

    2016-12-01

    Full Text Available Ephippium pigmentation is a plastic trait which can be related to a trade-off between visual predation pressure and better protection of cladoceran eggs against different types of stress. Experimental studies showed that planktivorous fish exert a greater predation pressure on individuals carrying darker ephippia, but little is known about the variation of ephippium pigmentation along gradients of fish predation pressure in natural conditions. For this study, our experimental design included four small boreal lakes with known fish assemblages. Two of the lakes have viable brook trout (Salvelinus fontinalis populations, whereas the other two lakes experienced brook trout extinctions during the 20th century. Cladoceran ephippia were extracted from sediment cores at layers corresponding to the documented post- extinction phase (1990's and from an older layer (1950's for which the brook trout population status is not known precisely. Our first objective was to determine whether brook trout extinction has a direct effect on both ephippium pigmentation and size. Our second objective was to give a preliminary assessment of the status of brook trout populations in the 1950's by comparing the variation in ephippia traits measured from this layer to those measured in the 1990's, for which the extinction patterns are well known. Cost-effective image analysis was used to assess variation in pigmentation levels in ephippia. This approach provided a proxy for the amount of melanin invested in each ephippium analysed. Our study clearly shows that ephippium pigmentation may represent a better indicator of the presence of fish predators than ephippium size, a trait that showed a less clear pattern of variation between lakes with and without fish. For the 1990's period, ephippia from fishless lakes were darker and showed a slight tendency to be larger than ephippia from lakes with brook trout. However, no clear differences in either ephippium size or pigmentation

  14. Fine-scale acoustic telemetry reveals unexpected lake trout, Salvelinus namaycush, spawning habitats in northern Lake Huron, North America

    Science.gov (United States)

    Binder, Thomas; Farha, Steve A.; Thompson, Henry T.; Holbrook, Christopher; Bergstedt, Roger A.; Riley, Stephen; Bronte, Charles R.; He, Ji; Krueger, Charles C.

    2018-01-01

    Previous studies of lake trout, Salvelinus namaycush, spawning habitat in the Laurentian Great Lakes have used time- and labour-intensive survey methods and have focused on areas with historic observations of spawning aggregations and on habitats prejudged by researchers to be suitable for spawning. As an alternative, we used fine-scale acoustic telemetry to locate, describe and compare lake trout spawning habitats. Adult lake trout were implanted with acoustic transmitters and tracked during five consecutive spawning seasons in a 19–27 km2 region of the Drummond Island Refuge, Lake Huron, using the VEMCO Positioning System. Acoustic telemetry revealed discrete areas of aggregation on at least five reefs in the study area, subsequently confirmed by divers to contain deposited eggs. Notably, several identified spawning sites would likely not have been discovered using traditional methods because either they were too small and obscure to stand out on a bathymetric map or because they did not conform to the conceptual model of spawning habitat held by many biologists. Our most unique observation was egg deposition in gravel and rubble substrates located at the base of and beneath overhanging edges of large boulders. Spawning sites typically comprised <10% of the reef area and were used consistently over the 5-year study. Evaluation of habitat selection from the perspective of fish behaviour through use of acoustic transmitters offers potential to expand current conceptual models of critical spawning habitat.

  15. Ecotoxicity of Lake Druksiai waters assessed by biotesting with rainbow trout spawn and larvae

    International Nuclear Information System (INIS)

    Kazlauskiene, N.; Cepuliene, Z.

    1998-01-01

    The toxicity of Lake Druksiai was assessed by testing with spawn and larvae of rainbow trout (Oncorhynchus mykiss). We sampled Ignalina NPP waste waters of various biotopes of the lake. Larvae of trout were found to be more sensitive to wastewaters than spawn. The hatching stage was one of the most sensitive stages in ontogenesis. Our data showed that the wastewater of Ignalina NPP was the most toxic, however waters of some biotopes of the lake were also toxic. That suggested that toxicants discharged into cooling reservoirs with NPP wastewater might affect test-organisms, disturbing their development and growth. The observed effects were irreversible and caused death. (author)

  16. Evaluation of glutamic acid and glycine as sources of nonessential amino acids for lake trout (Salvelinus namaycush) and rainbow trout (Salmo gairdnerii)

    Science.gov (United States)

    Hughes, S.G.

    1985-01-01

    1. A semi-purified test diet which contained either glutamic acid or glycine as the major source of nonessential amino acids (NEAA) was fed to lake and rainbow trout.2. Trout fed the diet containing glutamic acid consistently showed better growth and feed conversion efficiencies than those fed the diets containing glycine.3. The data indicate that these trout utilize glutamic acid more efficiently than glycine when no other major sources of NEAA are present.

  17. Temporal Genetic Variance and Propagule-Driven Genetic Structure Characterize Naturalized Rainbow Trout (Oncorhynchus mykiss) from a Patagonian Lake Impacted by Trout Farming.

    Science.gov (United States)

    Benavente, Javiera N; Seeb, Lisa W; Seeb, James E; Arismendi, Ivan; Hernández, Cristián E; Gajardo, Gonzalo; Galleguillos, Ricardo; Cádiz, Maria I; Musleh, Selim S; Gomez-Uchida, Daniel

    2015-01-01

    Knowledge about the genetic underpinnings of invasions-a theme addressed by invasion genetics as a discipline-is still scarce amid well documented ecological impacts of non-native species on ecosystems of Patagonia in South America. One of the most invasive species in Patagonia's freshwater systems and elsewhere is rainbow trout (Oncorhynchus mykiss). This species was introduced to Chile during the early twentieth century for stocking and promoting recreational fishing; during the late twentieth century was reintroduced for farming purposes and is now naturalized. We used population- and individual-based inference from single nucleotide polymorphisms (SNPs) to illuminate three objectives related to the establishment and naturalization of Rainbow Trout in Lake Llanquihue. This lake has been intensively used for trout farming during the last three decades. Our results emanate from samples collected from five inlet streams over two seasons, winter and spring. First, we found that significant intra- population (temporal) genetic variance was greater than inter-population (spatial) genetic variance, downplaying the importance of spatial divergence during the process of naturalization. Allele frequency differences between cohorts, consistent with variation in fish length between spring and winter collections, might explain temporal genetic differences. Second, individual-based Bayesian clustering suggested that genetic structure within Lake Llanquihue was largely driven by putative farm propagules found at one single stream during spring, but not in winter. This suggests that farm broodstock might migrate upstream to breed during spring at that particular stream. It is unclear whether interbreeding has occurred between "pure" naturalized and farm trout in this and other streams. Third, estimates of the annual number of breeders (Nb) were below 73 in half of the collections, suggestive of genetically small and recently founded populations that might experience substantial

  18. Impact of thiamine deficiency on T-cell dependent and T-cell independent antibody production in lake trout

    Science.gov (United States)

    Ottinger, Christopher A.; Honeyfield, Dale C.; Densmore, Christine L.; Iwanowicz, Luke R.

    2012-01-01

    Lake trout Salvelinus namaycush on thiamine-replete and thiamine-depleted diets were evaluated for the effects of thiamine status on in vivo responses to the T-dependent antigen trinitophenol (TNP)-keyhole limpet hemocyanin (TNP-KLH), the T-independent antigen trinitrophenol-lipolysaccaharide (TNP-LPS), or Dulbecco's phosphate-buffered saline (DPBS; negative control fish). Plasma antibody concentrations were evaluated for possible differences in total anti-TNP activity as well as differences in response kinetics. Associations between anti-TNP activity and muscle and liver thiamine concentrations as well as ratios of muscle-to-liver thiamine to anti-TNP activity were also examined. Thiamine-depleted lake trout that were injected with TNP-LPS exhibited significantly more anti-TNP activity than thiamine-replete fish. The depleted fish injected with TNP-LPS also exhibited significantly different response kinetics relative to thiamine-replete lake trout. No differences in activity or kinetics were observed between the thiamine-replete and -depleted fish injected with TNP-KLH or in the DPBS negative controls. Anti-TNP activity in thiamine-depleted lake trout injected with TNP-KLH was positively associated with muscle thiamine pyrophosphate (thiamine diphosphate; TPP) concentration. A negative association was observed between the ratio of muscle-to-liver TPP and T-independent responses. No significant associations between anti-TNP activity and tissue thiamine concentration were observed in the thiamine-replete fish. We demonstrated that thiamine deficiency leads to alterations in both T-dependent and T-independent immune responses in lake trout.

  19. Impact of thiamine deficiency on T-cell dependent and T-cell independent antibody production in lake trout.

    Science.gov (United States)

    Ottinger, Christopher A; Honeyfield, Dale C; Densmore, Christine L; Iwanowicz, Luke R

    2012-12-01

    Lake trout Salvelinus namaycush on thiamine-replete and thiamine-depleted diets were evaluated for the effects of thiamine status on in vivo responses to the T-dependent antigen trinitophenol (TNP)-keyhole limpet hemocyanin (TNP-KLH), the T-independent antigen trinitrophenol-lipolysaccaharide (TNP-LPS), or Dulbecco's phosphate-buffered saline (DPBS; negative control fish). Plasma antibody concentrations were evaluated for possible differences in total anti-TNP activity as well as differences in response kinetics. Associations between anti-TNP activity and muscle and liver thiamine concentrations as well as ratios of muscle-to-liver thiamine to anti-TNP activity were also examined. Thiamine-depleted lake trout that were injected with TNP-LPS exhibited significantly more anti-TNP activity than thiamine-replete fish. The depleted fish injected with TNP-LPS also exhibited significantly different response kinetics relative to thiamine-replete lake trout. No differences in activity or kinetics were observed between the thiamine-replete and -depleted fish injected with TNP-KLH or in the DPBS negative controls. Anti-TNP activity in thiamine-depleted lake trout injected with TNP-KLH was positively associated with muscle thiamine pyrophosphate (thiamine diphosphate; TPP) concentration. A negative association was observed between the ratio of muscle-to-liver TPP and T-independent responses. No significant associations between anti-TNP activity and tissue thiamine concentration were observed in the thiamine-replete fish. We demonstrated that thiamine deficiency leads to alterations in both T-dependent and T-independent immune responses in lake trout.

  20. Radiocesium in brown trout (Salmo trutta) from a subalpine lake ecosystem after the Chernobyl reactor accident

    International Nuclear Information System (INIS)

    Brittain, J.E.; Storruste, Anders; Larsen, Elena

    1991-01-01

    After Chernobyl in April 1986, radioactive cesium has been measured in Oevre Heimdalsvatn, a Norwegian subalpine lake, situated in an area of high fallout. The lake is an important reference site and has been the subject of extensive ecosystem studies since the 1950s. Emphasis has been given to measuring long-term trends in the activity content of radioactive cesium in the brown trout (Salmo trutta) population. After ice-break in June 1986, the average total cesium activity content rose to 7000 Bq/kg wet weight. The activity content fell during 1987 and at ice-break in 1988 was 4000 Bq/kg. However, there was no further reduction during the summers of 1988 and 1989, possibly due to increased inputs from the catchment. There is considerable variation in the radiocesium activity content measured in individual fish. On the basis of the changes in cesium activity content in trout since 1986, an observed half-life for 137 Cs and 134 Cs in trout of 3.0 and 1.3 years, respectively, has been estimated. (author)

  1. Limnology of nine small lakes, Matanuska-Susitna Borough, Alaska, and the survival and growth rates of rainbow trout

    Science.gov (United States)

    Woods, P.F.

    1985-01-01

    The survival and growth rates of rainbow trout (Salmo gairdnieri) were concurrently measured with selected limnological characteristics in nine small (surface area Gasterosteus aculeatus) also influenced survival of rainbow trout but their effects were overshadowed by winterkill. Predictive capability was also reduced because of inconsistencies in rankings generated by each of the four limnological variables chosen as indicators of potential biological productivity. A lake ranked low in productivity by one variable was commonly ranked high in productivity by another variable. The survivability of rainbow trout stocked in lakes such as these nine may be a more important indicator of potential biomass production than are indicators of lake fertility. Assessments of a lake 's susceptibility to winterkill and the degree of competition with threespine stickleback are suggested as important topics for additional research. (Author 's abstract)

  2. Biomagnification of mercury through lake trout (Salvelinus namaycush) food webs of lakes with different physical, chemical and biological characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Kidd, Karen A., E-mail: kiddk@unbsj.ca [Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, NB, Canada E2L 4L5 (Canada); Muir, Derek C.G., E-mail: derek.muir@ec.gc.ca [Aquatic Contaminants Research Division, Environment Canada, Burlington, ON, Canada L7R 4A6 (Canada); Evans, Marlene S., E-mail: marlene.evans@ec.gc.ca [Aquatic Contaminants Research Division, Environment Canada, Saskatoon, SK, Canada S7N 3H5 (Canada); Wang, Xioawa, E-mail: xiaowa.wang@ec.gc.ca [Aquatic Contaminants Research Division, Environment Canada, Burlington, ON, Canada L7R 4A6 (Canada); Whittle, Mike [Aquatic Contaminants Research Division, Environment Canada, Burlington, ON, Canada L7R 4A6 (Canada); Swanson, Heidi K., E-mail: heidikswanson@yahoo.ca [Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9 (Canada); Johnston, Tom, E-mail: tjohnston@laurentian.ca [Cooperative Freshwater Ecology Unit, Ontario Ministry of Natural Resources, and Biology Department, Laurentian University, Sudbury, ON, Canada P3E 2C6 (Canada); Guildford, Stephanie, E-mail: sguildfo@d.umn.edu [Department of Biology and Large Lakes Observatory, University of Minnesota Duluth, 2205 5th St., Duluth, MN, 55812 (United States)

    2012-11-01

    Mercury (Hg) biomagnification in aquatic ecosystems remains a concern because this pollutant is known to affect the health of fish-eating wildlife and humans, and the fish themselves. The 'rate' of mercury biomagnification is being assessed more frequently using stable nitrogen isotope ratios ({delta}{sup 15}N), a measure of relative trophic position of biota within a food web. Within food webs and across diverse systems, log-transformed Hg concentrations are significantly and positively related to {delta}{sup 15}N and the slopes of these models vary from one study to another for reasons that are not yet understood. Here we compared the rates of Hg biomagnification in 14 lake trout lakes from three provinces in Canada to understand whether any characteristics of the ecosystems explained this among-system variability. Several fish species, zooplankton and benthic invertebrates were collected from these lakes and analyzed for total Hg (fish only), methyl Hg (invertebrates) and stable isotopes ({delta}{sup 15}N; {delta}{sup 13}C to assess energy sources). Mercury biomagnification rates varied significantly across systems and were higher for food webs of larger (surface area), higher nutrient lakes. However, the slopes were not predictive of among-lake differences in Hg in the lake trout. Results indicate that among-system differences in the rates of Hg biomagnification seen in the literature may be due, in part, to differences in ecosystem characteristics although the mechanisms for this variability are not yet understood. -- Highlights: Black-Right-Pointing-Pointer Mercury biomagnifies through aquatic food webs to toxic levels in top predator fishes. Black-Right-Pointing-Pointer Among-system differences in mercury transfer through food webs occur but have not been explained. Black-Right-Pointing-Pointer Diverse lakes supporting lake trout were compared to understand the ecosystem processes that affect mercury biomagnification. Black

  3. Traditional ecological knowledge reveals the extent of sympatric lake trout diversity and habitat preferences

    Directory of Open Access Journals (Sweden)

    Kia Marin

    2017-06-01

    Full Text Available Multidisciplinary approaches to conservation have become increasingly important in northern regions. Because many First Nations communities have relied on freshwater fish populations for essential food over millennia, community members often possess traditional ecological knowledge (TEK. We consulted Cree First Nation fishers to collate TEK for one of Canada's most important subsistence fishes (lake trout in Québec's largest lake (Mistassini, 2335 km2. We further integrated TEK with what was regionally known scientifically about the species, toward effective fisheries conservation. Cree fishers described a richer diversity of sympatric lake trout forms than did scientific research that was conducted simultaneously, based on color, size, fin accent patterns, scale texture and depth, and spatial preferences. Traditional ecological knowledge also provided descriptions of lake trout seasonal movements, spawning locations, and reproductive timing that were not captured by scientific research, and highlighted several concerns or temporal changes of import to future management initiatives. Our study highlights the wealth of TEK on harvested species in First Nations communities. It further illustrates how TEK can reveal not only distinctions within species of relevance to natural resource management and taxonomy, but also informs upon the extent of such population differentiation, thereby providing important conservation benefits for remote and northern regions.

  4. Radiocaesium turnover in Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) in a Norwegian lake

    International Nuclear Information System (INIS)

    Forseth, T.; Ugedal, O.; Jonsson, B.; Langeland, A.; Njaastad, O.

    1991-01-01

    The radioactivity of brown trout (Salmo trutta L.) and Arctic charr (Salvelinus alpinus (L.)) was monitored in a Norwegian lake from 1986 to 1989. A distinct difference was observed between brown trout and Arctic charr in the accumulation of radiocaesium ( 134 Cs and 137 Cs) from the Chernobyl fallout, and the study focused on the understanding of this difference. Brown trout had a large food consumption and a corresponding high intake of radiocaesium. Excretion was 20% faster in brown trout than Arctic charr as brown trout lived at high temperatures in epilimnic water. Arctic charr had a lower food consumption (less than one-third of trout) and lived in colder meta-and hypolimnic water. Arctic charr therefore had a lower intake and slower excretion of radiocaesium. Brown trout an Arctic charr had different diets. For brown trout zoobenthos was the dominant food item, whereas Artic charr mainly fed on zooplankton. The radioactivity in the stomach contents of the two species was different in 1986, but similar for the rest of the period. Higher levels of radiocaesium in brown trout than Arctic charr in 1986 were due to a higher food consumption and more radioactive food items in its diet. The parallel development in accumulated radiocaesium through summer 1987 was probably formed by brown trout balancing a higher intake with a faster excretion. The ecological half-lives of radiocaesium in brown trout (357 days) and Arctic charr (550 days) from Lake Hoeysjoeen indicated a slow removal of the isotopes from the food webs. (author)

  5. Changing numbers of spawning cutthroat trout in tributary streams of Yellowstone Lake and estimates of grizzly bears visiting streams from DNA

    Science.gov (United States)

    Haroldson, M.A.; Gunther, K.A.; Reinhart, Daniel P.; Podruzny, S.R.; Cegelski, C.; Waits, L.; Wyman, T.C.; Smith, J.

    2005-01-01

    Spawning Yellowstone cutthroat trout (Oncorhynchus clarki) provide a source of highly digestible energy for grizzly bears (Ursus arctos) that visit tributary streams to Yellowstone Lake during the spring and early summer. During 1985–87, research documented grizzly bears fishing on 61% of the 124 tributary streams to the lake. Using track measurements, it was estimated that a minimum of 44 grizzly bears fished those streams annually. During 1994, non-native lake trout (Salvelinus namaycush) were discovered in Yellowstone Lake. Lake trout are efficient predators and have the potential to reduce the native cutthroat population and negatively impact terrestrial predators that use cutthroat trout as a food resource. In 1997, we began sampling a subset of streams (n = 25) from areas of Yellowstone Lake surveyed during the previous study to determine if changes in spawner numbers or bear use had occurred. Comparisons of peak numbers and duration suggested a considerable decline between study periods in streams in the West Thumb area of the lake. The apparent decline may be due to predation by lake trout. Indices of bear use also declined on West Thumb area streams. We used DNA from hair collected near spawning streams to estimate the minimum number of bears visiting the vicinity of spawning streams. Seventy-four individual bears were identified from 429 hair samples. The annual number of individuals detected ranged from 15 in 1997 to 33 in 2000. Seventy percent of genotypes identified were represented by more than 1 sample, but only 31% of bears were documented more than 1 year of the study. Sixty-two (84%) bears were only documented in 1 segment of the lake, whereas 12 (16%) were found in 2–3 lake segments. Twenty-seven bears were identified from hair collected at multiple streams. One bear was identified on 6 streams in 2 segments of the lake and during 3 years of the study. We used encounter histories derived from DNA and the Jolly-Seber procedure in Program MARK

  6. Genetic and phenotypic variation along an ecological gradient in lake trout Salvelinus namaycush

    Science.gov (United States)

    Baillie, Shauna M.; Muir, Andrew M.; Hansen, Michael J.; Krueger, Charles C.; Bentzen, Paul

    2016-01-01

    BackgroundAdaptive radiation involving a colonizing phenotype that rapidly evolves into at least one other ecological variant, or ecotype, has been observed in a variety of freshwater fishes in post-glacial environments. However, few studies consider how phenotypic traits vary with regard to neutral genetic partitioning along ecological gradients. Here, we present the first detailed investigation of lake trout Salvelinus namaycushthat considers variation as a cline rather than discriminatory among ecotypes. Genetic and phenotypic traits organized along common ecological gradients of water depth and geographic distance provide important insights into diversification processes in a lake with high levels of human disturbance from over-fishing.ResultsFour putative lake trout ecotypes could not be distinguished using population genetic methods, despite morphological differences. Neutral genetic partitioning in lake trout was stronger along a gradient of water depth, than by locality or ecotype. Contemporary genetic migration patterns were consistent with isolation-by-depth. Historical gene flow patterns indicated colonization from shallow to deep water. Comparison of phenotypic (Pst) and neutral genetic variation (Fst) revealed that morphological traits related to swimming performance (e.g., buoyancy, pelvic fin length) departed more strongly from neutral expectations along a depth gradient than craniofacial feeding traits. Elevated phenotypic variance with increasing water depth in pelvic fin length indicated possible ongoing character release and diversification. Finally, differences in early growth rate and asymptotic fish length across depth strata may be associated with limiting factors attributable to cold deep-water environments.ConclusionWe provide evidence of reductions in gene flow and divergent natural selection associated with water depth in Lake Superior. Such information is relevant for documenting intraspecific biodiversity in the largest freshwater lake

  7. Initial Detection and Molecular Characterization of Namaycush Herpesvirus (Salmonid Herpesvirus 5) in Lake Trout.

    Science.gov (United States)

    Glenney, Gavin W; Barbash, Patricia A; Coll, John A

    2016-03-01

    A novel herpesvirus was found by molecular methods in samples of Lake Trout Salvelinus namaycush from Lake Erie, Pennsylvania, and Lake Ontario, Keuka Lake, and Lake Otsego, New York. Based on PCR amplification and partial sequencing of polymerase, terminase, and glycoprotein genes, a number of isolates were identified as a novel virus, which we have named Namaycush herpesvirus (NamHV) salmonid herpesvirus 5 (SalHV5). Phylogenetic analyses of three NamHV genes indicated strong clustering with other members of the genus Salmonivirus, placing these isolates into family Alloherpesviridae. The NamHV isolates were identical in the three partially sequenced genes; however, they varied from other salmonid herpesviruses in nucleotide sequence identity. In all three of the genes sequenced, NamHV shared the highest sequence identity with Atlantic Salmon papillomatosis virus (ASPV; SalHV4) isolated from Atlantic Salmon Salmo salar in northern Europe, including northwestern Russia. These results lead one to believe that NamHV and ASPV have a common ancestor that may have made a relatively recent host jump from Atlantic Salmon to Lake Trout or vice versa. Partial nucleotide sequence comparisons between NamHV and ASPV for the polymerase and glycoprotein genes differ by >5% and >10%, respectively. Additional nucleotide sequence comparisons between NamHV and epizootic epitheliotropic disease virus (EEDV/SalHV3) in the terminase, glycoprotein, and polymerase genes differ by >5%, >20%, and >10%, respectively. Thus, NamHV and EEDV may be occupying discrete ecological niches in Lake Trout. Even though NamHV shared the highest genetic identity with ASPV, each of these viruses has a separate host species, which also implies speciation. Additionally, NamHV has been detected over the last 4 years in four separate water bodies across two states, which suggests that NamHV is a distinct, naturally replicating lineage. This, in combination with a divergence in nucleotide sequence from EEDV

  8. Lake trout otolith chronologies as multidecadal indicators of high-latitude freshwater ecosystems

    Science.gov (United States)

    Black, B.A.; Von Biela, V.R.; Zimmerman, C.E.; Brown, Randy J.

    2013-01-01

    High-latitude ecosystems are among the most vulnerable to long-term climate change, yet continuous, multidecadal indicators by which to gauge effects on biology are scarce, especially in freshwater environments. To address this issue, dendrochronology (tree-ring analysis) techniques were applied to growth-increment widths in otoliths from lake trout (Salvelinus namaycush) from the Chandler Lake system, Alaska (68.23°N, 152.70°W). All otoliths were collected in 1987 and exhibited highly synchronous patterns in growth-increment width. Increments were dated, the widths were measured, and age-related growth declines were removed using standard dendrochronology techniques. The detrended time series were averaged to generate an annually resolved chronology, which continuously spanned 1964–1984. The chronology positively and linearly correlated with August air temperature over the 22-year interval (p otolith chronologies could be used to examine responses between freshwater ecosystems and environmental variability across a range of temporal and spatial scales.

  9. Multiscale Terrain Analysis of Multibeam Bathymetry Data for Lake Trout Spawning Habitat Mapping in the Drummond Island Refuge, northern Lake Huron

    Science.gov (United States)

    Wattrus, N. J.; Binder, T.

    2012-12-01

    Until the 1950s, lake trout supported a valuable commercial fishery in the Great Lakes. The introduction of sea lamprey into the Great Lakes and overfishing resulted in the loss of most populations. Despite consistent stocking efforts since the 1960s, restoration of these populations has been slow. The reasons are numerous, but may be related to differences in the spawning behavior between hatchery and wild trout. A four-year study initiated in 2010, utilizes acoustic telemetry to characterize and compare the spawning behaviors of hatchery and wild lake trout in the Drummond Island Refuge in northern Lake Huron. In this project, the movement of tagged fish are monitored by an array of over 125 lake floor hydrophones during the fall spawning period. Fish behavior is overlaid over detailed bathymetric and substrate data and compared with environmental variables (e.g. water temperature, wind speed and direction, and wave height and direction) to develop a conceptual behavioral model. Sites suspected of being spawning sites based upon telemetry data are verified through the use of divers and trapping eggs and fry. Prior to this study, the factors that influenced how the spawning fish utilize the lake floor shoals have been poorly understood. Among the factors thought to impact spawning success were: bathymetry and substrate composition. Diver and telemetry data suggest that the fish(both hatchery raised and wild) are particularly attracted to rocky substrates and that fragment size is important. High resolution multibeam bathymetric surveys conducted in 2010 and 2011 have been used to characterize the shape and composition of the lake floor in the study area. Classification of the substrate is a labor intensive process requiring divers, drop cameras and sediment sampling. To improve this, the traditional approach has been to use supervised and unsupervised classification techniques that are based upon measured acoustic backscatter from an echosounder or sidescan sonar

  10. Lake Roosevelt Fisheries Evaluation Program; Evaluation of Limiting Factors for Stocked Kokanee and Rainbow Trout in Lake Roosevelt, Washington, 1999 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, Casey; Polacek, Matt

    2009-03-01

    Hatchery supplementation of kokanee Oncorhynchus nerka and rainbow trout O. mykiss has been the primary mitigation provided by Bonneville Power Administration for loss of anadromous fish to the waters above Grand Coulee Dam (GCD). The hatchery program for rainbow trout has consistently met management goals and provided a substantial contribution to the fishery; however, spawner returns and creel survey results for kokanee have been below management goals. Our objective was to identify factors that limit limnetic fish production in Lake Roosevelt by evaluating abiotic conditions, food limitations, piscivory, and entrainment. Dissolved oxygen concentration was adequate throughout most of the year; however, levels dropped to near 6 mg/L in late July. For kokanee, warm water temperatures during mid-late summer limited their nocturnal distribution to 80-100 m in the lower section of the reservoir. Kokanee spawner length was consistently several centimeters longer than in other Pacific Northwest systems, and the relative weights of rainbow trout and large kokanee were comparable to national averages. Large bodied daphnia (> 1.7 mm) were present in the zooplankton community during all seasons indicating that top down effects were not limiting secondary productivity. Walleye Stizostedion vitreum were the primary piscivore of salmonids in 1998 and 1999. Burbot Lota lota smallmouth bass Micropterus dolomieui, and northern pikeminnow Ptychocheilus oregonensis preyed on salmonids to a lesser degree. Age 3 and 4 walleye were responsible for the majority (65%) of the total walleye consumption of salmonids. Bioenergetics modeling indicated that reservoir wide consumption by walleye could account for a 31-39% loss of stocked kokanee but only 6-12% of rainbow trout. Size at release was the primary reason for differential mortality rates due to predation. Entrainment ranged from 2% to 16% of the monthly abundance estimates of limnetic fish, and could account for 30% of total

  11. Ecological factors affecting Rainbow Smelt recruitment in the main basin of Lake Huron, 1976-2010

    Science.gov (United States)

    O'Brien, Timothy P.; Taylor, William W.; Roseman, Edward F.; Madenjian, Charles P.; Riley, Stephen C.

    2014-01-01

    Rainbow Smelt Osmerus mordax are native to northeastern Atlantic and Pacific–Arctic drainages and have been widely introduced throughout North America. In the Great Lakes region, Rainbow Smelt are known predators and competitors of native fish and a primary prey species in pelagic food webs. Despite their widespread distribution, importance as a prey species, and potential to negatively interact with native fish species, there is limited information concerning stock–recruitment relationships for Rainbow Smelt. To better understand recruitment mechanisms, we evaluated potential ecological factors determining recruitment dynamics for Rainbow Smelt in Lake Huron using data from bottom trawl catches. We specifically evaluated influence of stock size, environmental factors (water temperature, lake levels, and precipitation), and salmonine predation on the production of age-0 recruits from 1976 to 2010. Rainbow Smelt recruitment was negatively related to stock size exceeding 10 kg/ha, indicating that compensatory, density-dependent mortality from cannibalism or intraspecific competition was an important factor related to the production of age-0 recruits. Recruitment was positively related to spring precipitation suggesting that the amount of stream-spawning habitat as determined by precipitation was important for the production of strong Rainbow Smelt recruitment. Additionally, density of age-0 Rainbow Smelt was positively related to Lake Trout Salvelinus namaycush abundance. However, spawning stock biomass of Rainbow Smelt, which declined substantially from 1989 to 2010, was negatively associated with Lake Trout catch per effort suggesting predation was an important factor related to the decline of age-2 and older Rainbow Smelt in Lake Huron. As such, we found that recruitment of Rainbow Smelt in Lake Huron was regulated by competition with or cannibalism by older conspecifics, spring precipitation influencing stream spawning habitats, and predation by Lake Trout on

  12. Spawning and rearing behavior of bull trout in a headwaterlake ecosystem

    Science.gov (United States)

    Lora B. Tennant,; Gresswell, Bob; Guy, Christopher S.; Michael H. Meeuwig,

    2015-01-01

    Numerous life histories have been documented for bull trout Salvelinus confluentus. Lacustrine-adfluvial bull trout populations that occupy small, headwater lake ecosystems and migrate short distances to natal tributaries to spawn are likely common; however, much of the research on potamodromous bull trout has focused on describing the spawning and rearing characteristics of bull trout populations that occupy large rivers and lakes and make long distance spawning migrations to natal headwater streams. This study describes the spawning and rearing characteristics of lacustrine-adfluvial bull trout in the Quartz Lake drainage, Glacier National Park, USA, a small headwater lake ecosystem. Many spawning and rearing characteristics of bull trout in the Quartz Lake drainage are similar to potamodromous bull trout that migrate long distances. For example, subadult bull trout distribution was positively associated with slow-water habitat unit types and maximum wetted width, and negatively associated with increased stream gradient. Bull trout spawning also occurred when water temperatures were between 5 and 9 °C, and redds were generally located in stream segments with low stream gradient and abundant gravel and cobble substrates. However, this study also elucidated characteristics of bull trout biology that are not well documented in the literature, but may be relatively widespread and have important implications regarding general characteristics of bull trout ecology, use of available habitat by bull trout, and persistence of lacustrine-adfluvial bull trout in small headwater lake ecosystems.

  13. Rubidium-strontium ages from the Oxford Lake-Knee Lake greenstone belt, northern Manitoba

    International Nuclear Information System (INIS)

    Clark, G.S.; Cheung, S.-P.

    1980-01-01

    Rb-Sr whole-rock ages have been determined for rocks from the Oxford Lake-Knee Lake-Gods Lake geenstone belt in the Superior Province of northeastern Manitoba. The age of the Magill Lake Pluton is 2455 +- 35 Ma(lambda 87 Rb = 1.42 x 10 -11 yr -1 ), with an initial 87 Sr/ 86 Sr ratio of 0.7078 +- 0.0043. This granite stock intrudes the Oxford Lake Group, so it is post-tectonic and probably related to the second, weaker stage of metamorphism. The age of the Bayly Lake Pluton is 2424 +- 74 Ma, with an initial 87 Sr/ 86 Sr ratio of 0.7029 +- 0.0001. This granodioritic batholith complex does not intrude the Oxford Lake Group. It is syn-tectonic and metamorphosed. The age of volcanic rocks of the Hayes River Group, from Goose Lake (30 km south of Gods Lake Narrows), is 2680 +- 125 Ma, with an initial 87 Sr/ 86 Sr ratio of 0.7014 +- 0.0009. The age for the Magill Lake and Bayly Lake Plutons can be interpreted as the minimum ages of granite intrusion in the area. The age for the Hayes River Group volcanic rocks is consistent with Rb-Sr ages of volcanic rocks from other Archean greenstone belts within the northwestern Superior Province. (auth)

  14. Factors influencing the distribution of native bull trout and westslope cutthroat trout in western Glacier National Park, Montana

    Science.gov (United States)

    D'Angelo, Vincent S.; Muhlfeld, Clint C.

    2013-01-01

    The widespread declines of native bull trout (Salvelinus confluentus) and westslope cutthroat trout (Oncorhynchus clarkii lewisi) populations prompted researchers to investigate factors influencing their distribution and status in western Glacier National Park, Montana. We evaluated the association of a suite of abiotic factors (stream width, elevation, gradient, large woody debris density, pool density, August mean stream temperature, reach surface area) with the occurrence (presence or absence) of bull trout and westslope cutthroat trout in 79 stream reaches in five sub-drainages containing glacial lakes. We modeled the occurrence of each species using logistic regression and evaluated competing models using an information theoretic approach. Westslope cutthroat trout were widely distributed (47 of 79 reaches), and there appeared to be no restrictions on their distribution other than physical barriers. Westslope cutthroat trout were most commonly found in relatively warm reaches downstream of lakes and in headwater reaches with large amounts of large woody debris and abundant pools. By contrast, bull trout were infrequently detected (10 of 79 reaches), with 7 of the 10 (70%) detections in sub-drainages that have not been compromised by non-native lake trout (S. namaycush). Bull trout were most often found in cold, low-gradient reaches upstream of glacial lakes. Our results indicate that complex stream habitats in sub-drainages free of non-native species are important to the persistence of native salmonids in western Glacier National Park. Results from this study may help managers monitor and protect important habitats and populations, inform conservation and recovery programs, and guide non-native species suppression efforts in Glacier National Park and elsewhere.

  15. Behavioral evidence for a role of chemoreception during reproduction in lake trout

    Science.gov (United States)

    Buchinger, Tyler J.; Li, Weiming; Johnson, Nicholas

    2015-01-01

    Chemoreception is hypothesized to influence spawning site selection, mate search, and synchronization of gamete release in chars (Salvelinus spp.), but behavioral evidence is generally lacking. Here, we provide a survey of the behavioral responses of reproductive male and female lake trout (Salvelinus namaycush) to natural conspecific chemosensory stimuli. A flow-through laboratory assay with side-by-side artificial spawning reefs was used to evaluate behavioral preferences of spawning-phase males and females for chemosensory stimuli from juveniles and from spawning-phase males and females. Males and females preferred male and juvenile stimuli over no stimuli, but only had weak preferences for female stimuli. Only females had a preference for male over juvenile stimuli when given a direct choice between the two. The unexpected observation of male attraction to male stimuli, even when offered female stimuli, indicates a fundamental difference from the existing models of chemical communication in fishes. We discuss our results from the perspectives of prespawning aggregation, mate evaluation, and spawning synchronization. Identification of specific components of the stimuli will allow confirmation of the function and may have management implications for native and invasive populations of lake trout that are ecologically and economically important.

  16. Organic contaminants in thermal plume resident brown trout

    International Nuclear Information System (INIS)

    Romberg, G.P.; Bourne, S.

    1978-01-01

    A pilot study was conducted to identify possible contaminants accumulated by thermal plume-resident fish in Lake Michigan. Brown trout were maintained in tanks receiving intake and discharge (less than or equal to 21 0 C) water from a power plant and were fed a diet of frozen alewife. Fish were sampled over a period of 127 days in order to estimate uptake rates and equilibrium levels for toxic organic and inorganic materials occurring in Lake Michigan fish and water. Experimental fish and natural samples were analyzed to determine the distribution of contaminants in various tissues and the corresponding pollutant levels in similar size brown trout from Lake Michigan. The quantitative analyses for the major organic contaminants are summarized. Without exception, the pyloric caecum of brown trout contained the highest concentration of lipids, PCB's, and chlorinated pesticides. Gill and kidney samples contained lower concentrations of contaminants than the caecum, while liver and muscle values were lowest

  17. Radionuclides and heavy metals in rainbow trout from Tsichomo, Nana Ka, Wen Povi, and Pin De Lakes in Santa Clara Canyon

    International Nuclear Information System (INIS)

    Fresquez, P.R.; Armstrong, D.R.; Naranjo, L. Jr.

    1998-04-01

    Radionuclide ( 3 H, 90 Sr, 137 Cs, 238 Pu, 239 Pu, and total uranium) and heavy metal (Ag, As, Ba, Be, Cd, Cr, Hg, Ni, Pb, Sb, Se, and TI) concentrations were determined in rainbow trout collected from Tsichomo, Nana Ka, Wen Povi, and Pin De lakes in Santa Clara Canyon in 1997. Most radionuclide and heavy metal concentrations in fish collected from these four lakes were within or just above upper limit background concentrations (Abiquiu reservoir), and as a group were statistically (p < 0.05) similar in most parameters to background

  18. In vitro immune functions in thiamine-replete and -depleted lake trout (Salvelinus namaycush)

    Science.gov (United States)

    Ottinger, Christopher A.; Honeyfield, Dale C.; Densmore, Christine L.; Iwanowicz, Luke R.

    2014-01-01

    In this study we examined the impacts of in vivo thiamine deficiency on lake trout leukocyte function measured in vitro. When compared outside the context of individual-specific thiamine concentrations no significant differences were observed in leukocyte bactericidal activity or in concanavalin A (Con A), and phytohemagglutinin-P (PHA-P) stimulated leukocyte proliferation. Placing immune functions into context with the ratio of in vivo liver thiamine monophosphate (TMP – biologically inactive form) to thiamine pyrophosphate (TPP – biologically active form) proved to be the best indicator of thiamine depletion impacts as determined using regression modeling. These observed relationships indicated differential effects on the immune measures with bactericidal activity exhibiting an inverse relationship with TMP to TPP ratios, Con A stimulated mitogenesis exhibiting a positive relationship with TMP to TPP ratios and PHA-P stimulated mitogenesis exhibiting no significant relationships. In addition, these relationships showed considerable complexity which included the consistent observation of a thiamine-replete subgroup with characteristics similar to those seen in the leukocytes from thiamine-depleted fish. When considered together, our observations indicate that lake trout leukocytes experience cell-type specific impacts as well as an altered physiologic environment when confronted with a thiamine-limited state.

  19. Short-and long term niche segregation and individual specialization of brown trout (Salmo trutta) in species poor Faroese lakes

    DEFF Research Database (Denmark)

    Brodersen, Jakob; Malmquist, Hilmar J.; Landkildehus, Frank

    2012-01-01

    fidelity to a niche may be variable both between and within populations. In order to study this complexity, relative simple systems with few species are needed. In this paper, we study how competitor presence affects the resource use of brown trout (Salmo trutta) in 11 species-poor Faroese lakes...... by comparing relative abundance, stable isotope ratios and diet in multiple habitats. In the presence of three-spined sticklebacks (Gasterosteus aculeatus), a higher proportion of the trout population was found in the pelagic habitat, and trout in general relied on a more pelagic diet base as compared to trout...... living in allopatry or in sympatry with Arctic charr (Salvelinus alpinus). Diet analyses revealed, however, that niche-segregation may be more complex than described on a one-dimensional pelagic-littoral axis. Trout from both littoral and offshore benthic habitats had in the presence of sticklebacks...

  20. Variability of kokanee and rainbow trout food habits, distribution, and population dynamics, in an ultraoligotrophic lake with no manipulative management

    Science.gov (United States)

    Buktenica, M.W.; Girdner, S.F.; Larson, G.L.; McIntire, C.D.

    2007-01-01

    Crater Lake is a unique environment to evaluate the ecology of introduced kokanee and rainbow trout because of its otherwise pristine state, low productivity, absence of manipulative management, and lack of lotic systems for fish spawning. Between 1986 and 2004, kokanee displayed a great deal of variation in population demographics with a pattern that reoccurred in about 10 years. We believe that the reoccurring pattern resulted from density dependent growth, and associated changes in reproduction and abundance, driven by prey resource limitation that resulted from low lake productivity exacerbated by prey consumption when kokanee were abundant. Kokanee fed primarily on small-bodied prey from the mid-water column; whereas rainbow trout fed on large-bodied prey from the benthos and lake surface. Cladoceran zooplankton abundance may be regulated by kokanee. And kokanee growth and reproductive success may be influenced by the availability of Daphnia pulicaria, which was absent in zooplankton samples collected annually from 1990 to 1995, and after 1999. Distribution and diel migration of kokanee varied over the duration of the study and appeared to be most closely associated with prey availability, maximization of bioenergetic efficiency, and fish density. Rainbow trout were less abundant than were kokanee and exhibited less variation in population demographics, distribution, and food habits. There is some evidence that the population dynamics of rainbow trout were in-part related to the availability of kokanee as prey. ?? 2007 Springer Science+Business Media B.V.

  1. Radionuclides and heavy metals in rainbow trout from Tsichomo, Nana Ka, Wen Povi, and Pin De Lakes in Santa Clara Canyon

    Energy Technology Data Exchange (ETDEWEB)

    Fresquez, P.R.; Armstrong, D.R.; Naranjo, L. Jr.

    1998-04-01

    Radionuclide ({sup 3}H, {sup 90}Sr, {sup 137}Cs, {sup 238}Pu, {sup 239}Pu, and total uranium) and heavy metal (Ag, As, Ba, Be, Cd, Cr, Hg, Ni, Pb, Sb, Se, and TI) concentrations were determined in rainbow trout collected from Tsichomo, Nana Ka, Wen Povi, and Pin De lakes in Santa Clara Canyon in 1997. Most radionuclide and heavy metal concentrations in fish collected from these four lakes were within or just above upper limit background concentrations (Abiquiu reservoir), and as a group were statistically (p < 0.05) similar in most parameters to background.

  2. Kokanee Stocking and Monitoring, Flathead Lake, 1993-1994 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Deleray, Mark (Montana Department of Fish, Wildlife and Parks, Kalispell, MT); Fredenberg, Wade (US Fish and Wildlife Service, Bozeman, MT); Hansen, Barry (Confederated Salish and Kootenai Tribes of the Flathead Nation, Pablo, MT)

    1995-07-01

    temperatures, an upsurge in the abundance of Duphniu rhorum, and saturation planting in an area believed to have lower lake trout densities was expected to maximize short-term survival of stocked kokanee. A net-pen experiment demonstrated that yearling hatchery kokanee, in the absence of predation, adjusted to conditions in Flathead Lake and utilized available zooplankton during June and July without substantial poststocking mortality. Kokanee captured after several months in the lake exhibited good growth and condition. We concluded that the food supply in Big Arm Bay was not limiting survival of stocked kokanee. The 1994 monitoring objective was to quantify lake trout predation of kokanee in Big Arm Bay in the first eight weeks following stocking. There were three components needed to quantify predation; estimated number of lake trout in Big Arm Bay, average number of kokanee consumed by lake trout, and estimated time required for lake trout to digest kokanee. As in the previous year, the monitoring results from the 1994 kokanee plant demonstrated that lake trout predation is the primary factor reducing survival of stocked kokanee. We estimated that lake trout consumed a minimum of 232,000 kokanee in Big Arm Bay during the first eight weeks following stocking. This represents 29 percent of kokanee planted. The consumption estimate was based on a hydroacoustic estimate for lake trout abundance (7,850 fish over 300 mm in total length), an incidence of kokanee per lake trout stomach sample which ranged from 2.99 to 0.22 fish, and a gastric evacuation rate of 47 hours for lake trout to digest consumed kokanee. Due to hydroacoustic limitations in identifying bottom-oriented lake trout, we underestimated the true abundance of lake trout, which led to an underestimate of kokanee mortality. By fall of 1994, we estimated that an additional 12.7 percent of surviving kokanee matured, based on observations of similar-sized fish in the hatchery. Thus, up to 72,000 additional fish were

  3. In vitro immune functions in thiamine-replete and -depleted lake trout (Salvelinus namaycush).

    Science.gov (United States)

    Ottinger, Christopher A; Honeyfield, Dale C; Densmore, Christine L; Iwanowicz, Luke R

    2014-05-01

    In this study we examined the impacts of in vivo thiamine deficiency on lake trout leukocyte function measured in vitro. When compared outside the context of individual-specific thiamine concentrations no significant differences were observed in leukocyte bactericidal activity or in concanavalin A (Con A), and phytohemagglutinin-P (PHA-P) stimulated leukocyte proliferation. Placing immune functions into context with the ratio of in vivo liver thiamine monophosphate (TMP--biologically inactive form) to thiamine pyrophosphate (TPP--biologically active form) proved to be the best indicator of thiamine depletion impacts as determined using regression modeling. These observed relationships indicated differential effects on the immune measures with bactericidal activity exhibiting an inverse relationship with TMP to TPP ratios, Con A stimulated mitogenesis exhibiting a positive relationship with TMP to TPP ratios and PHA-P stimulated mitogenesis exhibiting no significant relationships. In addition, these relationships showed considerable complexity which included the consistent observation of a thiamine-replete subgroup with characteristics similar to those seen in the leukocytes from thiamine-depleted fish. When considered together, our observations indicate that lake trout leukocytes experience cell-type specific impacts as well as an altered physiologic environment when confronted with a thiamine-limited state. Published by Elsevier Ltd.

  4. Diurnal stream habitat use of juvenile Atlantic salmon, brown trout and rainbow trout in winter

    Science.gov (United States)

    Johnson, J. H.; Douglass, K.A.

    2009-01-01

    The diurnal winter habitat of three species of juvenile salmonids was examined in a tributary of Skaneateles Lake, NY to compare habitat differences among species and to determine if species/age classes were selecting specific habitats. A total of 792 observations were made on the depth, velocity, substrate and cover (amount and type) used by sympatric subyearling Atlantic salmon, subyearling brown trout and subyearling and yearling rainbow trout. Subyearling Atlantic salmon occurred in shallower areas with faster velocities and less cover than the other salmonid groups. Subyearling salmon was also the only group associated with substrate of a size larger than the average size substrate in the study reach during both winters. Subyearling brown trout exhibited a preference for vegetative cover. Compared with available habitat, yearling rainbow trout were the most selective in their habitat use. All salmonid groups were associated with more substrate cover in 2002 under high flow conditions. Differences in the winter habitat use of these salmonid groups have important management implications in terms of both habitat protection and habitat enhancement.

  5. Mercury in fish from the Pinchi Lake Region, British Columbia, Canada

    International Nuclear Information System (INIS)

    Weech, S.A.; Scheuhammer, A.M.; Elliott, J.E.; Cheng, K.M.

    2004-01-01

    Water, surface sediments, and <40 cm rainbow trout (Oncorhynchus mykiss) and northern pikeminnow (Ptychocheilus oregonensis) were collected from Pinchi Lake, British Columbia, and from several nearby reference lakes. Hg concentrations in sediment samples from Pinchi L. were highly elevated compared to sediments from reference lakes, especially in sites adjacent to and downstream of a former Hg mine. In both fish species examined, Hg concentration was positively related to age and/or fork length. In northern pikeminnow, Hg concentrations were also positively related to trophic level (δN). Hg concentrations in both fish species were highest in Pinchi L., and were higher in pikeminnow than in rainbow trout of similar size. Average Hg concentrations in small rainbow trout from all lakes, including Pinchi L., were lower than dietary levels reported to cause reproductive impairment in common loons (Gavia immer); however, Hg levels in small pikeminnow from Pinchi L. were sufficiently high to be of concern. The risk for Hg toxicity in the study area is greatest for animals that consume larger piscivorous fish such as larger northern pikeminnow or lake trout, which are known from previous studies to contain higher Hg concentrations

  6. Diet and habitat use by age-0 deepwater sculpins in northern Lake Huron, Michigan and the Detroit River

    Science.gov (United States)

    Roseman, Edward F.

    2014-01-01

    Deepwater sculpins (Myoxocephalus thompsonii) are an important link in deepwater benthic foodwebs of the Great Lakes. Little information exists about deepwater sculpin spawning habits and early life history ecology due to difficulty in sampling deep offshore habitats. Larval and age-0 deepwater sculpins collected in northern Lake Huron and the Detroit River during 2007 were used to improve our understanding of their habitat use, diet, age, and growth. Peak larval density reached 8.4/1000 m3 in the Detroit River during April and was higher than that in Lake Huron. Offshore bottom trawls at DeTour and Hammond Bay first collected benthic age-0 deepwater sculpins in early September when fish were ≥ 25 mm TL. Otolith analysis revealed that hatch dates for pelagic larvae occurred during late March and larvae remained pelagic for 40 to 60 days. Diet of pelagic larvae (10–21 mm TL) was dominated by calanoid copepods at all sample locations. Diets of benthic age-0 fish varied by location and depth: Mysis and chironomids were prevalent in fish from Hammond Bay and the 91 m site at DeTour, but only chironomids were found in fish from the 37 m DeTour site. This work showed that nearshore epilimnetic sites were important for pelagic larvae and an ontogenetic shift from pelagic planktivore to benthivore occurred at about 25 mm TL in late summer. Age analysis showed that larvae remained pelagic long enough to be transported through the St. Clair–Detroit River system, Lake Erie, and the Niagara River, potentially contributing to populations in Lake Ontario.

  7. Behind the impact of introduced trout in high altitude lakes: adult, not juvenile fish are responsible of the selective predation on crustacean zooplankton

    Directory of Open Access Journals (Sweden)

    Rocco Tiberti

    2014-05-01

    Full Text Available Introduced fish seriously affect zooplankton communities in mountain lakes, often leading to the loss of large species. Selective predation is recognized to be the ultimate cause of such a strong impact. Here we describe the selection of zooplankton prey by analyzing the stomach contents of more than 300 brook trout (Salvelinus fontinalis inhabiting seven alpine lakes in the Gran Paradiso National Park (western Italian Alps. Our results show that planktivory is much more common in young fish, which feed on a larger number of taxa, but also adult fish maintain the ability to feed on zooplankton. There is a direct dependence between the length of zooplankton prey and the length of their fish predators, and adult, not juvenile fish are responsible of the selective predation on large crustacean zooplankton, which drive the impact of introduced fish throughout the entire zooplankton community. In some rare cases, large zooplankton populations develop in the presence of brook trout, and planktivory can become an important temporary resource for adult fish during the ice-free season. Thus, in the early stages of the establishment of non-native trout in alpine lakes, large-bodied zooplankton may represent an important food resource.

  8. Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project, Annual Report 2002-2003.

    Energy Technology Data Exchange (ETDEWEB)

    Sears, Sheryl

    2004-01-01

    The construction of Chief Joseph and Grand Coulee Dams completely and irrevocably blocked anadromous fish migrations to the Upper Columbia River. Historically this area hosted vast numbers of salmon returning to their natal waters to reproduce and die. For the native peoples of the region, salmon and steelhead were a principle food source, providing physical nourishment and spiritual sustenance, and contributing to the religious practices and the cultural basis of tribal communities. The decaying remains of spawned-out salmon carcasses contributed untold amounts of nutrients into the aquatic, aerial, and terrestrial ecosystems of tributary habitats in the upper basin. Near the present site of Kettle Falls, Washington, the second largest Indian fishery in the state existed for thousands of years. Returning salmon were caught in nets and baskets or speared on their migration to the headwater of the Columbia River in British Columbia. Catch estimates at Kettle Falls range from 600,000 in 1940 to two (2) million around the turn of the century (UCUT, Report No.2). The loss of anadromous fish limited the opportunities for fisheries management and enhancement exclusively to those actions addressed to resident fish. The Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project is a mitigation project intended to enhance resident fish populations and to partially mitigate for anadromous fish losses caused by hydropower system impacts. This substitution of resident fish for anadromous fish losses is considered in-place and out-of-kind mitigation. Upstream migration and passage barriers limit the amount of spawning and rearing habitat that might otherwise be utilized by rainbow trout. The results of even limited stream surveys and habitat inventories indicated that a potential for increased natural production exists. However, the lack of any comprehensive enhancement measures prompted the Upper Columbia United Tribes Fisheries Center (UCUT), Colville Confederated

  9. Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project, Annual Report 2001-2002.

    Energy Technology Data Exchange (ETDEWEB)

    Sears, Sheryl

    2003-01-01

    The construction of Chief Joseph and Grand Coulee Dams completely and irrevocably blocked anadromous fish migrations to the Upper Columbia River. Historically this area hosted vast numbers of salmon returning to their natal waters to reproduce and die. For the native peoples of the region, salmon and steelhead were a principle food source, providing physical nourishment and spiritual sustenance, and contributing to the religious practices and the cultural basis of tribal communities. The decaying remains of spawned-out salmon carcasses contributed untold amounts of nutrients into the aquatic, aerial, and terrestrial ecosystems of tributary habitats in the upper basin. Near the present site of Kettle Falls, Washington, the second largest Indian fishery in the state existed for thousands of years. Returning salmon were caught in nets and baskets or speared on their migration to the headwater of the Columbia River in British Columbia. Catch estimates at Kettle Falls range from 600,000 in 1940 to two (2) million around the turn of the century (UCUT, Report No.2). The loss of anadromous fish limited the opportunities for fisheries management and enhancement exclusively to those actions addressed to resident fish. The Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project is a mitigation project intended to enhance resident fish populations and to partially mitigate for anadromous fish losses caused by hydropower system impacts. This substitution of resident fish for anadromous fish losses is considered in-place and out-of-kind mitigation. Upstream migration and passage barriers limit the amount of spawning and rearing habitat that might otherwise be utilized by rainbow trout. The results of even limited stream surveys and habitat inventories indicated that a potential for increased natural production exists. However, the lack of any comprehensive enhancement measures prompted the Upper Columbia United Tribes Fisheries Center (UCUT), Colville Confederated

  10. Genetic Inventory of Bull Trout and Westslope Cutthroat Trout in the Pend Oreille Subbasin, 2002-2003 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Maroney, Joseph R. (Kalispel Tribe of Indians, Usk, WA); Shaklee, James B.; Young, Sewall F. (Washington Department of Fish and Wildlife, Olympia, WA)

    2003-10-01

    In 2002, the Kalispel Natural Resource Department (KNRD) collected tissue samples for genetic analysis from 280 bull trout and 940 westslope cutthroat. The Washington Department of Fish and Wildlife developed and applied microsatellite DNA screening protocols for the analysis of bull trout at 13 loci and 24 loci for cutthroat trout. This project will continue collection and analysis of additional samples for the next 2 years. At that time, a final annual report will be compiled for the three-year study that will describe the genetic characteristics for bull trout and westslope cutthroat trout. The extent of hybridization of bull trout (with brook trout) and westslope cutthroat trout (with Yellowstone cutthroat trout and rainbow trout) in the Priest Lake and Lower Pend Oreille subbasins will also be examined.

  11. Use of wild trout for PBDE assessment in freshwater environments: Review and summary of critical factors

    Directory of Open Access Journals (Sweden)

    Juan M. Ríos

    2015-11-01

    Full Text Available Certain wild animals represent sentinels to address issues related to environmental pollution, since they can provide integrative data on both pollutant exposure and biological effects. Despite their technological benefits, PBDEs are considered a threat to environmental health due to their persistence, toxicity, and capacity to be accumulated. These pollutants have been found geographically widespread in fish, particularly in predator species such as trout. The aim of this work is to critically review the applicability and usefulness of wild trout for assessing PBDEs in freshwater environments. Reviewed reports include data from highly industrialized areas as well as areas from remote regions with relatively low human activity, including European and North American great lakes and freshwater environments in Europe, Greenland, subarctic areas and Patagonia, respectively. A summary of relevant factors were grouped into organism-specific factors (food habits, age, size, lipid content, sex and reproduction, tissue type, mechanism of contaminant uptake and metabolism, and PBDE levels in the surrounding environment (sediment. Five wild trout species [rainbow trout (Oncorhynchus mykiss, brown trout (Salmo trutta, lake trout (Salvelinus namaycush, arctic char (Salvelinus alpinus, and brook trout (Salvelinus fontinalis], collected worldwide within the 1994 to present time frame, were considered. Multivariate techniques (principal component analysis-PCA and mapping approach, showed clear differences in geographic distribution patterns of PBDE levels in trout depending on the region studied: wild trout from European and North American great lakes have the highest PBDE loads. This pattern could be due to high industrial activity at these locations. A correlational approach used to explore intraspecific relationships between PBDE levels and morphometry, showed positive relationships only for brown trout. Further, brown trout showed the highest trout

  12. Interactions between hatch dates, growth rates, and mortality of Age-0 native Rainbow Smelt and nonnative Alewife in Lake Champlain

    Science.gov (United States)

    Parrish, Donna; Simonin, Paul W.; Rudstam, Lars G.; Pientka, Bernard; Sullivan, Patrick J.

    2016-01-01

    Timing of hatch in fish populations can be critical for first-year survival and, therefore, year-class strength and subsequent species interactions. We compared hatch timing, growth rates, and subsequent mortality of age-0 Rainbow Smelt Osmerus mordax and Alewife Alosa pseudoharengus, two common open-water fish species of northern North America. In our study site, Lake Champlain, Rainbow Smelt hatched (beginning May 26) almost a month earlier than Alewives (June 20). Abundance in the sampling area was highest in July for age-0 Rainbow Smelt and August for age-0 Alewives. Late-hatching individuals of both species grew faster than those hatching earlier (0.6 mm/d versus 0.4 for Rainbow Smelt; 0.7 mm/d versus 0.6 for Alewives). Mean mortality rate during the first 45 d of life was 3.4%/d for age-0 Rainbow Smelt and was 5.5%/d for age-0 Alewives. Alewife mortality rates did not differ with hatch timing but daily mortality rates of Rainbow Smelt were highest for early-hatching fish. Cannibalism is probably the primary mortality source for age-0 Rainbow Smelt in this lake. Therefore, hatching earlier may not be advantageous because the overlap of adult and age-0 Rainbow Smelt is highest earlier in the season. However, Alewives, first documented in Lake Champlain in 2003, may increase the mortality of age-0 Rainbow Smelt in the summer, which should favor selection for earlier hatching.

  13. Effect of artificial sunlight on the retention of external calcein marks on lake trout

    Science.gov (United States)

    Honeyfield, D.C.; Kehler, T.; Fletcher, J.W.; Mohler, J.W.

    2008-01-01

    When choosing a fish marking technique to address fishery related questions, it is important to consider factors that affect mark retention. Calcein, a chemical marking agent, is under investigation for potential use on fish. Two laboratory trials were conducted with calcein-marked lake trout Salvelinus namaycush to determine the effect of artificial sunlight on calcein mark intensity. In trial 1, fish exposed to 18,000 lx for 7 d lost 90% or more of the calcein mark intensity (relative to the colorimetric key, mg/L) on the head, body, ventral region, and pectoral fins relative to mark intensity in fish that were maintained in darkness. In trial 2, light intensity was reduced 2.5-3.0-fold. After 7 d of light exposure, calcein mark intensity on the head was reduced by 40-45% relative to mark intensity in fish that were held in darkness; by day 14, calcein mark intensity on the head was reduced by 55-60% relative to that of dark-treated fish. No further decline was observed in light-exposed fish, and head mark intensity values did not differ among days 14, 21, and 28 for this treatment group. Of the four areas evaluated, the head and pectoral fin were more easily read using a colorimetric key than the lateral or ventral regions of the fish. The concentration of calcein spotted on filter paper to devise the colorimetric key ranged from 1 to 100 mg/L. A difference of approximately 7 mg/L in apparent calcein mark intensity means for the head region could be detected using the colorimetric key. These trials showed that calcein mark intensity on lake trout declined when fish were exposed to artificial sunlight, and the use of a colorimetric key improved the objectivity of calcein mark intensity assessment.

  14. Mapping Lake Michigan Fish Catch Data

    OpenAIRE

    Wodd, Jacob; Doucette, Jarrod; Höök, Tomas O.

    2014-01-01

    The only Great Lake completely contained in the U.S., Lake Michigan offers an abundance of recreational fishing. This project takes 20 years’ worth of salmonid fish catch data, and uses GIS to organize and visually represent the data in a way that is meaningful and helpful to local fisherman and researchers. Species represented included Brown Trout, Lake Trout, Rainbow Trout, Chinook Salmon, and Coho Salmon. The species are organized by both decadal and yearly spans, as well as catch per t...

  15. Age- and stage-dependent variations of muscle-specific gene expression in brown trout Salmo trutta L.

    Science.gov (United States)

    Churova, Maria V; Meshcheryakova, Olga V; Ruchev, Mikhail; Nemova, Nina N

    2017-09-01

    This study was conducted to characterize the features of muscle-specific genes expression during development of brown trout Salmo trutta inhabiting the river Krivoy ruchey (Kola Peninsula, Russia). Gene expression levels of myogenic regulatory factors (MRFs - MyoD1 paralogs (MyoD1a, MyoD1b, MyoD1c), Myf5, myogenin), myostatin paralogs (MSTN-1a, MSTN-1b, MSTN-2a), fast skeletal myosin heavy chain (MyHC) were measured in the white muscles of brown trout parr of ages 0+ (under-yearling), 1+ (yearling) and 2+ (two year old) and smolts of age 2+. Multidirectional changes in MyoD1 and MSTN paralogs expression along with myogenin, Myf 5 and MyHC expression levels in white muscles in parr of trout with age were revealed. The expression of MyoD1c, myogenin, MSTN-2a was the highest in 0+ parr and then decreased. MyoD1a/b expression levels didn't differ between age groups. The simultaneous elevation of MyHC, Myf5, MSTN-1a, and MSTN-1b was found in trout yearlings. In smolts, expression levels of MSTN paralogs, MyHC, Myf5, MyoD1a was lower than in parr. But in contrast, the MyoD1c and myogenin mRNA levels was higher in smolts. The study revealed that there are definite patterns in simultaneous muscle-specific genes expression in age groups of parr and smolts. As MyoD and MSTN paralogs expression changed differently in dependence on age and stage, it was suggested that paralogs of the same gene complementarily control myogenesis during development. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Lake Pend Oreille Predation Research, Annual Report 2002-2003.

    Energy Technology Data Exchange (ETDEWEB)

    Bassista, Thomas

    2004-02-01

    During August 2002 we conducted a hydroacoustic survey to enumerate pelagic fish >406 mm in Lake Pend Oreille, Idaho. The purpose of this survey was to determine a collective lakewide biomass estimate of pelagic bull trout Salvelinus confluentus, rainbow trout Oncorhynchus mykiss, and lake trout S. namaycush and compare it to pelagic prey (kokanee salmon O. nerka) biomass. By developing hydroacoustic techniques to determine the pelagic predator to prey ratio, we can annually monitor their balance. Hydroacoustic surveys were also performed during December 2002 and February 2003 to investigate the effectiveness of autumn and winter surveys for pelagic predators. The inherent problem associated with hydroacoustic sampling is the inability to directly identify fish species. Therefore, we utilized sonic tracking techniques to describe rainbow trout and lake trout habitat use during our winter hydroacoustic survey to help identify fish targets from the hydroacoustic echograms. During August 2002 we estimated there were 39,044 pelagic fish >406 mm in Lake Pend Oreille (1.84 f/ha). Based on temperature and depth utilization, two distinct groups of pelagic fish >406 mm were located during August; one group was located between 10 and 35 m and the other between 40 and 70 m. The biomass for pelagic fish >406 mm during August 2002 was 73 t (metric ton). This would account for a ratio of 1 kg of pelagic predator for every 2.63 kg of kokanee prey, assuming all pelagic fish >406 mm are predators. During our late fall and winter hydroacoustic surveys, pelagic fish >406 mm were observed at lake depths between 20 and 90 m. During late fall and winter, we tracked three rainbow trout (168 habitat observations) and found that they mostly occupied pelagic areas and predominantly stayed within the top 10 m of the water column. During late fall (one lake trout) and winter (four lake trout), we found that lake trout (184 habitat observations) utilized benthic-nearshore areas 65% of the time

  17. Does the introduced brook trout ( Salvelinus fontinalis) affect growth of the native brown trout ( Salmo trutta)?

    Science.gov (United States)

    Korsu, Kai; Huusko, Ari; Muotka, Timo

    2009-03-01

    Non-native brook trout have become widely established in North European streams. We combined evidence from an artificial-stream experiment and drainage-scale field surveys to examine whether brook trout suppressed the growth of the native brown trout (age 0 to age 2). Our experimental results demonstrated that brown trout were unaffected by the presence of brook trout but that brook trout showed reduced growth in the presence of brown trout. However, the growth reduction only appeared in the experimental setting, indicating that the reduced spatial constraint of the experimental system may have forced the fish to unnaturally intense interactions. Indeed, in the field, no effect of either species on the growth of the putative competitor was detected. These results caution against uncritical acceptance of findings from small-scale experiments because they rarely scale up to more complex field situations. This and earlier work suggest that the establishment of brook trout in North European streams has taken place mainly because of the availability of unoccupied (or underutilized) niche space, rather than as a result of species trait combinations or interspecific competition per se.

  18. Determination of arsenic in some Lake Michigan fish using neutron activation analysis

    International Nuclear Information System (INIS)

    Nicholson, L.W.; Rengan, K.

    1979-01-01

    The level of arsenic in six different species of fish collected from Lake Michigan near Saugatuck, Michigan has been measured using radiochemical neutron activation analysis. The arsenic concentration was found to vary from 0.05 μg/g (wet weight) for yellow perch fillet to 1.4 μg/g (wet weight) for eviscerated bloater chubs. A significant correlation was observed between arsenic concentrations and number of years in the lake for lake trout; correlations were also observed between arsenic concentrations and length of lake trout and smelt. No such correlations were found for alewife or yellow perch. (author)

  19. Radiocaesium in Faeroese lakes after the Chernobyl accident

    International Nuclear Information System (INIS)

    Joensen, H.P.; Vestergaard, T.

    1992-01-01

    In order to follow the content and ecological decay of radiocaesium in brown trout, samples of trout were taken in July 1987 - July 1990 in three Faroese lakes, each with a nonmigratory stock of brown trout. Stomach contents indicated different diets in the three lakes. Trout from Storavatn, Toftavatn and Leitisvatn respectively had a descending order of trophism, which coincided with a decreasing level of 137 Cs - contamination. Length vs 137 Cs - activity distribution shifted from a nondescript pattern in 1987, to correlation in 1989 and 1990. Ecological half lives were comparable in lakes Storavatn and Leitisvatn, with t 1/2 around 430 days. Radiocaesium activity decreased rapidly in lake Toftavatn 1987-88, then much slower 1988-90, with t 1/2 = 895 days. (au)

  20. The effects of chronic cadmium exposure on repeat swimming performance and anaerobic metabolism in brown trout (Salmo trutta) and lake whitefish (Coregonus clupeaformis).

    Science.gov (United States)

    Cunningham, Jessie L; McGeer, James C

    2016-04-01

    This study investigates the effect of chronic Cd exposure on the ability to perform repeat swim challenges in brown trout (Salmo trutta) and lake whitefish (Coregonus clupeaformis). Fish were exposed to waterborne Cd (18nM) in moderately hard water (120mgL(-1) CaCO3) for 30 days. This level of exposure has been shown to cause sublethal physiological disruption and acclimation responses but no impairment of sustained swimming capacity (Ucrit) in single swim challenges. Swim trials were done over the course of the exposure and each one consisted of an initial swim to 85% of the Ucrit of control fish, a 30min recovery period and finally a second swim challenge to determine Ucrit. Plasma and tissue samples were collected before and after each of the swim periods. As expected from previous studies, Cd exposure resulted in significant accumulation of Cd in gills, liver and kidney but not in white muscle. Exposure also induced a loss of plasma Ca followed by subsequent recovery (in lake whitefish but not brown trout) with few mortalities (100% survival for lake whitefish and 93% for brown trout). Both control and exposed fish swam to 85% of the single swim Ucrit and no differences in performance were seen. The Ucrit of unexposed controls in the second swim challenges were not different from the single swim Ucrit. However, second swim performance was significantly reduced in Cd exposed fish, particularly after a week of exposure where 31% and 38% reductions were observed for brown trout and lake whitefish respectively. Swimming to 85% Ucrit resulted in metabolic expenditure with little recovery after 30min. Few differences were observed between control and Cd exposed fish with the exception of a reduction in resting white muscle ATP stores of Cd exposed fish after 1 week of exposure. The results show that chronic sublethal Cd exposure results in an impairment of swimming ability in repeat swim challenges but this impairment is generally not related to metabolic processes

  1. The effects of chronic cadmium exposure on repeat swimming performance and anaerobic metabolism in brown trout (Salmo trutta) and lake whitefish (Coregonus clupeaformis)

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, Jessie L.; McGeer, James C., E-mail: jmcgeer@wlu.ca

    2016-04-15

    Highlights: • Exposure to 18 nM waterborne Cd induced plasma Ca loss that recovered by day 30 for lake whitefish but not brown trout. • Ucrit measured after an initial swim to 85% of Ucrit and a 30 min rest period was reduced in 18 nM Cd exposed fish compared to controls. • Swimming to 85% of Ucrit resulted in decreased muscle glycogen and increased lactate that was not recovered in the 30 min recovery period. • Second swim impairment is not related to metabolic processes in white muscle. - Abstract: This study investigates the effect of chronic Cd exposure on the ability to perform repeat swim challenges in brown trout (Salmo trutta) and lake whitefish (Coregonus clupeaformis). Fish were exposed to waterborne Cd (18 nM) in moderately hard water (120 mg L{sup −1} CaCO{sub 3}) for 30 days. This level of exposure has been shown to cause sublethal physiological disruption and acclimation responses but no impairment of sustained swimming capacity (U{sub crit}) in single swim challenges. Swim trials were done over the course of the exposure and each one consisted of an initial swim to 85% of the U{sub crit} of control fish, a 30 min recovery period and finally a second swim challenge to determine U{sub crit}. Plasma and tissue samples were collected before and after each of the swim periods. As expected from previous studies, Cd exposure resulted in significant accumulation of Cd in gills, liver and kidney but not in white muscle. Exposure also induced a loss of plasma Ca followed by subsequent recovery (in lake whitefish but not brown trout) with few mortalities (100% survival for lake whitefish and 93% for brown trout). Both control and exposed fish swam to 85% of the single swim U{sub crit} and no differences in performance were seen. The Ucrit of unexposed controls in the second swim challenges were not different from the single swim Ucrit. However, second swim performance was significantly reduced in Cd exposed fish, particularly after a week of exposure

  2. A comparative and experimental evaluation of performance of stocked diploid and triploid brook trout

    Science.gov (United States)

    Budy, Phaedra E.; Thiede, G.P.; Dean, A.; Olsen, D.; Rowley, G.

    2012-01-01

    Despite numerous negative impacts, nonnative trout are still being stocked to provide economically and socially valuable sport fisheries in western mountain lakes. We evaluated relative performance and potential differences in feeding strategy and competitive ability of triploid versus diploid brook trout Salvelinus fontinalis in alpine lakes, as well as behavioral and performance differences of diploid and triploid brook trout in two controlled experimental settings: behavioral experiments in the laboratory and performance evaluations in ponds. Across lakes, catch per unit effort (CPUE) and relative weight (Wr ) were not significantly different between ploidy levels. Mean sizes were also similar between ploidy levels except in two of the larger lakes where diploids attained slightly larger sizes (approximately 20 mm longer). We observed no significant differences between diploids and triploids in diet, diet preference, or trophic structure. Similarly, growth and condition did not differ between ploidy levels in smaller-scale pond experiments, and aggressive behavior did not differ between ploidy levels (fed or unfed fish trials) in the laboratory. Independent of ploidy level, the relative performance of brook trout varied widely among lakes, a pattern that appeared to be a function of lake size or a factor that covaries with lake size such as temperature regime or carrying capacity. In summary, we observed no significant differences in the relative performance of brook trout from either ploidy level across a number of indices, systems, and environmental conditions, nor any indication that one group is more aggressive or a superior competitor than the other. Collectively, these results suggest that triploid brook trout will offer a more risk-averse and promising management opportunity when they are stocked to these lakes and elsewhere to simultaneously meet the needs for the sport fishery and conservation objectives.

  3. Diel resource partitioning among juvenile Atlantic Salmon, Brown Trout, and Rainbow Trout during summer

    Science.gov (United States)

    Johnson, James H.; McKenna, James E.

    2015-01-01

    Interspecific partitioning of food and habitat resources has been widely studied in stream salmonids. Most studies have examined resource partitioning between two native species or between a native species and one that has been introduced. In this study we examine the diel feeding ecology and habitat use of three species of juvenile salmonids (i.e., Atlantic Salmon Salmo salar, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss) in a tributary of Skaneateles Lake, New York. Subyearling Brown Trout and Rainbow Trout fed more heavily from the drift than the benthos, whereas subyearling Atlantic Salmon fed more from the benthos than either species of trout. Feeding activity of Atlantic Salmon and Rainbow Trout was similar, with both species increasing feeding at dusk, whereas Brown Trout had no discernable feeding peak or trough. Habitat availability was important in determining site-specific habitat use by juvenile salmonids. Habitat selection was greater during the day than at night. The intrastream, diel, intraspecific, and interspecific variation we observed in salmonid habitat use in Grout Brook illustrates the difficulty of acquiring habitat use information for widespread management applications.

  4. Brown Trout removal effects on short-term survival and movement of Myxobolus cerebralis-resistant rainbow trout

    Science.gov (United States)

    Fetherman, Eric R.; Winkelman, Dana L.; Bailey, Larissa L.; Schisler, George J.; Davies, K.

    2015-01-01

    Following establishment of Myxobolus cerebralis (the parasite responsible for salmonid whirling disease) in Colorado, populations of Rainbow Trout Oncorhynchus mykissexperienced significant declines, whereas Brown Trout Salmo trutta densities increased in many locations across the state, potentially influencing the success of M. cerebralis-resistant Rainbow Trout reintroductions. We examined the effects of Brown Trout removal on the short-term (3-month) survival and movement of two crosses of reintroduced, M. cerebralis-resistant Rainbow Trout in the Cache la Poudre River, Colorado. Radio frequency identification passive integrated transponder tags and antennas were used to track movements of wild Brown Trout and stocked Rainbow Trout in reaches where Brown Trout had or had not been removed. Multistate mark–recapture models were used to estimate tagged fish apparent survival and movement in these sections 3 months following Brown Trout removal. A cross between the German Rainbow Trout and Colorado River Rainbow Trout strains exhibited similar survival and movement probabilities in the reaches, suggesting that the presence of Brown Trout did not affect its survival or movement. However, a cross between the German Rainbow Trout and Harrison Lake Rainbow Trout exhibited less movement from the reach in which Brown Trout had been removed. Despite this, the overall short-term benefits of the removal were equivocal, suggesting that Brown Trout removal may not be beneficial for the reintroduction of Rainbow Trout. Additionally, the logistical constraints of conducting removals in large river systems are substantial and may not be a viable management option in many rivers.

  5. Effect of stocking sub-yearling Atlantic salmon on the habitat use of sub-yearling rainbow trout

    Science.gov (United States)

    Johnson, James H.

    2016-01-01

    Atlantic salmon (Salmo salar) restoration in the Lake Ontario watershed may depend on the species' ability to compete with naturalized non-native salmonids, including rainbow trout (Oncorhynchus mykiss) in Lake Ontario tributaries. This study examined interspecific habitat associations between sub-yearling Atlantic salmon and rainbow trout as well as the effect of salmon stocking on trout habitat in two streams in the Lake Ontario watershed. In sympatry, Atlantic salmon occupied significantly faster velocities and deeper areas than rainbow trout. However, when examining the habitat use of rainbow trout at all allopatric and sympatric sites in both streams, trout habitat use was more diverse at the sympatric sites with an orientation for increased cover and larger substrate. In Grout Brook, where available habitat remained constant, there was evidence suggesting that trout may have shifted to slower and shallower water in the presence of salmon. The ability of sub-yearling Atlantic salmon to affect a habitat shift in rainbow trout may be due to their larger body size and/or larger pectoral fin size. Future studies examining competitive interactions between these species during their first year of stream residence should consider the size advantage that earlier emerging Atlantic salmon will have over rainbow trout.

  6. The effects of chronic cadmium exposure on repeat swimming performance and anaerobic metabolism in brown trout (Salmo trutta) and lake whitefish (Coregonus clupeaformis)

    International Nuclear Information System (INIS)

    Cunningham, Jessie L.; McGeer, James C.

    2016-01-01

    Highlights: • Exposure to 18 nM waterborne Cd induced plasma Ca loss that recovered by day 30 for lake whitefish but not brown trout. • Ucrit measured after an initial swim to 85% of Ucrit and a 30 min rest period was reduced in 18 nM Cd exposed fish compared to controls. • Swimming to 85% of Ucrit resulted in decreased muscle glycogen and increased lactate that was not recovered in the 30 min recovery period. • Second swim impairment is not related to metabolic processes in white muscle. - Abstract: This study investigates the effect of chronic Cd exposure on the ability to perform repeat swim challenges in brown trout (Salmo trutta) and lake whitefish (Coregonus clupeaformis). Fish were exposed to waterborne Cd (18 nM) in moderately hard water (120 mg L"−"1 CaCO_3) for 30 days. This level of exposure has been shown to cause sublethal physiological disruption and acclimation responses but no impairment of sustained swimming capacity (U_c_r_i_t) in single swim challenges. Swim trials were done over the course of the exposure and each one consisted of an initial swim to 85% of the U_c_r_i_t of control fish, a 30 min recovery period and finally a second swim challenge to determine U_c_r_i_t. Plasma and tissue samples were collected before and after each of the swim periods. As expected from previous studies, Cd exposure resulted in significant accumulation of Cd in gills, liver and kidney but not in white muscle. Exposure also induced a loss of plasma Ca followed by subsequent recovery (in lake whitefish but not brown trout) with few mortalities (100% survival for lake whitefish and 93% for brown trout). Both control and exposed fish swam to 85% of the single swim U_c_r_i_t and no differences in performance were seen. The Ucrit of unexposed controls in the second swim challenges were not different from the single swim Ucrit. However, second swim performance was significantly reduced in Cd exposed fish, particularly after a week of exposure where 31% and 38

  7. Effects of density on foraging success and aggression in age-structured groups of brown trout

    DEFF Research Database (Denmark)

    Kaspersson, Rasmus; Höjesjö, Johan; Pedersen, Stig

    2010-01-01

    , as a consequence of, for example, age and/or body size. We used two age classes (i.e. size groups) of stream-living brown trout, Salmo trutta, to investigate this issue. While old (and large) trout are assumed to be superior during interference competition, younger individuals may be both numerically dominant...

  8. 77 FR 33230 - Notice of Intent To Prepare an Environmental Impact Statement for Proposed Strategies for Lake...

    Science.gov (United States)

    2012-06-05

    ... reduce non-native lake trout abundance in Flathead Lake to benefit native fish populations in Flathead... Forest Service, US Geological Survey, local fishing guides and anglers, Trout Unlimited, University of... action (maintain the status quo of lake trout harvest from general harvest and fishing contests); (2...

  9. Coupling age-structured stock assessment and fish bioenergetics models: a system of time-varying models for quantifying piscivory patterns during the rapid trophic shift in the main basin of Lake Huron

    Science.gov (United States)

    He, Ji X.; Bence, James R.; Madenjian, Charles P.; Pothoven, Steven A.; Dobiesz, Norine E.; Fielder, David G.; Johnson, James E.; Ebener, Mark P.; Cottrill, Adam R.; Mohr, Lloyd C.; Koproski, Scott R.

    2015-01-01

    We quantified piscivory patterns in the main basin of Lake Huron during 1984–2010 and found that the biomass transfer from prey fish to piscivores remained consistently high despite the rapid major trophic shift in the food webs. We coupled age-structured stock assessment models and fish bioenergetics models for lake trout (Salvelinus namaycush), Chinook salmon (Oncorhynchus tshawytscha), walleye (Sander vitreus), and lake whitefish (Coregonus clupeaformis). The model system also included time-varying parameters or variables of growth, length–mass relations, maturity schedules, energy density, and diets. These time-varying models reflected the dynamic connections that a fish cohort responded to year-to-year ecosystem changes at different ages and body sizes. We found that the ratio of annual predation by lake trout, Chinook salmon, and walleye combined with the biomass indices of age-1 and older alewives (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) increased more than tenfold during 1987–2010, and such increases in predation pressure were structured by relatively stable biomass of the three piscivores and stepwise declines in the biomass of alewives and rainbow smelt. The piscivore stability was supported by the use of alternative energy pathways and changes in relative composition of the three piscivores. In addition, lake whitefish became a new piscivore by feeding on round goby (Neogobius melanostomus). Their total fish consumption rivaled that of the other piscivores combined, although fish were still a modest proportion of their diet. Overall, the use of alternative energy pathways by piscivores allowed the increases in predation pressure on dominant diet species.

  10. Mercury biomagnification in three geothermally-influenced lakes differing in chemistry and algal biomass

    International Nuclear Information System (INIS)

    Verburg, Piet; Hickey, Christopher W.; Phillips, Ngaire

    2014-01-01

    Accumulation of Hg in aquatic organisms is influenced not only by the contaminant load but also by various environmental variables. We compared biomagnification of Hg in aquatic organisms, i.e., the rate at which Hg accumulates with increasing trophic position, in three lakes differing in trophic state. Total Hg (THg) concentrations in food webs were compared in an oligotrophic, a mesotrophic and a eutrophic lake with naturally elevated levels of Hg associated with geothermal water inputs. We explored relationships of physico-chemistry attributes of lakes with Hg concentrations in fish and biomagnification in the food web. Trophic positions of biota and food chain length were distinguished by stable isotope 15 N. As expected, THg in phytoplankton decreased with increasing eutrophication, suggesting the effect of biomass dilution. In contrast, THg biomagnification and THg concentrations in trout were controlled by environmental physico-chemistry and were highest in the eutrophic lake. In the more eutrophic lake frequent anoxia occurred, resulting in favorable conditions for Hg transfer into and up the food chain. The average concentration of THg in the top predator (rainbow trout) exceeded the maximum recommended level for consumption by up to 440%. While there were differences between lakes in food chain length between plankton and trout, THg concentration in trout did not increase with food chain length, suggesting other factors were more important. Differences between the lakes in biomagnification and THg concentration in trout correlated as expected from previous studies with eight physicochemical variables, resulting in enhanced biomagnification of THg in the eutrophic lake. - Highlights: • Relationships between Hg biomagnification and 11 variables in 3 lakes. • Hg in trout too high for consumption in two geothermally-influenced lakes. • Hg biomagnification was highest in the most eutrophic lake. • First study to compare Hg biomagnification in lakes

  11. Mercury biomagnification in three geothermally-influenced lakes differing in chemistry and algal biomass

    Energy Technology Data Exchange (ETDEWEB)

    Verburg, Piet, E-mail: piet.verburg@niwa.co.nz; Hickey, Christopher W.; Phillips, Ngaire

    2014-09-15

    Accumulation of Hg in aquatic organisms is influenced not only by the contaminant load but also by various environmental variables. We compared biomagnification of Hg in aquatic organisms, i.e., the rate at which Hg accumulates with increasing trophic position, in three lakes differing in trophic state. Total Hg (THg) concentrations in food webs were compared in an oligotrophic, a mesotrophic and a eutrophic lake with naturally elevated levels of Hg associated with geothermal water inputs. We explored relationships of physico-chemistry attributes of lakes with Hg concentrations in fish and biomagnification in the food web. Trophic positions of biota and food chain length were distinguished by stable isotope {sup 15}N. As expected, THg in phytoplankton decreased with increasing eutrophication, suggesting the effect of biomass dilution. In contrast, THg biomagnification and THg concentrations in trout were controlled by environmental physico-chemistry and were highest in the eutrophic lake. In the more eutrophic lake frequent anoxia occurred, resulting in favorable conditions for Hg transfer into and up the food chain. The average concentration of THg in the top predator (rainbow trout) exceeded the maximum recommended level for consumption by up to 440%. While there were differences between lakes in food chain length between plankton and trout, THg concentration in trout did not increase with food chain length, suggesting other factors were more important. Differences between the lakes in biomagnification and THg concentration in trout correlated as expected from previous studies with eight physicochemical variables, resulting in enhanced biomagnification of THg in the eutrophic lake. - Highlights: • Relationships between Hg biomagnification and 11 variables in 3 lakes. • Hg in trout too high for consumption in two geothermally-influenced lakes. • Hg biomagnification was highest in the most eutrophic lake. • First study to compare Hg biomagnification in

  12. Hydraulic, geomorphic, and trout habitat conditions of the Lake Fork of the Gunnison River in Hinsdale County, Lake City, Colorado, Water Years 2010-2011

    Science.gov (United States)

    Williams, Cory A.; Richards, Rodney J.; Schaffrath, Keelin R.

    2015-01-01

    Channel rehabilitation, or reconfiguration, to mitigate a variety of riverine problems has become a common practice in the western United States. However, additional work to monitor and assess the channel response to, and the effectiveness of, these modifications over longer periods of time (decadal or longer) is still needed. The Lake Fork of the Gunnison River has been an area of active channel modification to accommodate the needs of the Lake City community since the 1950s. The Lake Fork Valley Conservancy District began a planning process to assess restoration options for a reach of the Lake Fork in Lake City to enhance hydraulic and ecologic characteristics of the reach. Geomorphic channel form is affected by land-use changes within the basin and geologic controls within the reach. The historic channel was defined as a dynamic, braided channel with an active flood plain. This can result in a natural tendency for the channel to braid. A braided channel can affect channel stability of reconfigured reaches when a single-thread meandering channel is imposed on the stream. The U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board and Colorado River Water Conservation District, began a study in 2010 to quantify existing hydraulic and habitat conditions for a reach of the Lake Fork of the Gunnison River in Lake City, Colorado. The purpose of this report is to quantify existing Lake Fork hydraulic and habitat conditions and establish a baseline against which post-reconfiguration conditions can be compared. This report (1) quantifies the existing hydraulic and geomorphic conditions in a 1.1-kilometer section of the Lake Fork at Lake City that has been proposed as a location for future channel-rehabilitation efforts, (2) characterizes the habitat suitability of the reach for two trout species based on physical conditions within the stream, and (3) characterizes the current riparian canopy density.

  13. Contrasting past and current numbers of bears visiting Yellowstone cutthroat trout streams

    Science.gov (United States)

    Haroldson, Mark A.; Schwartz, Charles C.; Teisberg, Justin E.; Gunther, Kerry A.; Fortin, Jennifer K.; Robbins, Charles T.

    2014-01-01

    Spawning cutthroat trout (Oncorhynchus clarkii bouvieri) were historically abundant within tributary streams of Yellowstone Lake within Yellowstone National Park and were a highly digestible source of energy and protein for Yellowstone’s grizzly bears (Ursus arctos) and black bears (U. americanus). The cutthroat trout population has subsequently declined since the introduction of non-native lake trout (Salvelinus namaycush), and in response to effects of drought and whirling disease (Myxobolus cerebralis). The trout population, duration of spawning runs, and indices of bear use of spawning streams had declined in some regions of the lake by 1997–2000. We initiated a 3-year study in 2007 to assess whether numbers of spawning fish, black bears, and grizzly bears within and alongside stream corridors had changed since 1997– 2000. We estimated numbers of grizzly bears and black bears by first compiling encounter histories of individual bears visiting 48 hair-snag sites along 35 historically fished streams.We analyzed DNA encounter histories with Pradel-recruitment and Jolly-Seber (POPAN) capture-mark-recapture models. When compared to 1997–2000, the current number of spawning cutthroat trout per stream and the number of streams with cutthroat trout has decreased. We estimated that 48 (95% CI¼42–56) male and 23 (95% CI¼21–27) female grizzly bears visited the historically fished tributary streams during our study. In any 1- year, 46 to 59 independent grizzly bears (8–10% of estimated Greater Yellowstone Ecosystem population) visited these streams. When compared with estimates from the 1997 to 2000 study and adjusted for equal effort, the number of grizzly bears using the stream corridors decreased by 63%. Additionally, the number of black bears decreased between 64% and 84%. We also document an increased proportion of bears of both species visiting front-country (i.e., near human development) streams. With the recovery of cutthroat trout, we suggest bears

  14. The effects of Medieval dams on genetic divergence and demographic history in brown trout populations.

    Science.gov (United States)

    Hansen, Michael M; Limborg, Morten T; Ferchaud, Anne-Laure; Pujolar, José-Martin

    2014-06-05

    Habitat fragmentation has accelerated within the last century, but may have been ongoing over longer time scales. We analyzed the timing and genetic consequences of fragmentation in two isolated lake-dwelling brown trout populations. They are from the same river system (the Gudenå River, Denmark) and have been isolated from downstream anadromous trout by dams established ca. 600-800 years ago. For reference, we included ten other anadromous populations and two hatchery strains. Based on analysis of 44 microsatellite loci we investigated if the lake populations have been naturally genetically differentiated from anadromous trout for thousands of years, or have diverged recently due to the establishment of dams. Divergence time estimates were based on 1) Approximate Bayesian Computation and 2) a coalescent-based isolation-with-gene-flow model. Both methods suggested divergence times ca. 600-800 years bp, providing strong evidence for establishment of dams in the Medieval as the factor causing divergence. Bayesian cluster analysis showed influence of stocked trout in several reference populations, but not in the focal lake and anadromous populations. Estimates of effective population size using a linkage disequilibrium method ranged from 244 to > 1,000 in all but one anadromous population, but were lower (153 and 252) in the lake populations. We show that genetic divergence of lake-dwelling trout in two Danish lakes reflects establishment of water mills and impassable dams ca. 600-800 years ago rather than a natural genetic population structure. Although effective population sizes of the two lake populations are not critically low they may ultimately limit response to selection and thereby future adaptation. Our results demonstrate that populations may have been affected by anthropogenic disturbance over longer time scales than normally assumed.

  15. A comparison of the survival and migration of wild and F1-hatchery-reared brown trout (Salmo trutta) smolts traversing an artificial lake

    DEFF Research Database (Denmark)

    Schwinn, Michael; Baktoft, Henrik; Aarestrup, Kim

    2017-01-01

    rates from the sea of wild and 1-year old F1-hatchery-reared brown trout smolts in a Danish lowland stream that contains an artificial lake using passive integrated transponder telemetry in the years 2011–2013 and 2016. The majority of hatchery-reared smolts descended within 72 h after their release...

  16. Phylogeographic structure and demographic patterns of brown trout in North-West Africa.

    Science.gov (United States)

    Snoj, Aleš; Marić, Saša; Bajec, Simona Sušnik; Berrebi, Patrick; Janjani, Said; Schöffmann, Johannes

    2011-10-01

    The objectives of the study were to determine the phylogeographic structure of brown trout (Salmo trutta) in Morocco, elucidate their colonization patterns in North-West Africa and identify the mtDNA lineages involved in this process. We also aimed to resolve whether certain brown trout entities are also genetically distinct. Sixty-two brown trout from eleven locations across the Mediterranean and the Atlantic drainages in Morocco were surveyed using sequence analysis of the mtDNA control region and nuclear gene LDH, and by genotyping twelve microsatellite loci. Our study confirms that in Morocco both the Atlantic and Mediterranean basins are populated by Atlantic mtDNA lineage brown trout only, demonstrating that the Atlantic lineage (especially its southern clade) invaded initially not only the western part of the Mediterranean basin in Morocco but also expanded deep into the central area. Atlantic haplotypes identified here sort into three distinct groups suggesting Morocco was colonized in at least three successive waves (1.2, 0.4 and 0.2-0.1 MY ago). This notion becomes more pronounced with the finding of a distinct haplotype in the Dades river system, whose origin appears to coalesce with the nascent stage of the basal mtDNA evolutionary lineages of brown trout. According to our results, Salmo akairos, Salmo pellegrini and "green trout" from Lake Isli do not exhibited any character states that distinctively separate them from the other brown trout populations studied. Therefore, their status as distinct species was not confirmed. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Survival of migrating sea trout (Salmo trutta ) smolts during their passage of an artificial lake in a Danish lowland stream

    DEFF Research Database (Denmark)

    Schwinn, Michael; Aarestrup, Kim; Baktoft, Henrik

    2017-01-01

    Artificial lake development is often used as a management tool to reduce nutrient runoff to coastal waters. Denmark has restored more than 10 000 ha of wetlands and lakes in the last 14 years as a consequence of ‘Action Plans for the Aquatic Environment’, which aim to meet the demands...... of the European Union’s Water Framework Directive. Juvenile, seaward migrating salmonids are highly affected by impounded waterbodies, as they are subjected to extraordinary high mortalities due to predation and altered habitat. From 2005 to 2015, survival and migration patterns of wild brown trout (Salmo trutta....... Water temperature and discharge were key environmental factors affecting survival of the smolts during the passage of the lake. Furthermore, smolt survival was negatively correlated with condition factor. This elevated level of smolt mortality may seriously compromise self-sustaining anadromous salmonid...

  18. Productive characteristics of age-3 brood brown trout (Salmo trutta reared in the conditions industrial aquaculture

    Directory of Open Access Journals (Sweden)

    L. Haloyan

    2017-03-01

    Full Text Available Purpose. Study and analysis of productive and reproductive parameters of brood brown trout reared in the conditions of industrial aquaculture with the use of feeding with specialized artificial feeds. Methodology. Fish rearing was performed using a technology traditional for rainbow trout. Biological evaluation of fish was performed on live material according to the scheme developed by I.F. Pravdin (1966 for salmonids. Fish were anesthetized with “Propiscin”. Metric parameters were measured with the aid of a ruler and caliper. Fish weight was determined on electronic balances. Eggs were preserved in a 4% formalin solution, weight of individual eggs was determined with the aid of torsion balances, egg diameter with a caliper. The duration of spermatozoid motility in males was determined under a microscope under 10X40 magnification with the aid of a stopwatch, sperm concentration was determined in a Goriaev chamber. Multiple regression analysis was performed in JMP IN 4 (SAS Institute. The factor was considered significant if р <0.05. Findings. Brood brown trout reared on specialized artificial feeds had following productive parameters: mean body weight of age-3 fish was 458 g in males and 453 g in females. Mean working fecundity of age-3 fish as 1847 eggs, mean relative working fecundity was 3971 eggs, the mean qualitative parameters of which were: weight of 61.5 g, diameter of 74.7 mm. The reproductive characteristics of age-3 males was high – mean fecundity was 1391 million sperm cells, their motility was 35 sec. Originality. For the first time we reared a stock of brood brown trout in industrial conditions with the use of feeding with specialized artificial feeds. Practical value. The obtained results are a component of the development of a complex technology of salmonid fish rearing with an objective to broad the assortment of valuable gourmet products and to justify the measures on artificial reproduction of brown trout in rivers of

  19. The abundance of large, piscivorous Ferox Trout (Salmo trutta in Loch Rannoch, Scotland

    Directory of Open Access Journals (Sweden)

    Alastair Thorne

    2016-11-01

    Full Text Available Background Ferox Trout are large, long-lived piscivorous Brown Trout (Salmo trutta. Due to their exceptionally large size, Ferox Trout are highly sought after by anglers while their life-history strategy, which includes delayed maturation, multiphasic growth and extended longevity, is of interest to ecological and evolutionary modelers. However, despite their recreational and theoretical importance, little is known about the typical abundance of Ferox Trout. Methods To rectify this situation a 16 year angling-based mark-recapture study was conducted on Loch Rannoch, which at 19 km2 is one of the largest lakes in the United Kingdom. Results A hierarchical Bayesian Jolly-Seber analysis of the data suggest that if individual differences in catchability are negligible the population of Ferox Trout in Loch Rannoch in 2009 was approximately 71 fish. The results also suggest that a single, often unaccompanied, highly-experienced angler was able to catch roughly 8% of the available fish on an annual basis. Discussion It is recommended that anglers adopt a precautionary approach and release all trout with a fork length ≥400 mm caught by trolling in Loch Rannoch. There is an urgent need to assess the status of Ferox Trout in other lakes.

  20. Nonnative trout impact an alpine-nesting bird by altering aquatic-insect subsidies.

    Science.gov (United States)

    Epanchin, Peter N; Knapp, Roland A; Lawler, Sharon P

    2010-08-01

    Adjacent food webs may be linked by cross-boundary subsidies: more-productive donor systems can subsidize consumers in less-productive neighboring recipient systems. Introduced species are known to have direct effects on organisms within invaded communities. However, few studies have addressed the indirect effects of nonnative species in donor systems on organisms in recipient systems. We studied the direct role of introduced trout in altering a lake-derived resource subsidy and their indirect effects in altering a passerine bird's response to that subsidy. We compared the abundance of aquatic insects and foraging Gray-crowned Rosy-Finches (Leucosticte tephrocotis dawsoni, "Rosy-Finch") at fish-containing vs. fishless lakes in the Sierra Nevada Mountains of California (USA). Introduced trout outcompeted Rosy-Finches for emerging aquatic insects (i.e., mayflies). Fish-containing lakes had 98% fewer mayflies than did fishless lakes. In lakes without fish, Rosy-Finches showed an aggregative response to emerging aquatic insects with 5.9 times more Rosy-Finches at fishless lakes than at fish-containing lakes. Therefore, the introduction of nonnative fish into the donor system reduced both the magnitude of the resource subsidy and the strength of cross-boundary trophic interactions. Importantly, the timing of the subsidy occurs when Rosy-Finches feed their young. If Rosy-Finches rely on aquatic-insect subsidies to fledge their young, reductions in the subsidy by introduced trout may have decreased Rosy-Finch abundances from historic levels. We recommend that terrestrial recipients of aquatic subsidies be included in conservation and restoration plans for ecosystems with alpine lakes.

  1. Description age-3 brood rainbow trout bred in the conditions of the industral fish farm "Sloboda Banyliv"

    Directory of Open Access Journals (Sweden)

    P. Mendryshora

    2017-06-01

    Full Text Available Purpose. To analyze the results of cultivation and give fish-breeding and biological characteristics of age-3 brood rainbow trout grown using industrial technology in the conditions of the trout farm "Sloboda Banyliv." Methodology. Fish cultivation was carried in tank conditions of the trout farm "Sloboda Banyliv". The material for the study were age-3 brood rainbow trout obtained from eggs of the fall-spawning form of rainbow trout. Cultivation was carried out in a 216 m2 tank, stocking density of 255 fish/m2, using standard trout culture methods. Statistical analysis of the material was performed in Microsoft Office Excel (2003. Analysis of the variables was performed in the system of absolute values. The analysis criteria were their mean values mean deviations (M±m, standard error (σ, variability coefficient (Cv. Fish were fed with specialized feed manufactured by “BioMar” (Denmark with a high protein content (more than 40%. Findings. Based on the performed selective-breeding works aimed at creating brood stocks of rainbow trout, it was found that brood fish reared in the industrial conditions of the fish farm “Sloboda Banyliv”, despite instable culture conditions, were characterized by a moderate growth rate and had high values of productive and reproductive features. Mean weight of age-3 rainbow trout females was 1282.5 g, fecundity — 3.48 thousand eggs. Mean weight of produced eggs was 239.17 g, while individual parameters were 70.4 mg for the weight and 4.58 mm for the diameter. Originality. For the first time a study aimed at the formation of brood stocks of rainbow trout with analysis of phenotypic and productive features in the conditions of a fish farm with instable temperature and water regimes has been conducted. Practical value. The results of the performed work will allow selecting and forming a brood stock with high values of productive and reproductive features.

  2. Status and conservation of interior Redband Trout in the western United States

    Science.gov (United States)

    Muhlfeld, Clint C.; Albeke, Shannon E.; Gunckel, Stephanie L; Writer, Benjamin J; Shepard, Bradley B.; May, Bruce E

    2015-01-01

    In this article we describe the current status and conservation of interior (potamodromous) Redband Trout Oncorhynchus mykiss sspp. throughout its range in the western United States using extant data and expert opinion provided by fish managers. Redband Trout historically occupied 60,295 km of stream habitat and 152 natural lakes. Currently, Redband Trout occupy 25,417 km of stream habitat (42% of their historical range) and 124 lakes or reservoirs. Nonhybridized populations are assumed to occupy 11,695 km (46%) of currently occupied streams; however, fish from only 4,473 km (18%) have been genetically tested. Approximately 47% of the streams occupied by Redband Trout occur on private land, 45% on government lands, and 8% in protected areas. A total of 210 Redband Trout populations, occupying 15,252 km of stream habitat (60% of the current distribution) and 95,158 ha of lake habitat (52%), are being managed as “conservation populations.” Most conservation populations have been designated as weakly to strongly connected metapopulations (125; 60%) and occupy much more stream length (14,112 km; 93%) than isolated conservation populations (1,141 km; 7%). The primary threats to Redband Trout include invasive species, habitat degradation and fragmentation, and climate change. Although the historical distribution of interior Redband Trout has declined dramatically, we conclude that the species is not currently at imminent risk of extinction because it is still widely distributed with many populations isolated by physical barriers and active conservation efforts are occurring for many populations. However, the hybridization status of many populations has not been well quantified, and introgression may be more prevalent than documented here. We recommend (1) collecting additional genetic data and estimating distribution and abundance by means of a more rigorous spatial sampling design to reduce uncertainties, (2) collecting additional information to assess and

  3. Kootenai River fisheries investigations: rainbow and bull trout recruitment: annual progress report 1999; ANNUAL

    International Nuclear Information System (INIS)

    Walters, Jody P.; Downs, Christopher Charles

    2001-01-01

    Our 1999 objectives were to determine sources of rainbow trout Oncorhynchus mykiss and bull trout Salvelinus confluentus spawning and recruitment in the Idaho reach of the Kootenai River. We used a rotary-screw trap to capture juvenile trout to determine age at out-migration and to estimate total out-migration from the Boundary Creek drainage to the Kootenai River. The out-migrant estimate for March through August 1999 was 1,574 (95% C. I.= 825-3,283) juvenile rainbow trout. Most juveniles out-migrated at age-2 and age-3. No out-migrating bull trout were caught. Five of 17 rainbow trout radio-tagged in Idaho migrated upstream into Montana waters during the spawning season. Five bull trout originally radio-tagged in O'Brien Creek, Montana in early October moved downstream into Idaho and British Columbia by mid-October. Annual angler exploitation for the rainbow trout population upstream of Bonners Ferry, Idaho was estimated to be 58%. Multi-pass depletion estimates for index reaches of Caboose, Curley, and Debt creeks showed 0.20, 0.01, and 0.13 rainbow trout juveniles/m(sup 2), respectively. We estimated rainbow trout (180-415 mm TL) standing stock of 1.6 kg/ha for the Hemlock Bar reach (29.4 ha) of the Kootenai River, similar to the 1998 estimate. Recruitment of juvenile rainbow and bull trout from Idaho tributaries is not sufficient to be the sole source of subsequent older fish in the mainstem Kootenai River. These populations are at least partly dependent on recruitment from Montana waters. The low recruitment and high exploitation rate may be indicators of a rainbow trout population in danger of further decline

  4. Consequences of actively managing a small Bull Trout population in a fragmented landscape

    Science.gov (United States)

    Al-Chokhachy, Robert K.; Moran, Sean; McHugh, Peter; Bernall, Shana; Fredenberg, Wade; DosSantos, Joseph M.

    2015-01-01

    Habitat fragmentation, which affects many native salmonid species, is one of the major factors contributing to the declines in distribution and abundance of Bull Trout Salvelinus confluentus. Increasingly, managers are considering options to maintain and enhance the persistence of isolated local populations through active management strategies. Understanding the ecological consequences of such actions is a necessary step in conservation planning. We used an individual-based model to evaluate the consequences of an ongoing management program aimed at mitigating the anthropogenic fragmentation of the lower Clark Fork River in Montana. Under this program juvenile Bull Trout are trapped and transported from small, headwater source populations to Lake Pend Oreille, Idaho, for rearing, and adults are subsequently recaptured in their upstream migration and returned to the natal population for spawning. We examined one of these populations and integrated empirical estimates of demographic parameters to simulate different management scenarios where moderate (n = 4) and high (n = 8) numbers of age-2, age-3, or age-4 Bull Trout were removed for transport with variable return rates under both demographic stochasticity and environmental perturbations. Our results indicated the risks from removal with no returns increased substantially when removal totals and age of Bull Trout removed from the simulated population increased. Specifically, removing eight age-3 or age-4 individuals resulted in 26% and 62% reductions in average adult population size, respectively, across simulations. We found the risks of transport were not likely alleviated with low (3%) or moderate (6%) return rates, and there were considerable risks of declines for the source population even when return rates were extremely high (>12%). Our simulations indicated little risk of declines for the source population with removals of age-2 Bull Trout, and any risks were alleviated with low return rates. However, we

  5. Production and evaluation of YY-male Brook Trout to eradicate nonnative wild brook trout populations

    Science.gov (United States)

    Kennedy, Patrick; Schill, Daniel J.; Meyer, Kevin A.; Campbell, Matthew R.; Vu, Ninh V.; Hansen, Michael J.

    2017-01-01

    Nonnative Brook Trout Salvelinus fontinalis were introduced throughout western North America in the early 1900s, resulting in widespread self-sustaining populations that are difficult to eradicate and often threaten native salmonid populations. A novel approach for their eradication involves use of YY male (MYY) Brook Trout (created in the hatchery by feminizing XY males and crossing them with normal XY males). If MYY Brook Trout survive after stocking, and reproduce successfully with wild females, in theory this could eventually drive the sex ratio of the wild population to 100% males, at which point the population would not be able to reproduce and would be eradicated. This study represents the first successful development of a FYY and MYY salmonid broodstock, which was produced in four years at relatively low cost. Field trials demonstrated that stocked hatchery MYY Brook Trout survived and produced viable MYY offspring in streams, although reproductive fitness appeared to have been lower than their wild conspecifics. Even if reduced fitness is the norm in both streams and alpine lakes, our population simulations suggest that eradication can be achieved in reasonable time periods under some MYY stocking scenarios, especially when wild Brook Trout are simultaneously suppressed in the population.

  6. Low pH levels wipe out salmon and trout populations in southernmost Norway

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, K W; Snekvik, E

    1972-01-01

    A gradual decrease in pH has been documented for many Scandinavian rivers and lakes and there is little doubt that the main cause is acid precipitation (1-4). Eggs, fry, and alevins of salmon and brown trout are more susceptible to acid water than are the older fish. A gradually increasing acidity of trout biotopes will cause a reduction in the natural reproduction rate of trout, because eggs and fry succumb, while the older individuals in the population survive, at least until the pH level sinks low enough to affect them, as well. A study of the present situation and examination of the available data show that the salmon populations in a number of rivers in southernmost Norway have been nearly wiped out by low pH values. During the last twenty to thirty years, low pH levels have eliminated the brown trout populations in a great number of lakes and rivers in Norway's southernmost districts. This alarming development is continuing.

  7. Efficiency of advanced wastewater treatment technologies for the reduction of hormonal activity in effluents and connected surface water bodies by means of vitellogenin analyses in rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta f. fario).

    Science.gov (United States)

    Henneberg, Anja; Triebskorn, Rita

    2015-01-01

    Endocrine effects in the aquatic environment are in the focus of scientists and media along with debates on the necessity of further steps in wastewater treatment. In the present study VTG responses were compared to evaluate upgrades at wastewater treatment plants (WWTPs). We investigated several advanced sewage treatment technologies at two WWTPs connected to the Schussen, a tributary of Lake Constance, for the reduction of hormonal activity: (1) a powdered activated charcoal filter at the WWTP Langwiese; and (2) a combination of ozonation, sand filter, and granulated activated carbon filter at the WWTP Eriskirch. Rainbow trout and brown trout were either directly exposed to the effluents in aquaria or cages, or in a bypass system flown through by surface water of the Schussen. As a reference, trout were kept in bypass aquaria at the Argen River, which is less influenced by micropollutants. As a biomarker for estrogenicity, we analyzed the yolk precursor protein vitellogenin in immature rainbow trout and brown trout and in trout larvae (100 days post-fertilization) prior to and after the upgrade with the new technologies. Trout of different ages and species were used to detect differences in their sensitivity. At both bypass stations, larvae of brown trout showed significantly higher vitellogenin levels prior to the upgrade compared to negative control levels. Female brown trout exposed at the bypass station downstream of the WWTP showed decreased vitellogenin levels after the upgrade. In 1-year-old immature trout directly exposed to the respective effluents, no significant effects of the upgrades on vitellogenin levels were found. In general, larger effects were observed in brown trout than in rainbow trout, indicating that they are more sensitive test organisms.

  8. Use of naturally occurring mercury to determine the importance of cutthroat trout to Yellowstone grizzly bears

    Science.gov (United States)

    Felicetti, L.A.; Schwartz, C.C.; Rye, R.O.; Gunther, K.A.; Crock, J.G.; Haroldson, M.A.; Waits, L.; Robbins, C.T.

    2004-01-01

    Spawning cutthroat trout (Oncorhynchus clarki (Richardson, 1836)) are a potentially important food resource for grizzly bears (Ursus arctos horribilis Ord, 1815) in the Greater Yellowstone Ecosystem. We developed a method to estimate the amount of cutthroat trout ingested by grizzly bears living in the Yellowstone Lake area. The method utilized (i) the relatively high, naturally occurring concentration of mercury in Yellowstone Lake cutthroat trout (508 ± 93 ppb) and its virtual absence in all other bear foods (6 ppb), (ii) hair snares to remotely collect hair from bears visiting spawning cutthroat trout streams between 1997 and 2000, (iii) DNA analyses to identify the individual and sex of grizzly bears leaving a hair sample, (iv) feeding trials with captive bears to develop relationships between fish and mercury intake and hair mercury concentrations, and (v) mercury analyses of hair collected from wild bears to estimate the amount of trout consumed by each bear. Male grizzly bears consumed an average of 5 times more trout/kg bear than did female grizzly bears. Estimated cutthroat trout intake per year by the grizzly bear population was only a small fraction of that estimated by previous investigators, and males consumed 92% of all trout ingested by grizzly bears.

  9. Heavy metal contamination and hepatic toxicological responses in brown trout (Salmo trutta from the Kerguelen Islands

    Directory of Open Access Journals (Sweden)

    Ali Jaffal

    2015-09-01

    Full Text Available The Kerguelen Islands include various species of freshwater fish such as brown trout (Salmo trutta. These trout are among the most isolated from direct anthropogenic impact worldwide. This study was designed to analyse cadmium (Cd and copper (Cu concentrations in the liver of Kerguelen brown trout, and to assess the possible impacts of these metals on hepatic histopathology and oxidative stress parameters (superoxide dismutase and catalase activity and glutathione levels. Trout were caught in the Château River, the Studer Lakes and the Ferme Pond, close to the scientific station of the Kerguelen Islands, corresponding to three morphotypes (river, lake and station. Kerguelen trouts’ hepatic concentrations of Cd and Cur were similar to those reported in previous studies in salmonids populations from areas under anthropological impacts. Clear hepatic disturbances (fibrosis, nuclear alteration, increased immune response, melanomacrophage centres [MMCs] were observed in all tested trout. A similar histo-pathological trend was observed among the trout from the three morphotypes but anti-oxidative responses were higher in the trout from the “station” morphotype. Hepatic alterations and the presence of MMCs in the livers of Kerguelen brown trout may be related to the high levels of Cd and Cu measured in this fish at all sampling sites.

  10. Genetic Diversity and Conservation of the Prespa Trout in the Balkans

    Directory of Open Access Journals (Sweden)

    Patrick Berrebi

    2013-11-01

    Full Text Available The Balkans are known to have a high level of biodiversity and endemism. No less than 15 taxa have been recorded in salmonids of the Salmo genus. Among them, the Prespa trout is found in only four river systems flowing into Lake Macro Prespa, three in the Former Yugoslav Republic of Macedonia and one in Greece. This is the first comprehensive survey of all streams located within the Macro Prespa Basin, encompassing the whole taxon range. A large genetic sample of 536 Prespa trout was collected mainly between 2005 and 2007. The sampling included 59 individuals from the Golema river system, 93 from the Kranska, 260 from the Brajcinska, 119 from the Agios Germanos, and five individuals from the lake itself. These specimens were analyzed with six microsatellite markers and by sequencing the mitochondrial control region. Nuclear data were examined through multidimensional analysis and assignment tests. Five clusters were detected by assignment: Golema, Kranska, Brajcinska upstream, Rzanska Brajcinska tributary and Brajcinska downstream. Most of these river systems thus hosted differentiated Prespa trout populations (with past gene flows likely dating before the construction of dams, except Agios Germanos, which was found to be composed of 5% to 32% of each cluster. Among the five trout individuals from the lake, four originated from Kranska River and one was admixed. Supported parsimonious hypotheses are proposed to explain these specificities. Conservation of this endemic taxon should take these results into account. No translocation should be performed between different tributaries of the lake and preservation of the Brajcinska populations should address the upstream-downstream differentiation described.

  11. Physiological and biochemical responses of rainbow trout and brook trout exposed to elevated selenium from coal mines

    Energy Technology Data Exchange (ETDEWEB)

    Miller, L.; Rasmussen, J.; Hontela, A. [Lethbridge Univ., Lethbridge, AB (Canada); Palace, V.; Carroll, L. [Fisheries and Oceans Canada, Winnipeg, MB (Canada); Wang, F. [Manitoba Univ., Winnipeg, MB (Canada)

    2009-07-01

    Since selenium (Se) is an element that bioaccumulates, anthropogenic activities in areas that already have high Se in parent rock can result in an increase in Se in aquatic systems. Se causes reproductive deformities in rainbow trout (RT), at lower concentrations than for brook trout (BT). This presentation reported on a study conducted at coal mines in northeastern Alberta in which juvenile hatchery-reared RT and BT were stocked into 2 reference and 2 Se contaminated end pit lakes. Fish were sampled at 0, 6, and 12 months after stocking, and will be sampled at 18 and 24 months. Water Se levels were found to be high in contaminated lakes. Selenite, the more toxic form of Se, was the highest in Pit C4. Liver glutathione levels were similar in the 2 fish species, and cellular damage in the fish was beginning to increase. At 6 months, liver glycogen levels were higher in the BT than in the RT, but no tangible site specific patterns emerged. At all sites except Pit C4, the RT were in better condition than BT. BT from Pit C4 also had a lower ability to secrete cortisol, suggesting that the elevated selenite levels may negatively affect fish. Se accumulation results from 28 fish sampled at 12 months were also discussed.

  12. Assessing the consequences of nonnative trout in headwater ecosystems in western North America

    Science.gov (United States)

    Jason B. Dunham; David S. Pilliod; Michael K. Young

    2004-01-01

    Intentional introductions of nonnative trout into headwater lakes and streams can have numerous effects on the receiving ecosystems, potentially threatening native species and disrupting key ecological processes. In this perspective, we focus on seven key issues for assessing the biological and economic consequences of nonnative trout in headwater ecosystems: (1)...

  13. Seasonal patterns in growth, blood consumption, and effects on hosts by parasitic-phase sea lampreys in the Great Lakes: an individual-based model approach

    Science.gov (United States)

    Madenjian, Charles P.; Cochran, Philip A.; Bergstedt, Roger A.

    2003-01-01

    An individual-based model (IBM) was developed for sea lamprey (Petromyzon marinus) populations in the Laurentian Great Lakes. The IBM was then calibrated to observed growth, by season, for sea lampreys in northern Lake Huron under two different water temperature regimes: a regime experienced by Seneca-strain lake trout (Salvelinus namaycush) and a regime experienced by Marquettestrain lake trout. Modeling results indicated that seasonal blood consumption under the Seneca regime was very similar to that under the Marquette regime. Simulated mortality of lake trout directly due to blood removal by sea lampreys occurred at nearly twice the rate during August and September under the Marquette regime than under the Seneca regime. However, cumulative sea lamprey-induced mortality on lake trout over the entire duration of the sea lamprey's parasitic phase was only 7% higher for the Marquette regime compared with the Seneca regime. Thus, these modeling results indicated that the strain composition of the host (lake trout) population was not important in determining total number of lake trout deaths or total blood consumption attributable to the sea lamprey population, given the sea lamprey growth pattern. Regardless of water temperature regime, both blood consumption rate by sea lampreys and rate of sea lamprey-induced mortality on lake trout peaked in late October. Elevated blood consumption in late October appeared to be unrelated to changes in water temperature. The IBM approach should prove useful in optimizing control of sea lampreys in the Laurentian Great Lakes.

  14. Age and growth of the lake whitefish, Coregonus clupeaformis (Mitchill), in Lake Erie

    Science.gov (United States)

    Van Oosten, John; Hile, Ralph

    1949-01-01

    Although the whitefish has by no means ranked first from the standpoint of production, it has always been an important commercial species in Lake Erie. Trends in the output of whitefish have differed in the United States and Canadian waters of the lake. The 1893–1946 average annual yield of 1,201,000 pounds in the United States was only 38.3 percent of the 1879–1890 mean of 3,133,000 pounds, whereas in Canada the more recent (1907–1946) average annual take of 1,397,000 pounds has been 5.48 times the 1871–1906 mean of 255,000 pounds. The United States fishery was centered in the western part of Lake Erie (61.5 percent of the production in Michigan and Ohio) before 1921 and in the eastern part (62.6 percent in Pennsylvania and New York) in 1921–1946. The eastern part of Lake Erie (east of Port Burwell) dominated the Canadian production in 1900–1909 (65.4 percent) and in 1922–1946 (57.2 percent) but the western end was the more productive in 1871–1899 (79.8 percent) and 1910–1921 (69.7 percent). Ages were determined and individual growth histories calculated from the examination and measurement of the scales of 3,399 Lake Erie whitefish captured off four ports (Sandusky, Lorain, and Conneaut, Ohio, and Erie, Pennsylvania) over the period, 1927–1930. The number of specimens used for the investigation of other phases of the life history varied according to the amount of data available or required. Age-group III was typically (but not invariably) dominant in random samples from gear employed for the commercial production of whitefish (trap nets, pound nets, and large-mesh gill nets). The same age group also dominated most samples of the marketable catch (that is, whitefish that equalled or exceeded the minimum legal weight of 1 3/4 pounds) taken in late summer, autumn, and early winter. Age-group IV, however, was strongest among marketable fish from trap nets in early July although the III group was dominant in the random samples from the same nets

  15. Genetic and Phenotypic Catalog of Native Resident Trout of the interior Columbia River Basin : FY-2001 Report : Populations in the Wenatchee, Entiat, Lake Chelan and Methow River Drainages.

    Energy Technology Data Exchange (ETDEWEB)

    Trotter, Patrick C.

    2001-10-01

    The 1994 Fish and Wildlife Program of the Northwest Power Planning Council specifies the recovery and preservation of population health of native resident fishes of the Columbia River Basin. Among the native resident species of concern are interior rainbow trout of the Columbia River redband subspecies Oncorhynchus mykiss gairdneri 1 and westslope cutthroat trout O. clarki lewisi. The westslope cutthroat trout has been petitioned for listing under the U. S. Endangered Species Act (American Wildlands et al. 1997). Before at-risk populations can be protected, their presence and status must be established. Where introgression from introduced species is a concern, as in the case of both westslope cutthroat trout and redband rainbow trout, genetic issues must be addressed as well. As is true with native trout elsewhere in the western United States (Behnke 1992), most of the remaining pure populations of these species in the Columbia River Basin are in relatively remote headwater reaches. The objective of this project was to photo-document upper Columbia Basin native resident trout populations in Washington, and to ascertain their species or subspecies identity and relative genetic purity using a nonlethal DNA technique. FY-2001 was year three (and final year) of a project in which we conducted field visits to remote locations to seek out and catalog these populations. In FY-2001 we worked in collaboration with the Wenatchee National Forest to catalog populations in the Wenatchee, Entiat, Lake Chelan, and Methow River drainages of Washington State.

  16. Radiocarbon ages and age models for the past 30,000 years in Bear Lake, Utah and Idaho

    Science.gov (United States)

    Colman, Steven M.; Rosenbaum, J.G.; Kaufman, D.S.; Dean, W.E.; McGeehin, J.P.

    2009-01-01

    Radiocarbon analyses of pollen, ostracodes, and total organic carbon (TOC) provide a reliable chronology for the sediments deposited in Bear Lake over the past 30,000 years. The differences in apparent age between TOC, pollen, and carbonate fractions are consistent and in accord with the origins of these fractions. Comparisons among different fractions indicate that pollen sample ages are the most reliable, at least for the past 15,000 years. The post-glacial radiocarbon data also agree with ages independently estimated from aspartic acid racemization in ostracodes. Ages in the red, siliclastic unit, inferred to be of last glacial age, appear to be several thousand years too old, probably because of a high proportion of reworked, refractory organic carbon in the pollen samples. Age-depth models for five piston cores and the Bear Lake drill core (BL00-1) were constructed by using two methods: quadratic equations and smooth cubic-splinefits. The two types of age models differ only in detail for individual cores, and each approach has its own advantages. Specific lithological horizons were dated in several cores and correlated among them, producing robust average ages for these horizons. The age of the correlated horizons in the red, siliclastic unit can be estimated from the age model for BL00-1, which is controlled by ages above and below the red, siliclastic unit. These ages were then transferred to the correlative horizons in the shorter piston cores, providing control for the sections of the age models in those cores in the red, siliclastic unit. These age models are the backbone for reconstructions of past environmental conditions in Bear Lake. In general, sedimentation rates in Bear Lake have been quite uniform, mostly between 0.3 and 0.8 mm yr-1 in the Holocene, and close to 0.5 mm yr-1 for the longer sedimentary record in the drill core from the deepest part of the lake. Copyright ?? 2009 The Geological Society of America.

  17. Bioenergetic evaluation of diel vertical migration by bull trout (Salvelinus confluentus) in a thermally stratified reservoir

    Science.gov (United States)

    Eckmann, Madeleine; Dunham, Jason B.; Connor, Edward J.; Welch, Carmen A.

    2018-01-01

    Many species living in deeper lentic ecosystems exhibit daily movements that cycle through the water column, generally referred to as diel vertical migration (DVM). In this study, we applied bioenergetics modelling to evaluate growth as a hypothesis to explain DVM by bull trout (Salvelinus confluentus) in a thermally stratified reservoir (Ross Lake, WA, USA) during the peak of thermal stratification in July and August. Bioenergetics model parameters were derived from observed vertical distributions of temperature, prey and bull trout. Field sampling confirmed that bull trout prey almost exclusively on recently introduced redside shiner (Richardsonius balteatus). Model predictions revealed that deeper (>25 m) DVMs commonly exhibited by bull trout during peak thermal stratification cannot be explained by maximising growth. Survival, another common explanation for DVM, may have influenced bull trout depth use, but observations suggest there may be additional drivers of DVM. We propose these deeper summertime excursions may be partly explained by an alternative hypothesis: the importance of colder water for gametogenesis. In Ross Lake, reliance of bull trout on warm water prey (redside shiner) for consumption and growth poses a potential trade-off with the need for colder water for gametogenesis.

  18. The relationship between young brown trout density and water quality in tributary streams to lakes in three acidic watersheds; Effekter av vannkvalitet og habitat paa tettheten av aureunger i tilloepsbekker til innsjoeer i tre forsuringsomraader

    Energy Technology Data Exchange (ETDEWEB)

    Hesthagen, Trygve; Larsen, Bjoern M.; Berger, Hans M.; Forseth, Torbjoern

    1998-09-01

    This publication examines the relationship between young brown trout densities in lake tributaries, and water chemistry and habitat variables. The study was carried out during the autumn in three acidic, freshwater river systems in western and southwestern Norway. The variability in brown trout density in the three watersheds in relation to varying concentrations of calcium and inorganic Al, were investigated. Water chemistry variables seem to limit the density. 38 refs., 3 figs., 5 tabs.

  19. Incorporating movement patterns to improve survival estimates for juvenile bull trout

    Science.gov (United States)

    Bowerman, Tracy; Budy, Phaedra

    2012-01-01

    Populations of many fish species are sensitive to changes in vital rates during early life stages, but our understanding of the factors affecting growth, survival, and movement patterns is often extremely limited for juvenile fish. These critical information gaps are particularly evident for bull trout Salvelinus confluentus, a threatened Pacific Northwest char. We combined several active and passive mark–recapture and resight techniques to assess migration rates and estimate survival for juvenile bull trout (70–170 mm total length). We evaluated the relative performance of multiple survival estimation techniques by comparing results from a common Cormack–Jolly–Seber (CJS) model, the less widely used Barker model, and a simple return rate (an index of survival). Juvenile bull trout of all sizes emigrated from their natal habitat throughout the year, and thereafter migrated up to 50 km downstream. With the CJS model, high emigration rates led to an extreme underestimate of apparent survival, a combined estimate of site fidelity and survival. In contrast, the Barker model, which allows survival and emigration to be modeled as separate parameters, produced estimates of survival that were much less biased than the return rate. Estimates of age-class-specific annual survival from the Barker model based on all available data were 0.218±0.028 (estimate±SE) for age-1 bull trout and 0.231±0.065 for age-2 bull trout. This research demonstrates the importance of incorporating movement patterns into survival analyses, and we provide one of the first field-based estimates of juvenile bull trout annual survival in relatively pristine rearing conditions. These estimates can provide a baseline for comparison with future studies in more impacted systems and will help managers develop reliable stage-structured population models to evaluate future recovery strategies.

  20. The effects of medieval dams on genetic divergence and demographic history in brown trout populations

    DEFF Research Database (Denmark)

    Hansen, Michael Møller; Limborg, Morten; Ferchaud, A.-L.

    2014-01-01

    Background: Habitat fragmentation has accelerated within the last century, but may have been ongoing over longer time scales. We analyzed the timing and genetic consequences of fragmentation in two isolated lake-dwelling brown trout populations. They are from the same river system (the Gudenå River......, Denmark) and have been isolated from downstream anadromous trout by dams established ca. 600-800 years ago. For reference, we included ten other anadromous populations and two hatchery strains. Based on analysis of 44 microsatellite loci we investigated if the lake populations have been naturally...... genetically differentiated from anadromous trout for thousands of years, or have diverged recently due to the establishment of dams. Results: Divergence time estimates were based on 1) Approximate Bayesian Computation and 2) a coalescent-based isolation-with-gene-flow model. Both methods suggested divergence...

  1. Consistency in trophic magnification factors of cyclic methyl siloxanes in pelagic freshwater food webs leading to brown trout.

    Science.gov (United States)

    Borgå, Katrine; Fjeld, Eirik; Kierkegaard, Amelie; McLachlan, Michael S

    2013-12-17

    Cyclic volatile methyl siloxanes (cVMS) concentrations were analyzed in the pelagic food web of two Norwegian lakes (Mjøsa, Randsfjorden), and in brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) collected in a reference lake (Femunden), in 2012. Lakes receiving discharge from wastewater treatment plants (Mjøsa and Randsfjorden) had cVMS concentrations in trout that were up to 2 orders of magnitude higher than those in Femunden, where most samples were close to the limit of quantification (LOQ). Food web biomagnification of cVMS in Mjøsa and Randsfjorden was quantified by estimation of trophic magnification factors (TMFs). TMF for legacy persistent organic pollutants (POPs) were analyzed for comparison. Both decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) biomagnified with TMFs of 2.9 (2.1-4.0) and 2.3 (1.8-3.0), respectively. Octamethylcyclotetrasiloxane (D4) was below the LOQ in the majority of samples and had substantially lower biomagnification than for D5 and D6. The cVMS TMFs did not differ between the lakes, whereas the legacy POP TMFs were higher in Mjøsa than inRandsfjorden. Whitefish had lower cVMS bioaccumulation compared to legacy POPs, and affected the TMF significance for cVMS, but not for POPs. TMFs of D5 and legacy contaminants in Lake Mjøsa were consistent with those previously measured in Mjøsa.

  2. Seasonally dynamic diel vertical migrations of Mysis diluviana, coregonine fishes, and siscowet lake trout in the pelagia of western Lake Superior

    Science.gov (United States)

    Ahrenstorff, Tyler D.; Hrabik, Thomas R.; Stockwell, Jason D.; Yule, Daniel L.; Sass, Greg G.

    2011-01-01

    Diel vertical migrations are common among many aquatic species and are often associated with changing light levels. The underlying mechanisms are generally attributed to optimizing foraging efficiency or growth rates and avoiding predation risk (μ). The objectives of this study were to (1) assess seasonal and interannual changes in vertical migration patterns of three trophic levels in the Lake Superior pelagic food web and (2) examine the mechanisms underlying the observed variability by using models of foraging, growth, and μ. Our results suggest that the opossum shrimp Mysis diluviana, kiyi Coregonus kiyi, and siscowet lake trout Salvelinus namaycush migrate concurrently during each season, but spring migrations are less extensive than summer and fall migrations. In comparison with M. diluviana, kiyis, and siscowets, the migrations by ciscoes C. artedi were not as deep in the water column during the day, regardless of season. Foraging potential and μ probably drive the movement patterns of M. diluviana, while our modeling results indicate that movements by kiyis and ciscoes are related to foraging opportunity and growth potential and receive a lesser influence from μ. The siscowet is an abundant apex predator in the pelagia of Lake Superior and probably undertakes vertical migrations in the water column to optimize foraging efficiency and growth. The concurrent vertical movement patterns of most species are likely to facilitate nutrient transport in this exceedingly oligotrophic ecosystem, and they demonstrate strong linkages between predators and prey. Fishery management strategies should use an ecosystem approach and should consider how altering the densities of long-lived top predators produces cascading effects on the nutrient cycling and energy flow in lower trophic levels.

  3. Bull Trout Population Assessment in the White Salmon and Klickitat Rivers, Columbia River Gorge, Washington, 2001 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Thiesfeld, Steven L.; McPeak, Ronald H.; McNamara, Brian S. (Washington Department of Fish and Wildlife); Honanie, Isadore (Confederated Tribes and Bands, Yakama Nation)

    2002-01-01

    We utilized night snorkeling and single pass electroshocking to determine the presence or absence of bull trout Salvelinus confluentus in 26 stream reaches (3,415 m) in the White Salmon basin and in 71 stream reaches (9,005 m) in the Klickitat River basin during summer and fall 2001. We did not find any bull trout in the White Salmon River basin. In the Klickitat River basin, bull trout were found only in the West Fork Klickitat River drainage. We found bull trout in two streams not previously reported: Two Lakes Stream and an unnamed tributary to Fish Lake Stream (WRIA code number 30-0550). We attempted to capture downstream migrant bull trout in the West Fork Klickitat River by fishing a 1.5-m rotary screw trap at RM 4.3 from July 23 through October 17. Although we caught other salmonids, no bull trout were captured. The greatest limiting factor for bull trout in the West Fork Klickitat River is likely the small amount of available habitat resulting in a low total abundance, and the isolation of the population. Many of the streams are fragmented by natural falls, which are partial or complete barriers to upstream fish movement. To date, we have not been able to confirm that the occasional bull trout observed in the mainstem Klickitat River are migrating upstream into the West Fork Klickitat River.

  4. Genetic Diversity and Hybridisation between Native and Introduced Salmonidae Fishes in a Swedish Alpine Lake.

    Directory of Open Access Journals (Sweden)

    Leanne Faulks

    Full Text Available Understanding the processes underlying diversification can aid in formulating appropriate conservation management plans that help maintain the evolutionary potential of taxa, particularly under human-induced activities and climate change. Here we assessed the microsatellite genetic diversity and structure of three salmonid species, two native (Arctic charr, Salvelinus alpinus and brown trout, Salmo trutta and one introduced (brook charr, Salvelinus fontinalis, from an alpine lake in sub-arctic Sweden, Lake Ånn. The genetic diversity of the three species was similar and sufficiently high from a conservation genetics perspective: corrected total heterozygosity, H'T = 0.54, 0.66, 0.60 and allelic richness, AR = 4.93, 5.53 and 5.26 for Arctic charr, brown trout and brook charr, respectively. There were indications of elevated inbreeding coefficients in brown trout (GIS = 0.144 and brook charr (GIS = 0.129 although sibling relationships were likely a confounding factor, as a high proportion of siblings were observed in all species within and among sampling locations. Overall genetic structure differed between species, Fst = 0.01, 0.02 and 0.04 in Arctic charr, brown trout and brook charr respectively, and there was differentiation at only a few specific locations. There was clear evidence of hybridisation between the native Arctic charr and the introduced brook charr, with 6% of individuals being hybrids, all of which were sampled in tributary streams. The ecological and evolutionary consequences of the observed hybridisation are priorities for further research and the conservation of the evolutionary potential of native salmonid species.

  5. Sea growth of anadromous brown trout (Salmo trutta)

    NARCIS (Netherlands)

    Leeuw, de J.J.; Hofstede, ter R.; Winter, H.V.

    2007-01-01

    Sea growth rates were studied in anadromous brown trout caught in Lake IJsselmeer, The Netherlands. Growth in the first year at sea was estimated at 26 cm from length-frequency distributions, and at 21 cm from back-calculated growth rates from scale readings. These estimates are considerably higher

  6. Lake Roosevelt fisheries monitoring program

    International Nuclear Information System (INIS)

    Griffith, J.R.; Scholz, A.T.

    1991-01-01

    The purpose of this study was to provide baseline data that could be used to evaluate the effectiveness of two kokanee salmon hatcheries that will produce 8 million kokanee salmon (Oncorhynchus nerka) fry or 3.2 million adults for stocking into Lake Roosevelt. The hatcheries will also produce 500,000 rainbow trout (Oncorhynchus mykiss) fingerlings to support the Lake Roosevelt net-pen programs. The baseline data will also be used to evaluate the effectiveness of the habitat improvement projects ongoing on a separate contract. At the present time, the principle sport fish in the reservoir are net-pen rainbow trout and walleye (Stizostedion vitreum). The objectives of the second year of the monitoring program were: (1) to determine angling pressure, catch per unit effort, total harvest and the economic value; (2) to determine relative abundance of fish species in the reservoir by conducting electrofishing and gillnet surveys at nine index stations during May, August, and October; (3) to determine growth rates of kokanee, rainbow trout, and walleye based upon backcalculations from scales collected during May, August and October and creel surveys; (4) to determine density, size, and biomass of zooplankton and how reservoir operations affect their population dynamics; (5) to determine feeding habits of kokanee, rainbow trout, and walleye and their preferred prey densities; and (6) to determine migration patterns of tagged walleye and net-pen rainbow trout. 118 refs., 20 figs., 98 tabs

  7. Are brown trout replacing or displacing bull trout populations in a changing climate?

    Science.gov (United States)

    Al-Chokhachy, Robert K.; Schmetterling, David A.; Clancy, Chris; Saffel, Pat; Kovach, Ryan; Nyce, Leslie; Liermann, Brad; Fredenberg, Wade A.; Pierce, Ron

    2016-01-01

    Understanding how climate change may facilitate species turnover is an important step in identifying potential conservation strategies. We used data from 33 sites in western Montana to quantify climate associations with native bull trout (Salvelinus confluentus) and non-native brown trout (Salmo trutta) abundance and population growth rates (λ). We estimated λ using exponential growth state space models and delineated study sites based on bull trout use for either Spawning and Rearing (SR) or Foraging, Migrating, and Overwintering (FMO) habitat. Bull trout abundance was negatively associated with mean August stream temperatures within SR habitat (r = -0.75). Brown trout abundance was generally highest at temperatures between 12 and 14°C. We found bull trout λ were generally stable at sites with mean August temperature below 10°C but significantly decreasing, rare, or extirpated at 58% of the sites with temperatures exceeding 10°C. Brown trout λ were highest in SR and sites with temperatures exceeding 12°C. Declining bull trout λs at sites where brown trout were absent suggests brown trout are likely replacing bull trout in a warming climate.

  8. Precision and relative effectiveness of a purse seine for sampling age-0 river herring in lakes

    Science.gov (United States)

    Devine, Matthew T.; Roy, Allison; Whiteley, Andrew R.; Gahagan, Benjamin I.; Armstrong, Michael P.; Jordaan, Adrian

    2018-01-01

    Stock assessments for anadromous river herring, collectively Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis, lack adequate demographic information, particularly with respect to early life stages. Although sampling adult river herring is increasingly common throughout their range, currently no standardized, field‐based, analytical methods exist for estimating juvenile abundance in freshwater lakes. The objective of this research was to evaluate the relative effectiveness and sampling precision of a purse seine for estimating densities of age‐0 river herring in freshwater lakes. We used a purse seine to sample age‐0 river herring in June–September 2015 and June–July 2016 in 16 coastal freshwater lakes in the northeastern USA. Sampling effort varied from two seine hauls to more than 50 seine hauls per lake. Catch rates were highest in June and July, and sampling precision was maximized in July. Sampling at night (versus day) in open water (versus littoral areas) was most effective for capturing newly hatched larvae and juveniles up to ca. 100 mm TL. Bootstrap simulation results indicated that sampling precision of CPUE estimates increased with sampling effort, and there was a clear threshold beyond which increased effort resulted in negligible increases in precision. The effort required to produce precise CPUE estimates, as determined by the CV, was dependent on lake size; river herring densities could be estimated with up to 10 purse‐seine hauls (one‐two nights) in a small lake (50 ha). Fish collection techniques using a purse seine as described in this paper are likely to be effective for estimating recruit abundance of river herring in freshwater lakes across their range.

  9. Temporary Restoration of Bull Trout Passage at Albeni Falls Dam

    Energy Technology Data Exchange (ETDEWEB)

    Paluch, Mark; Scholz, Allan; McLellan, Holly [Eastern Washington University Department of Biology; Olson, Jason [Kalispel Tribe of Indians Natural Resources Department

    2009-07-13

    This study was designed to monitor movements of bull trout that were provided passage above Albeni Falls Dam, Pend Oreille River. Electrofishing and angling were used to collect bull trout below the dam. Tissue samples were collected from each bull trout and sent to the U. S. Fish and Wildlife Service Abernathy Fish Technology Center Conservation Genetics Lab, Washington. The DNA extracted from tissue samples were compared to a catalog of bull trout population DNA from the Priest River drainage, Lake Pend Oreille tributaries, and the Clark Fork drainage to determine the most probable tributary of origin. A combined acoustic radio or radio tag was implanted in each fish prior to being transported and released above the dam. Bull trout relocated above the dam were able to volitionally migrate into their natal tributary, drop back downstream, or migrate upstream to the next dam. A combination of stationary radio receiving stations and tracking via aircraft, boat, and vehicle were used to monitor the movement of tagged fish to determine if the spawning tributary it selected matched the tributary assigned from the genetic analysis. Seven bull trout were captured during electrofishing surveys in 2008. Of these seven, four were tagged and relocated above the dam. Two were tagged and left below the dam as part of a study monitoring movements below the dam. One was immature and too small at the time of capture to implant a tracking tag. All four fish released above the dam passed by stationary receivers stations leading into Lake Pend Oreille and no fish dropped back below the dam. One of the radio tags was recovered in the tributary corresponding with the results of the genetic test. Another fish was located in the vicinity of its assigned tributary, which was impassable due to low water discharge at its mouth. Two fish have not been located since entering the lake. Of these fish, one was immature and not expected to enter its natal tributary in the fall of 2008. The other

  10. Climate change expands the spatial extent and duration of preferred thermal habitat for lake Superior fishes.

    Directory of Open Access Journals (Sweden)

    Timothy J Cline

    Full Text Available Climate change is expected to alter species distributions and habitat suitability across the globe. Understanding these shifting distributions is critical for adaptive resource management. The role of temperature in fish habitat and energetics is well established and can be used to evaluate climate change effects on habitat distributions and food web interactions. Lake Superior water temperatures are rising rapidly in response to climate change and this is likely influencing species distributions and interactions. We use a three-dimensional hydrodynamic model that captures temperature changes in Lake Superior over the last 3 decades to investigate shifts in habitat size and duration of preferred temperatures for four different fishes. We evaluated habitat changes in two native lake trout (Salvelinus namaycush ecotypes, siscowet and lean lake trout, Chinook salmon (Oncorhynchus tshawytscha, and walleye (Sander vitreus. Between 1979 and 2006, days with available preferred thermal habitat increased at a mean rate of 6, 7, and 5 days per decade for lean lake trout, Chinook salmon, and walleye, respectively. Siscowet lake trout lost 3 days per decade. Consequently, preferred habitat spatial extents increased at a rate of 579, 495 and 419 km(2 per year for the lean lake trout, Chinook salmon, and walleye while siscowet lost 161 km(2 per year during the modeled period. Habitat increases could lead to increased growth and production for three of the four fishes. Consequently, greater habitat overlap may intensify interguild competition and food web interactions. Loss of cold-water habitat for siscowet, having the coldest thermal preference, could forecast potential changes from continued warming. Additionally, continued warming may render more suitable conditions for some invasive species.

  11. Growth rate differences between resident native brook trout and non-native brown trout

    Science.gov (United States)

    Carlson, S.M.; Hendry, A.P.; Letcher, B.H.

    2007-01-01

    Between species and across season variation in growth was examined by tagging and recapturing individual brook trout Salvelinus fontinalis and brown trout Salmo trutta across seasons in a small stream (West Brook, Massachusetts, U.S.A.). Detailed information on body size and growth are presented to (1) test whether the two species differed in growth within seasons and (2) characterize the seasonal growth patterns for two age classes of each species. Growth differed between species in nearly half of the season- and age-specific comparisons. When growth differed, non-native brown trout grew faster than native brook trout in all but one comparison. Moreover, species differences were most pronounced when overall growth was high during the spring and early summer. These growth differences resulted in size asymmetries that were sustained over the duration of the study. A literature survey also indicated that non-native salmonids typically grow faster than native salmonids when the two occur in sympatry. Taken together, these results suggest that differences in growth are not uncommon for coexisting native and non-native salmonids. ?? 2007 The Authors.

  12. The effects of inbreeding on sperm quality traits in captive‐bred lake trout, Salvelinus namaycush (Walbaum, 1972)

    DEFF Research Database (Denmark)

    Johnson, K.; Butts, I. A. E.; Smith, J. L.

    2015-01-01

    The effects of inbreeding in both captive and wild‐caught species and populations have been reported to affect a wide variety of life history traits. Recently, the effects of inbreeding on reproductive traits such as sperm quality have become a subject of particular interest for conservation...... biology, evolutionary ecology, and management of captive populations. This study investigated the effects of inbreeding on sperm quality in a captive population of experimentally inbred and outbred lake trout, Salvelinus namaycush. It was found for moderately to highly inbred males (males with half......‐sib and full‐sib parents, respectively), that sperm quality traits (velocity, motility, linearity, longevity, spermatocrit and morphology) showed no apparent inbreeding depression. The apparent lack of inbreeding effects on sperm quality traits may be due to several factors including (i) no inbreeding...

  13. Agonistic behavior among three stocked trout species in a novel reservoir fish community

    Science.gov (United States)

    Budy, Phaedra; Hafen, Konrad

    2015-01-01

    The popularity of reservoirs to support sport fisheries has led to the stocking of species that did not co-evolve, creating novel reservoir fish communities. In Utah, the Bear Lake strain of Bonneville Cutthroat Trout Oncorhynchus clarkii utah and tiger trout (female Brown Trout Salmo trutta × male Brook Trout Salvelinus fontinalis) are being more frequently added to a traditional stocking regimen consisting primarily of Rainbow TroutO. mykiss. Interactions between these three predatory species are not well understood, and studies evaluating community interactions have raised concern for an overall decrease of trout condition. To evaluate the potential for negative interactions among these species, we tested aggression in laboratory aquaria using three-species and pairwise combinations at three densities. Treatments were replicated before and after feeding. During the three-species trials Rainbow Trout initiated 24.8 times more aggressive interactions than Cutthroat Trout and 10.2 times more aggressive interactions than tiger trout, and tiger trout exhibited slightly (1.9 times) more aggressive initiations than Cutthroat Trout. There was no significant difference in behavior before versus after feeding for any species, and no indication of increased aggression at higher densities. Although Rainbow Trout in aquaria may benefit from their bold, aggressive behavior, given observations of decreased relative survival in the field, these benefits may be outweighed in reservoirs, possibly through unnecessary energy expenditure and exposure to predators.

  14. Stocking strategy for the rehabilitation of a regulated brown trout (Salmo trutta L.) river

    International Nuclear Information System (INIS)

    Aass, P.

    1993-01-01

    Regulation of the catchment area of the Norwegian river Gudbrandsdalslaagen began in 1919. The lowermost power station on the main river was completed in 1964 and is situated about 10 km above the large Norwegian lake, Mjoesa. The lake is the foraging area of the Hunderstrain of brown trout, the fastest growing of all Norwegian trout. The running of the power plant has led to a severe reduction in water flows below the dam, and the most important spawning and nursery areas of the Hunder strain has been affected. The natural smolt production has been permanently reduced. The rehabilitation programme has included the construction of a fish ladder through the dam and a fixed minimum flow. A hatchery was built and a stocking programme using the local strain was implemented. The effect of stocking has been the easiest of the relief measures to evaluate. Hatchery reared fish constitute a growing share of the spawning population. During the last three years their share has been close to 60%. Reared fish constitute 30-40% of the trout caught in Lake Mjoesa. The average and best returns of tagged groups have been 25 and 50%, respectively, but return rates are highly dependent on release length and time and place of stocking. (Author)

  15. Spatial segregation of spawning habitat limits hybridization between sympatric native Steelhead and Coastal Cutthroat Trout

    Science.gov (United States)

    Buehrens, T.W.; Glasgow, J.; Ostberg, Carl O.; Quinn, T.P.

    2013-01-01

    Native Coastal Cutthroat Trout Oncorhynchus clarkii clarkii and Coastal Steelhead O. mykiss irideus hybridize naturally in watersheds of the Pacific Northwest yet maintain species integrity. Partial reproductive isolation due to differences in spawning habitat may limit hybridization between these species, but this process is poorly understood. We used a riverscape approach to determine the spatial distribution of spawning habitats used by native Coastal Cutthroat Trout and Steelhead as evidenced by the distribution of recently emerged fry. Molecular genetic markers were used to classify individuals as pure species or hybrids, and individuals were assigned to age-classes based on length. Fish and physical habitat data were collected in a spatially continuous framework to assess the relationship between habitat and watershed features and the spatial distribution of parental species and hybrids. Sampling occurred in 35 reaches from tidewaters to headwaters in a small (20 km2) coastal watershed in Washington State. Cutthroat, Steelhead, and hybrid trout accounted for 35%, 42%, and 23% of the fish collected, respectively. Strong segregation of spawning areas between Coastal Cutthroat Trout and Steelhead was evidenced by the distribution of age-0 trout. Cutthroat Trout were located farther upstream and in smaller tributaries than Steelhead were. The best predictor of species occurrence at a site was the drainage area of the watershed that contributed to the site. This area was positively correlated with the occurrence of age-0 Steelhead and negatively with the presence of Cutthroat Trout, whereas hybrids were found in areas occupied by both parental species. A similar pattern was observed in older juveniles of both species but overlap was greater, suggesting substantial dispersal of trout after emergence. Our results offer support for spatial reproductive segregation as a factor limiting hybridization between Steelhead and Coastal Cutthroat Trout.

  16. Bull trout population assessment in the White Salmon and Klickitat Rivers, Columbia River Gorge, Washington; ANNUAL fiscal year 2001 annual report

    International Nuclear Information System (INIS)

    Thiesfield, Steven L.

    2002-01-01

    We utilized night snorkeling and single pass electroshocking to determine the presence or absence of bull trout Salvelinus confluentus in 26 stream reaches (3,415 m) in the White Salmon basin and in 71 stream reaches (9,005 m) in the Klickitat River basin during summer and fall 2001. We did not find any bull trout in the White Salmon River basin. In the Klickitat River basin, bull trout were found only in the West Fork Klickitat River drainage. We found bull trout in two streams not previously reported: Two Lakes Stream and an unnamed tributary to Fish Lake Stream (WRIA code number 30-0550). We attempted to capture downstream migrant bull trout in the West Fork Klickitat River by fishing a 1.5-m rotary screw trap at RM 4.3 from July 23 through October 17. Although we caught other salmonids, no bull trout were captured. The greatest limiting factor for bull trout in the West Fork Klickitat River is likely the small amount of available habitat resulting in a low total abundance, and the isolation of the population. Many of the streams are fragmented by natural falls, which are partial or complete barriers to upstream fish movement. To date, we have not been able to confirm that the occasional bull trout observed in the mainstem Klickitat River are migrating upstream into the West Fork Klickitat River

  17. Kootenai River fisheries investigations. Chapter 3: Mainstem habitat use and recruitment estimates of rainbow trout in the Kootenai River, Idaho. Annual report 1996

    International Nuclear Information System (INIS)

    Fredericks, J.; Hendricks, S.

    1997-09-01

    The objective of this study was to determine if recruitment is limiting the population of rainbow trout Oncorhynchus mykiss in the mainstem Kootenai River. The authors used snorkeling and electrofishing techniques to estimate juvenile rainbow trout density and total numbers in Idaho tributaries, and they trapped juvenile outmigrants to identify the age at which juvenile trout migrate from tributaries to the Kootenai River. The authors radio and reward-tagged post-spawn adult rainbow trout captured in Deep Creek to identify river reach and habitat used by those fish spawning and rearing in the Deep Creek drainage. They also conducted redd surveys in the Kootenai River to determine the extent of mainstem spawning. Based on the amount of available habitat and juvenile rainbow trout densities, the Deep Creek drainage was the most important area for juvenile production. Population estimates of age 0, age 1+, and age 2+ rainbow trout indicated moderate to high densities in several streams in the Deep Creek drainage whereas other streams, such as Deep Creek, had very low densities of juvenile trout. The total number of age 0, age 1+, and age 2+ rainbow trout in Deep Creek drainage in 1996 was estimated to be 63,743, 12,095, and 3,095, respectively. Radio telemetry efforts were hindered by the limited range of the transmitters, but movements of a radio-tagged trout and a returned reward tag indicated that at least a portion of the trout utilizing the Deep Creek drainage migrated downriver from the mouth of Deep Creek to the meandering section of river. They found no evidence of mainstem spawning by rainbow trout, but redd counting efforts were hindered by high flows from mid-April through June

  18. Evaluation of an Unsuccessful Brook Trout Electrofishing Removal Project in a Small Rocky Mountain Stream.

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Kevin A.; Lamansky, Jr., James A.; Schill, Daniel J.

    2006-01-26

    In the western United States, exotic brook trout Salvelinus fontinalis frequently have a deleterious effect on native salmonids, and biologists often attempt to remove brook trout from streams by means of electrofishing. Although the success of such projects typically is low, few studies have assessed the underlying mechanisms of failure, especially in terms of compensatory responses. A multiagency watershed advisory group (WAG) conducted a 3-year removal project to reduce brook trout and enhance native salmonids in 7.8 km of a southwestern Idaho stream. We evaluated the costs and success of their project in suppressing brook trout and looked for brook trout compensatory responses, such as decreased natural mortality, increased growth, increased fecundity at length, and earlier maturation. The total number of brook trout removed was 1,401 in 1998, 1,241 in 1999, and 890 in 2000; removal constituted an estimated 88% of the total number of brook trout in the stream in 1999 and 79% in 2000. Although abundance of age-1 and older brook trout declined slightly during and after the removals, abundance of age-0 brook trout increased 789% in the entire stream 2 years after the removals ceased. Total annual survival rate for age-2 and older brook trout did not decrease during the removals, and the removals failed to produce an increase in the abundance of native redband trout Oncorhynchus mykiss gairdneri. Lack of a meaningful decline and unchanged total mortality for older brook trout during the removals suggest that a compensatory response occurred in the brook trout population via reduced natural mortality, which offset the removal of large numbers of brook trout. Although we applaud WAG personnel for their goal of enhancing native salmonids by suppressing brook trout via electrofishing removal, we conclude that their efforts were unsuccessful and suggest that similar future projects elsewhere over such large stream lengths would be costly, quixotic enterprises.

  19. Sex-specific vitellogenin production in immature rainbow trout

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, D.B.; Williams, D.E.

    1999-10-01

    Many xenobiotics interact with hormone systems of animals, potentially leading to a phenomenon commonly called endocrine disruption. Much attention has focused on steroid hormone systems and corresponding receptor proteins, particularly estrogens. Vitellogenin (Vg) was measured in sexually immature rainbow trout (Oncorhynchus mykiss) exposed to 17{beta}-estradiol (E{sub 2}) in the diet. Mixed-sex populations of trout aged 3, 6, 12, or 18 months were maintained separately and fed E{sub 2} at 0.05 or 2.5 mg/kg for 7d. Females fed E{sub 2} at 0.05 mg/kg consistently produced three- to fourfold greater amounts of Vg than similarly aged males. Age- and sex-matched fish fed E{sub 2} at 2.5 mg/kg produced equivalent amounts of Vg. Sex differences in Vg production were apparent only at a dose of E{sub 2} (0.05 mg/kg) that results in submaximal Vg induction. Their results document the importance of considering the sex of juvenile fish when using Vg production as a marker of xenoestrogen exposure.

  20. The effects of chronological age and size on toxicity of zinc to juvenile brown trout

    Science.gov (United States)

    A series of toxicity tests were conducted to investigate the role of chronological age and organism weight on zinc tolerance in juvenile brown trout (Salmo trutta). Four different incubation temperatures were used to control the maturation of the juveniles prior to zinc exposure...

  1. Congener Patterns of Persistent Organic Pollutants Establish the Extent of Contaminant Biotransport by Pacific Salmon in the Great Lakes.

    Science.gov (United States)

    Gerig, Brandon S; Chaloner, Dominic T; Janetski, David J; Rediske, Richard R; O'Keefe, James P; Moerke, Ashley H; Lamberti, Gary A

    2016-01-19

    In the Great Lakes, introduced Pacific salmon (Oncorhynchus spp.) can transport persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), to new environments during their spawning migrations. To explore the nature and extent of POP biotransport by salmon, we compared 58 PCB and 6 PBDE congeners found in spawning salmon directly to those in resident stream fish. We hypothesized that stream fish exposed to salmon spawners would have congener patterns similar to those of salmon, the presumed contaminant source. Using permutational multivariate analysis of variance (PERMANOVA) and nonmetric multidimensional scaling (NMDS), we found that POP congener patterns of Pacific salmon varied among regions in the Great Lakes basin (i.e., Lake Huron, Lake Michigan, or Lake Superior), tissue type (whole fish or eggs), and contaminant type (PCB or PBDE). For stream-resident fish, POP congener pattern was influenced by the presence of salmon, location (i.e., Great Lakes Basin), and species identity (i.e., brook trout [Salvelinus fontinalis] or mottled sculpin [Cottus bairdii]). Similarity in congener patterns indicated that salmon are a source of POPs to brook trout in stream reaches receiving salmon spawners from Lake Michigan and Lake Huron but not from Lake Superior. Congener patterns of mottled sculpin differed from those of brook trout and salmon, suggesting that brook trout and mottled sculpin either use salmon tissue to differing degrees, acquire POPs from different dietary sources, or bioaccumulate or metabolize POPs differently. Overall, our analyses identified the important role of salmon in contaminant biotransport but also demonstrated that the extent of salmon-mediated POP transfer and uptake in Great Lakes tributaries is location- and species-specific.

  2. Determination of radiocarbon reservoir age of Lake Van by mineral magnetic and geochemical analysis

    Science.gov (United States)

    Makaroglu, Ozlem; Namik Cagatay, M.; Pesonen, Lauri J.; Orbay, Naci

    2017-04-01

    Lake Van is the largest soda lake in the world, located on the east Anatolian Plateau in Turkey. Its varved sediments provide an excellent archive of high-resolution paleoclimate record for the Near East. Varve counting and radiocarbon methods are therefore important dating techniques for investigating the Lake Van sedimentary paleoclimate record. In here we present detailed magnetic and geochemical record of Lake Van. We have studied 4.56 m (core VP0801) and 4.70 m (core VP0807) long cores recovered from 80 m and 65 m water depths located in SE and SW of Lake Van, respectively. Here, we have benefited from magnetic properties with associated remanent magnetization of the sediments from Lake Van to correlate the cores which contain of tephra layers. The cores cover the last 8.4 ka and lithologically include three laminated sedimentary units. From top to the bottom, the units were dated 4.2 ka BP-present, 5.4-4.2 ka BP and older than 5.4 ka BP. We identified tephra layers previously dated by varve counting, and used the varve ages to obtain age models for the cores. We also obtained a total of eight Accelerator Mass Spectrometry (AMS) 14C dates from total organic carbon (TOC) in the two cores, close to the tephra layers. Comparison of the varve ages of the AMS 14C dated samples with their corresponding AMS 14C dates indicates large differences, suggesting significant reservoir ages that range from 2.8 to 2.5 ka for 3.0-2.4 varve ka BP and from 2.8 to 3.3 ka for 8.0-5.9 varve ka BP. The results suggest that the reservoir age of the organic matter increases with the varve age of the sediments. This increase is mainly related to the rate of supply of "dead" carbon from the old carbonate rocks in the watershed of Lake Van, which was relatively higher during 8.4-5.9 ka than during 3.0-2.4 ka BP because of the higher atmospheric precipitation and higher rate of biochemical weathering during the former period.

  3. South Fork Flathead Watershed Westslope Cutthroat Trout Conservation Program, Annual Report 2002.

    Energy Technology Data Exchange (ETDEWEB)

    Grisak, Grant; Marotz, Brian

    2003-06-01

    In 1999, Montana Fish, Wildlife & Parks (MFWP) began a program aimed at conserving the genetically pure populations of westslope cutthroat trout in the South Fork Flathead River drainage. The objective of this program is to eliminate all of the exotic and hybrid trout that threaten the genetically pure westslope cutthroat populations in the South Fork Flathead. The exotic and hybrid trout populations occur in several headwater lakes and their outflow streams. In 2001 MFWP released a draft environmental assessment, pursuant to the Montana Environmental Policy Act (MEPA), that addressed the use of motorized equipment to deliver personnel and materials to some of these lakes in the Bob Marshall and Great Bear Wildernesses (Grisak 2001). After a 30-day public comment period, MFWP determined that the complexity of issues was too great and warranted a more detailed analysis. These issues included transportation options for personnel, equipment and materials, the use of motorized equipment in wilderness, fish removal methods, fish stocking, and the status and distribution of amphibian populations in the project area. Because the program also involves the U.S. Forest Service (USFS) and Bonneville Power Administration (BPA), the environmental analysis needs to comply with the National Environmental Policy Act (NEPA). In October 2001, pursuant to NEPA, MFWP, along with the USFS and BPA initiated an environmental assessment to address these issues. In June 2002, the three agencies determined that the scope of these issues warranted an Environmental Impact Statement. This specialist report describes the logistical, technical and biological issues associated with this project and provides an analysis of options for fish removal, transportation and fish stocking. It further analyzes issues and concerns associated with amphibian populations and creating new domesticated stocks of westslope cutthroat trout. Finally, this document provides a description of each lake, the best

  4. Lake Roosevelt fisheries and limnological research. Annual report 1996

    International Nuclear Information System (INIS)

    Cichosz, T.A.; Shields, J.P.; Underwood, K.D.; Scholz, A.; Tilson, M.B.

    1997-05-01

    The Lake Roosevelt Monitoring/Data Collection Program resulted from a merger between the Lake Roosevelt Monitoring Program and the Lake Roosevelt Data Collection Project. This project will model biological responses to reservoir operations, evaluate the effects of releasing hatchery origin kokanee salmon and rainbow trout on the fishery, and evaluate the success of various stocking strategies. In 1996, limnological, reservoir operation, zooplankton, and tagging data were collected. Mean reservoir elevation, storage volume and water retention time were reduced in 1996 relative to the last five years. In 1996, Lake Roosevelt reached a yearly low of 1,227 feet above mean sea level in April, a yearly high of 1,289 feet in July, and a mean yearly reservoir elevation of 1,271.4 feet. Mean monthly water retention times in Lake Roosevelt during 1996 ranged from 15.7 days in May to 49.2 days in October. Average zooplankton densities and biomass were lower in 1996 than 1995. Daphnia spp. and total zooplankton densities peaked during the summer, whereas minimum densities occurred during the spring. Approximately 300,000 kokanee salmon and 400,000 rainbow trout were released into Lake Roosevelt in 1996. The authors estimated 195,628 angler trips to Lake Roosevelt during 1996 with an economic value of $7,629,492

  5. Lake Roosevelt Fisheries and Limnological Research : 1996 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Cichosz, Thomas A.; Underwood, Keith D.; Shields, John; Scholz, Allan; Tilson, Mary Beth

    1997-05-01

    The Lake Roosevelt Monitoring/Data Collection Program resulted from a merger between the Lake Roosevelt Monitoring Program and the Lake Roosevelt Data Collection Project. This project will model biological responses to reservoir operations, evaluate the effects of releasing hatchery origin kokanee salmon and rainbow trout on the fishery, and evaluate the success of various stocking strategies. In 1996, limnological, reservoir operation, zooplankton, and tagging data were collected. Mean reservoir elevation, storage volume and water retention time were reduced in 1996 relative to the last five years. In 1996, Lake Roosevelt reached a yearly low of 1,227 feet above mean sea level in April, a yearly high of 1,289 feet in July, and a mean yearly reservoir elevation of 1,271.4 feet. Mean monthly water retention times in Lake Roosevelt during 1996 ranged from 15.7 days in May to 49.2 days in October. Average zooplankton densities and biomass were lower in 1996 than 1995. Daphnia spp. and total zooplankton densities peaked during the summer, whereas minimum densities occurred during the spring. Approximately 300,000 kokanee salmon and 400,000 rainbow trout were released into Lake Roosevelt in 1996. The authors estimated 195,628 angler trips to Lake Roosevelt during 1996 with an economic value of $7,629,492.

  6. Movement and survival of brown trout and rainbow trout in an ozark tailwater river

    Science.gov (United States)

    Quinn, J.W.; Kwak, T.J.

    2011-01-01

    We evaluated the movement of adult brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss in relation to a catch-andrelease area in the White River downstream from Beaver Dam, Arkansas. Nine fish of each species were implanted with radio transmitters and monitored from July 1996 to July 1997. The 1.5- km river length of a catch-and-release area (closed to angler harvest) was greater than the total linear range of 72% of the trout (13 of 18 fish), but it did not include two brown trout spawning riffles, suggesting that it effectively protects resident fish within the catch-and-release area except during spawning. The total detected linear range of movement varied from 172 to 3,559 m for brown trout and from 205 to 3,023mfor rainbow trout. The movements of both species appeared to be generally similar to that in unregulated river systems. The annual apparent survival of both trout species was less than 0.40, and exploitation was 44%.Management to protect fish on spawning riffles may be considered if management for wild brown trout becomes a priority. ?? American Fisheries Society 2011.

  7. Origin of fin-clipped salmonids collected at two thermal discharges on Lake Michigan

    International Nuclear Information System (INIS)

    Romberg, G.P.; Thommes, M.M.; Spigarelli, S.A.

    1974-01-01

    Fin clips observed on fish collected during tagging studies at the Point Beach and Waukegan thermal discharges were recorded and the data were tabulated by species. Using fin clip and fish size, attempts were made to identify probable stocking locations and dates from agency records. Data are presented for lake trout, rainbow trout, brown trout, and Coho salmon. Tables are presented to show probable stocking locations and dates

  8. Age determination of bottom sediments from Lake Hovsgol, Mongolia

    International Nuclear Information System (INIS)

    Ito, Kazumi; Nakamura, Toshio; Duller, Geoff; Hasebe, Noriko; Kashiwaya, Kenji

    2013-01-01

    Dating plays a key role in determining past environmental changes in lake sediments cores. The feldspar post-IR infrared stimulated luminescence (IRSL) procedure is one of the IRSL procedures and has a great potential to date older samples compared to quartz optically stimulated luminescence (OSL). In this study, the post-IR IRSL (pIRIR) procedure was applied to the polymineral fine grained sediments from Lake Khuvsgul (Hovsgol), Mongolia, and these ages were compared to 14 C ages of bulk samples from the certain depths. The pIRIR ages are always younger than 14 C ages from bulk samples, however, it was possible to construct the suitable age model based on luminescence and 14 C ages. Therefore, pIRIR 225 protocol can be contributed to estimate the sedimentation age of lake sediments as well as 14 C dating. (author)

  9. Mercury levels in herring gulls and fish: 42 years of spatio-temporal trends in the Great Lakes.

    Science.gov (United States)

    Blukacz-Richards, E Agnes; Visha, Ariola; Graham, Matthew L; McGoldrick, Daryl L; de Solla, Shane R; Moore, David J; Arhonditsis, George B

    2017-04-01

    Total mercury levels in aquatic birds and fish communities have been monitored across the Canadian Great Lakes by Environment and Climate Change Canada (ECCC) for the past 42 years (1974-2015). These data (22 sites) were used to examine spatio-temporal variability of mercury levels in herring gull (Larus argentatus) eggs, lake trout (Salvelinus namaycush), walleye (Sander vitreus), and rainbow smelt (Osmerus mordax). Trends were quantified with dynamic linear models, which provided time-variant rates of change of mercury concentrations. Lipid content (in both fish and eggs) and length in fish were used as covariates in all models. For the first three decades, mercury levels in gull eggs and fish declined at all stations. In the 2000s, trends for herring gull eggs reversed at two sites in Lake Erie and two sites in Lake Ontario. Similar trend reversals in the 2000s were observed for lake trout in Lake Superior and at a single station in Lake Ontario. Mercury levels in lake trout continued to slowly decline at all of the remaining stations, except for Lake Huron, where the levels remained stable. A post-hoc Bayesian regression analysis suggests strong trophic interactions between herring gulls and rainbow smelt in Lake Superior and Lake Ontario, but also pinpoints the likelihood of a trophic decoupling in Lake Huron and Lake Erie. Continued monitoring of mercury levels in herring gulls and fish is required to consolidate these trophic shifts and further evaluate their broader implications. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  10. Summer habitat use by Columbia River redband trout in the Kootenai River drainage, Montana

    Science.gov (United States)

    Muhlfeld, Clint C.; Bennett, David H.

    2001-01-01

    The reported decline in the abundance, distribution, and genetic diversity of Columbia River redband trout Oncorhynchus mykiss gairdneri (a rainbow trout subspecies) has prompted fisheries managers to investigate their habitat requirements, identify critical habitat, and develop effective conservation and recovery programs. We analyzed the microhabitat, mesohabitat, and macrohabitat use and distribution of Columbia River redband trout by means of snorkel surveys in two watersheds in the Kootenai River drainage, Montana and Idaho, during the summers of 1997 and 1998. Juvenile (36–125 mm total length, TL) and adult (>=126 mm TL) fish preferred deep microhabitats (>=0.4 m) with low to moderate velocities (thalweg. Conversely, age-0 (<=35 mm) fish selected slow water (<=0.1 m/s) and shallow depths (<=0.2 m) located in lateral areas of the channel. Age-0, juvenile, and adult fish strongly selected pool mesohabitats and avoided riffles; juveniles and adults generally used runs in proportion to their availability. At the macrohabitat scale, density of Columbia River redband trout (35 mm) was positively related to the abundance of pools and negatively related to stream gradient. The pool: riffle ratio, gradient, and stream size combined accounted for 80% of the variation in density among 23 stream reaches in five streams. Our results demonstrate that low-gradient, medium-elevation reaches with an abundance of complex pools are critical areas for the production of Columbia River redband trout. These data will be useful in assessing the impacts of land-use practices on the remaining populations and may assist with habitat restoration or enhancement efforts.

  11. VITELLOGENIN GENE EXPRESSION IN FATHEAD MINNOWS EXPOSED TO EE2 IN A WHOLE LAKE DOSING EXPERIMENT

    Science.gov (United States)

    A whole-lake endocrine disruption experiment was conducted by Fisheries and Oceans Canada at the Experimental Lakes Area (ELA), northwestern Ontario in 2001 and 2002. This experiment examined population, organism, biochemical and cellular-level effects in lake trout, white sucke...

  12. Ionoregulatory disruption as the acute toxic mechanism for lead in the rainbow trout (Oncorhynchus mykiss)

    International Nuclear Information System (INIS)

    Rogers, J.T.; Richards, J.G.; Wood, C.M.

    2003-01-01

    The mechanism for acute toxicity of lead (Pb) in rainbow trout (Oncorhynchus mykiss) was investigated at Pb concentrations close to the 96 h LC50 of 1.0 mg dissolved Pb l -1 (0.8-1.4, 95% C.I.) determined in dechlorinated Hamilton city tap water (from Lake Ontario, hardness=140 mg l -1 CaCO 3 ). Tissue Pb accumulation associated with death was highest in the gill, followed by kidney and liver. Significant ionoregulatory impacts were observed in adult rainbow trout (200-300 g) fitted with indwelling dorsal aortic catheters and exposed to 1.1±0.04 mg dissolved Pb l -1 . Decreased plasma [Ca 2+ ], [Na + ] and [Cl - ] occurred after 48 h of exposure through to 120 h, with increases in plasma [Mg 2+ ], ammonia, and cortisol. No marked changes in PaO 2 , PaCO 2 , pH, glucose, or hematological parameters were evident. Branchial Na + /K + ATPase activity in juvenile trout exposed to concentrations close to the 96 h LC50 was inhibited by approximately 40% after 48 h of Pb exposure. Calcium ion flux measurements using 45 Ca as a radiotracer showed 65% inhibition of Ca 2+ influx after 0, 12, 24 or 48 h exposure to the 96 h LC50 concentration of Pb. There was also significant inhibition (40-50%) of both Na + and Cl - uptake, measured with 22 Na and 36 Cl simultaneously. We conclude that the mechanism of acute toxicity for Pb in rainbow trout occurs by ionoregulatory disruption rather than respiratory or acid/base distress at Pb concentrations close to the 96 h LC50 in moderately hard water

  13. Microsatellite analyses of the trout of northwest Mexico

    Science.gov (United States)

    Nielsen, J.L.; Sage, G.K.

    2001-01-01

    The trout of northwest Mexico represent an undescribed group of fish considered part of the Oncorhynchus mykiss (Pacific trout) complex of species and subspecies. Recent genetic studies have shown these fish to have important genetic diversity and a unique evolutionary history when compared to coastal rainbow trout. Increased levels of allelic diversity have been found in this species at the southern extent of its range. In this study we describe the trout in the Sierra Madre Occidental from the rios Yaqui, Mayo, Casas Grandes and de Bavispe, and their relationship to the more southern distribution of Mexican golden trout (O. chrysogaster) using 11 microsatellite loci. Microsatellite allelic diversity in Mexican trout was high with a mean of 6.6 alleles/locus, average heterozygosity = 0.35, and a mean Fst = 0.43 for all loci combined. Microsatellite data were congruent with previously published mtDNA results showing unique panmictic population structure in the Rio Yaqui trout that differs from Pacific coastal trout and Mexican golden trout. These data also add support for the theory of headwaters transfer of trout across the Continental Divide from tributaries of the Rio de Bavispe into the Rio Casas Grandes. Rio Mayo trout share a close genetic relationship to trout in Rio Yaqui, but sample sizes from the Rio Mayo prevent significant comparisons in this study. Microsatellite analyses show significant allelic frequency differences between Rio Yaqui trout and O. chrysogaster in Sinaloa and Durango Mexico, adding further support for a unique evolutionary status for this group of northwestern Mexican trout.

  14. Simulation of climate-change effects on streamflow, lake water budgets, and stream temperature using GSFLOW and SNTEMP, Trout Lake Watershed, Wisconsin

    Science.gov (United States)

    Hunt, Randall J.; Walker, John F.; Selbig, William R.; Westenbroek, Stephen M.; Regan, R. Steve

    2013-01-01

    Although groundwater and surface water are considered a single resource, historically hydrologic simulations have not accounted for feedback loops between the groundwater system and other hydrologic processes. These feedbacks include timing and rates of evapotranspiration, surface runoff, soil-zone flow, and interactions with the groundwater system. Simulations that iteratively couple the surface-water and groundwater systems, however, are characterized by long run times and calibration challenges. In this study, calibrated, uncoupled transient surface-water and steady-state groundwater models were used to construct one coupled transient groundwater/surface-water model for the Trout Lake Watershed in north-central Wisconsin, USA. The computer code GSFLOW (Ground-water/Surface-water FLOW) was used to simulate the coupled hydrologic system; a surface-water model represented hydrologic processes in the atmosphere, at land surface, and within the soil-zone, and a groundwater-flow model represented the unsaturated zone, saturated zone, stream, and lake budgets. The coupled GSFLOW model was calibrated by using heads, streamflows, lake levels, actual evapotranspiration rates, solar radiation, and snowpack measurements collected during water years 1998–2007; calibration was performed by using advanced features present in the PEST parameter estimation software suite. Simulated streamflows from the calibrated GSFLOW model and other basin characteristics were used as input to the one-dimensional SNTEMP (Stream-Network TEMPerature) model to simulate daily stream temperature in selected tributaries in the watershed. The temperature model was calibrated to high-resolution stream temperature time-series data measured in 2002. The calibrated GSFLOW and SNTEMP models were then used to simulate effects of potential climate change for the period extending to the year 2100. An ensemble of climate models and emission scenarios was evaluated. Downscaled climate drivers for the period

  15. Determination of niclosamide residues in rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) fillet tissue by high-performance liquid chromatography

    Science.gov (United States)

    Schreier, Theresa M.; Dawson, V.K.; Cho, Yirang; Spanjers, N.J.; Boogaard, M.A.

    2000-01-01

    Bayluscide [the ethanolamine salt of niclosamide (NIC)] is a registered piscicide used in combination with 3-(trifluoromethyl)-4-nitrophenol (TFM) to control sea lamprey populations in streams tributary to the Great Lakes. A high-performance liquid chromatography (HPLC) method was developed for the determination of NIC residues in muscle fillet tissues of fish exposed to NIC and TFM during sea lamprey control treatments. NIC was extracted from fortified channel catfish and rainbow trout fillet tissue with a series of acetone extractions and cleaned up on C-18 solid-phase extraction cartridges. NIC concentrations were determined by HPLC with detection at 360 and 335 nm for rainbow trout and catfish, respectively. Recovery of NIC from rainbow trout (n = 7) fortified at 0.04 mu g/g was 77 +/- 6.5% and from channel catfish (n = 7) fortified at 0.02 mu g/g was 113 +/- 11%. NIC detection limit was 0.0107 mu g/g for rainbow trout and 0.0063 mu g/g for catfish. Percent recovery of incurred radioactive residues by this method from catfish exposed to [C-14]NIC was 89.3 +/- 4.1%. Percent recoveries of NIC from fortified storage stability tissue samples for rainbow trout (n = 3) analyzed at 5 and 7.5 month periods were 78 +/- 5.1 and 68 +/- 2.4%, respectively. Percent recoveries of NIC from fortified storage stability tissue samples for channel catfish (n = 3) analyzed at 5 and 7.5 month periods were 88 +/- 13 and 76 +/- 21%, respectively.

  16. Whirling disease among snake river cutthroat trout in two spring streams in Wyoming

    Science.gov (United States)

    Hubert, W.A.; Joyce, M.P.; Gipson, R.; Zafft, D.; Money, D.; Hawk, D.; Taro, B.

    2002-01-01

    We assessed endemic age-0 cutthroat trout Oncorhynchus clarki for evidence of pathology associated with Myxobolus cerebralis in two streams formed by springs in western Wyoming. We hypothesized that the location of spawning sites in spring streams would affect the extent of exposure of cutthroat trout fry to M. cerebralis triactinomyxons (tams), occurrence of the parasite in their bodies, and clinical signs of whirling disease. The spring streams were warm relative to nearby streams flowing from the mountains or spawning and emergence of fry was early compared with fish in mountain streams. Tams were abundant early in the summer and clinical signs of whirling disease among age-0 fish were seen as early as mid-June in one stream. There were high densities of tams in one stream, and densities declined with upstream progression from May through July, whereas in the other stream, low densities of tams were observed in the downstream portion early in the summer, and they were not detected in July and August. Age-0 cutthroat trout were abundant; clinical signs of whirling disease were evident, and histological evidence of whirling disease was common in the stream where tams were abundant. Low densities of age-0 cutthroat trout and no clinical signs of whirling disease were observed in the stream where tams were not abundant. Among sentinel fish in the stream with abundant tams, we found extensive occurrence of M. cerebralis, with many fish showing clinical signs and histological evidence of pathology associated with M. cerebralis. The proportion of sentinel fish with clinical and histological signs of whirling disease decreased with upstream progression. In the stream with low tam, densities sentinel fish became infected with M. cerebralis, but there were essentially no clinical signs or histological indications of whirling disease. ?? 2002 by the American Fisheries Society.

  17. Wigwam River Juvenile Bull Trout and Fish Habitat Monitoring Program : 2002 Data Report.

    Energy Technology Data Exchange (ETDEWEB)

    Cope, R.S. [Westslope Fisheries, Cranbrook, BC, Canada

    2003-03-01

    The Wigwam River bull trout (Salvelinus confluentus) and fish habitat monitoring program is a trans-boundary initiative implemented by the British Columbia Ministry of Water, Land, and Air Protection (MWLAP), in cooperation with Bonneville Power Administration (BPA). The Wigwam River is an important fisheries stream located in southeastern British Columbia that supports healthy populations of both bull trout and Westslope cutthroat trout (Figure 1). This river has been characterized as the single most important bull trout spawning stream in the Kootenay Region (Baxter and Westover 2000, Cope 1998). In addition, the Wigwam River supports some of the largest Westslope cutthroat trout (Oncorhynchus clarki lewisi) in the Kootenay Region. These fish are highly sought after by anglers (Westover 1999a, 1999b). Bull trout populations have declined in many areas of their range within Montana and throughout the northwest including British Columbia. Bull trout were blue listed as vulnerable in British Columbia by the B.C. Conservation Data Center (Cannings 1993) and although there are many healthy populations of bull trout in the East Kootenay they remain a species of special concern. Bull trout in the United States portion of the Columbia River were listed as threatened in 1998 under the Endangered Species Act by the U.S. Fish and Wildlife Service. The upper Kootenay River is within the Kootenai sub-basin of the Mountain Columbia Province, one of the eleven Eco-provinces that make up the Columbia River Basin. MWLAP applied for and received funding from BPA to assess and monitor the status of wild, native stocks of bull trout in tributaries to Lake Koocanusa (Libby Reservoir) and the upper Kootenay River. This task is one of many that were undertaken to ''Monitor and Protect Bull Trout for Koocanusa Reservoir'' (BPA Project Number 2000-04-00).

  18. Admixture analysis of stocked brown trout populations using mapped microsatellite DNA markers: indigenous trout persist in introgressed populations

    DEFF Research Database (Denmark)

    Hansen, Michael Møller; Mensberg, Karen-Lise Dons

    2009-01-01

    , but resolution is low if genetic differentiation is weak. Here, we analyse stocked brown trout populations represented by historical (1943-1956) and contemporary (2000s) samples, where genetic differentiation between wild populations and stocked trout is weak (pair-wise F-ST of 0.047 and 0.053). By analysing...... a high number of microsatellite DNA markers (50) and making use of linkage map information, we achieve clear identification of admixed and non-admixed trout. Moreover, despite strong population-level admixture by hatchery strain trout in one of the populations (70.8%), non-admixed individuals...... nevertheless persist (7 out of 53 individuals). These remnants of the indigenous population are characterized by later spawning time than the majority of the admixed individuals. We hypothesize that isolation by time mediated by spawning time differences between wild and hatchery strain trout is a major factor...

  19. Recent changes in the deep-water fish populations of Lake Michigan

    Science.gov (United States)

    Moffett, James W.

    1957-01-01

    The deep-water fish fauna of Lake Michigan consisted of lake trout (Salvelinus namaycush), burbot (Lota lota maculosa), seven species of chubs or deep-water ciscoes (Leucichthys spp.), and the deep-water sculpin (Myoxocephalus quadricornis). Other species occupied the deep-water zone but were not typically part of the fauna.

  20. Status and trends of the Lake Huron deepwater demersal fish ommunity, 2008

    Science.gov (United States)

    Roseman, Edward F.; O'Brien, Timothy P.; Riley, Stephen C.; Farha, Steve A.; French, John R.

    2009-01-01

    The U.S.Geological Survey Great Lakes Science Center has conducted trawl surveys to assess annual changes in the deepwater demersal fish community of Lake Huron since 1973. Since 1992, surveys have been carried out using a 21 m wing trawl towed on-contour at depths ranging from 9 to 110 m on fixed transects. Sample sites include five ports in U.S. waters with less frequent sampling near Goderich, Ontario. The 2008 fall bottom trawl survey was carried out between October 24 and November 20, 2008 and sampled only the three northern U.S. ports at DeTour, Hammond Bay, and Alpena due to mechanical problems with the research vessel and prolonged periods of bad weather. Therefore, all data presented for 2008 are based on samples collected from these ports. Compared to previous years, alewife populations in Lake Huron remain at low levels after collapsing in 2004. Age-0 alewife density and biomass appears to have increased slightly but overall levels remain near the nadir observed in 2004. Density and biomass of adult and juvenile rainbow smelt showed a decrease from 2007 despite record-high abundance of juveniles observed in 2005, suggesting recruitment was low. Numbers of adult and juvenile bloater were low despite recent high year-classes. Abundances for most other prey species were similar to the low levels observed in 2005 - 2007. We captured one wild juvenile lake trout in 2008 representing the fifth consecutive year that wild lake trout were captured in the survey. Based on pairwise graphical comparisons and nonparametric correlation analyses, dynamics of prey abundance at the three northern ports followed lakewide trends since 1992. Density of benthic macroinvertebrates was at an all-time low in 2008 since sampling began in 2001. The decline in abundance was due to decreases in all taxonomic groups and a large reduction in recruitment of quagga mussels. Density of Diporeia at northern ports in 2008 was the lowest observed. Diporeia were found only at 73-m sites of

  1. Resource Partitioning in Food, Space and Time between Arctic Charr (Salvelinus alpinus), Brown Trout (Salmo trutta) and European Whitefish (Coregonus lavaretus) at the Southern Edge of Their Continuous Coexistence.

    Science.gov (United States)

    Jensen, Hallvard; Kiljunen, Mikko; Knudsen, Rune; Amundsen, Per-Arne

    2017-01-01

    Arctic charr and European whitefish are considered to be strong competitors in lakes, with the latter usually being the superior species. However, high niche plasticity and lake morphometry may suggestively facilitate resource partitioning and coexistence between charr and whitefish. Here, we explore the trophic niche utilization (diet and habitat use) of charr and whitefish co-occurring with brown trout in the deep and oligotrophic Lake Fyresvatnet, southern Norway (59°05'N, 8°10'E). Using CPUE, stomach contents and stable isotope analyses, a distinct resource partitioning was revealed between brown trout and the other two species. Brown trout typically occupied the littoral zone, feeding on benthic invertebrates, surface insects and small-sized whitefish. In contrast, charr and whitefish were predominantly zooplanktivorous, but diverged somewhat in habitat utilization as charr shifted seasonally between the profundal and the littoral zone, whereas whitefish were found in the upper water layers (littoral and pelagic habitats). Accordingly, the stable isotope values of carbon (δ13C) reflected a pelagic orientated prey resource use for both charr and whitefish, whereas brown trout had elevated carbon and nitrogen (δ15N) signatures that reflected their benthivore and piscivore diet, respectively. The findings suggest that charr may not rely upon the profundal zone as a feeding habitat but as a refuge area, and may coexist with whitefish if a third competitive and predatory species like brown trout co-occur in the lake. The study indicates that a general high habitat plasticity of Arctic charr may be essential in the presently observed coexistence with a competitively superior fish species like whitefish, and that a third fish species like brown trout may facilitate this particular fish community structure.

  2. Ionoregulatory disruption as the acute toxic mechanism for lead in the rainbow trout (Oncorhynchus mykiss)

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.T.; Richards, J.G.; Wood, C.M

    2003-07-16

    The mechanism for acute toxicity of lead (Pb) in rainbow trout (Oncorhynchus mykiss) was investigated at Pb concentrations close to the 96 h LC50 of 1.0 mg dissolved Pb l{sup -1} (0.8-1.4, 95% C.I.) determined in dechlorinated Hamilton city tap water (from Lake Ontario, hardness=140 mg l{sup -1} CaCO{sub 3}). Tissue Pb accumulation associated with death was highest in the gill, followed by kidney and liver. Significant ionoregulatory impacts were observed in adult rainbow trout (200-300 g) fitted with indwelling dorsal aortic catheters and exposed to 1.1{+-}0.04 mg dissolved Pb l{sup -1}. Decreased plasma [Ca{sup 2+}], [Na{sup +}] and [Cl{sup -}] occurred after 48 h of exposure through to 120 h, with increases in plasma [Mg{sup 2+}], ammonia, and cortisol. No marked changes in PaO{sub 2}, PaCO{sub 2}, pH, glucose, or hematological parameters were evident. Branchial Na{sup +}/K{sup +} ATPase activity in juvenile trout exposed to concentrations close to the 96 h LC50 was inhibited by approximately 40% after 48 h of Pb exposure. Calcium ion flux measurements using {sup 45}Ca as a radiotracer showed 65% inhibition of Ca{sup 2+} influx after 0, 12, 24 or 48 h exposure to the 96 h LC50 concentration of Pb. There was also significant inhibition (40-50%) of both Na{sup +} and Cl{sup -} uptake, measured with {sup 22}Na and {sup 36}Cl simultaneously. We conclude that the mechanism of acute toxicity for Pb in rainbow trout occurs by ionoregulatory disruption rather than respiratory or acid/base distress at Pb concentrations close to the 96 h LC50 in moderately hard water.

  3. Plump Cutthroat Trout and Thin Rainbow Trout in a Lentic Ecosystem

    OpenAIRE

    Courtney, Joshua; Abbott, Jessica; Schmidt, Kerri; Courtney, Michael

    2012-01-01

    Background: Much has been written about introduced rainbow trout (Oncorhynchus mykiss) interbreeding and outcompeting cutthroat trout (Oncorhynchus clarkii). However, the specific mechanisms by which rainbow trout and their hybrids outcompete cutthroat trout have not been thoroughly explored, and the published data is limited to lotic ecosystems. Materials and Methods: Samples of rainbow trout and cutthroat trout were obtained from a lentic ecosystem by angling. The total length and weight of...

  4. Wigwam River juvenile bull trout and fish habitat monitoring program: 2000 data report; TOPICAL

    International Nuclear Information System (INIS)

    Cope, R.S.; Morris, K.J.

    2001-01-01

    The Wigwam River bull trout (Salvelinus confluentus) and fish habitat monitoring program is a trans-boundary initiative implemented by the British Columbia Ministry of Environment, Lands and Parks (MOE), in cooperation with Bonneville Power Administration (BPA). The Wigwam River is an important fisheries stream located in southeastern British Columbia that supports healthy populations of both bull trout and Westslope cutthroat trout (Figure 1.1). This river has been characterized as the single most important bull trout spawning stream in the Kootenay Region (Baxter and Westover 2000, Cope 1998). In addition, the Wigwam River supports some of the largest Westslope cutthroat trout (Oncorhynchus clarki lewisi) in the Kootenay Region. These fish are highly sought after by anglers (Westover 1999a, 1999b). Bull trout populations have declined in many areas of their range within Montana and throughout the northwest including British Columbia. Bull trout were blue listed as vulnerable in British Columbia by the B.C. Conservation Data Center (Cannings 1993) and although there are many healthy populations of bull trout in the East Kootenays they remain a species of special concern. Bull trout in the United States portion of the Columbia River were listed as threatened in 1998 under the Endangered Species Act by the U.S. Fish and Wildlife Service. The upper Kootenay River is within the Kootenai sub-basin of the Mountain Columbia Province, one of the eleven Eco-provinces that make up the Columbia River Basin. MOE applied for and received funding from BPA to assess and monitor the status of wild, native stocks of bull trout in tributaries to Lake Koocanusa (Libby Reservoir) and the upper Kootenay River. This task is one of many that was undertaken to ''Monitor and Protect Bull Trout for Koocanusa Reservoir'' (BPA Project Number 2000-04-00)

  5. Hypervariability of ribosomal DNA at multiple chromosomal sites in lake trout (Salvelinus namaycush).

    Science.gov (United States)

    Zhuo, L; Reed, K M; Phillips, R B

    1995-06-01

    Variation in the intergenic spacer (IGS) of the ribosomal DNA (rDNA) of lake trout (Salvelinus namaycush) was examined. Digestion of genomic DNA with restriction enzymes showed that almost every individual had a unique combination of length variants with most of this variation occurring within rather than between populations. Sequence analysis of a 2.3 kilobase (kb) EcoRI-DraI fragment spanning the 3' end of the 28S coding region and approximately 1.8 kb of the IGS revealed two blocks of repetitive DNA. Putative transcriptional termination sites were found approximately 220 bases (b) downstream from the end of the 28S coding region. Comparison of the 2.3-kb fragments with two longer (3.1 kb) fragments showed that the major difference in length resulted from variation in the number of short (89 b) repeats located 3' to the putative terminator. Repeat units within a single nucleolus organizer region (NOR) appeared relatively homogeneous and genetic analysis found variants to be stably inherited. A comparison of the number of spacer-length variants with the number of NORs found that the number of length variants per individual was always less than the number of NORs. Examination of spacer variants in five populations showed that populations with more NORs had more spacer variants, indicating that variants are present at different rDNA sites on nonhomologous chromosomes.

  6. BIOMASS AND DENSITY OF BROWN AND RAINBOW TROUT IN NEW MEXICO STREAMS

    Directory of Open Access Journals (Sweden)

    Srečko Lainer

    1995-03-01

    Full Text Available Mean stream numerical density of the brown trout (Salmo trutta m. fario Linnaeus, 1758 and the rainbow trout (Onchorhynchus mykiss Walbaum, 1792 was 0.090 fish/m2 of which brown trout averaged 69% (72% in total biomass in 15 high-elevation New Mexico streams (1,661-2,560 m above sea level. Total trout density varied from 0.008/m2 in 1988 and 1989. Mean trout density ranged between 0.023-0.121 fish/m2 at site s open to public fishing. Considerably higher densities (0.142-0.409 fish/m2 were observed at sites closed for fishing. In the seven selected streams shared by both species, brown trout density exceeded rainbow trout density except at the two sites closed to fishing. Brown trout were stocked only as fingerlings (average 7,000 fish/stream/year while rainbow trout were stocked only in harvestable sizes (11,000 fish/stream/year. Reported total trout yield rates exceeded the total number of fish estimated to be in the stream by 1.01 to 11.63 in most small streams open to fishing. The proportional stock density (PSD ranged between O and 50 percent. Streams with low to moderate intensities of fishing had the highest PSD.

  7. Molecular analysis of population genetic structure and recolonization of rainbow trout following the Cantara spill

    Science.gov (United States)

    Nielsen, J.L.; Heine, Erika L.; Gan, Christina A.; Fountain, Monique C.

    2000-01-01

    Mitochondrial DNA (mtDNA) sequence and allelic frequency data for 12 microsatellite loci were used to analyze population genetic structure and recolonization by rainbow trout, Oncorhynchus mykiss, following the 1991 Cantara spill on the upper Sacramento River, California. Genetic analyses were performed on 1,016 wild rainbow trout collected between 1993 and 1996 from the mainstem and in 8 tributaries. Wild trout genotypes were compared to genotypes for 79 Mount Shasta Hatchery rainbow trout. No genetic heterogeneity was found 2 years after the spill (1993) between tributary populations and geographically proximate mainstem fish, suggesting recolonization of the upper mainstem directly from adjacent tributaries. Trout collections made in 1996 showed significant year-class genetic variation for mtDNA and microsatellites when compared to fish from the same locations in 1993. Five years after the spill, mainstem populations appeared genetically mixed with no significant allelic frequency differences between mainstem populations and geographically proximate tributary trout. In our 1996 samples, we found no significant genetic differences due to season of capture (summer or fall) or sampling technique used to capture rainbow trout, with the exception of trout collected by electrofishing and hook and line near Prospect Avenue. Haplotype and allelic frequencies in wild rainbow trout populations captured in the upper Sacramento River and its tributaries were found to differ genetically from Mount Shasta Hatchery trout for both years, with the notable exception of trout collected in the lower mainstem river near Shasta Lake, where mtDNA and microsatellite data both suggested upstream colonization by hatchery fish from the reservoir. These data suggest that the chemical spill in the upper Sacramento River produced significant effects over time on the genetic population structure of rainbow trout throughout the entire upper river basin.

  8. Lake Ontario: Food web dynamics in a changing ecosystem (1970-2000)

    Science.gov (United States)

    Mills, E.L.; Casselman, J.M.; Dermott, R.; Fitzsimons, J.D.; Gal, G.; Holeck, K. T.; Hoyle, J.A.; Johannsson, O.E.; Lantry, B.F.; Makarewicz, J.C.; Millard, E.S.; Munawar, I.F.; Munawar, M.; O'Gorman, R.; Owens, R.W.; Rudstam, L. G.; Schaner, T.; Stewart, T.J.

    2003-01-01

    We examined stressors that have led to profound ecological changes in the Lake Ontario ecosystem and its fish community since 1970. The most notable changes have been reductions in phosphorus loading, invasion by Dreissena spp., fisheries management through stocking of exotic salmonids and control of sea lamprey (Petromyzon marinus), and fish harvest by anglers and double-crested cormorants (Phalacrocorax auritus). The response to these stressors has led to (i) declines in both algal photosynthesis and epilimnetic zooplankton production, (ii) decreases in alewife (Alosa pseudoharengus) abundance, (iii) declines in native Diporeia and lake whitefish (Coregonus clupeaformis), (iv) behavioral shifts in alewife spatial distribution benefitting native lake trout (Salvelinus namaycush), threespine stickleback (Gasterosteus aculeatus), and emerald shiner (Notropis atherinoides) populations, (v) dramatic increases in water clarity, (vi) predation impacts by cormorants on select fish species, and (vii) lake trout recruitment bottlenecks associated with alewife-induced thiamine deficiency. We expect stressor responses associated with anthropogenic forces like exotic species invasions and global climate warming to continue to impact the Lake Ontario ecosystem in the future and recommend continuous long-term ecological studies to enhance scientific understanding and management of this important resource.

  9. Mutagenic effect of sewage waters of the Ignalina NPP on the cells of sea-trout

    International Nuclear Information System (INIS)

    Stasiunaite, P.

    1996-01-01

    Using a developing embryos of sea-trout as a test-object, the mutagenicity of water in the first biotope of Lake Drukshiai as well as in industrial and rain water sewer pipe was evaluated. Artesian water was used as a control one. The mutagenic potential of water in station 1 of Lake Drukshiai approximately made up 8.1% and statistically did not differ from the control (7.0%). The effect of water of station 7 upon the inherited embryonic cells was significantly greater, average frequency of chromosome aberration reaching 27.3%. The analysis of the obtained data showed that industrial - rain sewage water constantly penetrating into Lake Drukshiai may significantly worsen its ecological situation, i.e. to increase the accumulation of mutations in the communities and their amount in the succeeding generations. The genotoxicity of water of the 1 st biotope of Lake Drukshiai, which is the farthest point from the Ignalina NPP, may be used as a control when investigating the mutagenic impact of water of other biotopes in the lake, especially in the stations located at the shortest distance from the energetic objects. 8 refs., 1 tab

  10. Investigations of Bull Trout (Salvelinus Confluentus), Steelhead Trout (Oncorhynchus Mykiss), and Spring Chinook Salmon (O. Tshawytscha) Interactions in Southeast Washington Streams : 1991 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Steven W.

    1992-07-01

    Bull trout (Salvelinus confluentus) are native to many tributaries of the Snake River in southeast Washington. The Washington Department of Wildlife (WDW) and the American Fisheries Society (AFS) have identified bull trout as a species of special concern which means that they may become threatened or endangered by relatively, minor disturbances to their habitat. Steelhead trout/rainbow trout (Oncorhynchus mykiss) and spring chinook salmon (O.tshawytscha) are also native to several tributaries of the Snake river in southeast Washington. These species of migratory fishes are depressed, partially due to the construction of several dams on the lower Snake river. In response to decreased run size, large hatchery program were initiated to produce juvenile steelhead and salmon to supplement repressed tributary stocks, a practice known as supplementation. There is a concern that supplementing streams with artificially high numbers of steelhead and salmon may have an impact on resident bull trout in these streams. Historically, these three species of fish existed together in large numbers, however, the amount of high-quality habitat necessary for reproduction and rearing has been severely reduced in recent years, as compared to historic amounts. The findings of the first year of a two year study aimed at identifying species interactions in southeast Washington streams are presented in this report. Data was collected to assess population dynamics; habitat utilization and preference, feeding habits, fish movement and migration, age, condition, growth, and the spawning requirements of bull trout in each of four streams. A comparison of the indices was then made between the study streams to determine if bull trout differ in the presence of the putative competitor species. Bull trout populations were highest in the Tucannon River (supplemented stream), followed by Mill Creek (unsupplemented stream). Young of the year bull trout utilized riffle and cascade habitat the most in all

  11. Sensitivity of Trout to Chronic Acute Exposure to Selenium

    DEFF Research Database (Denmark)

    Nielsen, Gunnar Gissel; Nielsen, M. Gissel

    1978-01-01

    Trout were exposed to selenite (Na2SeO3) solutions of varying concentrations (0.1-100 ppm Se) for periods of up to 4 wk. A chronic exposure to 0.1 ppm Se or less is non-lethal to trout. Lethality at higher concentrations depends on the length of exposure. Trout that survive for 10 days in tap...

  12. Mutagenic and DNA damaging activity in muscle of trout exposed in vivo to nitrite

    Energy Technology Data Exchange (ETDEWEB)

    De Flora, S; Arillo, A

    1983-09-01

    Muscle ether extracts of rainbow trout (Salmo gairdneri) exposed to lake water enriched with nitrite (450 micrograms/l) reverted plasmid-containing his- strains of Salmonella typhimurium, mainly eliciting frameshift mutations, and induced a DNA damage in Escherichia coli reparable through the recA/lexA-dependent SOS functions. The number of revertants was related to their content in nitroso-derivatives and to the physiological condition of the fish. Mutagenicity was efficiently decreased, through NADPH-requiring pathways, by liver S-9 fractions from rats or rainbow trout, while it was not affected by preliminary heating nor by pre-incubation with human gastric juice.

  13. Lake-0: A model for the simulation of nuclides transfer in lake scenarios

    International Nuclear Information System (INIS)

    Garcia-Olivares, A.; Aguero, A.; Pinedo, P.

    1994-01-01

    This report presents documentation and a user's manual for the program LAKE-0, a mathematical model of nuclides transfer in lake scenarios. Mathematical equations and physical principles used to develop the code are presented in section 2. The program use is presented in section 3 including input data sets and output data. Section 4 presents two example problems, and some results. The complete program listing including comments is presented in Appendix A. Nuclides are assumed to enter the lake via atmospheric deposition and carried by the water runoff and the dragged sediments from the adjacent catchment. The dynamics of the nuclides inside the lake is based in the model proposed by Codell (11) as modified in (5). The removal of concentration from the lake water is due to outflow from the lake and to the transfer of activity to the bottom sediments. The model has been applied to the Esthwaite Water (54 degree 21 minute N, 03 degree 00 minute W at 65 m. asl.) in the frame of the VAMP Aquatic Working Group (8) and to Devoke Water (54 degree 21 minute 5'N, 03 degree, 18 minute W at 230 m. asl.)

  14. LAKE-0: a model for the simulation of nuclides transfer in lake scenarios

    International Nuclear Information System (INIS)

    Garcia-Olivares, A.; Aguero, A.; Pinedo, P.

    1994-01-01

    This report presents documentation and a user's manual for the program LAKE-0, a mathematical model of nuclides transfer in lake scenarios. Mathematical equations and physical principles used to develop the code are presented in section 2. The program use is presented in section 3 including input data sets and output data. Section 4 presents two example problems, and some results. The complete program listing including comments is presented in Appendix A. Nuclides are assumed to center the lake via atmospheric deposition and carried by the water runoff and the dragged sediments from the adjacent catchment. The dynamics of the nuclides inside the lake is based in the model proposed by Codell (11) as modified in (5). The removal of concentration from the lake water is due to out flow from the lake and to the transfer of activity to the button sediments. The model has been applied to the Esthwaite Water (54 degree celsius 2 l'N, 03 degree celsius 00'W at 65 m. asi.) in the frame of the VAMP Aquatic Working Group (8) and to Devoke Water (5 21.5'N, 03H8'W at 230 m. asi.). (Author). 13 refs

  15. Broad-scale patterns of Brook Trout responses to introduced Brown Trout in New York

    Science.gov (United States)

    McKenna, James E.; Slattery, Michael T.; Kean M. Clifford,

    2013-01-01

    Brook Trout Salvelinus fontinalis and Brown Trout Salmo trutta are valuable sport fish that coexist in many parts of the world due to stocking introductions. Causes for the decline of Brook Trout within their native range are not clear but include competition with Brown Trout, habitat alteration, and repetitive stocking practices. New York State contains a large portion of the Brook Trout's native range, where both species are maintained by stocking and other management actions. We used artificial neural network models, regression, principal components analysis, and simulation to evaluate the effects of Brown Trout, environmental conditions, and stocking on the distribution of Brook Trout in the center of their native range. We found evidence for the decline of Brook Trout in the presence of Brown Trout across many watersheds; 22% of sampled reaches where both species were expected to occur contained only Brown Trout. However, a model of the direct relationship between Brook Trout and Brown Trout abundance explained less than 1% of data variation. Ordination showed extensive overlap of Brook Trout and Brown Trout habitat conditions, with only small components of the hypervolume (multidimensional space) being distinctive. Subsequent analysis indicated higher abundances of Brook Trout in highly forested areas, while Brown Trout were more abundant in areas with relatively high proportions of agriculture. Simulation results indicated that direct interactions and habitat conditions were relatively minor factors compared with the effects of repeated stocking of Brown Trout into Brook Trout habitat. Intensive annual stocking of Brown Trout could eliminate resident Brook Trout in less than a decade. Ecological differences, harvest behavior, and other habitat changes can exacerbate Brook Trout losses. Custom stocking scenarios with Brown Trout introductions at relatively low proportions of resident Brook Trout populations may be able to sustain healthy populations of both

  16. Wigwam River juvenile bull trout and fish habitat monitoring program : 2001 data report

    International Nuclear Information System (INIS)

    Cope, R.S.; Morris, K.J.; Bisset, J.E.

    2002-01-01

    The Wigwam River juvenile bull trout and fish habitat monitoring program is a co-operative initiative of the British Columbia Ministry of Water, Land, and Air Protection and Bonneville Power Administration. The Wigwam River has been characterized as the single most important bull trout spawning stream in the Kootenay Region. This report provides a summary of results obtained during the second year (2001) of the juvenile bull trout enumeration and fish habitat assessment program. This project was commissioned in planning for fish habitat protection and forest development within the upper Wigwam River valley. The broad intent is to develop a better understanding of juvenile bull trout and Westslope cutthroat trout recruitment and the ongoing hydrologic and morphologic processes in the upper Wigwam River, especially as they relate to spawning and rearing habitat quality. Five permanent sampling sites were established August 2000 in the Wigwam river drainage (one site on Bighorn Creek and four sites on the mainstem Wigwam River). At each site, juvenile (0(sup+), 1(sup+) and 2(sup+) age classes) fish densities and stream habitat conditions were measured over two stream meander wavelengths. Bull trout represented 95.1% of the catch and the mean density of juvenile bull trout was estimated to be 20.7 fish/100m(sup 2) (range 0.9 to 24.0 fish/100m(sup 2)). This compares to 17.2 fish/100m(sup 2) (+20%) for the previous year. Fry (0(sup+)) dominated the catch and this was a direct result of juvenile bull trout ecology and habitat partitioning among life history stages. Site selection was biased towards sample sites which favored high bull trout fry capture success. Comparison of fry density estimates replicated across both the preliminary survey (1997) and the current study (Cope and Morris 2001) illustrate the stable nature of these high densities. Bull trout populations have been shown to be extremely susceptible to habitat degradation and over-harvest and are ecologically

  17. Patterns of hybridization of nonnative cutthroat trout and hatchery rainbow trout with native redband trout in the Boise River, Idaho

    Science.gov (United States)

    Neville, Helen M.; Dunham, Jason B.

    2011-01-01

    Hybridization is one of the greatest threats to native fishes. Threats from hybridization are particularly important for native trout species as stocking of nonnative trout has been widespread within the ranges of native species, thus increasing the potential for hybridization. While many studies have documented hybridization between native cutthroat trout Oncorhynchus clarkii and nonnative rainbow trout O. mykiss, fewer have focused on this issue in native rainbow trout despite widespread threats from introductions of both nonnative cutthroat trout and hatchery rainbow trout. Here, we describe the current genetic (i.e., hybridization) status of native redband trout O. mykiss gairdneri populations in the upper Boise River, Idaho. Interspecific hybridization was widespread (detected at 14 of the 41 sampled locations), but high levels of hybridization between nonnative cutthroat trout and redband trout were detected in only a few streams. Intraspecific hybridization was considerably more widespread (almost 40% of sampled locations), and several local populations of native redband trout have been almost completely replaced with hatchery coastal rainbow trout O. mykiss irideus; other populations exist as hybrid swarms, some are in the process of being actively invaded, and some are maintaining genetic characteristics of native populations. The persistence of some redband trout populations with high genetic integrity provides some opportunity to conserve native genomes, but our findings also highlight the complex decisions facing managers today. Effective management strategies in this system may include analysis of the specific attributes of each site and population to evaluate the relative risks posed by isolation versus maintaining connectivity, identifying potential sites for control or eradication of nonnative trout, and long-term monitoring of the genetic integrity of remaining redband trout populations to track changes in their status.

  18. LAKE-0: a model for the simulation of nuclides transfer in lake scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Olivares, A.; Aguero, A.; Pinedo, P.

    1994-07-01

    This report presents documentation and a user's manual for the program LAKE-0, a mathematical model of nuclides transfer in lake scenarios. Mathematical equations and physical principles used to develop the code are presented in section 2. The program use is presented in section 3 including input data sets and output data. Section 4 presents two example problems, and some results. The complete program listing including comments is presented in Appendix A. Nuclides are assumed to center the lake via atmospheric deposition and carried by the water runoff and the dragged sediments from the adjacent catchment. The dynamics of the nuclides inside the lake is based in the model proposed by Codell (11) as modified in (5). The removal of concentration from the lake water is due to out flow from the lake and to the transfer of activity to the button sediments. The model has been applied to the Esthwaite Water (54 degree celsius 2 l'N, 03 degree celsius 00'W at 65 m. asi.) in the frame of the VAMP Aquatic Working Group (8) and to Devoke Water (5 21.5'N, 03H8'W at 230 m. asi.). (Author). 13 refs.

  19. Post Audit of Lake Michigan Lake Trout PCB Model Forecasts

    Science.gov (United States)

    The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

  20. Erosion of interspecific reproductive barriers resulting from hatchery supplementation of rainbow trout sympatric with cutthroat trout.

    Science.gov (United States)

    Docker, Margaret F; Dale, Angie; Heath, Daniel D

    2003-12-01

    The frequency of hybridization between cutthroat (Onchorhynchus clarki clarki) and rainbow (O. mykiss irideus) trout from coastal habitats in British Columbia, Canada, was examined in seven populations where the two species are sympatric with no history of rainbow trout stocking and compared with areas where native rainbow trout populations have been supplemented with hatchery fish (three populations). Four nuclear markers were used to identify each species and interspecific hybrids and one mitochondrial marker showed the direction of gene exchange between species. The frequency of hybrids was significantly higher (Fisher exact test, P < 0.001) in river systems where hatchery rainbow trout have been introduced (50.6% hybrids) than in populations where the two species naturally co-occur without supplementation (9.9% hybrids).

  1. Radioactive contamination of fishes in lake and streams impacted by the Fukushima nuclear power plant accident

    International Nuclear Information System (INIS)

    Yoshimura, Mayumi; Yokoduka, Tetsuya

    2014-01-01

    The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in March 2011 emitted radioactive substances into the environment, contaminating a wide array of organisms including fishes. We found higher concentrations of radioactive cesium ( 137 Cs) in brown trout (Salmo trutta) than in rainbow trout (Oncorhynchus nerka), and 137 Cs concentrations in brown trout were higher in a lake than in a stream. Our analyses indicated that these differences were primarily due to differences in diet, but that habitat also had an effect. Radiocesium concentrations ( 137 Cs) in stream charr (Salvelinus leucomaenis) were higher in regions with more concentrated aerial activity and in older fish. These results were also attributed to dietary and habitat differences. Preserving uncontaminated areas by remediating soils and releasing uncontaminated fish would help restore this popular fishing area but would require a significant effort, followed by a waiting period to allow activity concentrations to fall below the threshold limits for consumption. - Highlight: • Concentration of 137 Cs in brown trout was higher than in rainbow trout. • 137 Cs concentration of brown trout in a lake was higher than in a stream. • 137 Cs concentration of stream charr was higher in region with higher aerial activity. • Concentration of 137 Cs in stream charr was higher in older fish. • Difference of contamination among fishes was due to difference in diet and habitat

  2. Ontogenetic dynamics of infection with Diphyllobothrium spp. cestodes in sympatric Arctic charr Salvelinus alpinus (L.) and brown trout Salmo trutta L.

    Science.gov (United States)

    Henrickson, Eirik H.; Knudsen, Rune; Kristoffersen, Roar; Kuris, Armand M.; Lafferty, Kevin D.; Siwertsson, Anna; Amundsen, Per-Arne

    2016-01-01

    The trophic niches of Arctic charr and brown trout differ when the species occur in sympatry. Their trophically transmitted parasites are expected to reflect these differences. Here, we investigate how the infections of Diphyllobothrium dendriticum and D. ditremum differ between charr and trout. These tapeworms use copepods as their first intermediate hosts and fish can become infected as second intermediate hosts by consuming either infected copepods or infected fish. We examined 767 charr and 368 trout for Diphyllobothrium plerocercoids in a subarctic lake. The prevalence of D. ditremum was higher in charr (61.5%) than in trout, (39.5%), but the prevalence of D. dendriticum was higher in trout (31.2%) than in charr (19.3%). Diphyllobothrium spp. intensities were elevated in trout compared to charr, particularly for D. dendriticum. Large fish with massive parasite burdens were responsible for the high Diphyllobothrium spp. loads in trout. We hypothesize that fish prey may be the most important source for the Diphyllobothrium spp. infections in trout, whereas charr predominantly acquire Diphyllobothrium spp. by feeding on copepods. Our findings support previous suggestions that the ability to establish in a second piscine host is greater for D. dendriticum than for D. ditremum.

  3. Northern reservoirs as sinks for Chernobyl cesium: sustained accumulation via introduced Mysis relicta in arctic char and brown trout

    International Nuclear Information System (INIS)

    Hammar, J.

    1991-01-01

    Fallout radiocesium from the Chernobyl accident caused extensive contamination in a region of previously well studied alpine lake ecosystems in northern Sweden. Levels of Cs-137 in the barren catchment basins reached 20-50 kBq/m 2 during 1986. The distribution and major transport mechanisms of radiocesium through the lake ecosystems have been studied during 1986-1990. Levels of Cs-137 in water, sediment, and different trophic levels of the food chains of Arctic char (Salvelinus alphinus) and brown trout (Salmo trutta) were monitored in a series of natural lakes and lake reservoirs, with or without the introduced new fish food organisms, Mysis relicta. The reservoirs were found to act as sinks for radiocesium with extensive accumulation recorded in water, sediment, invertebrates and salmonids. The introduced Mysis relicta were enhancing the transport of Cs-137 from zooplankton and settling particles to Arctic char and brown trout. The results suggest a successive change in transport of radiocesium from water via zooplankton to planktivorous fish during the early summer of 1986 to post-depositional mobilization via benthic organisms to benthic fish in successive years. (au) (32 refs.)

  4. Hybridization dynamics between Colorado's native cutthroat trout and introduced rainbow trout.

    Science.gov (United States)

    Metcalf, Jessica L; Siegle, Matthew R; Martin, Andrew P

    2008-01-01

    Newly formed hybrid populations provide an opportunity to examine the initial consequences of secondary contact between species and identify genetic patterns that may be important early in the evolution of hybrid inviability. Widespread introductions of rainbow trout (Oncorhynchus mykiss) into watersheds with native cutthroat trout (Oncorhynchus clarkii) have resulted in hybridization. These introductions have contributed to the decline of native cutthroat trout populations. Here, we examine the pattern of hybridization between introduced rainbow trout and 2 populations of cutthroat trout native to Colorado. For this study, we utilized 7 diagnostic, codominant nuclear markers and a diagnostic mitochondrial marker to investigate hybridization in a population of greenback cutthroat trout (Oncorhynchus clarkii stomias) and a population of Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus). We infer that cutthroat-rainbow trout hybrid swarms have formed in both populations. Although a mixture of hybrid genotypes was present, not all genotype combinations were detected at expected frequencies. We found evidence that mitochondrial DNA introgression in hybrids is asymmetric and more likely from rainbow trout than from cutthroat trout. A difference in spawning time of the 2 species or differences in the fitness between the reciprocal crosses may explain the asymmetry. Additionally, the presence of intraspecific cytonuclear associations found in both populations is concordant with current hypotheses regarding coevolution of mitochondrial and nuclear genomes.

  5. Monitor and Protect Wigwam River Bull Trout for Koocanusa Reservoir : Summary of the Skookumchuck Creek Bull Trout Enumeration Project, Annual Report 2001.

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, James S.; Baxter, Jeremy

    2002-03-01

    This report summarizes the second year of a bull trout (Salvelinus confluentus) enumeration project on Skookumchuck Creek in southeastern British Columbia. An enumeration fence and traps were installed on the creek from September 6th to October 12th 2001 to enable the capture of post-spawning bull trout emigrating out of the watershed. During the study period, a total of 273 bull trout were sampled through the enumeration fence. Length and weight were determined for all bull trout captured. In total, 39 fish of undetermined sex, 61 males and 173 females were processed through the fence. An additional 19 bull trout were observed on a snorkel survey prior to the fence being removed on October 12th. Coupled with the fence count, the total bull trout enumerated during this project was 292 fish. Several other species of fish were captured at the enumeration fence including westslope cutthroat trout (Oncorhynchus clarki lewisi), Rocky Mountain whitefish (Prosopium williamsoni), and kokanee (O. nerka). A total of 143 bull trout redds were enumerated on the ground in two different locations (river km 27.5-30.5, and km 24.0-25.5) on October 3rd. The majority of redds (n=132) were observed in the 3.0 km index section (river km 27.5-30.5) that has been surveyed over the past five years. The additional 11 redds were observed in a 1.5 km section (river km 24.0-25.5). Summary plots of water temperature for Bradford Creek, Sandown Creek, Buhl Creek, and Skookumchuck Creek at three locations suggested that water temperatures were within the temperature range preferred by bull trout for spawning, egg incubation, and rearing.

  6. Lake Roosevelt Fisheries Evaluation Program, Part A; Fisheries Creel Survey and Population Status Analysis, 1998 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Spotts, Jim; Shields, John; Underwood, Keith

    2002-05-01

    The Lake Roosevelt Fisheries Evaluation Program is the result of a merger between two projects, the Lake Roosevelt Monitoring Program (BPA No. 8806300) and the Lake Roosevelt Data Collection Project (BPA No. 9404300). These projects were merged in 1996 to continue work historically completed under the separate projects, and is now referred to as the Lake Roosevelt Fisheries Evaluation Program. Creel and angler surveys estimated that anglers made 196,775 trips to Lake Roosevelt during 1998, with an economic value of $8.0 million dollars, based on the Consumer Price Index (CPI). In 1998 it was estimated that 9,980 kokanee salmon, 226,809 rainbow trout, 119,346 walleye, and over 14,000 smallmouth bass and other species were harvested. Creel data indicates that hatchery reared rainbow trout contribute substantially to the Lake Roosevelt fishery. The contribution of kokanee salmon to the creel has not met the expectations of fishery managers to date, and is limited by entrainment from the reservoir, predation, and possible fish culture obstacles. The 1998 Lake Roosevelt Fisheries Creel and Population Analysis Annual Report includes analyses of the relative abundance of fish species, and reservoir habitat relationships (1990-1998). Fisheries surveys (1990-1998) indicate that walleye and burbot populations appear to be increasing, while yellow perch, a preferred walleye prey species, and other prey species are decreasing in abundance. The long term decreasing abundance of yellow perch and other prey species are suspected to be the result of the lack of suitable multiple reservoir elevation spawning and rearing refugia for spring spawning reservoir prey species, resulting from seasonal spring-early summer reservoir elevation manipulations, and walleye predation. Reservoir water management is both directly, and indirectly influencing the success of mitigation hatchery production of kokanee salmon and rainbow trout. Tag return data suggested excessive entrainment occurred in

  7. Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Schiff, C J; Kaufman, D S; Wallace, K L; Werner, A; Ku, T L; Brown, T A

    2007-02-25

    A 5.6-m-long lake sediment core from Bear Lake, Alaska, located 22 km southeast of Redoubt Volcano, contains 67 tephra layers deposited over the last 8750 cal yr, comprising 15% of the total thickness of recovered sediment. Using 12 AMS {sup 14}C ages, along with the {sup 137}Cs and {sup 210}Pb activities of recent sediment, we evaluated different models to determine the age-depth relation of sediment, and to determine the age of each tephra deposit. The age model is based on a cubic smooth spline function that was passed through the adjusted tephra-free depth of each dated layer. The estimated age uncertainty of the 67 tephras averages {+-} 105 yr (1{sigma}). Tephra-fall frequency at Bear Lake was among the highest during the past 500 yr, with eight tephras deposited compared to an average of 3.7 per 500 yr over the last 8500 yr. Other periods of increased tephra fall occurred 2500-3500, 4500-5000, and 7000-7500 cal yr. Our record suggests that Bear Lake experienced extended periods (1000-2000 yr) of increased tephra fall separated by shorter periods (500-1000 yr) of apparent quiescence. The Bear Lake sediment core affords the most comprehensive tephrochronology from the base of the Redoubt Volcano to date, with an average tephra-fall frequency of once every 130 yr.

  8. Arrow Lakes Reservoir Fertilization Experiment, Technical Report 1999-2004.

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, E.

    2007-02-01

    The Arrow Lakes food web has been influenced by several anthropogenic stressors during the past 45 years. These include the introduction of mysid shrimp (Mysis relicta) in 1968 and 1974 and the construction of large hydroelectric impoundments in 1969, 1973 and 1983. The construction of the impoundments affected the fish stocks in Upper and Lower Arrow lakes in several ways. The construction of Hugh Keenleyside Dam (1969) resulted in flooding that eliminated an estimated 30% of the available kokanee spawning habitat in Lower Arrow tributaries and at least 20% of spawning habitat in Upper Arrow tributaries. The Mica Dam (1973) contributed to water level fluctuations and blocked upstream migration of all fish species including kokanee. The Revelstoke Dam (1983) flooded 150 km of the mainstem Columbia River and 80 km of tributary streams which were used by kokanee, bull trout, rainbow trout and other species. The construction of upstream dams also resulted in nutrient retention which ultimately reduced reservoir productivity. In Arrow Lakes Reservoir (ALR), nutrients settled out in the Revelstoke and Mica reservoirs, resulting in decreased productivity, a process known as oligotrophication. Kokanee are typically the first species to respond to oligotrophication resulting from aging impoundments. To address the ultra-oligotrophic status of ALR, a bottom-up approach was taken with the addition of nutrients (nitrogen and phosphorus in the form of liquid fertilizer from 1999 to 2004). Two of the main objectives of the experiment were to replace lost nutrients as a result of upstream impoundments and restore productivity in Upper Arrow and to restore kokanee and other sport fish abundance in the reservoir. The bottom-up approach to restoring kokanee in ALR has been successful by replacing nutrients lost as a result of upstream impoundments and has successfully restored the productivity of Upper Arrow. Primary production rates increased, the phytoplankton community responded

  9. Endocrine changes associated with spawning behavior and social stimuli in a wild population of rainbow trout (Salmo gairdneri). II. Females

    OpenAIRE

    Liley, N.R.; Fostier, Alexis; Breton, B.; Tan, E.S.P.

    1986-01-01

    Rainbow trout (Salmo gairdneri) were collected from a natural spawning population at Pennask Lake, B.C. Blood samples taken from female trout at different stages of spawning were assayed by radioimmunoassay for gonadotropin (GtH), estradiol-17 beta (E2), androgens, including testosterone (T), and 17α-hydroxy-20 β-dihydroprogesterone (17,20-P). Plasma levels of androgen and estradiol were highest in females sampled shortly before ovulation (ogreeno females) and declined in ovulated and sexuall...

  10. Ice processes affect habitat use and movements of adult cutthroat trout and brook trout in a Wyoming foothills stream

    Science.gov (United States)

    Lindstrom, J.W.; Hubert, W.A.

    2004-01-01

    Habitat use and movements of 25 adult cutthroat trout Oncorhynchus clarkii and 25 adult brook trout Salvelinus fontinalis from fall through winter 2002-2003 were assessed by means of radiotelemetry in a 7-km reach of a Rocky Mountains foothills stream. Temporal dynamics of winter habitat conditions were evaluated by regularly measuring the features of 30 pools and 5 beaver Castor canadensis ponds in the study reach. Groundwater inputs at three locations raised mean daily water temperatures in the stream channel during winter to 0.2-0.6??C and kept at least 250 m of the downstream channel free of ice, but the lack of surface ice further downstream led to the occurrence of frazil ice and anchor ice in pools and unstable habitat conditions for trout. Pools in segments that were not affected by groundwater inputs and beaver ponds tended to be stable and snow accumulated on the surface ice. Pools throughout the study reach tended to become more stable as snow accumulated. Both cutthroat trout and brook trout selected beaver ponds as winter progressed but tended to use lateral scour pools in proportion to their availability. Tagged fish not in beaver ponds selected lateral scour pools that were deeper than average and stable during winter. Movement frequencies by tagged fish decreased from fall through winter, but some individuals of both species moved during winter. Ice processes affected both the habitat use and movement patterns of cutthroat trout and brook trout in this foothills stream.

  11. Age at sexual maturity, sex ratio, fecundity, and longevity of isolated headwater populations of westslope cutthroat trout

    Science.gov (United States)

    Christopher C. Downs; Robert G. White; Bradley B. Shepard

    1997-01-01

    We sampled 19 isolated headwater populations of westslope cutthroat trout Oncorhynchus clarki lewisi in Montana to provide estimates of fecundity, longevity, sex ratio, and age at sexual maturity. Fecundity was estimated for 31 fish collected from two streams in the upper Missouri River drainage. Females smaller than 149 mm fork length (FL) were generally immature and...

  12. Brook trout use of thermal refugia and foraging habitat influenced by brown trout

    Science.gov (United States)

    Hitt, Nathaniel P.; Snook, Erin; Massie, Danielle L.

    2017-01-01

    The distribution of native brook trout (Salvelinus fontinalis) in eastern North America is often limited by temperature and introduced brown trout (Salmo trutta), the relative importance of which is poorly understood but critical for conservation and restoration planning. We evaluated effects of brown trout on brook trout behavior and habitat use in experimental streams across increasing temperatures (14–23 °C) with simulated groundwater upwelling zones providing thermal refugia (6–9 °C below ambient temperatures). Allopatric and sympatric trout populations increased their use of upwelling zones as ambient temperatures increased, demonstrating the importance of groundwater as thermal refugia in warming streams. Allopatric brook trout showed greater movement rates and more even spatial distributions within streams than sympatric brook trout, suggesting interference competition by brown trout for access to forage habitats located outside thermal refugia. Our results indicate that removal of introduced brown trout may facilitate native brook trout expansion and population viability in downstream reaches depending in part on the spatial configuration of groundwater upwelling zones.

  13. Lake Lysevatten - A study of liming and reacidification effects in a forest lake ecosystem in southwestern Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, B.I.; Hultberg, H.

    1997-02-01

    Long-term monitoring (1973 to 1987) of acidification and liming effects to a lake ecosystem is reported in this study. The liming intervention of Lake Lysevatten in spring 1974 resulted in neutralisation of lake water and positive alkalinity. Invasion and population expansion of new species started and proceeded for several years. Following the neutralisation Sphagnum was almost eradicated. The restocking with fish changed the predator-prey interactions, and the community composition gradually approached what would be expected to be within the normal range for an unacidified lake. Early signs of reacidification were: The appearance of filamentous algae; Decreased condition of Brown trout (Salmo trutta) caused by increased aluminium concentrations in connection with an acid event; Enhanced growth of Sphagnum surviving on profundal bottoms. Progressive reacidification to Ph 5.0 resulted in accelerated growth of Mougeotia reaching nuisance level. If implemented, liming should be prolonged by reinterventions before alkalinity and pH decrease to much. A stable circumneutral pH is a prerequisite to provide the timescale necessary for invasion and population growth of organisms with low dispersal capacity. Furthermore, the most sensitive organisms will be adversely affected already at pH-values around six. Extensive reacidification should by all means be prevented as development of a destabilized lake community could react rather unpredictably. 168 refs, 80 figs, 26 tabs

  14. Temporary Restoration of Bull Trout Passage at Albeni Falls Dam, 2008 Progress Report.

    Energy Technology Data Exchange (ETDEWEB)

    Bellgraph, Brian J. [Pacific Northwest National Laboratory

    2009-03-31

    The goal of this project is to provide temporary upstream passage of bull trout around Albeni Falls Dam on the Pend Oreille River, Idaho. Our specific objectives are to capture fish downstream of Albeni Falls Dam, tag them with combination acoustic and radio transmitters, release them upstream of Albeni Falls Dam, and determine if genetic information on tagged fish can be used to accurately establish where fish are located during the spawning season. In 2007, radio receiving stations were installed at several locations throughout the Pend Oreille River watershed to detect movements of adult bull trout; however, no bull trout were tagged during that year. In 2008, four bull trout were captured downstream of Albeni Falls Dam, implanted with transmitters, and released upstream of the dam at Priest River, Idaho. The most-likely natal tributaries of bull trout assigned using genetic analyses were Grouse Creek (N = 2); a tributary of the Pack River, Lightning Creek (N = 1); and Rattle Creek (N = 1), a tributary of Lightning Creek. All four bull trout migrated upstream from the release site in Priest River, Idaho, were detected at monitoring stations near Dover, Idaho, and were presumed to reside in Lake Pend Oreille from spring until fall 2008. The transmitter of one bull trout with a genetic assignment to Grouse Creek was found in Grouse Creek in October 2008; however, the fish was not found. The bull trout assigned to Rattle Creek was detected in the Clark Fork River downstream from Cabinet Gorge Dam (approximately 13 km from the mouth of Lightning Creek) in September but was not detected entering Lightning Creek. The remaining two bull trout were not detected in 2008 after detection at the Dover receiving stations. This report details the progress by work element in the 2008 statement of work, including data analyses of fish movements, and expands on the information reported in the quarterly Pisces status reports.

  15. Grizzly bear predation links the loss of native trout to the demography of migratory elk in Yellowstone

    Science.gov (United States)

    Middleton, Arthur D.; Morrison, Thomas A.; Fortin, Jennifer K.; Robbins, Charles T.; Proffitt, Kelly M.; White, P.J.; McWhirter, Douglas E.; Koel, Todd M.; Brimeyer, Douglas G.; Fairbanks, W. Sue; Kauffman, Matthew J.

    2013-01-01

    The loss of aquatic subsidies such as spawning salmonids is known to threaten a number of terrestrial predators, but the effects on alternative prey species are poorly understood. At the heart of the Greater Yellowstone ecosystem, an invasion of lake trout has driven a dramatic decline of native cutthroat trout that migrate up the shallow tributaries of Yellowstone Lake to spawn each spring. We explore whether this decline has amplified the effect of a generalist consumer, the grizzly bear, on populations of migratory elk that summer inside Yellowstone National Park (YNP). Recent studies of bear diets and elk populations indicate that the decline in cutthroat trout has contributed to increased predation by grizzly bears on the calves of migratory elk. Additionally, a demographic model that incorporates the increase in predation suggests that the magnitude of this diet shift has been sufficient to reduce elk calf recruitment (4–16%) and population growth (2–11%). The disruption of this aquatic–terrestrial linkage could permanently alter native species interactions in YNP. Although many recent ecological changes in YNP have been attributed to the recovery of large carnivores—particularly wolves—our work highlights a growing role of human impacts on the foraging behaviour of grizzly bears.

  16. Grizzly bear predation links the loss of native trout to the demography of migratory elk in Yellowstone.

    Science.gov (United States)

    Middleton, Arthur D; Morrison, Thomas A; Fortin, Jennifer K; Robbins, Charles T; Proffitt, Kelly M; White, P J; McWhirter, Douglas E; Koel, Todd M; Brimeyer, Douglas G; Fairbanks, W Sue; Kauffman, Matthew J

    2013-07-07

    The loss of aquatic subsidies such as spawning salmonids is known to threaten a number of terrestrial predators, but the effects on alternative prey species are poorly understood. At the heart of the Greater Yellowstone ecosystem, an invasion of lake trout has driven a dramatic decline of native cutthroat trout that migrate up the shallow tributaries of Yellowstone Lake to spawn each spring. We explore whether this decline has amplified the effect of a generalist consumer, the grizzly bear, on populations of migratory elk that summer inside Yellowstone National Park (YNP). Recent studies of bear diets and elk populations indicate that the decline in cutthroat trout has contributed to increased predation by grizzly bears on the calves of migratory elk. Additionally, a demographic model that incorporates the increase in predation suggests that the magnitude of this diet shift has been sufficient to reduce elk calf recruitment (4-16%) and population growth (2-11%). The disruption of this aquatic-terrestrial linkage could permanently alter native species interactions in YNP. Although many recent ecological changes in YNP have been attributed to the recovery of large carnivores--particularly wolves--our work highlights a growing role of human impacts on the foraging behaviour of grizzly bears.

  17. Radioactive contamination of fishes in lake and streams impacted by the Fukushima nuclear power plant accident

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, Mayumi, E-mail: yoshi887@ffpri.affrc.go.jp [Kansai Research Center, Forestry and Forest Products Research Institute, Nagaikyuutaro 68, Momoyama, Fushimi, Kyoto 612-0855 (Japan); Yokoduka, Tetsuya [Tochigi Prefectural Fisheries Experimental Station, Sarado 2599, Ohtawara, Tochigi 324-0404 (Japan)

    2014-06-01

    The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in March 2011 emitted radioactive substances into the environment, contaminating a wide array of organisms including fishes. We found higher concentrations of radioactive cesium ({sup 137}Cs) in brown trout (Salmo trutta) than in rainbow trout (Oncorhynchus nerka), and {sup 137}Cs concentrations in brown trout were higher in a lake than in a stream. Our analyses indicated that these differences were primarily due to differences in diet, but that habitat also had an effect. Radiocesium concentrations ({sup 137}Cs) in stream charr (Salvelinus leucomaenis) were higher in regions with more concentrated aerial activity and in older fish. These results were also attributed to dietary and habitat differences. Preserving uncontaminated areas by remediating soils and releasing uncontaminated fish would help restore this popular fishing area but would require a significant effort, followed by a waiting period to allow activity concentrations to fall below the threshold limits for consumption. - Highlight: • Concentration of {sup 137}Cs in brown trout was higher than in rainbow trout. • {sup 137}Cs concentration of brown trout in a lake was higher than in a stream. • {sup 137}Cs concentration of stream charr was higher in region with higher aerial activity. • Concentration of {sup 137}Cs in stream charr was higher in older fish. • Difference of contamination among fishes was due to difference in diet and habitat.

  18. MicroRNA expression profiles from eggs of different qualities associated with post-ovulatory ageing in rainbow trout (Oncorhynchus mykiss)

    Science.gov (United States)

    Background: Egg quality is an important aspect in rainbow trout farming. Post-ovulatory aging is one of the most important factors affecting egg quality. MicroRNAs (miRNAs) are the major regulators in various biological processes and their expression profiles could serve as reliable biomarkers for v...

  19. Silver contamination on abiotic and biotic compartments of Nahuel Huapi National Park lakes, Patagonia, Argentina

    International Nuclear Information System (INIS)

    Ribeiro Guevara, Sergio; Arribere, Maria; Bubach, Debora; Vigliano, Pablo; Rizzo, Andrea; Alonso, Marcelo; Sanchez, Ricardo

    2005-01-01

    The Ag contents of abiotic and biotic compartments of different lakes of Nahuel Huapi National Park, Patagonia, Argentina were analyzed. The water bodies studied were lakes Nahuel Huapi, Moreno, Escondido, Espejo Chico and Traful, the latter chosen as a reference lake. The Ag concentration profiles of short sediment cores, dated by 210 Pb and 137 Cs techniques, were analyzed, as well as suspended load collected from three sites of lake Nahuel Huapi. The biota studied were the native mussel Diplodon chilensis (digestive gland and total soft tissues pooled samples) and five species of fish, two native and three introduced (liver and muscle pooled samples). Ag contents were determined by Instrumental Neutron Activation Analysis (INAA). The upper layers of the sediment cores sampled in lake Nahuel Huapi were enriched in Ag contents compared to deep layers in accumulation periods corresponding to the second half of the 20th century, but this enrichment was neither observed in the reference lake Traful, nor in lakes Espejo Chico and Escondido. Ag was enriched over background level (0.1 μg g -1 ) also in suspended load collected in lake Nahuel Huapi. Ag fluxes to sediments were computed for suspended load and enriched sediment core layers. Highest Ag fluxes, from 350 to 470 μg m -2 year -1 , were measured in Nahuel Huapi near the site where the liquid effluents of the Bariloche city sewage treatment plant are released to the lake. The spatial distribution of the other Ag fluxes suggests that this is the main source of Ag to lake Nahuel Huapi and lateral transport occurs within the water body. Ag concentrations on biota samples were consistent with these conclusions. Mussels collected in lake Nahuel Huapi showed higher Ag concentrations than in the other lakes, especially when compared to lake Traful. Ag contents in mussels were strongly associated with sediment intake, but enriched probably due to sediment grain size sorting during the intake processes. Evidence of food

  20. The sexually dimorphic adipose fin is an androgen target tissue in the brown trout (Salmo trutta fario).

    Science.gov (United States)

    Hisar, Olcay; Sönmez, Adem Yavuz; Hisar, Şükriye Aras; Budak, Harun; Gültepe, Nejdet

    2013-04-01

    An investigation has been described on the relationship of body length, age and sex with adipose fin length and the number of androgen receptor (AR)-containing cells in the adipose fin as a secondary sexual characteristic for brown trout (Salmo trutta fario). Firstly, body and adipose fin lengths of 2- to 5-year-old brown trout were measured. Thereafter, these fish were killed by decapitation, then their sexes were determined, and adipose fins were excised. The cellular bases of AR binding activities in the adipose fins were analyzed with an antibody against human/rat AR peptide. Immunocytochemistry and western blotting techniques were performed with this antibody. Analysis of morphological measurements indicated that body length and age had a linear relationship with adipose fin length. The coefficients of determination for the body length and age were 0.92 and 0.85 in the male fish and 0.76 and 0.73 in the female fish against the adipose fin length, respectively. At 2 years of age, cells in the adipose fin did not exhibit AR immunoreactivity. However, AR-immunopositive cells were abundant in the adipose fin of 3- to 5-year-old fish. Moreover, the number of AR-immunopositive cells was significantly (P brown trout is a probable target for androgen action and that tissue function or development may to some extent be androgen dependent. In addition, it is likely that such an effect will be mediated by specific androgen receptors.

  1. Proliferative kidney disease (PKD) agent Tetracapsuloides bryosalmonae in brown trout populations in Estonia.

    Science.gov (United States)

    Dash, Megha; Vasemägi, Anti

    2014-05-13

    Proliferative kidney disease (PKD) caused by the myxozoan parasite Tetracapsuloides bryosalmonae is a serious parasitic disease threatening both farmed and wild salmonid populations, but very little is currently known about the distribution of the parasite in the Baltic Sea region. In this study we (1) report the development of a novel multiplex PCR method for fast and reliable screening of T. bryosalmonae; (2) use this multiplex PCR method to show that the PKD agent T. bryosalmonae is widespread in natural brown trout Salmo trutta L. populations in Estonia; (3) evaluate monthly and yearly variation of T. bryosalmonae prevalence in juvenile trout; (4) assess T. bryosalmonae prevalence in different age-classes of fish (0+ vs. 1+ and older) and report the presence of the PKD agent in the kidneys of returning sea trout spawners; and (5) suggest the freshwater bryozoan Plumatella fungosa as a putative invertebrate host of T. bryosalmonae in Estonia. Our results demonstrate a highly heterogeneous distribution of T. bryosalmonae at the micro-geographic scale, indicating that PKD could have an important negative effect on recruitment in Estonian brown trout populations.

  2. Experimental evaluation of rainbow trout Oncorhynchus mykiss predation on longnose dace Rhinichthys cataractae

    Science.gov (United States)

    Turek, Kelly C.; Pegg, Mark A.; Pope, Kevin L.

    2014-01-01

    Laboratory and in-stream enclosure experiments were used to determine whether rainbow trout Oncorhynchus mykiss influence survival of longnose dace Rhinichthys cataractae. In the laboratory, adult rainbow trout preyed on longnose dace in 42% of trials and juvenile rainbow trout did not prey on longnose dace during the first 6 h after rainbow trout introduction. Survival of longnose dace did not differ in the presence of adult rainbow trout previously exposed to active prey and those not previously exposed to active prey ( = 0.28, P = 0.60). In field enclosures, the number of longnose dace decreased at a faster rate in the presence of rainbow trout relative to controls within the first 72 h, but did not differ between moderate and high densities of rainbow trout (F2,258.9 = 3.73, P = 0.03). Additionally, longnose dace were found in 7% of rainbow trout stomachs after 72 h in enclosures. Rainbow trout acclimated to the stream for longer periods had a greater initial influence on the number of longnose dace remaining in enclosures relative to those acclimated for shorter periods regardless of rainbow trout density treatment (F4,148.5 = 2.50, P = 0.04). More research is needed to determine how predation rates will change in natural environments, under differing amounts of habitat and food resources and in the context of whole assemblages. However, if rainbow trout are introduced into the habitat of longnose dace, some predation on longnose dace is expected, even when rainbow trout have no previous experience with active prey.

  3. Distribution of polycyclic aromatic hydrocarbons in the food web of a high mountain lake, Pyrenees, Catalonia, Spain.

    Science.gov (United States)

    Vives, Ingrid; Grimalt, Joan O; Ventura, Marc; Catalan, Jordi

    2005-06-01

    We investigated the contents of polycyclic aromatic hydrocarbons (PAHs) in the food web organisms included in the diet of brown trout from a remote mountain lake. The preferential habitat and trophic level of the component species have been assessed from the signature of stable isotopes (delta13C and delta15N). Subsequently, the patterns of accumulation and transformation of these hydrocarbons in the food chain have been elucidated. Most of the food web organisms exhibit PAH distributions largely dominated by phenanthrene, which agrees with its predominance in atmospheric deposition, water, and suspended particles. Total PAH levels are higher in the organisms from the littoral habitat than from the deep sediments or the pelagic water column. However, organisms from deep sediments exhibit higher proportions of higher molecular weight PAH than those in other lake areas. Distinct organisms exhibit specific features in their relative PAH composition that point to different capacities for uptake and metabolic degradation. Brown trout show an elevated capacity for metabolic degradation because they have lower PAH concentrations than food and they are enriched strongly in lower molecular weight compounds. The PAH levels in trout highly depend on organisms living in the littoral areas. Fish exposure to PAH, therefore, may vary from lake to lake according to the relative contribution of littoral organisms to their diet.

  4. Extensive feeding on sockeye salmon Oncorhynchus nerka smolts by bull trout Salvelinus confluentus during initial outmigration into a small, unregulated and inland British Columbia river

    Science.gov (United States)

    Furey, Nathan B.; Hinch, Scott G.; Lotto, A.G.; Beauchamp, David A.

    2015-01-01

    Stomach contents were collected and analysed from 22 bull trout Salvelinus confluentus at the edge of the Chilko Lake and Chilko River in British Columbia, Canada, during spring outmigration of sockeye salmon Oncorhynchus nerka smolts. Twenty of the 22 (>90%) stomachs contained prey items, virtually all identifiable prey items were outmigrant O. nerka smolts and stomach contents represented a large portion (0·0–12·6%) of estimated S. confluentus mass. The results demonstrate nearly exclusive and intense feeding by S. confluentus on outmigrant smolts, and support recent telemetry observations of high disappearance rates of O. nerka smolts leaving large natural lake systems prior to entering high-order unregulated river systems.

  5. Comparison of biochemical parameters of rainbow trout (Oncorhynchus mykiss) reared in two different trout farms'

    Science.gov (United States)

    Karatas, Tayfun

    2016-04-01

    The aim of this study was to compare biochemical parameters of cultured rainbow trouts (Oncorhynchus mykiss, Walbaum, 1972) reared in two different trout farms' (Agri and Erzurum). The average weights of fish were 150±10gr for first station (Agri), 230±10gr for second station (Erzurum). Fishes used in research were randomly caught from pools, and fifteen pieces were used for each group. Fishes were fed with commercial trout feed with 45-50% crude protein twice a day. The levels of AST, ALT, LDL, total cholesterol and triglyceride in the second station (Erzurum) were found to be higher (p<0.05) than that of first station (Agri). Whereas, the levels of HDL in the second station (Erzurum) were found to be lower (p<0.05) than that of first station (Agri). Differences in the levels of total cholesterol and AST, ALT, HDL, LDL, triglyceride may be associated with size, sex, sexual maturity and environmental conditions (temperature, pH, hardness and dissolved oxygen).

  6. Using invertebrate remains and pigments in the sediment to infer changes in trophic structure after fish introduction in Lake Fogo: a crater lake in the Azores

    DEFF Research Database (Denmark)

    Skov, Tue; Buchaca, T; Amsinck, Susanne Lildal

    2010-01-01

    Fish introduction may have marked effects on the trophic dynamics and ecological state of former fishless lakes, but due to scarcity of historical data this can seldom be documented. We used remains of cladoceran, chironomid and pigment assemblages in the sediment archive to unravel the effect...... to a pelagic dominated ecosystem, as cryptophytes became markedly more abundant at the expense of benthic diatoms. Trout introduction was followed by a return to a more benthic cladoceran and benthic algae (pigments) dominated state, which we attribute to trout predation on carp leading to improved water...

  7. Angler-caught piscivore diets reflect fish community changes in Lake Huron

    Science.gov (United States)

    Roseman, Edward F.; Schaeffer, Jeff; Bright, Ethan; Fielder, David G.

    2014-01-01

    Examination of angler-caught piscivore stomachs revealed that Lake Trout Salvelinus namaycush, Chinook Salmon Oncorhynchus tshawytscha, and Walleyes Sander vitreus altered theirdiets in response to unprecedented declines in Lake Huron's main-basin prey fish community.Diets varied by predator species, season, and location but were nearly always dominated numerically by some combination of Alewife Alosa pseudoharengus, Rainbow Smelt Osmerus mordax, Emerald Shiner Notropis atherinoides, Round Goby Neogobius melanostomus, or terrestrial insects. Rainbow Trout Oncorhynchus mykiss (steelhead), Coho Salmon Oncorhynchus kisutch, and Atlantic Salmon Salmo salar had varied diets that reflected higher contributions of insects. Compared with an earlier (1983–1986) examination of angler-caught predator fishes from Lake Huron, the contemporary results showed an increase in consumption of nontraditional prey (including conspecifics), use of smaller prey, and an increase in insects in the diet, suggesting that piscivores were faced with chronic prey limitation during this study. The management of all piscivores in Lake Huron will likely require consideration of the pervasive effects of changes in food webs, especially if prey fish remain at low levels.

  8. Hexabromocyclododecane (HBCDD) Flame Retardant in Top Predator Fish across Canada and its 36-Year Temporal Trends for Lake Ontario.

    Science.gov (United States)

    Su, Guanyong; McGoldrick, Daryl; Clark, Mandi G; Evans, Marlene; Gledhill, Melissa; Garron, Christine; Armellin, Alain; Backus, Sean; Letcher, Robert J

    2018-05-08

    Hexabromocyclododecane (HBCDD) is a high concern environmental pollutant due to its persistent, bioaccumulative and toxic properties. The spatial distribution of HBCDD was investigated in top predator fish (Lake Trout, Walleye or Brook Trout) collected in 2013 (n=165) from nineteen sampling sites and in 2015 (n=145) from twenty sites across Canada. HBCDD was measurable in at least one sample at each sampling site regardless of sampling year with the exception of Walleye from the south basin of Lake Winnipeg (2013). Sampling sites in or near the Laurentian Great Lakes had greater HBCDD concentrations compared to locations to the west or east. The greatest mean HBCDD concentration was 72.6 ng/g lw in fish from Lake Huron-Goderich (2015). Regardless of the sampling sites, α-HBCDD was the dominant congener followed by γ-HBCDD, whereas β-HBCDD was barely detectable. In fish from the same waterbody there were comparable α/γ isomer concentration ratios. The greatest ratio was 20.8 in fish from Lake Ontario, whereas the lowest ratio was 6.3 for fish from Lac Memphrémagog (Québec) likely related to more recent emissions of technical HBCDD mixture. Temporal trends of HBCDD in Lake Trout from Lake Ontario showed a significant decreasing trend for γ-HBCDD with a half-life estimate of 10 years over a 36-year period (1979-2015), and for -HBCDD with a half-life of 11 years over the years of 2008 to 2015. The proportion of α-HBCDD to ΣHBCDD increased significantly during 1979 to 2015. The present study provided novel information on the isomer-specific HBCDDs in Canada freshwater fish.

  9. Growth, morphology, and developmental instability of rainbow trout, Yellowstone cutthroat trout, and four hybrid generations

    Science.gov (United States)

    Ostberg, C.O.; Duda, J.J.; Graham, J.H.; Zhang, S.; Haywood, K. P.; Miller, B.; Lerud, T.L.

    2011-01-01

    Hybridization of cutthroat trout Oncorhynchus clarkii with nonindigenous rainbow trout O. mykiss contributes to the decline of cutthroat trout subspecies throughout their native range. Introgression by rainbow trout can swamp the gene pools of cutthroat trout populations, especially if there is little selection against hybrids. We used rainbow trout, Yellowstone cutthroat trout O. clarkii bouvieri, and rainbow trout × Yellowstone cutthroat trout F1 hybrids as parents to construct seven different line crosses: F1 hybrids (both reciprocal crosses), F2 hybrids, first-generation backcrosses (both rainbow trout and Yellowstone cutthroat trout), and both parental taxa. We compared growth, morphology, and developmental instability among these seven crosses reared at two different temperatures. Growth was related to the proportion of rainbow trout genome present within the crosses. Meristic traits were influenced by maternal, additive, dominant, overdominant, and (probably) epistatic genetic effects. Developmental stability, however, was not disturbed in F1 hybrids, F2 hybrids, or backcrosses. Backcrosses were morphologically similar to their recurrent parent. The lack of developmental instability in hybrids suggests that there are few genetic incompatibilities preventing introgression. Our findings suggest that hybrids are not equal: that is, growth, development, character traits, and morphology differ depending on the genomic contribution from each parental species as well as the hybrid generation.

  10. Altitudinal and thermal gradients of hepatic Cyp1A gene expression in natural populations of Salmo trutta from high mountain lakes and their correlation with organohalogen loads

    Energy Technology Data Exchange (ETDEWEB)

    Jarque, Sergio; Gallego, Eva [Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18, 08034-Barcelona, Catalonia (Spain); Bartrons, Mireia; Catalan, Jordi [Center for Advanced Studies of Blanes (CEAB-CSIC), Acces Cala St. Francesc 14, 17300-Blanes, Catalonia (Spain); Grimalt, Joan O. [Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18, 08034-Barcelona, Catalonia (Spain); Pina, Benjamin, E-mail: bpcbmc@cid.csic.e [Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18, 08034-Barcelona, Catalonia (Spain)

    2010-05-15

    The biomarker of xenobiotic exposure cytochrome p450A1 (Cyp1A) was used to analyze the biological response to chemical pollution in Salmo trutta (brown trout) from nine high mountain European lakes in Norway, Tatras, Tyrol, and central Pyrenees. Hepatic Cyp1A mRNA levels correlated both with the reciprocal of absolute annual average air temperatures of the sampled lakes and with muscle concentrations of several hydrophobic organohalogen compounds (OC), including chlorinated polychlorobiphenyls (PCB), DDE, and DDT. The correlation between Cyp1A expression and OC content was observed across the whole temperature range (between -0.7 deg. C and +6.2 deg. C), but also in the absence of any thermal gradient. We concluded that airborne pollutants accumulate in high mountain lake fish at concentrations high enough to increase Cyp1A expression, among other possible effects. As geographical distribution of semi-volatile OC is strongly influenced by air temperatures, future climate modifications will potentially enhance their physiological effects in lake ecosystems. - Altitudinal gradients of hepatic Cyp1A gene expression in mountain trout correlate with geographic and individual organohalogen distribution.

  11. Foraging mechanisms of siscowet lake trout (Salvelinus namaycush siscowet) on pelagic prey

    Science.gov (United States)

    Keyler, Trevor D.; Hrabik, Thomas R.; Austin, C. Lee; Gorman, Owen T.; Mensinger, Allen F.

    2015-01-01

    The reaction distance, angle of attack, and foraging success were determined for siscowet lake trout (Salvelinus namaycush siscowet) during laboratory trials under lighting conditions that approximated downwelling spectral irradiance and intensity (9.00 × 108–1.06 × 1014 photons m− 2 s− 1) at daytime depths. Siscowet reaction distance in response to golden shiners (Notemigonus crysoleucas) was directly correlated with increasing light intensity until saturation at 1.86 × 1011 photons m− 2 s− 1, above which reaction distance was constant within the range of tested light intensities. At the lowest tested light intensity, sensory detection was sufficient to locate prey at 25 ± 2 cm, while increasing light intensities increased reaction distance up to 59 ± 2 cm at 1.06 × 1014 photons m− 2 s− 1. Larger prey elicited higher reaction distances than smaller prey at all light intensities while moving prey elicited higher reaction distances than stationary prey at the higher light intensities (6.00 × 109 to 1.06 × 1014 photons m− 2 s− 1). The capture and consumption of prey similarly increased with increasing light intensity while time to capture decreased with increasing light intensity. The majority of orientations toward prey occurred within 120° of the longitudinal axis of the siscowet's eyes, although reaction distances among 30° increments along the entire axis were not significantly different. The developed predictive model will help determine reaction distances for siscowet in various photic environments and will help identify the mechanisms and behavior that allow for low light intensity foraging within freshwater systems.

  12. Competition and predation as mechanisms for displacement of greenback cutthroat trout by brook trout

    Science.gov (United States)

    C. C. McGrath; W. M. Lewis

    2007-01-01

    Cutthroat trout Oncorhynchus clarkii frequently are displaced by nonnative brook trout Salvelinus fontinalis, but the ecological mechanisms of displacement are not understood. Competition for food and predation between greenback cutthroat trout O. c. stomias and brook trout were investigated in montane streams of...

  13. Intercohort density dependence drives brown trout habitat selection

    Science.gov (United States)

    Ayllón, Daniel; Nicola, Graciela G.; Parra, Irene; Elvira, Benigno; Almodóvar, Ana

    2013-01-01

    Habitat selection can be viewed as an emergent property of the quality and availability of habitat but also of the number of individuals and the way they compete for its use. Consequently, habitat selection can change across years due to fluctuating resources or to changes in population numbers. However, habitat selection predictive models often do not account for ecological dynamics, especially density dependent processes. In stage-structured population, the strength of density dependent interactions between individuals of different age classes can exert a profound influence on population trajectories and evolutionary processes. In this study, we aimed to assess the effects of fluctuating densities of both older and younger competing life stages on the habitat selection patterns (described as univariate and multivariate resource selection functions) of young-of-the-year, juvenile and adult brown trout Salmo trutta. We observed all age classes were selective in habitat choice but changed their selection patterns across years consistently with variations in the densities of older but not of younger age classes. Trout of an age increased selectivity for positions highly selected by older individuals when their density decreased, but this pattern did not hold when the density of younger age classes varied. It suggests that younger individuals are dominated by older ones but can expand their range of selected habitats when density of competitors decreases, while older trout do not seem to consider the density of younger individuals when distributing themselves even though they can negatively affect their final performance. Since these results may entail critical implications for conservation and management practices based on habitat selection models, further research should involve a wider range of river typologies and/or longer time frames to fully understand the patterns of and the mechanisms underlying the operation of density dependence on brown trout habitat

  14. Assessing diet compositions of Lake Ontario predators using fatty acid profiles of prey fishes

    Science.gov (United States)

    Happell, Austin; Pattridge, Robert; Rinchard, Jacques; Walsh, Maureen

    2017-01-01

    Fatty acid profiles are used in food web studies to assess trophic interactions between predator and prey. The present study provides the first comprehensive fatty acid dataset for important prey and predator species in Lake Ontario. Three major prey fish (alewife, rainbow smelt, and round goby) were collected at three sites along the southern shore of Lake Ontario during the spring and fall of 2013, and predator species were collected in similar locations during the summer of 2013. Fatty acid compositions were compared among all prey species, all predator species, and information from both predator and prey was used to infer foraging differences among predators. Seasonal differences in fatty acids were found within each prey species studied. Differences among prey species were greater than any spatio-temporal differences detected within species. Fatty acids of predators revealed species-specific differences that matched known foraging habits. Chinook and Coho salmon, which are known to select alewife as their dominant prey item, had relatively little variation in fatty acid profiles. Conversely, brown trout, lake trout, yellow perch and esocids had highly variable fatty acid profiles and likely highly variable diet compositions. In general, our data suggested three dominant foraging patterns: 1) diet composed of nearly exclusively alewife for Chinook and Coho Salmon; 2) a mixed diet of alewife and round goby for brown and lake trout, and both rock and smallmouth bass; 3) a diet that is likely comprised of forage fishes other than those included in our study for northern pike and chain pickerel.

  15. Fall and winter survival of brook trout and brown trout in a north-central Pennsylvania watershed

    Science.gov (United States)

    Sweka, John A.; Davis, Lori A.; Wagner, Tyler

    2017-01-01

    Stream-dwelling salmonids that spawn in the fall generally experience their lowest survival during the fall and winter due to behavioral changes associated with spawning and energetic deficiencies during this time of year. We used data from Brook Trout Salvelinus fontinalis and Brown Trout Salmo trutta implanted with radio transmitters in tributaries of the Hunts Run watershed of north-central Pennsylvania to estimate survival from the fall into the winter seasons (September 2012–February 2013). We examined the effects that individual-level covariates (trout species, size, and movement rates) and stream-level covariates (individual stream and cumulative drainage area of a stream) have on survival. Brook Trout experienced significantly lower survival than Brown Trout, especially in the early fall during their peak spawning period. Besides a significant species effect, none of the other covariates examined influenced survival for either species. A difference in life history between these species, with Brook Trout having a shorter life expectancy than Brown Trout, is likely the primary reason for the lower survival of Brook Trout. However, Brook Trout also spawn earlier in the fall than Brown Trout and low flows during Brook Trout spawning may have resulted in a greater risk of predation for Brook Trout compared with Brown Trout, thereby also contributing to the observed differences in survival between these species. Our estimates of survival can aid parameterization of future population models for Brook Trout and Brown Trout through the spawning season and into winter.

  16. Estrogenic effects of phytoestrogens in brown trout (Salmo trutta)

    DEFF Research Database (Denmark)

    Nielsen, Louise Marie; Holbech, Henrik; Bjerregaard, Poul

    2010-01-01

    , the potential effect of the waterborne phytoestrogens on endemic fish species is largely unknown. In the present investigation, the estrogenic effect of biochanin A was tested in brown trout through water exposure experiments. Juvenile brown trout of both sexes were exposed to different concentrations...... of biochanin A. In a ten day exposure experiments, NOEC and LOEC for plasma vitellogenin induction in brown trout were found to be 0.8µg biochanin A/L and 1.2µg biochanin A/L, respectively. A six hour pulse experiment resulted in NOEC and LOEC for induction of plasma vitellogenin in brown trout of 48µg...... biochanin A/L and 186µg biochanin A/L, respectively. Investigations of the ability of genistein to induce vitellogenin synthesis in brown trout are ongoing....

  17. Investigations into the temporal development of epitheliocystis infections in brown trout: a histological study.

    Science.gov (United States)

    Guevara Soto, M; Vidondo, B; Vaughan, L; Rubin, J-F; Segner, H; Samartin, S; Schmidt-Posthaus, H

    2017-06-01

    Epitheliocystis in Swiss brown trout (Salmo trutta) is a chlamydial infection, mainly caused by Candidatus Piscichlamydia salmonis and Candidatus Clavichlamydia salmonicola. To gain a better understanding of the temporal development of infections in wild brown trout, we investigated epitheliocystis infections during the course of the summer and autumn months of a single year (2015), and compared this to sampling points over the span of the years 2012-2014. The survey focused on tributaries (Venoge and Boiron) of the Rhone flowing in to Lake Geneva. When evaluated histologically, epitheliocystis infections were found throughout the period of investigation with the exception of the month of June. Fifty to 86 animals per sampling were investigated. Highest prevalence and infection intensities were seen in September. A correlation between epitheliocystis infection and water temperatures was not evident. Interyear comparison revealed consistent levels of prevalence and infection intensities in late summer. The absence of infections in June, combined with the consistent interyear results, indicates seasonal fluctuation of epitheliocystis infections in brown trout with a reservoir persisting during winter months from which infections can re-initiate each year. This could either be at levels below detection limits within the brown trout population itself or in an alternative host. © 2016 John Wiley & Sons Ltd.

  18. Ontogenetic shifts in terrestrial reliance of stream-dwelling brown trout

    Directory of Open Access Journals (Sweden)

    Javier Sánchez-Hernández

    2016-07-01

    Full Text Available This study focuses on terrestrial reliance of brown trout (Salmo trutta and compared it to the potential prey available (macrozoobenthos and drifting invertebrates in three temperate rivers (Galicia, NW Spain, with special emphasis on variations in terrestrial energy intake through the ontogeny of brown trout. Additionally, we paid particular attention to individual variation of terrestrial resource use within and between age classes. Prey items were grouped in four categories: i aquatic invertebrates; ii imagoes of aquatic invertebrates; iii terrestrial invertebrates; and iv fish prey. Next, energy composition was measured according to dry weight-energy equations for each individual in line with above-mentioned prey categories. Our findings illustrate that terrestrial invertebrates appeared to be scarce in the environment, whereas aquatic food resources were rather abundant and accessible. The use of terrestrial invertebrates tended to increase with age, but with a high degree of inter-individual variation in resource use. In fact, the individual reliance of brown trout on terrestrial invertebrates may vary considerably (between 0% and 76.9%. Besides, the frequency of terrestrial foragers, i.e., individuals with terrestrial invertebrates in their stomachs, increased with age, except in one population which had the maximum value in the age-2 class. The acquisition of terrestrial invertebrates thus appears to be a process strongly dependent upon the actual food availability in the environment, but with a high degree of individual variance in resource use within the same age class. Finally, we discuss that terrestrial invertebrates may largely contribute to cover the energy intake of the species, highlighting the interface between terrestrial and aquatic ecosystems, and thereby the importance of riparian canopy cover as a key factor for food supply of stream-dwelling salmonids species.

  19. Movement of bull trout in the upper Jarbidge River watershed, Idaho and Nevada, 2008-09--A supplement to Open-File Report 2010-1033

    Science.gov (United States)

    Munz, Carrie S.; Allen, M. Brady; Connolly, Patrick J.

    2011-01-01

    We monitored bull trout (Salvelinus confluentus) in 2008 and 2009 as a continuation of our work in 2006 and 2007, which involved the tagging of 1,536 bull trout with passive integrated transponder (PIT) tags in the East Fork Jarbidge River and West Fork Jarbidge River and their tributaries in northeastern Nevada and southern Idaho. We installed PIT tag interrogation systems (PTISs) at established locations soon after ice-out, and maintained the PTISs in order to collect information on bull trout movements through December of each year. We observed a marked increase of movement in 2008 and 2009. Bull trout tagged in the uppermost portions of the East Fork Jarbidge River at altitudes greater than 2,100 meters moved to the confluence of the East Fork Jarbidge River and West Fork Jarbidge River in summer and autumn. Ten bull trout tagged upstream of the confluence of Pine Creek and the West Fork Jarbidge River moved downstream and then upstream in the East Fork Jarbidge River, and then past the PTIS at Murphy Hot Springs (river kilometer [rkm] 4.1). Two of these fish ascended Dave Creek, a tributary of the East Fork Jarbidge River, past the PTIS at rkm 0.4. One bull trout that was tagged at rkm 11 in Dave Creek on June 28, 2007 moved downstream to the confluence of the East Fork Jarbidge River and West Fork Jarbidge River (rkm 0) on July 28, 2007, and it was then detected in the West Fork Jarbidge River moving past our PTIS at rkm 15 on May 4, 2008. Combined, the extent and types of bull trout movements observed indicated that the primarily age-1 and age-2 bull trout that we tagged in 2006 and 2007 showed increased movement with age and evidence of a substantial amount of fluvial life history. The movements suggest strong connectivity between spawning areas and downstream mainstem areas, as well as between the East Fork Jarbidge River and West Fork Jarbidge River.

  20. Lake depth rather than fish planktivory determines cladoceran community structure in Faroese lakes - evidence from contemporary data and sediments

    DEFF Research Database (Denmark)

    Amsinck, S.L.; Strzelczak, A.; Bjerring, R.

    2006-01-01

    development was inferred by cladoceran-based paleolimnological investigations of a 14C-dated sediment core covering the last ca 5700 years. 3. The 29 study lakes were overall shallow, small-sized, oligotrophic and dominated by brown trout (Salmo trutta). Cladoceran species richness was overall higher...... depth. A recent increase in inferred Zmax may, however, be an artefact induced by, for instance, eutrophication....

  1. Summary of the Skookumchuck Creek bull trout enumeration project 2001.; TOPICAL

    International Nuclear Information System (INIS)

    Baxter, James S.; Baxter, Jeremy

    2002-01-01

    This report summarizes the second year of a bull trout (Salvelinus confluentus) enumeration project on Skookumchuck Creek in southeastern British Columbia. An enumeration fence and traps were installed on the creek from September 6th to October 12th 2001 to enable the capture of post-spawning bull trout emigrating out of the watershed. During the study period, a total of 273 bull trout were sampled through the enumeration fence. Length and weight were determined for all bull trout captured. In total, 39 fish of undetermined sex, 61 males and 173 females were processed through the fence. An additional 19 bull trout were observed on a snorkel survey prior to the fence being removed on October 12th. Coupled with the fence count, the total bull trout enumerated during this project was 292 fish. Several other species of fish were captured at the enumeration fence including westslope cutthroat trout (Oncorhynchus clarki lewisi), Rocky Mountain whitefish (Prosopium williamsoni), and kokanee (O. nerka). A total of 143 bull trout redds were enumerated on the ground in two different locations (river km 27.5-30.5, and km 24.0-25.5) on October 3rd. The majority of redds (n=132) were observed in the 3.0 km index section (river km 27.5-30.5) that has been surveyed over the past five years. The additional 11 redds were observed in a 1.5 km section (river km 24.0-25.5). Summary plots of water temperature for Bradford Creek, Sandown Creek, Buhl Creek, and Skookumchuck Creek at three locations suggested that water temperatures were within the temperature range preferred by bull trout for spawning, egg incubation, and rearing

  2. Prevalence and location of Listeria monocytogenes in farmed rainbow trout.

    Science.gov (United States)

    Miettinen, Hanna; Wirtanen, Gun

    2005-10-15

    A total of 510 rainbow trout originating from fish farms in lakes and sea areas around Finland were studied for the presence of Listeria monocytogenes. Samples were studied as pools from five fish. Gill, viscera, and skin from the pooled samples were analysed separately. The individual samples were analysed later if the pooled sample was found to be Listeria positive. The prevalence of Listeria spp. and L. monocytogenes in pooled unprocessed fresh rainbow trout was on average 35.0% and 14.6%, respectively. On the other hand, the prevalence of Listeria spp. and L. monocytogenes in individual thawed fish was found to be 14.3% and 8.8%, respectively. These numbers tend to overestimate and underestimate the real situation because not all fish in pooled samples were necessarily contaminated and in some of the Listeria positive pooled samples all individual samples turned out to be Listeria free. The prevalence of L. monocytogenes varied greatly between different fish farms from zero to 100% in pooled samples and from zero to 75% according to individually studied fish samples. Some indications of the influence of weather conditions and seasonal variations that strongly affected the Listeria contamination of fish were also noticed. The location of Listeria spp. and L. monocytogenes in different parts of the fish differed with statistical significance in rainbow trout. Up to 95.6% of the L. monocytogenes and 84.5% of Listeria spp. positive samples were gill samples. Only 4.4% (2/45) of the L. monocytogenes positive samples were obtained from skin or viscera. Closer study at one fish farm revealed that there was only one L. monocytogenes ribotype present in the contaminated fish, although water and surfaces were heavily contaminated with six other L. monocytogenes ribotypes.

  3. Silver contamination on abiotic and biotic compartments of Nahuel Huapi National Park lakes, Patagonia, Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro Guevara, Sergio; Arribere, Maria; Bubach, Debora; Vigliano, Pablo; Rizzo, Andrea; Alonso, Marcelo; Sanchez, Ricardo

    2005-01-05

    The Ag contents of abiotic and biotic compartments of different lakes of Nahuel Huapi National Park, Patagonia, Argentina were analyzed. The water bodies studied were lakes Nahuel Huapi, Moreno, Escondido, Espejo Chico and Traful, the latter chosen as a reference lake. The Ag concentration profiles of short sediment cores, dated by {sup 210}Pb and {sup 137}Cs techniques, were analyzed, as well as suspended load collected from three sites of lake Nahuel Huapi. The biota studied were the native mussel Diplodon chilensis (digestive gland and total soft tissues pooled samples) and five species of fish, two native and three introduced (liver and muscle pooled samples). Ag contents were determined by Instrumental Neutron Activation Analysis (INAA). The upper layers of the sediment cores sampled in lake Nahuel Huapi were enriched in Ag contents compared to deep layers in accumulation periods corresponding to the second half of the 20th century, but this enrichment was neither observed in the reference lake Traful, nor in lakes Espejo Chico and Escondido. Ag was enriched over background level (0.1 {mu}g g{sup -1}) also in suspended load collected in lake Nahuel Huapi. Ag fluxes to sediments were computed for suspended load and enriched sediment core layers. Highest Ag fluxes, from 350 to 470 {mu}g m{sup -2} year{sup -1}, were measured in Nahuel Huapi near the site where the liquid effluents of the Bariloche city sewage treatment plant are released to the lake. The spatial distribution of the other Ag fluxes suggests that this is the main source of Ag to lake Nahuel Huapi and lateral transport occurs within the water body. Ag concentrations on biota samples were consistent with these conclusions. Mussels collected in lake Nahuel Huapi showed higher Ag concentrations than in the other lakes, especially when compared to lake Traful. Ag contents in mussels were strongly associated with sediment intake, but enriched probably due to sediment grain size sorting during the intake

  4. Allantoinase in lake trout (Salvelinus namaycush): In vitro effects of PCBs, DDT and metals

    Science.gov (United States)

    Passino, Dora R. May; Cotant, Carol A.

    1979-01-01

    1. Allantoinase, an enzyme in the purine-urea cycle, was found in livers of Salvelinus namaycush (Osteichthyes: Salmoniformes).2. The enzyme was active from pH 6.6 to 8.2 at 37°C and from pH 7.4 to 9.0 at 10°C and had an Arrhenius energy was activation of 11.0 kcal/mol and a temperature quotient of 2.0. The Km of the enzyme homogenate was 8.4 mM allantoin.3. The concentrations of inorganic metals at which 50% inhibition occurred during in vitro exposure were 6.0 mg/l Cu2+, 6.7 mg/l Cd2+, 34 mg/l Hg2+ and 52 mg/l Pb2+. The in vitro sensitivity to PCBs, DDT and DDE and kinetics in the presence of metals were determined.4. Allantoinase activity was negatively correlated with body length for fish from Lake Michigan but not from Lake Superior or the laboratory.

  5. Analysis of hepatic deiodinase 2 mRNA levels in natural fish lake populations exposed to different levels of putative thyroid disrupters

    International Nuclear Information System (INIS)

    Jarque, Sergio; Bosch, Carme; Casado, Marta; Grimalt, Joan O.; Raldúa, Demetrio; Piña, Benjamin

    2014-01-01

    Hepatic mRNA levels of the dio2 gene (deiodinase 2), implicated in thyroid hormone homeostasis, were analyzed in trout from six remote lakes in the Pyrenees (Spain) and the Tatra Mountains (Slovakia). Highest levels corresponded to fish from the two coldest lakes in Pyrenees, whereas relatively low levels were found in the Tatra lakes. These values correlated with the presence of highly-brominated polybrominated diphenyl ethers (PBDE) congeners in the muscle of the same animals, reflecting the distribution of these compounds across European mountain ranges. In contrast, cyp1a expression levels, diagnostic for the presence of dioxin-like pollutants, mirrored the distribution of semi-volatile organochlorine compounds, indicating the specificity of the two types of biological responses. Exposure to PDBEs is known to increase transcription of dio2 and other thyroid-related genes in laboratory experiments; we propose that our data reflects the same phenomenon in natural populations, driven by anthropogenic pollutants at the environmental concentrations. - Highlights: • Hepatic deiodinase 2 (dio2) mRNA levels vary among mountain lake trout populations. • High dio2 expression correlated with elevated levels of PBDE 153 and 154 in muscle. • Expression patterns of dio2 and cyp1a diverge among the same fish populations. • Elevated biological responses associated to high loads of specific pollutants. • These data indicate that thyroid disruption may occur in remote ecosystems. - Deionidase dio2 expression as a marker for exposure to putative thyroid disruptors in mountain lake trout

  6. The diet of introduced brook trout (Salvelinus fontinalis; Mitchill, 1814 in an alpine area and a literature review on its feeding ecology

    Directory of Open Access Journals (Sweden)

    Rocco Tiberti

    2016-05-01

    Full Text Available Introduced fish are a major threat for high altitude aquatic habitats and Salvelinus fontinalis have been widely used throughout the Alps for stocking lakes and rivers. Understanding its feeding ecology is a basic, but essential tool for interpreting its impact. To assess which factors determine the diet of S. fontinalis we analyzed more than 500 stomachs from several introduced populations from the Gran Paradiso National Park (GPNP, Western Italian Alps and we measured the availability of several prey groups (zooplankton, aquatic invertebrates, terrestrial invertebrates. We complemented the study with a short, but exhaustive literature review on the S. fontinalis feeding ecology. In general the food composition reflected the availability of prey -confirming that S. fontinalis is an opportunistic predator- and was influenced by habitat type (stream vs lake, fish size, and seasonality. The obtained results were discussed in the light of the existing literature on the feeding ecology and ecological impact of S. fontinalis. Large benthonic insects account for a substantial part of  the diet of stream dwelling brook trout, while they are almost absent both in the diet and in the prey species pool of lake-dwelling brook trout, probably reflecting a stronger ecological impact in the lakes.

  7. A catastrophic event in Lake Geneva region during the Early Bronze Age?

    Science.gov (United States)

    Kremer, Katrina; Yrro, Blé; Marillier, François; Hilbe, Michael; Corboud, Pierre; Rachoud-Schneider, Anne-Marie; Girardclos, Stéphanie

    2013-04-01

    Similarly to steep oceanic continental margins, lake slopes can collapse, producing large sublacustrine landslides and tsunamis. Lake sediments are excellent natural archives of such mass movements and their study allows the reconstructions of these prehistoric events, such as the 563 AD large tsunami over Lake Geneva (Kremer et al, 2012). In Lake Geneva, more than 100 km of high-resolution seismic reflection profiles reveal the late Holocene sedimentation history. The seismic record shows a succession of five large lens-shaped seismic units (A to I), characterized by transparent/chaotic seismic facies with irregular lower boundaries, and interpreted as mass-movement deposits. These units are interbedded with parallel, continuous and strong amplitude reflections, interpreted as the 'background' lake sediments. The oldest dated mass movement (Unit D) covers a surface of 22 km2 in the deep basin, near the city of Lausanne. This deposit has an estimated minimum volume of 0.18 km3 and thus was very likely tsunamigenic (Kremer et al, 2012). A 12-m-long sediment core confirms the seismic interpretation of the mass movement unit and shows that the uppermost 3 m of Unit D are characterized by deformed hemipelagic sediments topped by a 5 cm thick turbidite. This deposit can be classified as a slump whose scar can be interpreted in the seismic data and visualized by multibeam bathymetry. This slump of Lausanne was likely triggered by an earthquake but a spontaneous slope collapse cannot be excluded (Girardclos et al, 2007). Radiocarbon dating of plant macro-remains reveals that the unit D happened during Early Bronze Age. Three other mass wasting deposits occurred during the same time period and may have been triggered during the same event, either by a single earthquake or by a tsunami generated by the slump of Lausanne. Although the exact trigger mechanism of the all these mass-wasting deposits remains unknown, a tsunami likely generated by this event may have affected the

  8. Radionuclide concentrations in fish collected from Jemez, Nambe, and San Ildefonso Tribal Lakes

    International Nuclear Information System (INIS)

    Fresquez, P.R.; Armstrong, D.R.; Salazar, J.G.

    1995-02-01

    Radionuclide concentrations ( 90 Sr, 137 Cs, 238 Pu, 239 Pu,and total uranium) were determined in fish collected from Jemez, Nambe, and San Ildefonso tribal lakes. With the exception of 137 Cs, all other radionuclides were not significantly different in (stocked) rainbow trout collected from Jemez and Nambe as compared with game fish collected from Abiquiu, Heron, and El Vado Reservoirs. Although 137 Cs levels in trout from Jemez (3.2 x 10 -2 pCi per dry gram) and Nambe (7.5 x 10 -2 pCi per dry gram) were significantly higher than 137 Cs concentrations in fish from Abiquiu, Heron, and El Vado, they were still well below the regional statistical (worldwide fallout) reference level (i.e., -2 pCi per dry gram). Game and nongame fish collected from San Ildefonso contained higher and significantly higher concentrations of uranium, respectively, as compared with fish collected from Abiquiu, Heron, and El Vado. The higher uranium concentrations in fish from San Ildefonso as compared with fish from Abiquiu, Heron, and El Vado were attributed to the higher natural soil uranium contents in the area as compared with the geology of the area upstream of San Ildefonso. The effective (radiation) dose equivalent (EDE) from consuming 46 lb of game fish from Jemez, Nambe, and San Ildefonso lakes, after natural background has been subtracted, was 0.013 (±0.002), 0.019 (±0.012), and 0.017 (±0.028) mrem/yr, respectively. Similarly, the EDE from consuming nongame fish from San Ildefonso was 0.0092 (±0.0084) mrem/yr. The highest calculated dose, based on the mean + 2 standard deviation (95% confidence level), was 0.073 mrem/yr; this was <0.08% of the International Commission on Radiological Protection permissible dose limit for protecting members of the public

  9. Fate of Tetracapsuloides bryosalmonae (Myxozoa) after infection of brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss.

    Science.gov (United States)

    Kumar, Gokhlesh; Abd-Elfattah, Ahmed; Saleh, Mona; El-Matbouli, Mansour

    2013-11-25

    Tetracapsuloides bryosalmonae (Myxozoa) is the causative agent of proliferative kidney disease in salmonids. We assessed differences in intensity of T. bryosalmonae infection between brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss from the clinical phase of infection onwards. Specific pathogen-free fish were exposed to T. bryosalmonae spores under controlled laboratory conditions and sampled at 6, 8, 10, 12, 14, and 17 wk post exposure (wpe), and the transmission of T. bryosalmonae from infected fish to the bryozoan Fredericella sultana was observed. Parasite load was determined in fish kidneys by quantitative real-time PCR (qRT-PCR), and parasite stages were detected in kidney, liver, and spleen tissues at different time points by immunohistochemistry. T. bryosalmonae was successfully transmitted from infected brown trout to F. sultana colonies but not from infected rainbow trout. Body length and weight of infected brown trout did not differ significantly from control brown trout during all time points, while length and weight of infected rainbow trout differed significantly compared to controls from 10 to 17 wpe. qRT-PCR revealed that parasite load was significantly higher in kidneys of brown trout compared with rainbow trout. Immunohistochemistry showed high numbers of intra-luminal stages (sporogonic stages) in kidneys of brown trout with low numbers of pre-sporogonic stages. Sporogonic stages were not seen in kidneys of rainbow trout; only high numbers of pre-sporogonic stages were detected. Numbers of pre-sporogonic stages were low in the spleen and liver of brown trout but high in rainbow trout. These data confirmed that there are differences in the development and infection progress of T. bryosalmonae between brown trout and rainbow trout.

  10. Fate of Tetracapsuloides bryosalmonae (Myxozoa) after infection of brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss

    Science.gov (United States)

    Kumar, Gokhlesh; Abd-Elfattah, Ahmed; Saleh, Mona; El-Matbouli, Mansour

    2014-01-01

    Tetracapsuloides bryosalmonae (Myxozoa) is the causative agent of proliferative kidney disease in salmonids. We assessed differences in intensity of T. bryosalmonae infection between brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss from the clinical phase of infection onwards. Specific pathogen-free fish were exposed to T. bryosalmonae spores under controlled laboratory conditions and sampled at 6, 8, 10, 12, 14, and 17 wk post exposure (wpe), and the transmission of T. bryosalmonae from infected fish to the bryozoan Fredericella sultana was observed. Parasite load was determined in fish kidneys by quantitative real-time PCR (qRT-PCR), and parasite stages were detected in kidney, liver, and spleen tissues at different time points by immunohistochemistry. T. bryosalmonae was successfully transmitted from infected brown trout to F. sultana colonies but not from infected rainbow trout. Body length and weight of infected brown trout did not differ significantly from control brown trout during all time points, while length and weight of infected rainbow trout differed significantly compared to controls from 10 to 17 wpe. qRT-PCR revealed that parasite load was significantly higher in kidneys of brown trout compared with rainbow trout. Immunohistochemistry showed high numbers of intra-luminal stages (sporogonic stages) in kidneys of brown trout with low numbers of pre-sporogonic stages. Sporogonic stages were not seen in kidneys of rainbow trout; only high numbers of pre-sporogonic stages were detected. Numbers of pre-sporogonic stages were low in the spleen and liver of brown trout but high in rainbow trout. These data confirmed that there are differences in the development and infection progress of T. bryosalmonae between brown trout and rainbow trout. PMID:24270019

  11. Effects of dressing and cooking on DDT concentrations in certain fish from Lake Michigan

    Science.gov (United States)

    Reinert, Robert E.; Stewart, Donald; Seagran, Harry L.

    1972-01-01

    Concentrations of DDT residues were highest in parts of the body with the highest oil content in four species of fish from Lake Michigan: yellow perch (Perca flavescens), bloater (Coregonus hoyi), lake trout (Salvelinus namaycush), and coho salmon (Oncorhynchus kisutch). Dressing reduced the DDT residues and oil content by more than 90% in yellow perch but had little effect in the other three species. The concentration of DDT residues in bloaters was changed little by smoking but was reduced 64–72% by other methods of cooking: from 8.0 ppm (raw) to 2.2 ppm after frying in corn oil; from 10.7 to 3.9 ppm after frying in lard; and from 9.1 to 3.2 ppm after broiling. The concentration of DDT residues in fillets of yellow perch changed only from 0.3 ppm (raw) to 0.4 or 0.5 ppm after baking, frying, or broiling.

  12. Effect of electric barrier on passage and physical condition of juvenile and adult rainbow trout

    Science.gov (United States)

    Layhee, Megan J.; Sepulveda, Adam; Shaw, Amy; Smuckall, Matthew; Kapperman, Kevin; Reyes, Alejandro

    2016-01-01

    Electric barriers can inhibit passage and injure fish. Few data exist on electric barrier parameters that minimize these impacts and on how body size affects susceptibility, especially to nontarget fish species. The goal of this study was to determine electric barrier voltage and pulse-width settings that inhibit passage of larger bodied rainbow trout Oncorhynchus mykiss (215–410 mm fork length) while allowing passage of smaller bodied juvenile rainbow trout (52–126 mm) in a static laboratory setting. We exposed rainbow trout to 30-Hz pulsed-direct current voltage gradients (0.00–0.45 V cm−1) and pulse widths (0.00.7 ms) and recorded their movement, injury incidence, and mortality. No settings tested allowed all juveniles to pass while impeding all adult passage. Juvenile and adult rainbow trout avoided the barrier at higher pulse widths, and fewer rainbow trout passed the barrier at 0.7-ms pulse width compared to 0.1 ms and when the barrier was turned off. We found no effect of voltage gradient on fish passage. No mortality occurred, and we observed external bruising in 5 (7%) juvenile rainbow trout and 15 (21%) adult rainbow trout. This study may aid managers in selecting barrier settings that allow for increased juvenile passage.

  13. Snake River Sockeye Salmon Captive Broodstock Program; Research Element, 2001 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Hebdon, J. Lance; Castillo, Jason; Willard, Catherine (Idaho Department of Fish and Game, Boise, ID)

    2003-12-01

    yearly since 1992. We continue to have difficulty capturing age-0 kokanee in the midwater trawl on Pettit Lake. Angler surveys were conducted on Redfish and Alturas lakes to estimate kokanee harvest and to estimate return to creel for hatchery rainbow trout planted in Alturas Lake. We failed to encounter any kokanee that had been harvested in 88 angler interviews conducted between May 26 and August 7, resulting in an estimated kokanee harvest of zero. On Alturas Lake, we again failed to encounter any harvested kokanee in 116 angler interviews, resulting in an estimated kokanee harvest of zero. We estimated that anglers harvested 9.5% of the 6,598 rainbow trout planted in Alturas Lake. We estimated that 110 wild/natural and 9,616 hatchery-produced sockeye salmon smolts out-migrated from Redfish Lake in 2001. This was the lowest estimate of unmarked smolt out-migration since monitoring began in 1991. The trap on Redfish Lake Creek was operated from April 22 to June 6, 2001 to estimate out-migration. Mean travel times for PIT-tagged smolts from Redfish Lake Creek Trap to Lower Granite Dam was 10.3 days for wild/natural smolts and 10.6 days for hatchery-produced smolts. Based on cumulative unique PIT tag interrogations from Sawtooth basin traps to mainstem Snake and Columbia river dams, the Redfish Lake wild/natural smolts, Redfish fall direct presmolts group, and Alturas Lake fall direct presmolts recorded the highest detection rates. In 2001, 65 hatchery-raised and 14 anadromous adult sockeye salmon were released to Redfish Lake for natural spawning. We observed 12 to 15 areas of excavation in the lake that were possible redds. We monitored bull trout spawning on Fishhook Creek, a tributary to Redfish Lake, and on Alpine Creek, a tributary to Alturas Lake. This represented the fourth consecutive year that the index reaches have been surveyed on these two streams. Adult counts on Fishhook Creek were similar to previous years as were redd counts. On Alpine Creek, bull trout

  14. Lake Roosevelt Fisheries Monitoring Program; 1990 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, Janelle R.; Scholz, Allan T. (Eastern Washington University, Upper Columbia United Tribes Fisheries Research Center, Cheney, WA)

    1991-09-01

    As partial mitigation for the loss of anadromous salmon and steelhead incurred by construction of Grand Coulee Dam, the Northwest Power Planning Council directed Bonneville Power Administration (BPA) to construct two kokanee salmon (Oncorhynchus nerka) hatcheries on Lake Roosevelt (NPPC 1987 [Section 903 (g)(l)(C)]). The hatcheries are to produce 8 million kokanee salmon fry or 3.2 million adults for outplanting into Lake Roosevelt as well as 500,000 rainbow trout (Oncorhynchus mykiss) for the Lake Roosevelt net-pen programs. In section 903 (g)(l)(E), the Council also directed BPA to fund a monitoring program to evaluate the effectiveness of the kokanee hatcheries. The monitoring program included the following components: (1) conduction of a year-round creel census survey to determine angler pressure, catch rates and composition, growth and condition of fish caught by anglers, and economic value of the fishery. Comparisons will be made before and after hatcheries are on-line to determine hatchery effectiveness; (2) conduct an assessment of kokanee, rainbow trout, and walleye feeding habits, growth rates, and densities of their preferred prey at different locations in the reservoir and how reservoir operations affect population dynamics of preferred prey organisms. This information will be used to determine kokanee and rainbow trout stocking locations, stocking densities and stocking times; (3) conduct a mark-recapture study designed to assess effectiveness of various release times and locations for hatchery-raised kokanee and net-pen raised rainbow so fish-loss over Grand Coulee Dam will be minimized, homing to egg collection sites will be improved and angler harvest will be increased. The above measures were adopted by the Council based on a management plan developed by Upper Columbia United Tribes Fisheries Center, Spokane Indian Tribe, Colville Confederated Tribes, Washington Department of Wildlife, and the National Park Service. This plan examined the

  15. Movement of resident rainbow trout transplanted below a barrier to anadromy

    Science.gov (United States)

    Wilzbach, Margaret A.; Ashenfelter, Mark J.; Ricker, Seth J.

    2012-01-01

    We tracked the movement of resident coastal rainbow trout Oncorhynchus mykiss irideus that were experimentally transplanted below a migration barrier in a northern California stream. In 2005 and 2006, age-1 and older rainbow trout were captured above a 5-m-high waterfall in Freshwater Creek and individually marked with passive integrated transponder tags. Otolith microchemistry confirmed that the above-barrier trout were the progeny of resident rather than anadromous parents, and genetic analysis indicated that the rainbow trout were introgressed with cutthroat trout O. clarkii. At each of three sampling events, half of the tagged individuals (n = 22 and 43 trout in 2005 and 2006, respectively) were released 5 km downstream from the waterfall (approximately 10 km upstream from tidewater), and an equal number of tagged individuals were released above the barrier. Tagged individuals were subsequently relocated with stationary and mobile antennae or recaptured in downstream migrant traps, or both, until tracking ceased in October 2007. Most transplanted individuals remained within a few hundred meters of their release location. Three individuals, including one rainbow trout released above the waterfall, were last detected in the tidally influenced lower creek. Two additional tagged individuals released above the barrier were found alive in below-barrier reaches and had presumably washed over the falls. Two of seven tagged rainbow trout captured in downstream migrant traps had smolted and one was a presmolt. The smoltification of at least some individuals, coupled with above-barrier "leakage" of fish downstream, suggests that above-barrier resident trout have the potential to exhibit migratory behavior and to enter breeding populations of steelhead (anadromous rainbow trout) within the basin.

  16. Tissue astaxanthin and canthaxanthin distribution in rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar).

    Science.gov (United States)

    Page, G I; Davies, S J

    2006-01-01

    A comparative investigation of tissue carotenoid distribution between rainbow trout, Oncorhynchus mykiss, and Atlantic salmon, Salmo salar, was undertaken to identify the relative efficiency of utilization of astaxanthin and canthaxanthin. Higher apparent digestibility coefficients (ADCs) (96% in trout vs. 28-31% in salmon; Ptrout vs. 5.5% in salmon; Ptrout. Astaxanthin deposition was higher than canthaxanthin in rainbow trout, while the reverse was true for Atlantic salmon, suggesting species-specificity in carotenoid utilization. The white muscle (95% in trout vs. 93% in salmon) and kidneys (0.5% in trout vs. 0.2% in salmon) represented higher proportions of the total body carotenoid pool in rainbow trout than in Atlantic salmon (Ptrout; Ptrout. Liver catabolism is suspected to be a critical determinant in carotenoid clearance, with higher catabolism expected in Atlantic salmon than in rainbow trout.

  17. Diagnostic single nucleotide polymorphisms for identifying westslope cutthroat trout (Oncorhynchus clarki lewisi), Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) and rainbow trout (Oncorhynchus mykiss).

    Science.gov (United States)

    Kalinowski, S T; Novak, B J; Drinan, D P; Jennings, R deM; Vu, N V

    2011-03-01

    We describe 12 diagnostic single nucleotide polymorphism (SNP) assays for use in species identification among rainbow and cutthroat trout: five of these loci have alleles unique to rainbow trout (Oncorhynchus mykiss), three unique to westslope cutthroat trout (O. clarkii lewisi) and four unique to Yellowstone cutthroat trout (O. clarkii bouvieri). These diagnostic assays were identified using a total of 489 individuals from 26 populations and five fish hatchery strains. © 2010 Blackwell Publishing Ltd.

  18. Age, growth and sex composition of the American smelt Osmerus mordax(Mitchill), of western Lake Superior

    Science.gov (United States)

    Bailey, Merryll M.

    1964-01-01

    This study is based on 4,561 smelt collected in Chequamegon Bay, the Apostle Islands, the Brule River, and Superior Harbor, all in western Lake Superior. Commercial production in the Great Lakes (U.S. and Canada combined) reached a peak of nearly 16 million pounds in 1960. Production in Lake Superior has generally been small but increased during the 1950's to reach 948,000 pounds in 1960. All O-group and spring I-group smelt had scales with sufficient sculpturing to permit detection of the first annulus. Annulus formation began after 6 June in 1960. In 1961, all smelt had completed the annulus by 24 August. The body-scale relation is a straight line with an intercept of -0.9 inch on the axis of fish length. The weight of western Lake Superior smelt increased as the 2.952 power of the length. A large range of length in each age group and resulting overlap of age-groups II-VI made length a poor index of age. Female smelt grew faster than males after the second year and dominated strongly in age-groups IV-VII. Both sexes made their best annual growth in length (3.3 inches) during their second year of life; the largest weight increments (0.74 ounce, males; 0.85 ounce, females) came in the third year. Best production from a commercial pound net in 1961 occurred when the sex ratios of spawning smelt were nearest 50:50. Spawning male smelt were consistently shorter than females and the average lengths of both sexes decreased as the spawning season progressed. Shortest mature smelt of each sex were 5.0 to 5.2 inches but the males are probably the first to reach 100 percent maturity. All year-old smelt were immature. Among 2-year-old fish, 40.7 per cent of the males and 17.7 percent of the females had reached maturity. All smelt more than 2 years old were mature. Ovaries of 10 smelt contained an average of 31,338 eggs for fish 7.3 to 8.8 inches long.

  19. Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change

    Science.gov (United States)

    Gaglioti, Benjamin V.; Mann, Daniel H.; Jones, Benjamin M.; Pohlman, John W.; Kunz, Michael L.; Wooller, Matthew J.

    2014-01-01

    Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of radiocarbon age-offsets (14C) between the bulk lake sediment and plant macrofossils deposited in an arctic lake as an archive for soil and permafrost OC release over the last 14,500 years. The lake traps and archives OC imported from the watershed and allows us to test whether prior warming events stimulated old carbon release and heightened age-offsets. Today, the age-offset (2 ka; thousand of calibrated years before A.D. 1950) and the depositional rate of ancient OC from the watershed into the lake are relatively low and similar to those during the Younger Dryas cold interval (occurring 12.9–11.7 ka). In contrast, age-offsets were higher (3.0–5.0 ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7–9.0 ka) and Bølling-Allerød periods (14.5–12.9 ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were ~10 times greater than today. Although permafrost OC was vulnerable to climate warming in the past, we suggest surface soil organic horizons and peat are presently limiting summer thaw and carbon release. As a result, the temperature threshold to trigger widespread permafrost OC release is higher than during previous warming events.

  20. Morphological Traits of Brown Trout (Salmo Trutta Fario from Fiad Trout Farm, Bistrița-Năsăud County

    Directory of Open Access Journals (Sweden)

    Paul UIUIU

    2017-11-01

    Full Text Available The purpose of this this study was to complete the data from the specialized literature regarding some morphological charactersof male and female breeders of brown trout (Salmo trutta fario, exploited in Fiad trout farm, Bistrița-Năsăud County, Romania. The body mass (Bm of males ranged from 0.67 kg to 1.39 kg with a mean value of 0.96 ±0.07 kg. The body mass of females (Bm ranged from 0.50 kg to 0.90 kg with a mean value of 0.73±0.04 kg. In terms of descriptive statistics, the values of variability of studied characters, both males and females, are low. This low variability, shows the existence of a good homogeneity of the breeding group from Fiad trout farm.The One-Way ANOVA analysis showed that there is no statistically significance difference for the means of studied characters, except for commercial length and small perimeter of fishes. The results of t-test for showed that there is a statistically significance difference between the measurements and the gender of the specimens.

  1. Juvenile Lost River and shortnose sucker year class strength, survival, and growth in Upper Klamath Lake, Oregon, and Clear Lake Reservoir, California—2016 Monitoring Report

    Science.gov (United States)

    Burdick, Summer M.; Ostberg, Carl O.; Hoy, Marshal S.

    2018-04-20

    Executive SummaryThe largest populations of federally endangered Lost River (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) exist in Upper Klamath Lake, Oregon, and Clear Lake Reservoir, California. Upper Klamath Lake populations are decreasing because adult mortality, which is relatively low, is not being balanced by recruitment of young adult suckers into known spawning aggregations. Most Upper Klamath Lake juvenile sucker mortality appears to occur within the first year of life. Annual production of juvenile suckers in Clear Lake Reservoir appears to be highly variable and may not occur at all in very dry years. However, juvenile sucker survival is much higher in Clear Lake, with non-trivial numbers of suckers surviving to join spawning aggregations. Long-term monitoring of juvenile sucker populations is needed to (1) determine if there are annual and species-specific differences in production, survival, and growth, (2) to identify the season (summer or winter) in which most mortality occurs, and (3) to help identify potential causes of high juvenile sucker mortality, particularly in Upper Klamath Lake.We initiated an annual juvenile sucker monitoring program in 2015 to track cohorts in 3 months (June, August, and September) annually in Upper Klamath Lake and Clear Lake Reservoir. We tracked annual variability in age-0 sucker apparent production, juvenile sucker apparent survival, and apparent growth. Using genetic markers, we were able to classify suckers as one of three taxa: shortnose or Klamath largescale suckers, Lost River, or suckers with genetic markers of both species (Intermediate Prob[LRS]). Using catch data, we generated taxa-specific indices of year class strength, August–September apparent survival, and overwinter apparent survival. We also examined prevalence and severity of afflictions such as parasites, wounds, and deformities.Indices of year class strength in Upper Klamath Lake were similar for shortnose suckers in 2015

  2. Age and growth of the kiyi, Leucichthys kiyi Koelz, in Lake Michigan

    Science.gov (United States)

    Deason, Hilary J.; Hile, Ralph

    1947-01-01

    lengths indicated, for example, that the females did not attain a total length of 10 inches until the fifth year of life or the males until the sixth. Similarly, the calculated weight of 4 ounces was not reached until the fifth or sixth year (with the actual time varying with sex and locality). The season's growth of the kiyi probably begins sometime in May and most or all of the growth is completed by the end of August. The calculated lengths of the age groups exhibited large discrepancies that differed from “Lee's phenomenon” as ordinarily observed in that the data for the later rather than the earlier years of life were affected most severely. Chief among the factors held responsible for these discrepancies were gear selection and the selective destruction of the more rapidly growing individuals in the fishery. Errors inherent in the (direct-proportion) method of computing growth from scale measurements were considered to have been unimportant. The Lake Michigan kiyi exhibits growth compensation–the tendency for the smaller of the young fish to have the more rapid growth in the later years of life. Comparisons with the average lengths and weights of the age groups of the Lake Ontario kiyi given by Pritchard (1931) indicated the Lake Michigan fish to be the larger at the earlier ages (age-groups II and III) and the smaller at the later ages (age-groups IV to VI). The length-frequency distributions of the age groups exhibited extensive overlap. As many as eight age groups were represented in a single centimeter interval of length. The length frequencies and average lengths of all fish collected, arranged according to the mesh sizes of the gill nets by which they were captured, revealed that the selective action of these nets in the taking of kiyis was much more obvious in the numbers of fish in the catch than in their average size. As an illustration, in 1930–1931, the 2 3/4-inch mesh nets took fish that were only 0.1 inch longer than those in 2 1/2-inch meshes

  3. GROWTH, MORTALITY AND PRODUCTION OF BROWN AND RAINBOW TROUT IN NEW MEXICO STREAMS

    Directory of Open Access Journals (Sweden)

    S Leiner

    1995-06-01

    Full Text Available Thirty-two representative trout sites in 15 high elevation New Mexico streams (1,661 - 2560 m above sea level were sampled in 1988 and 1989. Fish was captured by consecutive removal via electrofishing in net-blocked segments from 65 to 160 m long. Maximum estimated trout length (Lm.ax was related inversely to yield (r2 = 0.351; p = 0.055. Instantaneous rate of mortality was also marginally related to yield (r2 = 0.294. The production index ranged from 1,38 to 32.02 g/m2/year. Variation in production was highly correlated to trout biomass (r2 = 0.910. Trout growth and production were best defined by the relationships where: cover, stream width, water temperature, yield by anglers, LMAX, and nitrate-nitrogen concentration were included.

  4. Groundwater age and chemistry, and future nutrient loads for selected Rotorua Lakes catchments

    International Nuclear Information System (INIS)

    Morgenstern, U.; Reevers, R.R.; Daugney, C.J.; Cameron, S.; Gordon, D.

    2005-01-01

    since catchment development) of less than 80%. Significant fractions of these groundwaters were therefore recharged before land-use intensification, and these water discharges do not yet reflect the full effect of current land-use practices on the groundwater quality. Further deterioration of water quality must therefore be expected. Age dating of the main groundwater-fed streams in the Lake Rotorua catchment revealed mostly mean residence times between 35 and 130 years. The streams with the oldest water are Waingaehe (127 years), Hamurana (110 years), Awahou (61 years), and Utuhina streams (48 years). Only Ngongotaha Stream has younger water of 16 years mean residence time. Total phosphorus increases with groundwater age, concentration in young groundwater is 20 years. Trends for nitrate (NO 3 , potassium (K) and sulphate (SO 4 ) indicate that these are increased in the young groundwaters as result of land-use intensification. The natural background level of groundwater NO 3 -N is determined from old groundwater (pre-land-use intensification) to 0.14 mg/L, and the current level is determined from young groundwater (post-land-use intensification) to 1.6 mg/L. Therefore, 9% of the current level can be attributed to the natural background, and 91% to land-use impacts. This is an increase in NO 3 by a factor 11. Potassium concentrations indicate a natural background level of 0.6 mg/L and a current level of 3.8 mg/L. About 16% of the current K level is therefore natural background, and 84% is land-use impact, an increase by a factor 6. SO 4 shows a trend of elevated values of 3 mg/L in young waters compared to older water of 1.5 mg/L. Nitrogen loading was calculated from a mass budget for the major streams to Lake Rotorua. Only NO 3 -N, the main N component, was considered. Most of the nutrient flux via surface streams (ca. 90%) is contributed by the western catchment - Hamurana, Awahou, Puarenga, Waiteti, Ngongotaha and Utuhina streams. The total load of NO 3 -N is

  5. Measurement of Lake Roosevelt biota in relation to reservoir operations. Final report 1993

    International Nuclear Information System (INIS)

    Voeller, A.C.

    1993-01-01

    The purpose of this study was to collect biological data from Lake Roosevelt to be used in the design of a computer model that will predict biological responses to reservoir operations as part of the System Operation Review Program. This study worked in conjunction with Lake Roosevelt Monitoring Project which investigated the effectiveness of two kokanee salmon hatcheries. This report summarized the data collected from Lake Roosevelt from 1993 and includes limnological, reservoir operation, zooplankton, benthic macroinvertebrate, experimental trawling, and net-pen rainbow trout tagging data. Major components of the Lake Roosevelt model include quantification of impacts to zooplankton, benthic macroinvertebrates, and fish caused by reservoir drawdowns and low water retention times

  6. Scale-dependent seasonal pool habitat use by sympatric Wild Brook Trout and Brown Trout populations

    Science.gov (United States)

    Davis, Lori A.; Wagner, Tyler

    2016-01-01

    Sympatric populations of native Brook Trout Salvelinus fontinalis and naturalized Brown Trout Salmo truttaexist throughout the eastern USA. An understanding of habitat use by sympatric populations is of importance for fisheries management agencies because of the close association between habitat and population dynamics. Moreover, habitat use by stream-dwelling salmonids may be further complicated by several factors, including the potential for fish to display scale-dependent habitat use. Discrete-choice models were used to (1) evaluate fall and early winter daytime habitat use by sympatric Brook Trout and Brown Trout populations based on available residual pool habitat within a stream network and (2) assess the sensitivity of inferred habitat use to changes in the spatial scale of the assumed available habitat. Trout exhibited an overall preference for pool habitats over nonpool habitats; however, the use of pools was nonlinear over time. Brook Trout displayed a greater preference for deep residual pool habitats than for shallow pool and nonpool habitats, whereas Brown Trout selected for all pool habitat categories similarly. Habitat use by both species was found to be scale dependent. At the smallest spatial scale (50 m), habitat use was primarily related to the time of year and fish weight. However, at larger spatial scales (250 and 450 m), habitat use varied over time according to the study stream in which a fish was located. Scale-dependent relationships in seasonal habitat use by Brook Trout and Brown Trout highlight the importance of considering scale when attempting to make inferences about habitat use; fisheries managers may want to consider identifying the appropriate spatial scale when devising actions to restore and protect Brook Trout populations and their habitats.

  7. Founding population size of an aquatic invasive species

    Science.gov (United States)

    Kalinowski, Steven T.; Muhlfeld, Clint C.; Guy, Christopher S.; Benjamin Cox,

    2010-01-01

    Non-native species of fish threaten native fishes throughout North America, and in the Rocky Mountains, introduced populations of lake trout threaten native populations of bull trout. Effective management of lake trout and other exotic species require understanding the dynamics of invasion in order to either suppress non-native populations or to prevent their spread. In this study, we used microsatellite genetic data to estimate the number of lake trout that invaded a population of bull trout in Swan Lake, MT. Examination of genetic diversity and allele frequencies within the Swan Lake populations showed that most of the genes in the lake trout population are descended from two founders. This emphasizes the importance of preventing even a few lake trout from colonizing new territory.

  8. Comparison of genetic and visual identification of cisco and lake whitefish larvae from Chaumont Bay, Lake Ontario

    Science.gov (United States)

    George, Ellen M.; Hare, Matthew P.; Crabtree, Darran L.; Lantry, Brian F.; Rudstam, Lars G.

    2017-01-01

    Cisco Coregonus artedi are an important component of native food webs in the Great Lakes, and their restoration is instrumental to the recovery of lake trout Salvelinus namaycush and Atlantic salmon Salmo salar. Difficulties with visual identification of larvae can confound early life history surveys, as cisco are often difficult to distinguish from lake whitefish C. clupeaformis. We compared traditional visual species identification methods to genetic identifications based on barcoding of the mitochondrial cytochrome C oxidase I gene for 726 coregonine larvae caught in Chaumont Bay, Lake Ontario. We found little agreement between the visual characteristics of cisco identified by genetic barcoding and the most widely used dichotomous key, and the considerable overlap in ranges of traditionally utilized metrics suggest that visual identification of coregonine larvae from Chaumont Bay is impractical. Coregonines are highly variable and plastic species, and often display wide variations in morphometric characteristics across their broad range. This study highlights the importance of developing accurate, geographically appropriate larval identification methods in order to best inform cisco restoration and management efforts.

  9. Thermal regimes, nonnative trout, and their influences on native Bull Trout in the Upper Klamath River Basin, Oregon

    Science.gov (United States)

    Benjamin, Joseph R.; Heltzel, Jeannie; Dunham, Jason B.; Heck, Michael; Banish, Nolan P.

    2016-01-01

    The occurrence of fish species may be strongly influenced by a stream’s thermal regime (magnitude, frequency, variation, and timing). For instance, magnitude and frequency provide information about sublethal temperatures, variability in temperature can affect behavioral thermoregulation and bioenergetics, and timing of thermal events may cue life history events, such as spawning and migration. We explored the relationship between thermal regimes and the occurrences of native Bull Trout Salvelinus confluentus and nonnative Brook Trout Salvelinus fontinalis and Brown Trout Salmo trutta across 87 sites in the upper Klamath River basin, Oregon. Our objectives were to associate descriptors of the thermal regime with trout occurrence, predict the probability of Bull Trout occurrence, and estimate upper thermal tolerances of the trout species. We found that each species was associated with a different suite of thermal regime descriptors. Bull Trout were present at sites that were cooler, had fewer high-temperature events, had less variability, and took longer to warm. Brook Trout were also observed at cooler sites with fewer high-temperature events, but the sites were more variable and Brook Trout occurrence was not associated with a timing descriptor. In contrast, Brown Trout were present at sites that were warmer and reached higher temperatures faster, but they were not associated with frequency or variability descriptors. Among the descriptors considered, magnitude (specifically June degree-days) was the most important in predicting the probability of Bull Trout occurrence, and model predictions were strengthened by including Brook Trout occurrence. Last, all three trout species exhibited contrasting patterns of tolerating longer exposures to lower temperatures. Tolerance limits for Bull Trout were lower than those for Brook Trout and Brown Trout, with contrasts especially evident for thermal maxima. Our results confirm the value of exploring a suite of thermal

  10. Bull trout distribution and abundance in the waters on and bordering the Warm Springs Indian Reservation: 2001 annual report

    International Nuclear Information System (INIS)

    Brun, Christopher V.; Dodson, Rebekah D.

    2002-01-01

    The range of bull trout (Salvelinus confluentus) in the Deschutes River basin has decreased from historic levels due to many factors including dam construction, habitat degradation, brook trout introduction and eradication efforts. While the bull trout population appears to be stable in the Metolius River-Lake Billy Chinook system they have been largely extirpated from the upper Deschutes River (Buchanan et al. 1997). Little was known about bull trout in the lower Deschutes basin until BPA funded project No.9405400 began during 1998. In this progress report we describe the findings from the fourth year (2001) of the multi-year study aimed at determining the life history, habitat needs and limiting factors of bull trout in the lower Deschutes subbasin. Juvenile bull trout and brook trout (Salvelinus fontinalis) relative abundance was assessed in the Warm Springs River and Shitike Creek by night snorkeling. In the Warm Springs R. juvenile bull trout were slightly more numerous than brook trout, however, both were found in low densities. Relative densities of both species were the lowest observed since surveys began in 1999. Relative densities of juvenile bull trout and brook trout increased in Shitike Cr. Juvenile bull trout vastly out numbered brook trout in Shitike Cr. The utility of using index reaches to monitor trends in juvenile bull trout and brook trout relative abundance was assessed in the Warm Springs R. for the third year. Mean relative densities of juvenile bull trout within the index reaches was slightly higher than what was observed in the 2.4 km control reach. However, the mean relative density of brook trout in the 2.4 km control reach was slightly higher than what was observed in within the index reaches. Habitat use by both juvenile bull trout and brook trout was determined in the Warm Springs R. Juvenile bull trout and brook trout occupied pools more frequently than glides, riffles and rapids. However, pools accounted for only a small percentage

  11. The effects of varied densities on the growth and emigration of adult cutthroat trout and brook trout in fenced stream enclosures

    Science.gov (United States)

    Buys, D.J.; Hilderbrand, R.H.; Kershner, J.L.

    2009-01-01

    We evaluated the effects of various density treatments on adult fish growth and emigration rates between Bonneville cutthroat trout Oncorhynchus clarki utah and brook trout Salvelinus fontinalis in stream enclosures in Beaver Creek, Idaho, We used 3 density treatments (low, ambient, and high fish densities) to evaluate density-related effects and to ensure a response. Intraspecific ambient-density tests using cutthroat trout only were also performed. Results indicated an absence of cage effects in the stream enclosures and no differences in fish growth between ambient-density stream-enclosure fish and free-range fish. Brook trout outgrew and moved less than cutthroat trout in the stream enclosures, especially as density increased, In all 3 density treatments, brook trout gained more weight than cutthroat trout, with brook trout gaining weight in each density treatment and cutthroat trout losing weight at the highest density. At high densities, cutthroat trout attempted to emigrate more frequently than brook trout in sympatry and allopatry. We observed a negative correlation between growth and emigration for interspecific cutthroat trout, indicating a possible competitive response due to the presence of brook trout. We observed similar responses for weight and emigration in trials of allopatric cutthroat trout, indicating strong intraspecific effects as density increased. While cutthroat trout showed a response to experimental manipulation with brook trout at different densities, there has been long-term coexistence between these species in Beaver Creek, This system presents a unique opportunity to study the mechanisms that lead cutthroat trout to coexist with rather than be replaced by nonnative brook trout.

  12. Impacts of Northern Pike on stocked Rainbow Trout in Pactola Reservoir, South Dakota

    Science.gov (United States)

    Scheibel, Natalie C.; Dembkowski, Daniel J.; Davis, Jacob L.; Chipps, Steven R.

    2016-01-01

    Establishment of nonnative Northern Pike Esox lucius in Pactola Reservoir, South Dakota, has prompted concern among biologists about the influence of this species on the lake’s intensively managed salmonid fisheries. Ancedotal information suggests that catch rates of Rainbow Trout Oncorhynchus mykiss have declined while mean size and abundance of Northern Pike has increased, although quantitative information on diet and growth of the Northern Pike population is lacking. To address potential interactions between Northern Pike and Rainbow Trout, we assessed size-dependent predation by Northern Pike on Rainbow Trout and determined the relative energetic contribution of stocked Rainbow Trout to Northern Pike growth using bioenergetics modeling. Stable isotopes combined with traditional diet analyses revealed that smaller Northern Pike (Trout contributed less than 10% to their annual energy consumption. In contrast, larger Northern Pike (≥600 mm TL) consumed primarily Rainbow Trout, which accounted for 56% of their annual energy consumption. Combining estimates of Northern Pike predation with production costs of catchable-size Rainbow Trout revealed that annual economic losses ranged from US$15,259 to $24,801 per year. Over its lifespan, an age-10 Northern Pike was estimated to consume ~117 Rainbow Trout worth approximately $340. Thus, Northern Pike predation substantially influences salmonid management initiatives and is likely a primary factor contributing to reduced Rainbow Trout abundance and return to anglers in Pactola Reservoir. Strategies for reducing Northern Pike predation on Rainbow Trout include increasing the size of stocked fish or altering the timing and spatial distribution of stocking events.

  13. Landscape-scale evaluation of asymmetric interactions between Brown Trout and Brook Trout using two-species occupancy models

    Science.gov (United States)

    Wagner, Tyler; Jefferson T. Deweber,; Jason Detar,; John A. Sweka,

    2013-01-01

    Predicting the distribution of native stream fishes is fundamental to the management and conservation of many species. Modeling species distributions often consists of quantifying relationships between species occurrence and abundance data at known locations with environmental data at those locations. However, it is well documented that native stream fish distributions can be altered as a result of asymmetric interactions between dominant exotic and subordinate native species. For example, the naturalized exotic Brown Trout Salmo trutta has been identified as a threat to native Brook Trout Salvelinus fontinalis in the eastern United States. To evaluate large-scale patterns of co-occurrence and to quantify the potential effects of Brown Trout presence on Brook Trout occupancy, we used data from 624 stream sites to fit two-species occupancy models. These models assumed that asymmetric interactions occurred between the two species. In addition, we examined natural and anthropogenic landscape characteristics we hypothesized would be important predictors of occurrence of both species. Estimated occupancy for Brook Trout, from a co-occurrence model with no landscape covariates, at sites with Brown Trout present was substantially lower than sites where Brown Trout were absent. We also observed opposing patterns for Brook and Brown Trout occurrence in relation to percentage forest, impervious surface, and agriculture within the network catchment. Our results are consistent with other studies and suggest that alterations to the landscape, and specifically the transition from a forested catchment to one that contains impervious surface or agriculture, reduces the occurrence probability of wild Brook Trout. Our results, however, also suggest that the presence of Brown Trout results in lower occurrence probability of Brook Trout over a range of anthropogenic landscape characteristics, compared with streams where Brown Trout were absent.

  14. Revised age of deglaciation of Lake Emma based on new radiocarbon and macrofossil analyses

    Science.gov (United States)

    Elias, S.A.; Carrara, P.E.; Toolin, L.J.; Jull, A.J.T.

    1991-01-01

    Previous radiocarbon ages of detrital moss fragments in basal organic sediments of Lake Emma indicated that extensive deglaciation of the San Juan Mountains occurred prior to 14,900 yr B.P. (Carrara et al., 1984). Paleoecological analyses of insect and plant macrofossils from these basal sediments cast doubt on the reliability of the radiocarbon ages. Subsequent accelerator radiocarbon dates of insect fossils and wood fragments indicate an early Holocene age, rather than a late Pleistocene age, for the basal sediments of Lake Emma. These new radiocarbon ages suggest that by at least 10,000 yr B.P. deglaciation of the San Juan Mountains was complete. The insect and plant macrofossils from the basal organic sediments indicate a higher-than-present treeline during the early Holocene. The insect assemblages consisted of about 30% bark beetles, which contrasts markedly with the composition of insects from modern lake sediments and modern specimens collected in the Lake Emma cirque, in which bark beetles comprise only about 3% of the assemblages. In addition, in the fossil assemblages there were a number of flightless insect species (not subject to upslope transport by wind) indicative of coniferous forest environments. These insects were likewise absent in the modern assemblage. ?? 1991.

  15. Radionuclide and heavy metal concentrations in soil, vegetation, and fish collected around and within Tsicoma Lake in Santa Clara Canyon

    International Nuclear Information System (INIS)

    Fresquez, P.R.; Armstrong, D.R.; Naranjo, L. Jr.

    1996-03-01

    Radionuclide ( 3 H, 90 Sr, 137 Cs, 238 Pu, 239 Pu, total U) and heavy metal (Ag, As, Ba, Be, Cd, Cr, Hg, Ni, Pb, Sb, Se, Tl) contents were determined in soil, vegetation (overstory and understory), and fish (rainbow trout) collected around and within Tsicoma Lake in Santa Clara Canyon in 1995. All heavy metal and most radionuclide contents around or within the lake, except for U in soil, vegetation, and fish, were within or just above upper limit background. Detectable levels (where the analytical result was greater than two times counting uncertainty) of U in soils, vegetation, and fish were found in slightly higher concentrations than in background samples. Overall, however, maximum total committed effective dose equivalent (CEDE)(95% confidence level)--based on consumption of 46 lb of fish--from Tsicoma Lake (0.066 mrem/y) was within the maximum total CEDE from the ingestion of fish from the Mescalero National Fish Hatchery (background)(0.113 mrem/y)

  16. Cesium in Arctic char lakes - effects of the Chernobyl accident

    International Nuclear Information System (INIS)

    Hammar, J.; Notter, M.; Neumann, G.

    1991-01-01

    Fallout radiocesium from the Chernobyl accident caused extensive contamination in a region of previously well studied alpine lake ecosystems in northern Sweden. Levels of Cs-137 in the barren catchment basins reached 20-50 kBq/m 2 during 1986. The distribution, pathways and major transport mechanisms of radiocesium through the lake ecosystems were studied during 1986-1990. Levels of Cs-137, Cs-134 and K-40 in water, surface sediment, detritus (sediment traps) and different trophic levels of the food chains of Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) were monitored in a series of lakes forming a matrix of 4 natural lakes and 3 lake reservoirs, with or without the introduced new fish food organism, Mysis relicta. The reservoirs were found to act as sinks for radiocesium with extensive accumulation recorded in water, detritus, sediment, invertebrates and salmonids. Whereas concentrations in water and biota have declined from the extreme peak levels in 1986-1987, the levels in surface sediment increased extensively until fall of 1988. The concentration of Cs-137 in fish populations feeding on benthic invertebrates, i.e. mysids and amphipods, were significantly higher than in planktivorous fish. During the three first winters a significant increase in levels of Cs-137 in winter active Arctic char were recorded, whereas the levels declined during the succeeding summers. The introduced Mysis relicta were found to enhance the transport of Cs-137 from zooplankton and settling particles to Arctic char and brown trout. The results suggest a successive change in transport of radiocesium from water via zooplankton to planktivorous fish during the early summer of 1986 to post-depositional mobilization via benthic organisms to benthic fish in successive years. (213 refs.) (au)

  17. Monitor and Protect Wigwam River Bull Trout for Koocanusa Reservoir : Summary of the Skookumchuck Creek Bull Trout Enumeration Project Final Report 2000-2002.

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, Jeremy; Baxter, James S.

    2002-12-01

    This report summarizes the third and final year of a bull trout (Salvelinus confluentus) enumeration project on Skookumchuck Creek in southeastern British Columbia. The fence and traps were operated from September 6th to October 11th 2002 in order to enumerate post-spawning bull trout. During the study period a total of 309 bull trout were captured at the fence. In total, 16 fish of undetermined sex, 114 males and 179 females were processed at the fence. Length and weight data, as well as recapture information, were collected for these fish. An additional 41 bull trout were enumerated upstream of the fence by snorkeling prior to fence removal. Coupled with the fence count, the total bull trout enumerated during the project was 350 individuals. Several fish that were tagged in the lower Bull River were recaptured in 2002, as were repeat and alternate year spawners previously enumerated in past years at the fence. A total of 149 bull trout redds were enumerated on the ground in 2002, of which 143 were in the 3.0 km index section (river km 27.5-30.5) that has been surveyed over the past six years. The results of the three year project are summarized, and population characteristics are discussed.

  18. Constraint on radiocarbon age correction in Lake Biwa environment from the middle to late Holocene

    Energy Technology Data Exchange (ETDEWEB)

    Miyata, Y., E-mail: miyata@nendai.nagoya-u.ac.jp [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan); National Museum of Japanese History, Sakura 285-8502 (Japan); Minami, M. [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan); Onbe, S. [National Museum of Japanese History, Sakura 285-8502 (Japan); Archaeological Heritage Management Office, Tokushima University, Tokushima 770-8503 (Japan); Sakamoto, M. [National Museum of Japanese History, Sakura 285-8502 (Japan); Nakamura, T. [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan); Imamura, M. [National Museum of Japanese History, Sakura 285-8502 (Japan)

    2013-01-15

    Using data from previous studies and newly collected data, we compared the measured radiocarbon ages of molluscan shells, common reed (Phragmites australis) and pine needles (Pinus thunbergii) collected in 1966, 1970, 1990 and 2008 at Lake Biwa in Japan, and of archaeological samples, to examine radiocarbon reservoir effects at Lake Biwa. We also tested for differences in the radiocarbon reservoir effect between species and locations in the lake. The effects of nuclear bomb tests conducted in the 1950s and 1960s are clear, the offset between atmospheric {sup 14}C and the Lake Biwa freshwater {sup 14}C is larger for this period because the atmospheric {sup 14}C is so high. The semiclosed Lake Biwa system is in dynamic equilibrium with the atmosphere, resulting in the {sup 14}C content of the water following the changes in atmospheric {sup 14}C caused by nuclear testing. The shells collected after 1990 had radiocarbon ages that were 330-450 {sup 14}C years older than those of the coeval atmosphere. The apparent differences in radiocarbon age (about 300 {sup 14}C years) between shell fossils and wood samples excavated from the same layer of the submerged Awazu shell midden at Lake Biwa suggest that the radiocarbon reservoir effect also existed in the middle Holocene (the Middle Jomon period, about 5000 years ago). Because the present-day average residence time of Lake Biwa water is 3-6 years, its direct influence on the radiocarbon reservoir effect is small, which suggests that old carbon has been supplied into Lake Biwa.

  19. Age and growth of the whitefish in Lake Superior

    Science.gov (United States)

    Dryer, William R.

    1963-01-01

    The average annual commercial production of whitefish in the U.S. waters of Lake Superior dropped from 2,194,000 pounds in 1879-1908 to 504,000 pounds in 1911-59. The modern production, though far below the earlier, has accounted for more than 10 percent of the total value of the fishery in all but one of the last 20 years. Data are given on growth rate, age and year-class composition, size distribution, and length-weight relation of 1,800 fish collected in 1957-59 at Bayfield, Wis., and Marquette, Whitefish Point, and Dollar Settlement, Mich. Studies of the body-scale relation, sex ratio, and age and size at maturity were limited to fish collected at Bayfield. The age composition and mean age varied widely by port and year of capture. Oldest fish were those of the 1957 Bayfield samples which were dominated by age group VII and averaged 5.5 years old. The youngest were from Whitefish Point in 1959; age-group III was dominant, and the mean age was 3.2 years. The evidence on the strength of year classes was not clear-cut, but it was obvious that fluctuations in stocks of different areas were largely independent. The percentage of legal-size fish (17 inches or longer) in age groups ranged widely; only 8.6 percent of the V group were legal in the 1957 Bayfield collections, whereas 100 percent of fish of the same age were legal in the 1957-59 collections from Whitefish Point. The weight of whitefish in the combined samples increased as the 3.2408 power of the length. The growth rate from the fastest to the slowest growing stocks ranked as follows: Whitefish Point; Dollar Settlement and Marquette (fish from the two ports reversed ranks after 3 years); Bayfield. The major differences in growth in length among the various stocks occurred during the first years of life. Beyond the fifth year the annual increments were nearly the same in all stocks. The whitefish from Whitefish Point, Dollar Settlement, and Marquette are among the fastest growing in the Great Lakes. The

  20. Dynamics of zooplankton community of Lake Tarasmozero in long-term anthropogenic pollution

    Directory of Open Access Journals (Sweden)

    Kuchko Yaroslav Alexandrovich

    2014-11-01

    Full Text Available In the article the results of zooplankton studies in Lake Tarasmozero (Lizhma river basin are presented. Wastes from the trout-breeding complex "Kedrozero" have been collected in this pond since 1992. The obtained data showed that from 1989 to 2012 a number of changes in zooplankton community take place and it is the evidence of the gradual increase in the trophic status of the reservoir. The average biomass of zooplankton increased from 500 to 1000 mg/m3. According to the trophic index (Myaemets, 1979, Tarasmozero is replaced into the category of mesotrophic water reservoirs (0.5 - 1.0. Saprobity index raised from 0.95 to 1.42. In the composition of the zooplankton there noted such species, as Polyarthra luminosa, Filinia longiseta, Trichocerca insignis, Daphnia longispina, Cyclops kolensis, which serve as indicators of increased trophic level in the conditions of moderate latitudes. After the trout farm started off, Bcrus/Brot indicator considerably decreased indicating to increasing role of rotifers in the formation of the total biomass of the zooplankton. Currently, the dominant species include D. longispina, Bosmina longirostris, Mesocyclops leuckarti, Asplanchna priodonta. In spite of the fact that the current changes are not catastrophic, it is reasonable to monitor regularly the initial links of the trophic chain of the reservoir ecosystem

  1. Food web accumulation of cyclic siloxanes in Lake Mjøsa, Norway.

    Science.gov (United States)

    Borgå, Katrine; Fjeld, Eirik; Kierkegaard, Amelie; McLachlan, Michael S

    2012-06-05

    The biomagnification of the cyclic volatile methyl siloxanes octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexatetrasiloxane (D6) was analyzed in the Lake Mjøsa food web in Norway from zooplankton and Mysis to planktivorous and piscivorous fish. The trophic magnification factor (TMF) for D5 was determined and compared with TMFs of several legacy contaminants: polychlorinated biphenyl (PCB) congeners 153 and 180, polybrominated diphenyl ether (PBDE) congeners 47 and 99, and p,p'-DDE. D5 showed TMF significantly greater than 1, implying food web biomagnification (TMF = 2.28, CI: 1.22-4.29). This contrasts with two studies that reported TMF < 1, which may reflect variability in TMF between food webs. The Lake Mjøsa D5 TMF was sensitive to the species included at the higher trophic level; whole food web TMF differed from TMF excluding smelt (Osmerus eperlanus) or brown trout (Salmo trutta) (TMF(-SMELT) = 1.62, CI: 0.96-2.72; TMF(-TROUT) = 3.58, CI: 1.82-7.03). For legacy contaminants (e.g., PCB-153 and PCB-180), the TMFs were less sensitive to the food web composition, and a better model fit was obtained compared to D5. The differences in biomagnification behavior between D5 and the legacy contaminants suggest that the biomagnification of D5 is being governed by species-specific properties such as biotransformation rate or tissue distribution that differ from those of legacy contaminants.

  2. Bull Trout Population Assessment in the Columbia River Gorge : Annual Report 2000.

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, Jim; McPeak, Ron

    2001-02-01

    We summarized existing knowledge regarding the known distribution of bull trout (Salvelinus confluentus) across four sub-basins in the Columbia River Gorge in Washington. The Wind River, Little White Salmon River, White Salmon River, and the Klickitat River sub-basins were analyzed. Cold water is essential to the survival, spawning, and rearing of bull trout. We analyzed existing temperature data, installed Onset temperature loggers in the areas of the four sub-basins where data was not available, and determined that mean daily water temperatures were <15 C and appropriate for spawning and rearing of bull trout. We snorkel surveyed more than 74 km (46.25 mi.) of rivers and streams in the four sub-basins (13.8 km at night and 60.2 km during the day) and found that night snorkeling was superior to day snorkeling for locating bull trout. Surveys incorporated the Draft Interim Protocol for Determining Bull Trout Presence (Peterson et al. In Press). However, due to access and safety issues, we were unable to randomly select sample sites nor use block nets as recommended. Additionally, we also implemented the Bull Trout/Dolly Varden sampling methodology described in Bonar et al. (1997). No bull trout were found in the Wind River, Little White Salmon, or White Salmon River sub-basins. We found bull trout in the West Fork Klickitat drainage of the Klickitat River Sub-basin. Bull trout averaged 6.7 fish/100m{sup 2} in Trappers Creek, 2.6 fish/100m{sup 2} on Clearwater Creek, and 0.4 fish/100m{sup 2} in Little Muddy Creek. Bull trout was the only species of salmonid encountered in Trappers Creek and dominated in Clearwater Creek. Little Muddy Creek was the only creek where bull trout and introduced brook trout occurred together. We found bull trout only at night and typically in low flow regimes. A single fish, believed to be a bull trout x brook trout hybrid, was observed in the Little Muddy Creek. Additional surveys are needed in the West Fork Klickitat and mainstem

  3. Eradication of non-native fish from a small mountain lake: gill netting as a non-toxic alternative to the use of rotenone.

    Science.gov (United States)

    R.A. Knapp; K.R. Matthews

    1998-01-01

    Nearly all mountain lakes in the western United States were historically fishless, but most now contain introduced trout populations. As a result of the impacts of these introductions on ecosystem structure and function, there is increasing interest in restoring some lakes to a fishless condition. To date, however, the only effective method of fish eradication is the...

  4. How systematic age underestimation can impede understanding of fish population dynamics: Lessons learned from a Lake Superior cisco stock

    Science.gov (United States)

    Yule, D.L.; Stockwell, J.D.; Black, J.A.; Cullis, K.I.; Cholwek, G.A.; Myers, J.T.

    2008-01-01

    Systematic underestimation of fish age can impede understanding of recruitment variability and adaptive strategies (like longevity) and can bias estimates of survivorship. We suspected that previous estimates of annual survival (S; range = 0.20-0.44) for Lake Superior ciscoes Coregonus artedi developed from scale ages were biased low. To test this hypothesis, we estimated the total instantaneous mortality rate of adult ciscoes from the Thunder Bay, Ontario, stock by use of cohort-based catch curves developed from commercial gill-net catches and otolith-aged fish. Mean S based on otolith ages was greater for adult females (0.80) than for adult males (0.75), but these differences were not significant. Applying the results of a study of agreement between scale and otolith ages, we modeled a scale age for each otolith-aged fish to reconstruct catch curves. Using modeled scale ages, estimates of S (0.42 for females, 0.36 for males) were comparable with those reported in past studies. We conducted a November 2005 acoustic and midwater trawl survey to estimate the abundance of ciscoes when the fish were being harvested for roe. Estimated exploitation rates were 0.085 for females and 0.025 for males, and the instantaneous rates of fishing mortality were 0.089 for females and 0.025 for males. The instantaneous rates of natural mortality were 0.131 and 0.265 for females and males, respectively. Using otolith ages, we found that strong year-classes at large during November 2005 were caught in high numbers as age-1 fish in previous annual bottom trawl surveys, whereas weak or absent year-classes were not. For decades, large-scale fisheries on the Great Lakes were allowed to operate because ciscoes were assumed to be short lived and to have regular recruitment. We postulate that the collapse of these fisheries was linked in part to a misunderstanding of cisco biology driven by scale-ageing error. ?? Copyright by the American Fisheries Society 2008.

  5. Life+ Trout Project (LIFE12 NAT/IT/0000940 for the recovery and conservation of Mediterranean trout (Salmo trutta complex in the central Apennines (Italy.

    Directory of Open Access Journals (Sweden)

    Vincenzo Caputo Barucchi

    2015-11-01

    At present the genetic and demographic characterization of the trout populations is completed. Table 1 and Figures 1-2 show the results of abundance analysis of the fish assemblages divided by basin. The standing crop’s mean values can be considered in the standard range, according to the small size and the limited productivity that generally characterized the watercourses analyzed, as most of the Apennine rivers. The differences of the mean values among basins were highly statistically significant according to the ANOVA analysis (density: F= 5.24, p=0.001; standing crop: F=12.42, p=0.001. The results of genetic analysis separated clearly native and aliene genomes (K = 2, Fig. 3a and showed the presence of three distinct genetic stocks of native Apennine trout (K = 4, Fig. 3b: i Tevere (green bars, ii Tenna (red and iii Chienti /Potenza/Metauro/Esino (yellow. Populations characterized by very low introgression values will be the source of wild individuals to produce pure juvenile trouts in captivity. Four moderately introgressed populations will be subject to supportive breeding activities. Finally, six stream, where trouts showed almost exclusively an alien genetic make-up will be selected for the eradication activities. The data collected are the indispensable premise for the adoption of the necessary strategies for conservation of the Apennine trout in Central Italy.

  6. Glacial lakes in Austria - Distribution and formation since the Little Ice Age

    Science.gov (United States)

    Buckel, J.; Otto, J. C.; Prasicek, G.; Keuschnig, M.

    2018-05-01

    Glacial lakes constitute a substantial part of the legacy of vanishing mountain glaciation and act as water storage, sediment traps and sources of both natural hazards and leisure activities. For these reasons, they receive growing attention by scientists and society. However, while the evolution of glacial lakes has been studied intensively over timescales tied to remote sensing-based approaches, the longer-term perspective has been omitted due a lack of suitable data sources. We mapped and analyzed the spatial distribution of glacial lakes in the Austrian Alps. We trace the development of number and area of glacial lakes in the Austrian Alps since the Little Ice Age (LIA) based on a unique combination of a lake inventory and an extensive record of glacier retreat. We find that bedrock-dammed lakes are the dominant lake type in the inventory. Bedrock- and moraine-dammed lakes populate the highest landscape domains located in cirques and hanging valleys. We observe lakes embedded in glacial deposits at lower locations on average below 2000 m a.s.l. In general, the distribution of glacial lakes over elevation reflects glacier erosional and depositional dynamics rather than the distribution of total area. The rate of formation of new glacial lakes (number, area) has continuously accelerated over time with present rates showing an eight-fold increase since LIA. At the same time the total glacier area decreased by two-thirds. This development coincides with a long-term trend of rising temperatures and a significant stepping up of this trend within the last 20 years in the Austrian Alps.

  7. Experimental validation of geosmin uptake in rainbow trout, Oncorhynchus mykiss (Waldbaum) suggests biotransformation

    NARCIS (Netherlands)

    Schram, Edward; Schrama, Johan W.; Kooten, van Tobias; Kwadijk, Christiaan J.A.F.; Kampen, Harm; Kampen, Harm; Heul, van de Jan W.; Verreth, Johan A.J.; Murk, Albertinka J.

    2018-01-01

    The bioconcentration of waterborne geosmin in rainbow trout, Oncorhynchus mykiss (Waldbaum) was assessed. Fifty rainbow trout with a mean (SD) weight of 226.6 (29.0) g and lipid content of 6.2 (0.6) % (w/w) were exposed to geosmin in static water for 0, 2, 4, 6, 8, 12, 24, 36, 48 and 120 hr, with

  8. A trial of two trouts: Comparing the impacts of rainbow and brown trout on a native galaxiid

    Science.gov (United States)

    Young, K.A.; Dunham, J.B.; Stephenson, J.F.; Terreau, A.; Thailly, A.F.; Gajardo, G.; de Leaniz, C. G.

    2010-01-01

    Rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta are the world's two most widespread exotic fishes, dominate the fish communities of most cold-temperate waters in the southern hemisphere and are implicated in the decline and extirpation of native fish species. Here, we provide the first direct comparison of the impacts of rainbow and brown trout on populations of a native fish by quantifying three components of exotic species impact: range, abundance and effect. We surveyed 54 small streams on the island of Chilo?? in Chilean Patagonia and found that the rainbow trout has colonized significantly more streams and has a wider geographic range than brown trout. The two species had similar post-yearling abundances in allopatry and sympatry, and their abundances depended similarly on reach-level variation in the physical habitat. The species appeared to have dramatically different effects on native drift-feeding Aplochiton spp., which were virtually absent from streams invaded by brown trout but shared a broad sympatric range with rainbow trout. Within this range, the species' post-yearling abundances varied independently before and after controlling for variation in the physical habitat. In the north of the island, Aplochiton spp. inhabited streams uninvaded by exotic trouts. Our results provide a context for investigating the mechanisms responsible for apparent differences in rainbow and brown trout invasion biology and can help inform conservation strategies for native fishes in Chilo?? and elsewhere. ?? 2010 The Authors. Journal compilation ?? 2010 The Zoological Society of London.

  9. The effect of farmed trout on cardiovascular risk markers in healthy men

    DEFF Research Database (Denmark)

    Hallund, Jesper; Madsen, Birgitte Overgaard; Bügel, Susanne H.

    2010-01-01

    , insulin, C-reactive protein (CRP) and other markers of inflammation were measured at weeks 0 and 8. RBC content of total n-3 LCPUFA, both EPA and DHA, was significantly higher among men consuming trout raised on marine feed compared with men consuming the vegetable-fed trout or chicken. The three...... meal with 150 g farmed trout raised on either marine or vegetable-based feed, or a reference meal containing 150 g chicken. Twenty-four hour BP, pulse wave velocity, augmentation index, fatty acid composition of erythrocyte (RBC), and concentrations of TAG, HDL-cholesterol, LDL-cholesterol, glucose...... risk markers after daily consumption of trout with high or low n-3 LCPUFA content. However, trout raised on vegetable-based feed had less pronounced impact on RBC n-3 LCPUFA status....

  10. Banks Lake Fishery Evaluation Project Annual Report : Fiscal Year 2008 (March 1, 2008 to February 1, 2009).

    Energy Technology Data Exchange (ETDEWEB)

    Polacek, Matt [Washington Department of Fish and Wildlife

    2009-07-15

    The Washington Department of Fish and Wildlife implemented the Banks Lake Fishery Evaluation Project (BLFEP) in September 2001 with funds from the Bonneville Power Administration, and continued project tasks in 2008. The objective was to evaluate factors that could limit kokanee in Banks Lake, including water quality, prey availability, harvest, and acute predation during hatchery releases. Water quality parameters were collected twice monthly from March through November. Banks Lake water temperatures began to increase in May and stratification was apparent by July. By late August, the thermocline had dropped to 15 meters deep, with temperatures of 21-23 C in the epilimnion and 16-19 C in the hypolimnion. Dissolved oxygen levels were generally above 8 mg/L until August when they dropped near or below 5 mg/L deeper than 20-meters. Secchi depths ranged from 3.2 to 6.2 meters and varied spatially and temporally. Daphnia and copepod densities were the highest in May and June, reaching densities of 26 copepods/liter and 9 Daphnia/liter. Fish surveys were conducted in July and October 2008 using boat electrofishing, gill netting, and hydroacoustic surveys. Lake whitefish (71%) and yellow perch (16%) dominated the limnetic fish assemblage in the summer, while lake whitefish (46%) and walleye (22%) were the most abundant in gill net catch during the fall survey. Piscivore diets switched from crayfish prior to the release of rainbow trout to crayfish and rainbow trout following the release. The highest angling pressure occurred in May, when anglers were primarily targeting walleye and smallmouth bass. Boat anglers utilized Steamboat State Park more frequently than any other boat ramp on Banks Lake. Shore anglers used the rock jetty at Coulee City Park 45% of the time, with highest use occurring from November through April. Ice fishing occurred in January and February at the south end of the lake. An estimated total of 4,397 smallmouth bass, 11,106 walleye, 371 rainbow trout

  11. Species succession and sustainability of the Great Lakes fish community

    Science.gov (United States)

    Eshenroder, Randy L.; Burnham-Curtis, Mary K.; Taylor, William W.; Ferreri, C. Paola

    1999-01-01

    This article concentrates on the sustainability of the offshore pelagic and deepwater fish communities that were historically dominated by lake trout (Salvelinus namaycush). The causes of alteration in these fish communities (i.e., overfishing, introductions, and cultural eutrophication) were identified by Loftus and Regier (1972). Here we look at the ecology of these altered communities in relation to sustainability and discuss the need for restoration.

  12. The Application of a Phosphorus Budget Model Estimating the Carrying Capacity of Kesikköprü Dam Lake

    OpenAIRE

    PULATSÜ, Serap

    2014-01-01

    The aim of this study was to estimate the carrying capacity of Kesikköprü Dam Lake, Ankara, where cage farms for the intensive culture of rainbow trout are located. For this purpose Dillon and Rigler's phosphorus budget model was applied in a series of steps and the carrying capacity of the lake was found to be 3335 tonnes per year. This estimated value was about 10 times higher than the present production level of the lake. It seems possible to orientate the fish culture in cages in...

  13. Bull trout life history, genetics, habitat needs, and limiting fact in central and northeast Oregon/1999; ANNUAL

    International Nuclear Information System (INIS)

    Hemmingsen, A.R.; Gunckel, S.L.; Howell, P.J.

    2001-01-01

    This section describes work accomplished in 1999 that continued to address two objectives of this project. These objectives are (1) determine the distribution of juvenile and adult bull trout Salvelinus confluentus and habitats associated with that distribution, and (2) determine fluvial and resident bull trout life history patterns. Completion of these objectives is intended through studies of bull trout in the Grande Ronde, Walla Walla, and John Day basins. These basins were selected because they provide a variety of habitats, from relatively degraded to pristine, and bull trout populations were thought to vary from relatively depressed to robust. In all three basins we used radio telemetry to determine the seasonal movements of bull trout. In the John Day and Walla Walla basins we also used traps to capture migrant bull trout. With these traps, we intended to determine the timing of bull trout movements both upstream and downstream, determine the relative abundance, size and age of migrant fish, and capture bull trout to be implanted with radio transmitters. In the John Day basin, we captured adult and juvenile bull trout from the upper John Day River and its tributaries, Call Creek, Reynolds Creek, and Roberts Creek. In the Walla Walla basin, we captured adult and juvenile bull trout from Mill Creek

  14. Effects of High-Flow Experiments from Glen Canyon Dam on Abundance, Growth, and Survival Rates of Early Life Stages of Rainbow Trout in the Lees Ferry Reach of the Colorado River

    Science.gov (United States)

    Korman, Josh; Kaplinski, Matthew; Melis, Theodore S.

    2010-01-01

    High-flow experiments (HFEs) from Glen Canyon Dam are primarily intended to conserve fine sediment and improve habitat conditions for native fish in the Colorado River as it flows through Grand Canyon National Park, Arizona. These experimental flows also have the potential to affect the rainbow trout (Oncorhynchus mykiss) population in the Lees Ferry tailwater reach immediately below the dam, which supports a highly valued recreational fishery and likely influences the abundance of rainbow trout in Grand Canyon. Understanding how flow regimes affect the survival and growth of juvenile rainbow trout is critical to interpreting trends in adult abundance. This study reports on the effects of HFEs in 2004 and 2008 on early life stages of rainbow trout in the Lees Ferry reach on the basis of monthly sampling of redds (egg nests) and the abundance of the age-0 trout (fertilization to about 1 to 2 months from emergence) and their growth during a 7-year period between 2003 and 2009. Multiple lines of evidence indicate that the March 2008 HFE resulted in a large increase in early survival rates of age-0 trout because of an improvement in habitat conditions. A stock-recruitment analysis demonstrated that age-0 abundance in July 2008 was more than fourfold higher than expected, given the number of viable eggs that produced these fish. A hatch-date analysis showed that early survival rates were much higher for cohorts that hatched about 1 month after the 2008 HFE (about April 15, 2008) relative to those fish that hatched before this date. These cohorts, fertilized after the 2008 HFE, would have emerged into a benthic invertebrate community that had recovered, and was possibly enhanced by, the HFE. Interannual differences in growth of age-0 trout, determined on the basis of otolith microstructure, support this hypothesis. Growth rates in the summer and fall of 2008 (0.44 mm/day) were virtually the same as in 2006 (0.46 mm/day), the highest recorded during 6 years, even though

  15. Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 1. Flow Patterns, Age of Groundwater, and Influence of Lake Water Leakage

    Science.gov (United States)

    Katz, Brian G.; Lee, Terrie M.; Plummer, L. Niel; Busenberg, Eurybiades

    1995-06-01

    Leakage from sinkhole lakes significantly influences recharge to the Upper Floridan aquifer in poorly confined sediments in northern Florida. Environmental isotopes (oxygen 18, deuterium, and tritium), chlorofluorocarbons (CFCs: CFC-11, CCl3F; CFC-12, CCl2F2; and CFC-113, C2Cl3F3), and solute tracers were used to investigate groundwater flow patterns near Lake Barco, a seepage lake in a mantled karst setting in northern Florida. Stable isotope data indicated that the groundwater downgradient from the lake contained 11-67% lake water leakage, with a limit of detection of lake water in groundwater of 4.3%. The mixing fractions of lake water leakage, which passed through organic-rich sediments in the lake bottom, were directly proportional to the observed methane concentrations and increased with depth in the groundwater flow system. In aerobic groundwater upgradient from Lake Barco, CFC-modeled recharge dates ranged from 1987 near the water table to the mid 1970s for water collected at a depth of 30 m below the water table. CFC-modeled recharge dates (based on CFC-12) for anaerobic groundwater downgradient from the lake ranged from the late 1950s to the mid 1970s and were consistent with tritium data. CFC-modeled recharge dates based on CFC-11 indicated preferential microbial degradation in anoxic waters. Vertical hydraulic conductivities, calculated using CFC-12 modeled recharge dates and Darcy's law, were 0.17, 0.033, and 0.019 m/d for the surficial aquifer, intermediate confining unit, and lake sediments, respectively. These conductivities agreed closely with those used in the calibration of a three-dimensional groundwater flow model for transient and steady state flow conditions.

  16. Recovery after local extinction: factors affecting re-establishment of alpine lake zooplankton.

    Science.gov (United States)

    Knapp, Roland A; Sarnelle, Orlando

    2008-12-01

    The introduction of fishes into naturally fishless mountain lakes often results in the extirpation of large-bodied zooplankton species. The ability to predict whether or not particular species will recover following fish removal is critically important for the design and implementation of lake restoration efforts but is currently not possible because of a lack of information on what factors affect recovery. The objective of this study was to identify the factors influencing recovery probability in two large-bodied zooplankton species following fish removal. We predicted that (1) Daphnia melanica would have a higher probability of recovery than Hesperodiaptomus shoshone due to differences in reproductive mode (D. melanica is parthenogenetic, H. shoshone is obligately sexual), (2) recovery probability would be a decreasing function of fish residence time due to the negative relationship between fish residence time and size of the egg bank, and (3) recovery probability would be an increasing function of lake depth as a consequence of a positive relationship between lake depth and egg bank size. To test these predictions, we sampled contemporary zooplankton populations and collected paleolimnological data from 44 naturally fishless lakes that were stocked with trout for varying lengths of time before reverting to a fishless condition. D. melanica had a significantly higher probability of recovery than did H. shoshone (0.82 vs. 0.54, respectively). The probability of recovery for H. shoshone was also significantly influenced by lake depth, fish residence time, and elevation, but only elevation influenced the probability of recovery in D. melanica. These results are consistent with between-species differences in reproductive mode combined with the much greater longevity of diapausing eggs in D. melanica than in H. shoshone. Our data also suggest that H. shoshone will often fail to recover in lakes with fish residence times exceeding 50 years.

  17. Temporal stability and rates of post-depositional change in geochemical signatures of brown trout Salmo trutta scales.

    Science.gov (United States)

    Ryan, D; Shephard, S; Kelly, F L

    2016-09-01

    This study investigates temporal stability in the scale microchemistry of brown trout Salmo trutta in feeder streams of a large heterogeneous lake catchment and rates of change after migration into the lake. Laser-ablation inductively coupled plasma mass spectrometry was used to quantify the elemental concentrations of Na, Mg, Mn, Cu, Zn, Ba and Sr in archived (1997-2002) scales of juvenile S. trutta collected from six major feeder streams of Lough Mask, County Mayo, Ireland. Water-element Ca ratios within these streams were determined for the fish sampling period and for a later period (2013-2015). Salmo trutta scale Sr and Ba concentrations were significantly (P < 0·05) correlated with stream water sample Sr:Ca and Ba:Ca ratios respectively from both periods, indicating multi-annual stability in scale and water-elemental signatures. Discriminant analysis of scale chemistries correctly classified 91% of sampled juvenile S. trutta to their stream of origin using a cross-validated classification model. This model was used to test whether assumed post-depositional change in scale element concentrations reduced correct natal stream classification of S. trutta in successive years after migration into Lough Mask. Fish residing in the lake for 1-3 years could be reliably classified to their most likely natal stream, but the probability of correct classification diminished strongly with longer lake residence. Use of scale chemistry to identify natal streams of lake S. trutta should focus on recent migrants, but may not require contemporary water chemistry data. © 2016 The Fisheries Society of the British Isles.

  18. Larger eggs in resident brown trout living in sympatry with anadromous brown trout

    DEFF Research Database (Denmark)

    Olofsson, H.; Mosegaard, Henrik

    1999-01-01

    Freshwater resident brown trout (Salmo trutta L.) in the stream Jorlandaan (southwestern Sweden) had larger eggs (range of actual mean egg wet weights, 65.9-108.5 mg) than both sympatric migratory trout (76.8-84.2 mg) and trout from five other Swedish streams with allopatric resident (23.7-80.1 mg......) or migratory populations (44.5-121.9 mg), after accounting for differences in body size. In Jorlandaan, some resident females even had a larger absolute mean egg weight than any of the migratory females found in the stream Resident trout had low absolute fecundity, and our data suggest that resident females...... in Jorlandan produce large eggs at the expense of their fecundity The extremely large relative egg size in resident Jorlandaan females suggests that the production of large offspring enhances fitness, possibly through increased fry survival....

  19. Do native brown trout and non-native brook trout interact reproductively?

    Science.gov (United States)

    Cucherousset, J.; Aymes, J. C.; Poulet, N.; Santoul, F.; Céréghino, R.

    2008-07-01

    Reproductive interactions between native and non-native species of fish have received little attention compared to other types of interactions such as predation or competition for food and habitat. We studied the reproductive interactions between non-native brook trout ( Salvelinus fontinalis) and native brown trout ( Salmo trutta) in a Pyrenees Mountain stream (SW France). We found evidence of significant interspecific interactions owing to consistent spatial and temporal overlap in redd localizations and spawning periods. We observed mixed spawning groups composed of the two species, interspecific subordinate males, and presence of natural hybrids (tiger trout). These reproductive interactions could be detrimental to the reproduction success of both species. Our study shows that non-native species might have detrimental effects on native species via subtle hybridization behavior.

  20. Malheur River Basin cooperative bull trout/redband trout research project, annual report FY 1999; ANNUAL

    International Nuclear Information System (INIS)

    Schwabe, Lawrence; Tiley, Mark

    2000-01-01

    The purpose of this study is to document the seasonal distribution of adult/sub-adult bull trout (Salvelinus confluentus) in the Malheur River basin. Due to the decline of bull trout in the Columbia Basin, the United States Fish and Wildlife Service listed bull trout as a threatened species in June 1998. Past land management activities; construction of dams; and fish eradication projects in the North Fork and Middle Fork Malheur River by poisoning have worked in concert to cumulatively impact native species in the Malheur Basin (Bowers et. al. 1993). Survival of the remaining bull trout populations is severely threatened (Buchanan 1997). 1999 Research Objects are: (1) Document the migratory patterns of adult/sub-adult bull trout in the North Fork Malheur River; (2) Determine the seasonal bull trout use of Beulah Reservoir and bull trout entrainment; and (3) Timing and location of bull trout spawning in the North Fork Malheur River basin. The study area includes the Malheur basin from the mouth of the Malheur River located near Ontario, Oregon to the headwaters of the North Fork Malheur River (Map 1). All fish collected and most of the telemetry effort was done on the North Fork Malheur River subbasin (Map 2). Fish collection was conducted on the North Fork Malheur River at the tailwaters of Beulah Reservoir (RK 29), Beulah Reservoir (RK 29-RK 33), and in the North Fork Malheur River at Crane Crossing (RK 69) to the headwaters of the North Fork Malheur. Radio telemetry was done from the mouth of the Malheur River in Ontario, Oregon to the headwaters of the North Fork Malheur. This report will reflect all migration data collected from 3/1/99 to 12/31/99

  1. Complex interaction between proliferative kidney disease, water temperature and concurrent nematode infection in brown trout.

    Science.gov (United States)

    Schmidt-Posthaus, Heike; Steiner, Pascale; Müller, Barbara; Casanova-Nakayama, Ayako

    2013-04-29

    Proliferative kidney disease (PKD) is a temperature-dependent disease caused by the myxozoan Tetracapsuloides bryosalmonae. It is an emerging threat to wild brown trout Salmo trutta fario populations in Switzerland. Here we examined (1) how PKD prevalence and pathology in young-of-the-year (YOY) brown trout relate to water temperature, (2) whether wild brown trout can completely recover from T. bryosalmonae-induced renal lesions and eliminate T. bryosalmonae over the winter months, and (3) whether this rate and/or extent of the recovery is influenced by concurrent infection. A longitudinal field study on a wild brown trout cohort was conducted over 16 mo. YOY and age 1+ fish were sampled from 7 different field sites with various temperature regimes, and monitored for infection with T. bryosalmonae and the nematode Raphidascaris acus. T. bryosamonae was detectable in brown trout YOY from all sampling sites, with similar renal pathology, independent of water temperature. During winter months, recovery was mainly influenced by the presence or absence of concurrent infection with R. acus larvae. While brown trout without R. acus regenerated completely, concurrently infected brown trout showed incomplete recovery, with chronic renal lesions and incomplete translocation of T. bryosalmonae from the renal interstitium into the tubular lumen. Water temperature seemed to influence complete excretion of T. bryosalmonae, with spores remaining in trout from summer-warm rivers, but absent in trout from summer-cool rivers. In the following summer months, we found PKD infections in 1+ brown trout from all investigated river sites. The pathological lesions indicated a re-infection rather than a proliferation of remaining T. bryosalmonae. However, disease prevalence in 1+ trout was lower than in YOY.

  2. NITRO MUSK ADDUCTS OF RAINBOW TROUT ...

    Science.gov (United States)

    Rainbow trout and other fish species can serve as 'sentinel' species for the assessment of ecological status and the presence of certain environmental contaminants. As such they act as bioindicators of exposure. Here we present seminal data regarding dose-response and toxicokinetics of trout hemoglobin adduct formation from exposure to nitro musks that are frequently used as fragrance ingredients in formulations of personal care products. Hemoglobin adducts serve as biomarkers of exposure of the sentinel species as we have shown in previous studies of hemoglobin adducts formed in trout and environmental carp exposed to musk xylene (MX) and musk ketone (MK). Gas chromatography-electron capture negative ion chemical ionization-mass spectrometry (GC-NICI-MS) employing selected ion monitoring is used to measure 4-amino-MX (4-AMX), 2-amino-MX (2-AMX), and 2-amino-MK (2-AMK) released by alkaline hydrolysis from the sulfinamide adducts of hemoglobin. Dose-response and toxicokinetics were investigated using this sensitive method for analysis of these metabolites. In the dose-response investigation, the concentrations of 4-AMX and 2-2AMX are observed to pass through a maximum at 0.10 mg/g. In the case of 2-AMK, the adduct concentration is almost the same at dosages in the range of 0.030 to 0.10 mg/g. For toxicokinetics, the concentration of the metabolites in the Hb reaches a maximum in the 3-day sample after administration of MX or MK. Further elimination of the metabo

  3. AMS radiocarbon analyses from Lake Baikal, Siberia: Challenges of dating sediments from a large, oligotrophic lake

    Science.gov (United States)

    Colman, Steven M.; Jones, Glenn A.; Rubin, M.; King, J.W.; Peck, J.A.; Orem, W.H.

    1996-01-01

    A suite of 146 new accelerator-mass spectrometer (AMS) radiocarbon ages provides the first reliable chronology for late Quaternary sediments in Lake Baikal. In this large, highly oligotrophic lake, biogenic and authigenic carbonate are absent, and plant macrofossils are extremely rare. Total organic carbon is therefore the primary material available for dating. Several problems are associated with the TOC ages. One is the mixture of carbon sources in TOC, not all of which are syndepositional in age. This problem manifests itself in apparent ages for the sediment surface that are greater than zero. However, because most of the organic carbon in Lake Baikal sediments is algal (autochthonous) in origin, this effect is limited to about 1000+500 years, which can be corrected, at least for young deposits. The other major problem with dating Lake Baikal sediments is the very low carbon contents of glacial-age deposits, which makes them extremely susceptible to contamination with modern carbon. This problem can be minimized by careful sampling and handling procedures. The ages show almost an order of magnitude difference in sediment-accumulation rates among different sedimentary environments in Lake Baikal, from about 0.04 mm/year on isolated banks such as Academician Ridge, to nearly 0.3 mm/year in the turbidite depositional areas beneath the deep basin floors, such as the Central Basin. The new AMS ages clearly indicate that the dramatic increase in diatom productivity in the lake, as evidenced by increases in biogenic silica and organic carbon, began about 13 ka, in contrast to previous estimates of 7 ka for the age of this transition. Holocene net sedimentation rates may be less than, equal to, or greater than those in the late Pleistocene, depending on the site. This variability reflects the balance between variable terrigenous sedimentation and increased biogenic sedimentation during interglaciations. The ages reported here, and the temporal and spatial variation in

  4. Phylogenetic status of brown trout Salmo trutta populations in five rivers from the southern Caspian Sea and two inland lake basins, Iran: a morphogenetic approach.

    Science.gov (United States)

    Hashemzadeh Segherloo, I; Farahmand, H; Abdoli, A; Bernatchez, L; Primmer, C R; Swatdipong, A; Karami, M; Khalili, B

    2012-10-01

    Interrelationships, origin and phylogenetic affinities of brown trout Salmo trutta populations from the southern Caspian Sea basin, Orumieh and Namak Lake basins in Iran were analysed from complete mtDNA control region sequences, 12 microsatellite loci and morphological characters. Among 129 specimens from six populations, seven haplotypes were observed. Based on mtDNA haplotype data, the Orumieh and southern Caspian populations did not differ significantly, but the Namak basin-Karaj population presented a unique haplotype closely related to the haplotypes of the other populations (0·1% Kimura two-parameter, K2P divergence). All Iranian haplotypes clustered as a distinct group within the Danube phylogenetic grouping, with an average K2P distance of 0·41% relative to other Danubian haplotypes. The Karaj haplotype in the Namak basin was related to a haplotype (Da26) formerly identified in the Tigris basin in Turkey, to a Salmo trutta oxianus haplotype from the Aral Sea basin, and to haplotype Da1a with two mutational steps, as well as to other Iranian haplotypes with one to two mutational steps, which may indicate a centre of origin in the Caspian basin. In contrast to results of the mtDNA analysis, more pronounced differentiation was observed among the populations studied in the morphological and microsatellite DNA data, except for the two populations from the Orumieh basin, which were similar, possibly due to anthropogenic causes. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

  5. Bull Trout Life History, Genetics, Habitat Needs, and Limiting Fact in Central and Northeast Oregon. Annual Report 1999.

    Energy Technology Data Exchange (ETDEWEB)

    Hemmingsen, Alan R.; Gunckel, Stephanie L.; Howell, Philip J.

    2001-08-01

    This section describes work accomplished in 1999 that continued to address two objectives of this project. These objectives are (1) determine the distribution of juvenile and adult bull trout Salvelinus confluentus and habitats associated with that distribution, and (2) determine fluvial and resident bull trout life history patterns. Completion of these objectives is intended through studies of bull trout in the Grande Ronde, Walla Walla, and John Day basins. These basins were selected because they provide a variety of habitats, from relatively degraded to pristine, and bull trout populations were thought to vary from relatively depressed to robust. In all three basins we used radio telemetry to determine the seasonal movements of bull trout. In the John Day and Walla Walla basins we also used traps to capture migrant bull trout. With these traps, we intended to determine the timing of bull trout movements both upstream and downstream, determine the relative abundance, size and age of migrant fish, and capture bull trout to be implanted with radio transmitters. In the John Day basin, we captured adult and juvenile bull trout from the upper John Day River and its tributaries, Call Creek, Reynolds Creek, and Roberts Creek. In the Walla Walla basin, we captured adult and juvenile bull trout from Mill Creek.

  6. Estrogenic effect of dietary 4-tert-octylphenol in rainbow trout (Oncorhynchus mykiss)

    DEFF Research Database (Denmark)

    Pedersen, Kristine H; Pedersen, Søren N; Pedersen, Knud L

    2003-01-01

    The estrogenic effect of dietary 4-tert-octylphenol (octylphenol) in rainbow trout Oncorhynchus mykiss was investigated. Octylphenol was administered orally to sexually immature rainbow trout every second day for 11 days in doses between 0.4 and 50 mgkg(-1)2 d(-1). Plasma vitellogenin was measured...

  7. The Share of Internal Organs and Viscera in Rainbow Trout (Oncorhynchus Mykiss Reared in Different Growth Systems

    Directory of Open Access Journals (Sweden)

    Daniel Cocan

    2012-10-01

    Full Text Available In this experiment we followed the influence of growth system on the share of internal organs and viscera by the total body mass on rainbow trout (Oncorhynchus mykiss. The importance of this study results from the need to reach as favourable slaughter yield. For this, were slaughtered 25 rainbow trout from the Fiad trout farm (conventional farm, Bistriţa-Năsăud County (control group – M, respectively 25 rainbow trout grown in a recirculating system arranged in Cluj-Napoca (experimental group – E. Body weight of the studied specimens was 228.96±1.21 g – M group, respectively 229.40±1.24 g – E group, the difference between the two groups being insignificant (p>0.05. The slaughter yield was favorable for E group – 90.55±0.03%, compared with M group – 89.23±0.05% (p<0.001. We analyzed the total gravimetric share of the internal organs and viscera at trout from the two groups and individual weights of esophagus, stomach, pyloric caeca, medium intestine and duodenum, rectum, liver, pancreas, heart, spleen, air bladder and kidney. The results showed a higher share of this organs at trout from the Fiad trout farm (M group, except stomach (2.38±0.01g – M group vs. 2.45±0.008 g – E group; p<0.05, and liver respectively (4.83±0.02 g – M group vs. 5.36±0.04 g – E group; p<0.001. In accordance with the values obtained, the resulting conclusion is that in the recirculating system, due to optimal environmental conditions, trout have a higher slaughter yield compared with those of conventional farm, accumulating in the same time fat reserves deposited in the liver.

  8. Effects of hybridization between nonnative Rainbow Trout and native Westslope Cutthroat Trout on fitness-related traits

    Science.gov (United States)

    Drinan, Daniel P.; Webb, Molly A. H.; Naish, Kerry A.; Kalinowski, Steven T.; Boyer, Matthew C.; Steed, Amber C.; Shepard, Bradley B.; Muhlfeld, Clint C.

    2015-01-01

    Hybridization between introduced and native fauna is a risk to native species and may threaten the long-term persistence of numerous taxa. Rainbow Trout Oncorhynchus mykiss has been one of the most widely introduced species around the globe and often hybridizes with native Cutthroat Trout O. clarkii in the Rocky Mountains. Previous work has shown that hybridization negatively affects reproductive success, but identification of the traits contributing to that reduction has been elusive. In this study, we used a combination of field and laboratory techniques to assess how hybridization with Rainbow Trout affects seven traits during several stages of Westslope Cutthroat Trout development: embryonic survival, ova size, ova energy concentration, sperm motility, juvenile weight, juvenile survival, and burst swimming endurance. Rainbow Trout admixture was correlated with an increase in embryonic survival and ova energy concentration but with a decrease in juvenile weight and burst swimming endurance. These correlations differed from previously observed patterns of reproductive success and likely do not explain the declines in reproductive success associated with admixture. Future investigation of additional, unstudied traits and the use of different environments may shed light on the traits responsible for reproductive success in admixed Cutthroat Trout.

  9. Biomagnification and tissue distribution of perfluoroalkyl substances (PFASs) in market-size rainbow trout (Oncorhynchus mykiss).

    Science.gov (United States)

    Goeritz, Ina; Falk, Sandy; Stahl, Thorsten; Schäfers, Christoph; Schlechtriem, Christian

    2013-09-01

    The present study investigated the biomagnification potential as well as the substance and tissue-specific distribution of perfluoroalkyl substances (PFASs) in market-size rainbow trout (Oncorhynchus mykiss). Rainbow trout with an average body weight of 314 ± 21 g were exposed to perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) in the diet for 28 d. The accumulation phase was followed by a 28-d depuration phase, in which the test animals were fed with nonspiked trout feed. On days 0, 7, 14, 28, 31, 35, 42, and 56 of the present study, fish were sampled from the test basin for PFAS analysis. Biomagnification factors (BMFs) for all test compounds were determined based on a kinetic approach. Distribution factors were calculated for each test compound to illustrate the disposition of PFASs in rainbow trout after 28 d of exposure. Dietary exposure of market-size rainbow trout to PFASs did not result in biomagnification; BMF values were calculated as 0.42 for PFOS, >0.23 for PFNA, >0.18 for PFHxS, >0.04 for PFOA, and >0.02 for PFBS, which are below the biomagnification threshold of 1. Liver, blood, kidney, and skin were identified as the main target tissues for PFASs in market-size rainbow trout. Evidence was shown that despite relative low PFAS contamination, the edible parts of the fish (the fillet and skin) can significantly contribute to the whole-body burden. Copyright © 2013 SETAC.

  10. The age, growth, and feeding habits of the whitefish Coregonus clupeaformis (Mitchell), of Lake Champlain

    Science.gov (United States)

    Van Oosten, John; Deason, Hilary J.

    1939-01-01

    This study is based on 120 whitefish collected in northern Lake Champlain (Missisquoi Bay) in 1930 and on 175 whitefish taken in southern Lake Champlain in 1931. Since the whitefish population had not been exploited commercially after 1912 in United States waters and after 1915 in Canadian waters, its study should be of interest in showing the characteristics of a population practically untouched by man. Data have been presented on length frequencies, age composition, growth, coefficient of condition, sex ratio, standard length-total length relationship, and feeding habits. The data indicated that the Missisquoi Bay population was disturbed (probably by the early fall seining of 1930) before our samples were taken so that the original length distributions no longer existed. The southern Lake Champlain material, however, showed a consistency which indicated that the population had not been exploited to any extensive degree, if at all. When the northern population was compared with the southern the former was found to differ from the latter in the following respects, which differences pointed to some disturbance of the northern stock in the lake 1. By possession of lower modes and smaller grand averages of length. 2. By absence of very old individuals. 3. By absence of a series of equally abundant age groups or, in other words, by the presence of a decided dominance of one or two age groups. 4. By a radical disagreement between the sexes in their age-frequency distribution. 5. By a disagreement between the sexes with respect to maximum lengths attained. All of the differences between the two collections could, however, not be attributed to exploitation. The following characteristics indicated the presence of two distinct populations in the lake 1. Presence of a spawning ground at each end of the lake. 2. Differences in calculated lengths and increments of length (growth rates). 3. Differences in the actual lengths and weights of corresponding age groups at capture. 4

  11. Morphological differences in the skin of marble trout Salmo marmoratus and of brown trout Salmo trutta

    Directory of Open Access Journals (Sweden)

    Urška Sivka

    2012-07-01

    Full Text Available Despite being genetically very closely related, the marble trout Salmo marmoratus and the brown trout Salmo trutta exhibit marked phenotypic differences, particularly with regard to skin pigmentation. Histological analysis of skin from the head and gill cover of differently aged individuals of the two species was carried out in order to characterize differences in skin structure. The basic structure of skin of the individuals studied corresponded with that described for other salmonids, though the head epidermis was somewhat thicker in S. marmoratus than in S. trutta, thickening with age in both species. Numerous secretory goblet cells and sporadic secretory sacciform cells were observed in the upper and middle part of the epidermis in both species. Melanophores were present in both species only in the dermis, and were bigger in S. marmoratus and present at lower average density than in S. trutta, and more or less constant across all age classes. In adult S. marmoratus with fully established marble pigmentation, light areas at low density with small (i.e. aggregated melanophores were present, while in S. trutta melanophores were more uniformly distributed.

  12. Differential Accumulation of Mercury and Selenium in Brown Trout Tissues of a High-Gradient Urbanized Stream in Colorado, USA.

    Science.gov (United States)

    Herrmann, S J; Nimmo, D R; Carsella, J S; Herrmann-Hoesing, L M; Turner, J A; Gregorich, J M; Heuvel, B D Vanden; Nehring, R B; Foutz, H P

    2016-02-01

    Total mercury (THg) and selenium (Se) were analyzed by Inductively Coupled Plasma Mass Spectrometry in 11 internal and external tissues and stomach contents from 23 brown trout, Salmo trutta, of a 22.9-km reach of a high-gradient stream (upper Fountain Creek) in Colorado, USA, impacted by coal-fired power plants, shale deposits, and urbanization. Trout and water were sampled from four sites ranging from 2335 to 1818 m elevation. Lengths, weights, and ages of fish between pairs of the four sites were not significantly different. The dry weight (dw) to wet weight (ww) conversion factor for each tissue was calculated with egg-ovary highest at 0.379 and epaxial muscle fourth highest at 0.223. THg and Se in stomach contents indicated diet and not ambient water was the major source of Hg and Se bioaccumulated. Mean THg ww in kidney was 40.33 µg/kg, and epaxial muscle second highest at 36.76 µg/kg. None of the tissues exceeded the human critical threshold for Hg. However, all 23 trout had at least one tissue type that exceeded 0.02 mg/kg THg ww for birds, and four trout tissues exceeded 0.1 mg/kg THg ww for mammals, indicating that piscivorous mammals and birds should be monitored. Se concentrations in tissues varied depending on ww or dw listing. Mean Se dw in liver was higher than ovary at the uppermost site and the two lower sites. Liver tissue, in addition to egg-ovary, should be utilized as an indicator tissue for Se toxicity.

  13. Liming the acid lake Hovvatn, Norway: a whole-ecosystem study

    Energy Technology Data Exchange (ETDEWEB)

    Raddum, G G; Brettum, P; Matzow, D; Nilssen, J P; Skov, A; Sveaelv, T; Wright, R F

    1986-12-01

    Hovvatn, a 1 sq. km. chronically-acidified lake in southernmost Norway, was treated with 200 tonne of powdered limestone in March 1981. An additional 40 tonne were added to a 0.046 sq km pond (Pollen) draining into Hovvatn. The lakes were stocked with brown trout in June 1981 and in each subsequent year. At ice-out pH rose from 4.4 to 6.3 (Hovvatn) and 7.5 (Pollen), Ca and alkalinity increased, and total Al decreased by 120 ..mu..g/l. None of the other major ions exhibited significant changes in concentration. Total organic C and P increased after liming. The phytoplankton community was dominated by chrysophytes and did not change significantly following liming. The zooplankton community was typical of acid lakes prior to liming. There was a clear succession in species dominance following treatment, although no new species immigrated to the lakes. Zoobenthos changed from a community characterized by low abundance and reduced number of species to increased abundance of oligochaetes, mayflies and chironomids. Hovvatn and Pollen were barren of fish prior to stocking. The stocked fish showed remarkably high growth rate during the first years. Liming apparently improved conditions for zoobenthos, enhancing the processing of fine detritus which in turn resulted in elevated levels of TOC and P in the lakewaters during the first year after liming. The oligotrophication process typical of acid lakes was temporarily reversed by liming. The interactions between groups of organisms in Hovvatn and Pollen indicates that many years are required before a new steady-state can be attained following liming. 61 references.

  14. Use of microsatellite markers for identification of indigenous brown trout in a geographical region heavily influenced by stocked domesticated trout

    DEFF Research Database (Denmark)

    Fritzner, N.G.; Hansen, Michael Møller; Madsen, S.S.

    2001-01-01

    Based on estimates of genetic differentiation between populations, assignment tests and analysis of isolation by distance, stocked populations of brown trout Salmo trutta of Funen Island, Denmark, had been genetically affected by domesticated trout, whereas the stocking of wild exogenous trout...... into one of the rivers had little or no impact. At the same time, there were clear indications of remaining indigenous gene pools in the Funen populations. The management implications of these findings are discussed and changes in trout release activity are recommended to avoid further mixing of trout gene...

  15. Zooplankton size selection relative to gill raker spacing in rainbow trout

    Science.gov (United States)

    Budy, P.; Haddix, T.; Schneidervin, R.

    2005-01-01

    Rainbow trout Oncorhynchus mykiss are one of the most widely stocked salmonids worldwide, often based on the assumption that they will effectively utilize abundant invertebrate food resources. We evaluated the potential for feeding morphology to affect prey selection by rainbow trout using a combination of laboratory feeding experiments and field observations in Flaming Gorge Reservoir, Utah-Wyoming. For rainbow trout collected from the reservoir, inter-gill raker spacing averaged 1.09 mm and there was low variation among fish overall (SD = 0.28). Ninety-seven percent of all zooplankton observed in the diets of rainbow trout collected in the reservoir were larger than the interraker spacing, while only 29% of the zooplankton found in the environment were larger than the interraker spacing. Over the size range of rainbow trout evaluated here (200-475 mm), interraker spacing increased moderately with increasing fish length; however, the size of zooplankton found in the diet did not increase with increasing fish length. In laboratory experiments, rainbow trout consumed the largest zooplankton available; the mean size of zooplankton observed in the diets was significantly larger than the mean size of zooplankton available. Electivity indices for both laboratory and field observations indicated strong selection for larger-sized zooplankton. The size threshold at which electivity switched from selection against smaller-sized zooplankton to selection for larger-sized zooplankton closely corresponded to the mean interraker spacing for both groups (???1-1.2 mm). The combination of results observed here indicates that rainbow trout morphology limits the retention of different-sized zooplankton prey and reinforces the importance of understanding how effectively rainbow trout can utilize the type and sizes of different prey available in a given system. These considerations may improve our ability to predict the potential for growth and survival of rainbow trout within and

  16. A chronology for glacial Lake Agassiz shorelines along Upham's namesake transect

    Science.gov (United States)

    Lepper, Kenneth; Buell, Alex W.; Fisher, Timothy G.; Lowell, Thomas V.

    2013-07-01

    Four traditionally recognized strandline complexes in the southern basin of glacial Lake Agassiz are the Herman, Norcross, Tintah and Campbell, whose names correspond to towns in west-central Minnesota that lie on a linear transect defined by the Great Northern railroad grade; the active corridor for commerce at the time when Warren Upham was mapping and naming the shorelines of Lake Agassiz (ca.1880-1895). Because shorelines represent static water planes, their extension around the lake margin establishes time-synchronous lake levels. Transitions between shoreline positions represent significant water-level fluctuations. However, geologic ages have never been obtained from sites near the namesake towns in the vicinity of the southern outlet. Here we report the first geologic ages for Lake Agassiz shorelines obtained at field sites along the namesake transect, and evaluate the emerging chronology in light of other paleoclimate records. Our current work from 11 sampling sites has yielded 16 independent ages. These results combined with a growing OSL age data set for Lake Agassiz's southern basin provide robust age constraints for the Herman, Norcross and Campbell strandlines with averages and standard deviations of 14.1 ± 0.3 ka, 13.6 ± 0.2 ka, and 10.5 ± 0.3 ka, respectively.

  17. Bull trout population assessment in the Columbia River Gorge/annual report fy2000; ANNUAL

    International Nuclear Information System (INIS)

    Byrne, Jim; McPeak, Ron

    2001-01-01

    We summarized existing knowledge regarding the known distribution of bull trout (Salvelinus confluentus) across four sub-basins in the Columbia River Gorge in Washington. The Wind River, Little White Salmon River, White Salmon River, and the Klickitat River sub-basins were analyzed. Cold water is essential to the survival, spawning, and rearing of bull trout. We analyzed existing temperature data, installed Onset temperature loggers in the areas of the four sub-basins where data was not available, and determined that mean daily water temperatures were and lt;15 C and appropriate for spawning and rearing of bull trout. We snorkel surveyed more than 74 km (46.25 mi.) of rivers and streams in the four sub-basins (13.8 km at night and 60.2 km during the day) and found that night snorkeling was superior to day snorkeling for locating bull trout. Surveys incorporated the Draft Interim Protocol for Determining Bull Trout Presence (Peterson et al. In Press). However, due to access and safety issues, we were unable to randomly select sample sites nor use block nets as recommended. Additionally, we also implemented the Bull Trout/Dolly Varden sampling methodology described in Bonar et al. (1997). No bull trout were found in the Wind River, Little White Salmon, or White Salmon River sub-basins. We found bull trout in the West Fork Klickitat drainage of the Klickitat River Sub-basin. Bull trout averaged 6.7 fish/100m(sup 2) in Trappers Creek, 2.6 fish/100m(sup 2) on Clearwater Creek, and 0.4 fish/100m(sup 2) in Little Muddy Creek. Bull trout was the only species of salmonid encountered in Trappers Creek and dominated in Clearwater Creek. Little Muddy Creek was the only creek where bull trout and introduced brook trout occurred together. We found bull trout only at night and typically in low flow regimes. A single fish, believed to be a bull trout x brook trout hybrid, was observed in the Little Muddy Creek. Additional surveys are needed in the West Fork Klickitat and mainstem

  18. Chromosome rearrangements, recombination suppression, and limited segregation distortion in hybrids between Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) and rainbow trout (O. mykiss)

    Science.gov (United States)

    2013-01-01

    Background Introgressive hybridization is an important evolutionary process that can lead to the creation of novel genome structures and thus potentially new genetic variation for selection to act upon. On the other hand, hybridization with introduced species can threaten native species, such as cutthroat trout (Oncorhynchus clarkii) following the introduction of rainbow trout (O. mykiss). Neither the evolutionary consequences nor conservation implications of rainbow trout introgression in cutthroat trout is well understood. Therefore, we generated a genetic linkage map for rainbow-Yellowstone cutthroat trout (O. clarkii bouvieri) hybrids to evaluate genome processes that may help explain how introgression affects hybrid genome evolution. Results The hybrid map closely aligned with the rainbow trout map (a cutthroat trout map does not exist), sharing all but one linkage group. This linkage group (RYHyb20) represented a fusion between an acrocentric (Omy28) and a metacentric chromosome (Omy20) in rainbow trout. Additional mapping in Yellowstone cutthroat trout indicated the two rainbow trout homologues were fused in the Yellowstone genome. Variation in the number of hybrid linkage groups (28 or 29) likely depended on a Robertsonian rearrangement polymorphism within the rainbow trout stock. Comparison between the female-merged F1 map and a female consensus rainbow trout map revealed that introgression suppressed recombination across large genomic regions in 5 hybrid linkage groups. Two of these linkage groups (RYHyb20 and RYHyb25_29) contained confirmed chromosome rearrangements between rainbow and Yellowstone cutthroat trout indicating that rearrangements may suppress recombination. The frequency of allelic and genotypic segregation distortion varied among parents and families, suggesting few incompatibilities exist between rainbow and Yellowstone cutthroat trout genomes. Conclusions Chromosome rearrangements suppressed recombination in the hybrids. This result

  19. Occurrence, size, and tag retention of sneaker male hatchery rainbow trout

    Science.gov (United States)

    Isely, J.J.; Grabowski, T.B.

    2004-01-01

    One alternative reproductive tactic involving early-maturing, cryptic males is referred to as "sneaking." Although sneakers tend to be easily detectable upon close inspection, little is known about the proportion of a fish population consisting of sneakers. We examined 15,400 age-1 rainbow trout Oncorhynchus mykiss in a hatchery. Total length (mm), wet weight (g), and sex (sneaker male or unknown) were recorded for each fish. We also individually tagged each sneaker male with soft visual implant alphanumeric (VIalpha) tags that were sequentially numbered and held the fish for 25 d before inspection. Sneakers constituted 2.8% of the hatchery rainbow trout population and were smaller in total length and weight than typical rainbow trout of the same age. Retention of the VIalpha tags in sneakers was 58.9%, significantly lower than has been reported under similar circumstances. We found that sneaker males may contribute substantially to hatchery populations. Reduced tag retention in sneakers may bias studies evaluating the effect of hatchery fish on wild populations. We believe that hatchery-produced sneaker males have the potential to contribute importantly to the genetic composition of wild populations.

  20. Factors affecting competitive dominance of rainbow trout over brook trout in southern Appalachian streams: Implications of an individual-based model

    Energy Technology Data Exchange (ETDEWEB)

    Clark, M.E. [Univ. of Tennessee, Knoxville, TN (United States); Rose, K.A. [Oak Ridge National Lab., TN (United States)

    1997-01-01

    We used an individual-based model to examine possible explanations for the dominance of rainbow trout Oncorhynchus mykiss over brook trout Salvelinus fontinalis in southern Appalachian streams. Model simulations were used to quantify the effects on interspecific competition of (1) competitive advantage for feeding sites by rainbow trout, (2) latitudinal differences in stream temperatures, flows, and daylight, (3) year-class failures, (4) lower fecundity of brook trout, and (5) reductions in spawning habitat. The model tracks the daily spawning, growth, and survival of individuals of both species throughout their lifetime in a series of connected stream habitat units (pools, runs, or riffles). Average densities of each species based on 100-year simulations were compared for several levels of each of the five factors and for sympatric and allopatric conditions. Based on model results and empirical information, we conclude that more frequent year-class failures and the lower fecundity of brook trout are both possible and likely explanations for rainbow trout dominance, that warmer temperatures due to latitude and limited spawning habitat are possible but unlikely explanations, and that competitive advantage for feeding sites by rainbow trout is an unlikely explanation. Additional field work should focus on comparative studies of the reproductive success and the early life stage mortalities of brook and rainbow trout among Appalachian streams with varying rainbow trout dominance. 53 refs., 11 figs.

  1. Bony fish myelin: evidence for common major structural glycoproteins in central and peripheral myelin of trout.

    Science.gov (United States)

    Jeserich, G; Waehneldt, T V

    1986-02-01

    Peripheral nervous system (PNS) myelin from the rainbow trout (Salmo gairdneri) banded at a density of 0.38 M sucrose. The main myelin proteins consisted of (1) two basic proteins, BPa and BPb (11,500 and 13,000 MW, similar to those of trout central nervous system (CNS) myelin proteins BP1 and BP2), and (2) two glycosylated components, IPb (24,400 MW) and IPc (26,200 MW). IPc comigrated with trout CNS myelin protein IP2 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereas trout CNS myelin protein IP1 had a lower molecular weight (23,000). Following two-dimensional separation, however, both IPb and IPc from PNS showed two components; the more acidic component of IPc comigrated with IP2 from CNS. PNS tissue autolysis led to the formation of IPa (20,000 MW), consisting of two components in isoelectric focusing of which again the more acidic one comigrated with the CNS autolysis product IP0. Limited enzymatic digestion of isolated IP proteins from PNS and CNS led to closely similar degradation patterns, being most pronounced in the case of IP2 and IPc. Immunoblotting revealed that all IP components from trout PNS and CNS myelins reacted with antibodies to trout IP1 (CNS) and bovine P0 protein (PNS) whereas antibodies to rat PLP (CNS) were entirely unreactive. All BP components from trout PNS and CNS myelins bound to antibodies against human myelin basic protein. On the basis of these studies trout PNS and CNS myelins contain at least one common IP glycoprotein, whereas other members of the IP myelin protein family appear closely related. In the CNS myelin of trout the IP components appear to replace PLP.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. HABITAT USE BY NATIVE AND STOCKED TROUT (SALMO TRUTTA L. IN TWO NORTHEAST STREAMS, PORTUGAL

    Directory of Open Access Journals (Sweden)

    TEIXEIRA A.

    2006-04-01

    Full Text Available Habitat use by stocked and native brown trout (Salmo trutta L. was assessed in two headwater streams of North-eastern Portugal. Underwater observations were made during the summer season in three successive years to evaluate the effect of supplemental trout stocking. Multivariate analysis techniques applied to data sets on microhabitat use were exploited to identify the focal elevation (distance of fish from the bottom, total depth and cover as the variables that contribute most to the discrimination between stocked and native trout. Preference curves computed for native and stocked trout of the same age (1+, showed a distinct pattern in their ability to explore the available microhabitat resources. Stocked trout tended to occupy deeper pools (total depth > 100 cm vs. 60-100 cm for native trout, holding higher focal elevations (140-160 cm vs. 22.5 cm and cover (combination of boulders and overhanging vegetation or undercut banks. Furthermore, a high poststocking movement of 80% hatchery-reared fish was verified just one month after their release, suggesting that stocking did not contribute to the sustainable populations in either stream, and is far from being an adequate management technique.

  3. Identification of differentially expressed genes of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) in response to Tetracapsuloides bryosalmonae (Myxozoa).

    Science.gov (United States)

    Kumar, Gokhlesh; Abd-Elfattah, Ahmed; El-Matbouli, Mansour

    2015-03-01

    Tetracapsuloides bryosalmonae Canning et al., 1999 (Myxozoa) is the causative agent of proliferative kidney disease in various species of salmonids in Europe and North America. We have shown previously that the development and distribution of the European strain of T. bryosalmonae differs in the kidney of brown trout (Salmo trutta) Linnaeus, 1758 and rainbow trout (Oncorhynchus mykiss) Walbaum, 1792, and that intra-luminal sporogonic stages were found in brown trout but not in rainbow trout. We have now compared transcriptomes from kidneys of brown trout and rainbow trout infected with T. bryosalmonae using suppressive subtractive hybridization (SSH). The differentially expressed transcripts produced by SSH were cloned, transformed, and tested by colony PCR. Differential expression screening of PCR products was validated using dot blot, and positive clones having different signal intensities were sequenced. Differential screening and a subsequent NCBI-BLAST analysis of expressed sequence tags revealed nine clones expressed differently between both fish species. These differentially expressed genes were validated by quantitative real-time PCR of kidney samples from both fish species at different time points of infection. Expression of anti-inflammatory (TSC22 domain family protein 3) and cell proliferation (Prothymin alpha) genes were upregulated significantly in brown trout but downregulated in rainbow trout. The expression of humoral immune response (immunoglobulin mu) and endocytic pathway (Ras-related protein Rab-11b) genes were significantly upregulated in rainbow trout but downregulated in brown trout. This study suggests that differential expression of host anti-inflammatory, humoral immune and endocytic pathway responses, cell proliferation, and cell growth processes do not inhibit the development of intra-luminal sporogonic stages of the European strain of T. bryosalmonae in brown trout but may suppress it in rainbow trout.

  4. Integrating chronological uncertainties for annually laminated lake sediments using layer counting, independent chronologies and Bayesian age modelling (Lake Ohau, South Island, New Zealand)

    Science.gov (United States)

    Vandergoes, Marcus J.; Howarth, Jamie D.; Dunbar, Gavin B.; Turnbull, Jocelyn C.; Roop, Heidi A.; Levy, Richard H.; Li, Xun; Prior, Christine; Norris, Margaret; Keller, Liz D.; Baisden, W. Troy; Ditchburn, Robert; Fitzsimons, Sean J.; Bronk Ramsey, Christopher

    2018-05-01

    Annually resolved (varved) lake sequences are important palaeoenvironmental archives as they offer a direct incremental dating technique for high-frequency reconstruction of environmental and climate change. Despite the importance of these records, establishing a robust chronology and quantifying its precision and accuracy (estimations of error) remains an essential but challenging component of their development. We outline an approach for building reliable independent chronologies, testing the accuracy of layer counts and integrating all chronological uncertainties to provide quantitative age and error estimates for varved lake sequences. The approach incorporates (1) layer counts and estimates of counting precision; (2) radiometric and biostratigrapic dating techniques to derive independent chronology; and (3) the application of Bayesian age modelling to produce an integrated age model. This approach is applied to a case study of an annually resolved sediment record from Lake Ohau, New Zealand. The most robust age model provides an average error of 72 years across the whole depth range. This represents a fractional uncertainty of ∼5%, higher than the <3% quoted for most published varve records. However, the age model and reported uncertainty represent the best fit between layer counts and independent chronology and the uncertainties account for both layer counting precision and the chronological accuracy of the layer counts. This integrated approach provides a more representative estimate of age uncertainty and therefore represents a statistically more robust chronology.

  5. Microsatellite and mitochondrial DNA polymorphism reveals life history dependent interbreeding between hatchery and wild brown trout ( Salmo trutta L.)

    DEFF Research Database (Denmark)

    Hansen, Michael Møller; Ruzzante, D.E.; Eg Nielsen, Einar

    2000-01-01

    The effects of stocking hatchery trout into wild populations were studied in a Danish river, using microsatellite and mitochondrial DNA (mtDNA) markers. Baseline samples were taken from hatchery trout and wild trout assumed to be unaffected by previous stocking. Also, samples were taken from...... resident and sea trout from a stocked section of the river. Genetic differentiation between the hatchery strain and the local wild population was modest (microsatellite F-ST = 0.06). Using assignment tests, more than 90% of individuals from the baseline samples were classified correctly. Assignment tests...... involving samples from the stocked river section suggested that the contribution by hatchery trout was low among sea trout (trout. Hybrid index analysis and a high percentage of mtDNA haplotypes specific to indigenous trout observed among resident trout that were assigned...

  6. Fish populations in a large group of acid-stressed lakes

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, H H

    1975-01-01

    The purpose of this study was to determine the effects of environmental stress on the number and diversity of fish species in a group of acid-stressed lakes. The study area was the La Cloche Mountains, a series of quartzite ridges covering 1,300 km/sup 2/ along the north shore of Georgian Bay and north channel of Lake Huron. Within these ridges are 173 lakes; 68 of the largest of these made up the study sample. The lakes of the La Cloche Mountains are undergoing rapid acidification. Coincident with this there has been the loss of sport fishes from several lakes. Lakes such as Nellie, Lumsden, O.S.A., Acid and Killarney supported good sport fisheries for the lake trout, (Salvelinus namaycush) for many years, but have ceased to do so in the last 5 to 15 years. Other sport fishes, notably the walleye (Stizostedion vitreum) and smallmouth bass (micropterus dolomieu) have disappeared from some of the La Cloche Lakes. Thus recreational fishing alone could not have been the cause of the change. Beamish (1974) recorded the extreme sparcity of the three remaining fish species in O.S.A. Lake. Many of the lakes of the La Cloche mountains are accessible only with difficulty and little or no information exists for these lakes prior to this study. This precluded simple comparison of these lakes before and during acidification. This lack of historic data determined in part the approach taken in this study; a comparison of the fish communities of a group of lakes differing in degree of acid stress.

  7. TAILLE À 3 ANS DE LA TRUITE COMMUNE (SALMO TRUTTA L. DANS LES RIVIÈRES DES PYRÉNÉES FRANÇAISES : RELATIONS AVEC LES CARACTÉRISTIQUES MÉSOLOGIQUES ET INFLUENCE DES AMÉNAGEMENTS HYDROÉLECTRIQUES. TOTAL LENGTH OF AGE-3 BROWN TROUT (SALMO TRUTTA L. IN FRENCH PYRENEAN STREAMS : RELATIONSHIPS WITH ENVIRONMENTAL FACTORS AND INFLUENCE OF HYDROELECTRIC FACILITIES.

    Directory of Open Access Journals (Sweden)

    LAGARRIGUE T.

    2008-05-01

    Full Text Available La croissance de populations de truite commune (Salmo trutta L. a été étudiée sur 84 cours d'eau répartis sur l'ensemble de la chaîne des Pyrénées. Pour cela, des échantillons d'écailles ont été récoltés dans 215 sites situés à des altitudes comprises entre 185 et 2000 m, pour des largeurs variant de 1,2 à 60 m. La croissance des individus a été déterminée par scalimétrie. La longueur totale moyenne atteinte par les individus à l'âge de 3 ans a été retenue comme variable biologique. La taille moyenne à 3 ans des individus est fortement structurée par l'altitude, ce gradient altitudinal représentant en grande partie un gradient thermique. Elle est corrélée négativement avec l'altitude et la densité totale en truites communes et positivement avec la largeur du cours d'eau et la conductivité estivale. La nature du débit joue également un rôle important sur la croissance puisqu'à altitude et à température moyenne estivale équivalentes, la taille moyenne à 3 ans est significativement plus faible en site soumis à un débit réservé qu'en site à débit naturel. Selon la nature du débit, deux modèles prédictifs de la taille moyenne à 3 ans (T3 en fonction de l'altitude (ALT et de la largeur du cours d'eau (L ont été établis par régression multiple pas à pas : - sites à débit naturel : Log (T3 = 2.457 - 0.007 x sgrt ALT + 0.066 x Log (L 65.5 % (p The growth of brown trout (Salmo trutta L. populations has been studied on 84 streams distributed over the whole range of the Pyrenees. Samples of scales were collected in 215 sites located at altitudes ranging between 185 and 2000 m, for width varying from 1,2 to 60 m. The growth of individuals was determined by scale reading. The mean total length of age-3 trout was selected as the biological variable. The mean total length of age-3 trout was strongly structured by altitude, this altitudinal gradient mainly representing a thermal gradient. It is

  8. Lake Roosevelt Fisheries Monitoring Program; 1988-1989 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Peone, Tim L.; Scholz, Allan T.; Griffith, James R.

    1990-10-01

    In the Northwest Power Planning Council's 1987 Columbia River Basin Fish and Wildlife Program (NPPC 1987), the Council directed the Bonneville Power Administration (BPA) to construct two kokanee salmon (Oncorhynchus nerka) hatcheries as partial mitigation for the loss of anadromous salmon and steelhead incurred by construction of Grand Coulee Dam [Section 903 (g)(l)(C)]. The hatcheries will produce kokanee salmon for outplanting into Lake Roosevelt as well as rainbow trout (Oncorhynchus mykiss) for the Lake Roosevelt net-pen program. In section 903 (g)(l)(E), the Council also directed BPA to fund a monitoring program to evaluate the effectiveness of the kokanee hatcheries. The monitoring program included the following components: (1) a year-round, reservoir-wide, creel survey to determine angler use, catch rates and composition, and growth and condition of fish; (2) assessment of kokanee, rainbow, and walleye (Stizostedion vitreum) feeding habits and densities of their preferred prey, and; (3) a mark and recapture study designed to assess the effectiveness of different locations where hatchery-raised kokanee and net pen reared rainbow trout are released. The above measures were adopted by the Council based on a management plan, developed by the Upper Columbia United Tribes Fisheries Center, Spokane Indian Tribe, Colville Confederated Tribes, Washington Department of Wildlife, and National Park Service, that examined the feasibility of restoring and enhancing Lake Roosevelt fisheries (Scholz et al. 1986). In July 1988, BPA entered into a contract with the Spokane Indian Tribe to initiate the monitoring program. The projected duration of the monitoring program is through 1995. This report contains the results of the monitoring program from August 1988 to December 1989.

  9. Nucleotide variation in the mitochondrial genome provides evidence for dual routes of postglacial recolonization and genetic recombination in the northeastern brook trout (Salvelinus fontinalis).

    Science.gov (United States)

    Pilgrim, B L; Perry, R C; Barron, J L; Marshall, H D

    2012-09-26

    Levels and patterns of mitochondrial DNA (mtDNA) variation were examined to investigate the population structure and possible routes of postglacial recolonization of the world's northernmost native populations of brook trout (Salvelinus fontinalis), which are found in Labrador, Canada. We analyzed the sequence diversity of a 1960-bp portion of the mitochondrial genome (NADH dehydrogenase 1 gene and part of cytochrome oxidase 1) of 126 fish from 32 lakes distributed throughout seven regions of northeastern Canada. These populations were found to have low levels of mtDNA diversity, a characteristic trait of populations at northern extremes, with significant structuring at the level of the watershed. Upon comparison of northeastern brook trout sequences to the publicly available brook trout whole mitochondrial genome (GenBank AF154850), we infer that the GenBank sequence is from a fish whose mtDNA has recombined with that of Arctic charr (S. alpinus). The haplotype distribution provides evidence of two different postglacial founding groups contributing to present-day brook trout populations in the northernmost part of their range; the evolution of the majority of the haplotypes coincides with the timing of glacier retreat from Labrador. Our results exemplify the strong influence that historical processes such as glaciations have had on shaping the current genetic structure of northern species such as the brook trout.

  10. Transforming growth factor-β1 expression in endangered age-0 shortnose suckers (Chasmistes brevirostris) from Upper Klamath Lake, OR relative to histopathology, meristic, spatial, and temporal data.

    Science.gov (United States)

    Ottinger, Christopher A; Densmore, Christine L; Robertson, Laura S; Iwanowicz, Deborah D; VanderKooi, Scott P

    2016-02-01

    During July-September of 2008, 2009, and 2010 endangered age-0 juvenile shortnose suckers were sampled from Upper Klamath Lake, OR in a health evaluation that included the measurement of transforming growth factor - beta (TGF-β) expression in spleen in combination with a histopathology assessment. This analysis was performed to determine if the expression of this immuno-regulator could be used as a component of a larger health evaluation intended to identify potential risk-factors that may help to explain why very few of these fish survive to age-1. Potential associations between TGF-β1 expression, histopathological findings, meristic data as well as temporal and spatial data were evaluated using analysis-of-variance. In this analysis, the absence or presence of opercula deformity and hepatic cell necrosis were identified as significant factors in accounting for the variance in TGF-β1 expression observed in age-0 shortnose suckers (n = 122, squared multiple R = 0.989). Location of sample collection and the absence or presence of anchor worms (Lernaea spp.) were identified as significant cofactors. The actual mechanisms involved with these relationships have yet to be determined. The strength, however, of our findings support the concept of using TGF-β1 expression as part of a broader fish health assessment and suggests the potential for using additional immunologic measures in future studies. Specifically, our results indicate that the measure of TGF-β1 expression in age-0 shortnose sucker health assessments can facilitate the process of identifying disease risks that are associated with the documented lack of recruitment into the adult population. Published by Elsevier Ltd.

  11. Detecting Renibacterium salmoninarum in wild brown trout by use of multiple organ samples and diagnostic methods

    Science.gov (United States)

    Guomundsdottir, S.; Applegate, Lynn M.; Arnason, I.O.; Kristmundsson, A.; Purcell, Maureen K.; Elliott, Diane G.

    2017-01-01

    Renibacterium salmoninarum, the causative agent of salmonid bacterial kidney disease (BKD), is endemic in many wild trout species in northerly regions. The aim of the present study was to determine the optimal R. salmoninarum sampling/testing strategy for wild brown trout (Salmo trutta L.) populations in Iceland. Fish were netted in a lake and multiple organs—kidney, spleen, gills, oesophagus and mid-gut—were sampled and subjected to five detection tests i.e. culture, polyclonal enzyme-linked immunosorbent assay (pELISA) and three different PCR tests. The results showed that each fish had encountered R. salmoninarum but there were marked differences between results obtained depending on organ and test. The bacterium was not cultured from any kidney sample while all kidney samples were positive by pELISA. At least one organ from 92.9% of the fish tested positive by PCR. The results demonstrated that the choice of tissue and diagnostic method can dramatically influence the outcome of R. salmoninarum surveys.

  12. Feeding habits of the alien brook trout Salvelinus fontinalis and the native brown trout Salmo trutta in Czech mountain streams

    Directory of Open Access Journals (Sweden)

    Horká Petra

    2017-01-01

    Full Text Available Quantifying patterns of prey resource use is fundamental to identify mechanisms enabling the coexistence of related fish species. Trophic interactions between the native brown trout, Salmo trutta, and the introduced brook trout, Salvelinus fontinalis, were studied monthly from May to October in three mountain streams in Central Europe (Czech Republic. To evaluate whether the feeding habits differ between separated and coexisting populations of these species, one locality where both species coexist, and two allopatric populations of either species were studied. Across the study period, the mean stomach fullness of fish varied, being highest in spring and declining through autumn. The diet overlap (Schoener's overlap index between the species increased through the studied season (from 54.5% in July to 81.5% in October. In allopatry, both species had nearly the same feeding habits. However, in sympatry, brook trout consumed higher proportion of terrestrial invertebrates, while brown trout showed no changes either in the proportions of aquatic and terrestrial prey utilized or in the selectivity for prey categories in comparison to allopatric conditions. The dietary shift observed for brook trout, but not for brown trout, suggests that brown trout is a stronger competitor in the studied sympatric locality, leading the brook trout to change its feeding habits to reduce interspecific competition.

  13. Evaluate Bull Trout Movements in the Tucannon and Lower Snake Rivers, 2002-2003 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Faler, Michael P. (US Fish and Wildlife Service, Idaho Fishery Resource Office, Ahsahka, ID); Mendel, Glen W.; Fulton, Carl (Washington Department of Fish and Wildlife, Fish Management Division, Dayton, WA)

    2004-04-01

    We collected 279 adult bull trout (Salvelinus confluentus) in the Tucannon River during the Spring and Fall of 2003. Passive Integrated Transponder (PIT) tags were inserted in 191 of them, and we detected existing PIT tags in an additional 31bull trout. Thirty five of these were also surgically implanted with radio-tags, and we monitored the movements of these fish throughout the year. Fourteen radio-tags were recovered shortly after tagging, and as a result, 21 remained in the river through December 31, 2003. Four bull trout that were radio-tagged in spring 2002 were known to survive and carry their tags through the spring and/or summer of 2003. One of these fish spent the winter near river mile (RM) 13.0; the other 3 over-wintered in the vicinity of the Tucannon Hatchery between RM 34 and 36. Twenty-one radio tags from bull trout tagged in 2002 were recovered during the spring and summer, 2003. These tags became stationary the winter of 2002/2003, and were recovered between RM 11 and 55. We were unable to recover the remaining 15 tags from 2002. During the month of July, radio-tagged bull trout exhibited a general upstream movement into the upper reaches of the Tucannon subbasin. We observed some downstream movements of radio-tagged bull trout in mid to late September and throughout October. By late November and early December, radio tagged bull trout were relatively stationary, and were distributed from the headwaters downstream to river mile 6.4, near Lower Monumental Pool. As in 2002, we did not conduct work associated with objectives 2, 3, or 4 of this study, because we were unable to monitor migratory movement of radio-tagged bull trout into the Federal hydropower system on the mainstem Snake River. Transmission tests of submerged ATS model F1830 radio-tags in Lower Granite Pool showed that audible detection and individual tag identification was possible at depths of 20 and 30 ft. Tests were conducted using an ATS R-4000 Receiver equipped with an &apos

  14. Age, growth and fall diet of channel catfish in Cheat Lake, West Virginia

    Science.gov (United States)

    Hilling, Corbin D.; Welsh, Stuart A.; Smith, Dustin M.

    2016-01-01

    Acidification has historically impaired Cheat Lake's fish community, but recent mitigation efforts within the Cheat River watershed have improved water quality and species richness. Presently, channel catfish Ictalurus punctatus are abundant and attain desirable sizes for anglers. We evaluated the age, growth, and fall diet of the population. We collected a sample of 155 channel catfish from Cheat Lake from 5 August to 4 December 2014, a subset of which we aged (n = 148) using lapillus otoliths. We fit four growth models (von Bertalanffy, logistic, Gompertz, and power) to length-at-age data and compared models using an information theoretic approach. We collected fall diets from 55 fish sampled from 13 October to 4 December 2014. Total lengths of individuals in the sample ranged from 154 to 721 mm and ages ranged from 2 to 19 y. We AICc-selected the von Bertalanffy growth model as the best approximating model, and the power and Gompertz models also had considerable support. Diets were numerically dominated by Diptera larvae, specifically Chironomidae and Chaoboridae, while 39% of stomachs contained terrestrial food items. This study provides baseline data for management of Cheat Lake's channel catfish population. Further, this study fills a knowledge gap in the scientific literature on channel catfish, because few previously published studies have examined the population ecology of channel catfish in the Central Appalachian region.

  15. Juvenile competitive bottleneck in the production of brown trout in hydroelectric reservoirs due to intraspecific habitat segregation

    International Nuclear Information System (INIS)

    Hegge, O.; Hesthagen, T.; Skurdal, J.

    1993-01-01

    Resource utilization and growth of brown trout were studied in four deep (mean depths 16.2 - 37.5 m) Norwegian hydroelectric reservoirs by benthic and pelagic gillnet sampling. In all the reservoirs supplementary stockings are carried out. The brown trout were spatially segregated according to size as the habitat use of small individuals (< 180-220 mm) was completely restricted to benthic habitats, whereas larger individuals mainly utilized the upper strata of pelagic waters. It is argued that the pelagic habitat is the more rewarding, and that small-sized brown trout are forced into the less favourable benthic habitat through social interactions with larger specimens. This is supported by an increase in growth of brown trout from their third to fifth year of life, which seems to be related to the shift from benthic to pelagic behaviour. It is also argued that the conditions for small-sized brown trout may be a bottleneck in the capacity to produce brown trout in hydroelectric reservoirs with limited benthic feeding conditions, despite ample access to food in pelagic habitats. When evaluating the possibility of increasing the yield of brown trout through supplementary stockings, it is therefore important to consider food and growth conditions for all age and size groups of brown trout. In reservoirs with poor benthic feeding conditions it may be necessary to stock with brown trout of sizes that are large enough to utilize pelagic habitat, to avoid the limiting benthic living stage. (Author)

  16. Recovery history of greenback cutthroat trout: population characteristics, hatchery involvement, and bibliography, version 1.0

    Science.gov (United States)

    Michael K. Young; Amy L. Harig; Bruce Rosenlund; Chris. Kennedy

    2002-01-01

    The greenback cutthroat trout (Oncorhynchus clarki stomias) is native to the mountain and foothill waters of the South Platte and Arkansas river basins in Colorado. This taxon declined rapidly beginning near the turn of the century and was listed under the Endangered Species Act in 1973. We assembled all available information from a variety of...

  17. Status and trends of prey fish populations in Lake Michigan, 2013

    Science.gov (United States)

    Madenjian, Charles P.; Bunnell, David B.; Desorcie, Timothy J.; Kostich, Melissa Jean; Armenio, Patricia M.; Adams, Jean V.

    2015-01-01

    The U.S. Geological Survey Great Lakes Science Center has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size and age structure, and condition of individual fishes are used to estimate various population parameters that are in turn used by state and tribal agencies in managing Lake Michigan fish stocks. All seven established index transects of the survey were completed in 2013. The survey provides relative abundance and biomass estimates between the 5-m and 114-m depth contours of the lake (herein, lake-wide) for prey fish populations, as well as burbot, yellow perch, and the introduced dreissenid mussels. Lake-wide biomass of alewives in 2013 was estimated at 29 kilotonnes (kt, 1 kt = 1000 metric tonnes), which was more than three times the 2012 estimate. However, the unusually high standard error associated with the 2013 estimate indicated no significant increase in lake-wide biomass between 2012 and 2013. Moreover, the age distribution of alewives remained truncated with no alewife exceeding an age of 5. The population of age-1 and older alewives was dominated (i.e., 88%) by the 2010 and 2012 year-classes. Record low biomass was observed for deepwater sculpin (1.3 kt) and ninespine stickleback (0.004 kt) in 2013, while bloater (1.6 kt) and rainbow smelt (0.2 kt) biomasses remained at low levels. Slimy sculpin lake-wide biomass was 0.32 kt in 2013, marking the fourth consecutive year of a decline. The 2013 biomass of round goby was estimated at 10.9 kt, which represented the peak estimate to date. Burbot lake-wide biomass (0.4 kt in 2013) has remained below 3 kt since 2001. Numeric density of age-0 yellow perch (i.e., fish per ha, which is indicative of a relatively poor year-class. Lake-wide biomass estimate of dreissenid mussels in 2013 was 23.2 kt. Overall, the total

  18. Brown trout and food web interactions in a Minnesota stream

    Science.gov (United States)

    Zimmerman, J.K.H.; Vondracek, B.

    2007-01-01

    1. We examined indirect, community-level interactions in a stream that contained non-native brown trout (Salmo trutta Linnaeus), native brook trout (Salvelinus fontinalis Mitchill) and native slimy sculpin (Cottus cognatus Richardson). Our objectives were to examine benthic invertebrate composition and prey selection of fishes (measured by total invertebrate dry mass, dry mass of individual invertebrate taxa and relative proportion of invertebrate taxa in the benthos and diet) among treatments (no fish, juvenile brook trout alone, juvenile brown trout alone, sculpin with brook trout and sculpin with brown trout). 2. We assigned treatments to 1 m2 enclosures/exclosures placed in riffles in Valley Creek, Minnesota, and conducted six experimental trials. We used three designs of fish densities (addition of trout to a constant number of sculpin with unequal numbers of trout and sculpin; addition of trout to a constant number of sculpin with equal numbers of trout and sculpin; and replacement of half the sculpin with an equal number of trout) to investigate the relative strength of interspecific versus intraspecific interactions. 3. Presence of fish (all three species, alone or in combined-species treatments) was not associated with changes in total dry mass of benthic invertebrates or shifts in relative abundance of benthic invertebrate taxa, regardless of fish density design. 4. Brook trout and sculpin diets did not change when each species was alone compared with treatments of both species together. Likewise, we did not find evidence for shifts in brown trout or sculpin diets when each species was alone or together. 5. We suggest that native brook trout and non-native brown trout fill similar niches in Valley Creek. We did not find evidence that either species had an effect on stream communities, potentially due to high invertebrate productivity in Valley Creek. ?? 2007 Blackwell Publishing Ltd.

  19. Age and growth of dominant cichlids in Gbedikere Lake, Kogi Statr ...

    African Journals Online (AJOL)

    Sixty samples of the fish species comprising thirty Tilapia zilli and thirty Oreochromis niloticus were obtained from the Artisanal fishers from the common landing site along the lake. Age was determined from Bhattacharya's length frequency assortment method using where applicable the scale of fish and opercula bones.

  20. Biotic interactions in temporal trends (1992–2010) of organochlorine contaminants in the aquatic food web of Lake Laberge, Yukon Territory

    International Nuclear Information System (INIS)

    Ryan, M.J.; Stern, G.A.; Kidd, K.A.; Croft, M.V.; Gewurtz, S.; Diamond, M.; Kinnear, L.; Roach, P.

    2013-01-01

    Declines in 6 organochlorine (OC) contaminant groups; chlordane (CHL), DDT, HCH, toxaphene (CHB), PCB and chlorinated benzenes (CBz) were measured in biota of a sub-Arctic lake (Lake Laberge, YT) following the closure of a commercial fishery in 1991. This study examined morphological (length, weight, age), biochemical (lipid content, δ 13 C, δ 15 N), population and OC data for 9 fishes and zooplankton between 1993 and 2003 (2010 for lake trout) to investigate causes for the OC declines. Growth dilution was a major factor influencing the decrease of OCs in lake trout, round whitefish and possibly zooplankton most notably in the early 2000s. A decline in lipids of most fish species also contributed to OC declines, although no such change was evident for zooplankton. It is suspected that increases in fish populations or climate variations over the 1990s, may have contributed towards a shift in plankton community composition. From 1991 to 1999, CPUE increased for 7 of the fish species and declined for 2 others. Concurrently, the zooplankton community shifted from an abundance of C. scutifer in 1993 to dominance by D. pribilofensis in 2001. Nitrogen and carbon stable isotope data suggested that food web interactions for most fish species have not changed over time. Although concentrations of OCs have declined in many fishes, the “rate” of OC transfer (using slopes of log OC vs. nitrogen isotope ratios) through the food web was greater in 2001 than in 1993. Overall, the declines in OC concentrations in the fish from Lake Laberge occurred concurrently with changes in their growth, lipid, and abundance, suggesting that ecosystem responses to the closure of the fishery were in part responsible for the lower contaminants in these fishes. As a result of this study, the Yukon government rescinded the health advisory for limiting the consumption of fish from Lake Laberge. - Highlights: ► Organochlorine contaminants in a sub-Arctic lake were monitored post

  1. Biotic interactions in temporal trends (1992–2010) of organochlorine contaminants in the aquatic food web of Lake Laberge, Yukon Territory

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, M.J. [Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6 (Canada); University of Manitoba, Dept. of Soil Science, Winnipeg, Manitoba, Canada R3T 2N2 (Canada); Stern, G.A., E-mail: gary.stern@dfo-mpo.gc.ca [Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6 (Canada); Kidd, K.A. [University of New Brunswick, Canadian Rivers Institute and Department of Biology, Saint John, New Brunswick, Canada E2L 4E5 (Canada); Croft, M.V. [Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6 (Canada); Gewurtz, S.; Diamond, M. [University of Toronto, Department of Geography, Toronto, Ontario, Canada M5S 3G3 (Canada); Kinnear, L. [Northern Climate Exchange, Yukon Research Center, Yukon College, Whitehorse, Yukon Territory, Canada Y1A 5K4 (Canada); Roach, P. [Aboriginal Affairs and Northern Development Canada, Rm 415C - 300 Main St., Whitehorse, Yukon Territory, Canada Y1A 2B5 (Canada)

    2013-01-15

    Declines in 6 organochlorine (OC) contaminant groups; chlordane (CHL), DDT, HCH, toxaphene (CHB), PCB and chlorinated benzenes (CBz) were measured in biota of a sub-Arctic lake (Lake Laberge, YT) following the closure of a commercial fishery in 1991. This study examined morphological (length, weight, age), biochemical (lipid content, δ{sup 13}C, δ{sup 15}N), population and OC data for 9 fishes and zooplankton between 1993 and 2003 (2010 for lake trout) to investigate causes for the OC declines. Growth dilution was a major factor influencing the decrease of OCs in lake trout, round whitefish and possibly zooplankton most notably in the early 2000s. A decline in lipids of most fish species also contributed to OC declines, although no such change was evident for zooplankton. It is suspected that increases in fish populations or climate variations over the 1990s, may have contributed towards a shift in plankton community composition. From 1991 to 1999, CPUE increased for 7 of the fish species and declined for 2 others. Concurrently, the zooplankton community shifted from an abundance of C. scutifer in 1993 to dominance by D. pribilofensis in 2001. Nitrogen and carbon stable isotope data suggested that food web interactions for most fish species have not changed over time. Although concentrations of OCs have declined in many fishes, the “rate” of OC transfer (using slopes of log OC vs. nitrogen isotope ratios) through the food web was greater in 2001 than in 1993. Overall, the declines in OC concentrations in the fish from Lake Laberge occurred concurrently with changes in their growth, lipid, and abundance, suggesting that ecosystem responses to the closure of the fishery were in part responsible for the lower contaminants in these fishes. As a result of this study, the Yukon government rescinded the health advisory for limiting the consumption of fish from Lake Laberge. - Highlights: ► Organochlorine contaminants in a sub-Arctic lake were monitored post

  2. Regional prediction of basin-scale brown trout habitat suitability

    Directory of Open Access Journals (Sweden)

    S. Ceola

    2014-09-01

    Full Text Available In this study we propose a novel method for the estimation of ecological indices describing the habitat suitability of brown trout (Salmo trutta. Traditional hydrological tools are coupled with an innovative regional geostatistical technique, aiming at the prediction of the brown trout habitat suitability index where partial or totally ungauged conditions occur. Several methods for the assessment of ecological indices are already proposed in the scientific literature, but the possibility of exploiting a geostatistical prediction model, such as Topological Kriging, has never been investigated before. In order to develop a regional habitat suitability model we use the habitat suitability curve, obtained from measured data of brown trout adult individuals collected in several river basins across the USA. The Top-kriging prediction model is then employed to assess the spatial correlation between upstream and downstream habitat suitability indices. The study area is the Metauro River basin, located in the central part of Italy (Marche region, for which both water depth and streamflow data were collected. The present analysis focuses on discharge values corresponding to the 0.1-, 0.5-, 0.9-empirical quantiles derived from flow-duration curves available for seven gauging stations located within the study area, for which three different suitability indices (i.e. ψ10, ψ50 and ψ90 are evaluated. The results of this preliminary analysis are encouraging showing Nash-Sutcliffe efficiencies equal to 0.52, 0.65, and 0.69, respectively.

  3. Regional prediction of basin-scale brown trout habitat suitability

    Science.gov (United States)

    Ceola, S.; Pugliese, A.

    2014-09-01

    In this study we propose a novel method for the estimation of ecological indices describing the habitat suitability of brown trout (Salmo trutta). Traditional hydrological tools are coupled with an innovative regional geostatistical technique, aiming at the prediction of the brown trout habitat suitability index where partial or totally ungauged conditions occur. Several methods for the assessment of ecological indices are already proposed in the scientific literature, but the possibility of exploiting a geostatistical prediction model, such as Topological Kriging, has never been investigated before. In order to develop a regional habitat suitability model we use the habitat suitability curve, obtained from measured data of brown trout adult individuals collected in several river basins across the USA. The Top-kriging prediction model is then employed to assess the spatial correlation between upstream and downstream habitat suitability indices. The study area is the Metauro River basin, located in the central part of Italy (Marche region), for which both water depth and streamflow data were collected. The present analysis focuses on discharge values corresponding to the 0.1-, 0.5-, 0.9-empirical quantiles derived from flow-duration curves available for seven gauging stations located within the study area, for which three different suitability indices (i.e. ψ10, ψ50 and ψ90) are evaluated. The results of this preliminary analysis are encouraging showing Nash-Sutcliffe efficiencies equal to 0.52, 0.65, and 0.69, respectively.

  4. Relying on fin erosion to identify hatchery-reared brown trout in a Tennessee river

    Science.gov (United States)

    Meerbeek, Jonathan R.; Bettoli, Phillip William

    2012-01-01

    Hatchery-induced fin erosion can be used to identify recently stocked catchable-size brown trout Salmo trutta during annual surveys to qualitatively estimate contributions to a fishery. However, little is known about the longevity of this mark and its effectiveness as a short-term (≤ 1 year) mass-marking technique. We evaluated hatchery-induced pectoral fin erosion as a mass-marking technique for short-term stocking evaluations by stocking microtagged brown trout in a tailwater and repeatedly sampling those fish to observe and measure their pectoral fins. At Dale Hollow National Fish Hatchery, 99.1% (228 of 230) of microtagged brown trout in outdoor concrete raceways had eroded pectoral fins 1 d prior to stocking. Between 34 and 68 microtagged and 26-35 wild brown trout were collected during eight subsequent electrofishing samples. In a blind test based on visual examination of pectoral fins at up to 322 d poststocking, one observer correctly identified 91.7% to 100.0% (mean of 96.9%) of microtagged brown trout prior to checking for microtags. In the laboratory, pectoral fin length and width measurements were recorded to statistically compare the fin measurements of wild and microtagged hatchery brown trout. With only one exception, all pectoral fin measurements on each date averaged significantly larger for wild trout than for microtagged brown trout. Based on the number of pectoral fin measurements falling below 95% prediction intervals, 93.7% (148 of 158) of microtagged trout were correctly identified as hatchery fish based on regression models up to 160 d poststocking. Only 72.2% (70 of 97) of microtagged trout were identified correctly after 160 d based on pectoral fin measurements and the regression models. We concluded that visual examination of pectoral fin erosion was a very effective way to identify stocked brown trout for up to 322 d poststocking.

  5. Geochemical pathways and biological uptake of radium in small Canadian Shield lakes

    International Nuclear Information System (INIS)

    Hesslein, R.H.; Slavicek, E.

    1984-01-01

    The sediment-water interactions and biological uptake of 226 Ra are described for four small Canadian Shield lakes at the Experimental Lakes Area, Kenora, Ontario. A single addition of 226 Ra was made to each lake between 1970 and 1976. Approximately 90 percent of the added 226 Ra initially sorbed to the sediments. Outflow from the lakes showed losses of only 5-11 percent 226 Ra per year. Models are proposed for adsorption and outflow of 226 Ra from lakes. Biological uptake and long-term 226 Ra concentrations were measured in three species of macrophytes, crayfish, and five species of fish. Bioaccumulation ranged from 1100 to 5000 in macrophytes, 705 in crayfish, from 30 to 80 in large trout (Salvelinus namaycush), white sucker (Catostomus commersoni), and lake whitefish (Coregonus clupeaformis), and from 230 to 1200 in fathead minnows (Pimephales promelas), pearl dace (Semotilus margarita), and northern redbelly dace (Chrosomus eos). The concept of Ra/Ca ratio in organisms versus water and food is used to explain the differences in bioaccumulation. 226 Ra is discriminated against versus calcium by fish but favoured by macrophytes and crayfish

  6. CHEMICAL COMPOSITION AND ENERGY VALUE IN THE MEAT OF THE MACEDONIAN AND OHRID TROUT

    Directory of Open Access Journals (Sweden)

    Aleksandar SAVESKI

    2017-03-01

    Full Text Available The aim of this research is to conduct a comparative analysis and to verify the quality properties of meat of the Macedonian trout (Salmo macedonicus and the Ohrid trout (Salmo letnica, from aquaculture production, bred on a fish farm under controlled conditions. In order to determine the quality of meat of the Macedonian and Ohrid trout, analyses of the chemical composition have been conducted: the amount of proteins, fat, water, minerals, as well as a determination of the energy value of the meat. The analyses have been made on samples from Macedonian and Ohrid trout, with size of consumption between 200g and 300g. By these analyses, it has been confirmed that in the meat of the Macedonian trout, the amount of water is 77.122%, 17.800% proteins, 3.333% fat and 1.667% minerals, whereas in the meat of the Ohrid trout 75.923% water, 16.783% proteins, 5.403% fat and 1.080% minerals. Though the established difference in the amount of water and fat is not significant, the differences determined in the contents of proteins and minerals are significant on a level p>0,05. The energy value of Macedonian trout meat is 435.29 KJ/100gm, i.e. and 498.49 KJ/100gm in the Ohrid trout meat.

  7. Changes in aquatic insect emergence in response to whole-lake experimental manipulations of introduced trout

    Science.gov (United States)

    Karen L. Pope; Jonah Piovia-Scott; Sharon P. Lawler

    2009-01-01

    1. Insects emerging from mountain lakes provide an important food source for many terrestrial predators. The amount of insect subsidy that emerges from lakes is influenced by predator composition, but predator effects could be ameliorated by greater habitat complexity. We conducted a replicated whole-lake experiment to test the effects of introduced fish...

  8. Is water age a reliable indicator for evaluating water quality effectiveness of water diversion projects in eutrophic lakes?

    Science.gov (United States)

    Zhang, Xiaoling; Zou, Rui; Wang, Yilin; Liu, Yong; Zhao, Lei; Zhu, Xiang; Guo, Huaicheng

    2016-11-01

    Water diversion has been applied increasingly to promote the exchange of lake water and to control eutrophication of lakes. The accelerated water exchange and mass transport by water diversion can usually be represented by water age. But the responses of water quality after water diversion is still disputed. The reliability of using water age for evaluating the effectiveness of water diversion projects in eutrophic lakes should be thereby explored further. Lake Dianchi, a semi-closed plateau lake in China, has suffered severe eutrophication since the 1980s, and it is one of the three most eutrophic lakes in China. There was no significant improvement in water quality after an investment of approximately 7.7 billion USD and numerous project efforts from 1996 to 2015. After the approval of the Chinese State Council, water has been transferred to Lake Dianchi to alleviate eutrophication since December 2013. A three-dimensional hydrodynamic and water quality model and eight scenarios were developed in this study to quantity the influence of this water diversion project on water quality in Lake Dianchi. The model results showed that (a) Water quality (TP, TN, and Chla) could be improved by 13.5-32.2%, much lower than the approximate 50% reduction in water age; (b) Water exchange had a strong positive relationship with mean TP, and mean Chla had exactly the same response to water diversion as mean TN; (c) Water level was more beneficial for improving hydrodynamic and nutrient concentrations than variation in the diverted inflowing water volume; (d) The water diversion scenario of doubling the diverted inflow rate in the wet season with the water level of 1886.5 m and 1887 m in the remaining months was the best water diversion mode for mean hydrodynamics and TP, but the scenario of doubling the diverted inflow rate in the wet season with 1887 m throughout the year was optimum for mean TN and Chla; (e) Water age influenced the effectiveness of water diversion on the

  9. Synthetic Musk fragrances in Trout from Danish fish farms and human milk

    DEFF Research Database (Denmark)

    Duedahl-Olesen, Lene; Cederberg, Tommy Licht; Pedersen, K. H.

    2005-01-01

    Synthetic musk compounds used in detergents and cosmetics include nitro and polycyclic musk compounds. These compounds are discharged after use via domestic wastewater and sewage treatment plants to the aquatic environment. Quantitative detection of nitro musk and polycyclic musk compounds by GC....../HRMS in Danish farmed trout and human milk from primiparous mothers are reported. The polycyclic musk, HHCB, dominated the synthetic musk compounds found in trout samples from 1999 with a median concentration of 5.0 mu g/kg fresh weight (n.d.-52.6 mu g/kg fresh weight) and in trout samples collected in 2003....../kg fresh weight in 1999 and to a median less than the detection limit (0.23 mu g/kg fresh weight) in 2003. HHCB also dominated in Danish human milk samples collected in 1999 with a median concentration of 147 mu g/kg fat (38.0-422 mu g/kg fat). Human dietary intake assessment and body burden calculations...

  10. Exotic "Gill Lice" Species (Copepoda: Lernaeopodidae: Salmincola SPP.) Infect Rainbow Trout (Oncorhynchus mykiss) and Brook Trout (Salvelinus fontinalis) in the Southeastern United States.

    Science.gov (United States)

    Ruiz, Carlos F; Rash, Jacob M; Besler, Doug A; Roberts, Jackson R; Warren, Micah B; Arias, Cova R; Bullard, Stephen A

    2017-08-01

    Salmincola californiensis infected 25 of 31 (prevalence 0.8; intensity 2-35 [mean 6.6 ± standard deviation 7.7; n = 25]) rainbow trout, Oncorhynchus mykiss, from a private trout farm connected to the Watauga River, North Carolina. Salmincola edwardsii infected all of 9 (1.0; 2-43 [9.3 ± 13.0; 9]) brook trout, Salvelinus fontinalis, from Big Norton Prong, a tributary of the Little Tennessee River, North Carolina. Both lernaeopodids are well-known salmonid pathogens, but neither is native to, nor has been previously taxonomically confirmed from, the southeastern United States. Herein, we (1) use light and scanning electron microscopy to identify and provide supplemental morphological observations of these lernaeopodids, (2) furnish complementary molecular sequence data from the 28S rDNA (28S), and (3) document the pathological effects of gill infections. We identified and differentiated these lernaeopodids by the second antenna (exopod tip with large [S. californiensis] vs. slender [S. edwardsii] spines; endopod terminal segment with subequal ventral processes shorter than [S. californiensis] vs. longer than or equal to [S. edwardsii] dorsal hook), maxilliped palp (length typically ≤1/3 [S. californiensis] vs. 1/3-1/2 [S. edwardsii] subchela length exclusive of claw), and bulla (sub-circular and concave on manubrium's side [S. californiensis] vs. non-stellate [S. edwardsii]). Analysis of the 28S rDNA sequences confirmed our taxonomic assignments as demonstrated by 100% sequence similarity among the sympatric, morphologically-conspecific isolates. Histopathology revealed focal gill epithelial hyperplasia, obstruction of interlamellar water channels, lamellar fusion, and crypting of gill filaments. High intensity infections by either lernaeopodid are surveillance-worthy because they are potentially pathogenic to trout in the southeastern United States.

  11. Occurrence of chlorinated paraffins in beluga whales (Delphinapterus leucas) from the St. Lawrence River and rainbow trout (Oncorhynchus mykiss) and carp (Cyprinus carpio) from Lake Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Bennie, D. T.; Sullivan, C. A.; Maguire, R. J. [Envirronment Canada, National Water Research Institute, Burlington, ON (Canada)

    2000-07-01

    Samples of 25 dead beluga whales from the St. Lawrence River estuary, as well as samples of 10 rainbow trout and three carps caught in western Lake Ontario were analyzed for total short and medium chain chlorinated paraffins using gas chromatography-low resolution negative chemical ionization spectroscopy. Both short and medium-chain chlorinated paraffins were quantitatively identified in all samples using two commercial preparations. Beluga results were found to be higher than concentrations reported for marine mammals in Europe, but comparable to total PCB and total DDT results for the same population of beluga whales. Results for freshwater species are comparable to those reported for fish sampled from other industrially impacted waterways in North America, but elevated compared to marine species from European studies. Comparisons of the results with gas chromatography-negative ion mass spectroscopy analysis from another study indicated that the two analytical techniques are not congruent. The differences may be accounted for by different effects of interfering organochlorine substances on the analysis of chlorinated paraffins. 22 refs., 5 tabs., 1 fig.

  12. Investigations of bull trout (Salvelinus confluentus), steelhead trout (Oncorhynchus mykiss), and spring chinook salmon (O. tshawytscha) interactions in Southeast Washington streams. Final report 1992

    International Nuclear Information System (INIS)

    Underwood, K.D.; Martin, S.W.; Schuck, M.L.; Scholz, A.T.

    1995-01-01

    The goal of this two year study was to determine if supplementation with hatchery reared steelhead trout (Oncorhynchus mykiss) and spring chinook salmon (O. tshawytscha) negatively impacted wild native bull trout (Salvelinus confluentus) through competitive interactions. Four streams with varying levels of fish supplementation activity were sampled in Southeast Washington. Tasks performed during this study were population density, relative abundance, microhabitat utilization, habitat availability, diet analysis, bull trout spawning ground surveys, radio telemetry of adult bull trout, and growth analysis. Results indicate that bull trout overlapped geographically with the supplemented species in each of the study streams suggesting competition among species was possible. Within a stream, bull trout and the supplemented species utilized dissimilar microhabitats and microhabitat utilization by each species was the same among streams suggesting that there was no shifts in microhabitat utilization among streams. The diet of bull trout and O. mykiss significantly overlapped in each of the study streams. The stream most intensely supplemented contained bull trout with the slowest growth and the non-supplemented stream contained bull trout with the fastest growth. Conversely, the stream most intensely supplemented contain steelhead with the fastest growth and the non-supplemented stream contained steelhead with the slowest growth. Growth indicated that bull trout may have been negatively impacted from supplementation, although other factors may have contributed. At current population levels, and current habitat quantity and quality, no impacts to bull trout as a result of supplementation with hatchery reared steelhead trout and spring chinook salmon were detected. Project limitations and future research recommendations are discussed

  13. Investigations of Bull Trout (Salvelinus Confluentus), Steelhead Trout (Oncorhynchus Mykiss), and Spring Chinook Salmon (O. Tshawytscha) Interactions in Southeast Washington Streams. Final Report 1992.

    Energy Technology Data Exchange (ETDEWEB)

    Underwood, Keith D.

    1995-01-01

    The goal of this two year study was to determine if supplementation with hatchery reared steelhead trout (Oncorhynchus mykiss) and spring chinook salmon (O. tshawytscha) negatively impacted wild native bull trout (Salvelinus confluentus) through competitive interactions. Four streams with varying levels of fish supplementation activity were sampled in Southeast Washington. Tasks performed during this study were population density, relative abundance, microhabitat utilization, habitat availability, diet analysis, bull trout spawning ground surveys, radio telemetry of adult bull trout, and growth analysis. Results indicate that bull trout overlapped geographically with the supplemented species in each of the study streams suggesting competition among species was possible. Within a stream, bull trout and the supplemented species utilized dissimilar microhabitats and microhabitat utilization by each species was the same among streams suggesting that there was no shifts in microhabitat utilization among streams. The diet of bull trout and O. mykiss significantly overlapped in each of the study streams. The stream most intensely supplemented contained bull trout with the slowest growth and the non-supplemented stream contained bull trout with the fastest growth. Conversely, the stream most intensely supplemented contain steelhead with the fastest growth and the non-supplemented stream contained steelhead with the slowest growth. Growth indicated that bull trout may have been negatively impacted from supplementation, although other factors may have contributed. At current population levels, and current habitat quantity and quality, no impacts to bull trout as a result of supplementation with hatchery reared steelhead trout and spring chinook salmon were detected. Project limitations and future research recommendations are discussed.

  14. Effects of water temperature and fish size on predation vulnerability of juvenile humpback chub to rainbow trout and brown trout

    Science.gov (United States)

    Ward, David L.; Morton-Starner, Rylan

    2015-01-01

    Predation on juvenile native fish by introduced Rainbow Trout and Brown Trout is considered a significant threat to the persistence of endangered Humpback Chub Gila cypha in the Colorado River in the Grand Canyon. Diet studies of Rainbow Trout and Brown Trout in Glen and Grand canyons indicate that these species do eat native fish, but impacts are difficult to assess because predation vulnerability is highly variable, depending on prey size, predator size, and the water temperatures under which the predation interactions take place. We conducted laboratory experiments to evaluate how short-term predation vulnerability of juvenile native fish changes in response to fish size and water temperature using captivity-reared Humpback Chub, Bonytail, and Roundtail Chub. Juvenile chub 45–90 mm total length (TL) were exposed to adult Rainbow and Brown trouts at 10, 15, and 20°C to measure predation vulnerability as a function of water temperature and fish size. A 1°C increase in water temperature decreased short-term predation vulnerability of Humpback Chub to Rainbow Trout by about 5%, although the relationship is not linear. Brown Trout were highly piscivorous in the laboratory at any size > 220 mm TL and at all water temperatures we tested. Understanding the effects of predation by trout on endangered Humpback Chub is critical in evaluating management options aimed at preserving native fishes in Grand Canyon National Park.

  15. Native and exotic fishes in a Patagonian reservoir with rainbow trout cage culture: spatial and trophic resource use

    Directory of Open Access Journals (Sweden)

    Nabaes Jodar Diego N.

    2017-01-01

    Full Text Available Although the interactions of exotic salmonids with native Patagonian fishes are well known, little is known about the ecology and impact of farmed fish escapees. Salmonid production in Argentina is largely concentrated in the Alicurá reservoir in north Patagonia, where fish community studies have been scarce. Here, we assess and compare the spatial distribution, body size–condition and diet of the different fish species in this reservoir. Strong vertical segregation was observed between exotic rainbow trout Oncorhynchus mykiss (both escapees and wild, dominating the littoral zone, and native Percichthys trucha which dominate the medium and deep strata. Low piscivory–benthivory and high zooplanktivory were observed for rainbow trout, both traits being uncommon at a regional scale. Escaped farmed rainbow trout (ERT diet included abundant indigestible items along with wild prey. Higher body condition of P. trucha close to farms, as well as the regionally unprecedented high incidence of Daphnia sp. in the guts of all the species suggest that farm nutrient discharges have had significant impacts. Finally, the high body condition of ERT, together with their wild food diet and the long dispersal distance observed, demonstrate post-escape success, drawing our attention to potential upstream dispersion affecting the biodiversity and fisheries of Patagonian rivers and lakes.

  16. New records of Ergasilus (Copepoda: Ergasilidae) in the Laurentian Great Lakes, including a lakewide review of records and host associations

    Science.gov (United States)

    Hudson, Patrick L.; Bowen, Charles A.; Stedman, Ralph M.

    1994-01-01

    Ergasilus nerkae was found infecting ninespine stickleback (Pungitius pungitius) in lakes Huron, Michigan, and Superior and threespine stickleback (Gasterosteus aculeatus) and round whitefish (Prosopium cylindraceum) in Lake Huron. Based upon the literature and study of archived material, we propose that E. nerkae is enzootic to the Great Lakes and that ninespine stickleback are a preferred host in Lake Huron. Prevalence of E. nerkae on ninespine stickleback increased from 17% in June to 68% in September, but mean intensity remained light. Prevalence and mean intensity increased with host length. Ergasilus luciopercarum is also reported on lake trout (Salvelinus namaycush) and largemouth bass (Micropterus salmoides) for the first time. Host-parasite records of Ergasilus spp. in North America are reviewed, biology and taxonomy are summarized, and a checklist of Great Lakes host-parasite-locality records is provided. At present, eight species of Ergasilus are known to infect 42 Great Lakes fish species.

  17. A Reassessment of U-Th and 14C Ages for Late-Glacial High-Frequency Hydrological Events at Searles Lake, California

    Science.gov (United States)

    Lin, J.C.; Broecker, W.S.; Hemming, S.R.; Hajdas, I.; Anderson, Robert F.; Smith, G.I.; Kelley, M.; Bonani, G.

    1998-01-01

    U-Th isochron ages of tufas formed on shorelines suggest that the last pluvial event in Lake Lahontan and Searles Lake was synchronous at about 16,500 cal yr B.P. (equivalent to a radiocarbon age of between 14,000 and 13,500 yr B.P.), whereas the timing of this pluvial event determined by radiocarbon dating is on the order of 1000 yr younger. The timing of seven distinct periods of near desiccation in Searles Lake during late-glacial time has been reinvestigated for U-Th age determination by mass spectrometry. U-Th dating of evaporite layers in the interbedded mud and salt unit called the Lower Salt in Searles Lake was hampered by the uncertainty in assessing the initial 230Th/232Th of the samples. The resulting ages, corrected by a conservative range of initial 230Th/ 232Th ratios, suggest close correlation of the abrupt changes recorded in Greenland ice cores (Dansgaard-Oeschger events) and wet-dry conditions in Searles Lake between 35,000 and 24,000 Cal yr B.P. ?? 1998 University of Washington.

  18. Spokane Tribal Hatchery, 2003 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Peone, Tim L. (Spokane Tribe of Indians, Wellpinit, WA)

    2004-05-01

    Due to the construction and operation of Grand Coulee Dam (1939), anadromous salmon have been eradicated and resident fish populations permanently altered in the upper Columbia River region. Federal and private hydropower dam operations throughout the Columbia River system severely limits indigenous fish populations in the upper Columbia. Artificial production has been determined appropriate for supporting a harvestable fishery for kokanee salmon (Oncorhynchus nerka) and rainbow trout (Oncorhynchus mykiss) in Lake Roosevelt and Banks Lake (Grand Coulee Dam impoundments). A collaborative multi-agency artificial production program for the Lake Roosevelt and Banks Lake fisheries exists consisting of the Spokane Tribal Hatchery, Sherman Creek Hatchery, Ford Trout Hatchery and the Lake Roosevelt Kokanee and Rainbow Trout Net Pen Rearing Projects. These projects operate complementary of one another to target an annual release of 1 million yearling kokanee and 500,000 yearling rainbow trout for Lake Roosevelt and 1.4 million kokanee fry/fingerlings for Banks Lake. Combined fish stocking by the hatcheries and net pen rearing projects in 2003 included: 899,168 kokanee yearlings released into Lake Roosevelt; 1,087,331 kokanee fry/fingerlings released into Banks Lake, 44,000 rainbow trout fingerlings and; 580,880 rainbow trout yearlings released into Lake Roosevelt. Stock composition of 2003 releases consisted of Lake Whatcom kokanee, 50:50 diploid-triploid Spokane Trout Hatchery (McCloud River) rainbow trout and Phalon Lake red-band rainbow trout. All kokanee were marked with either thermal, oxytetracyline or fin clips prior to release. Preliminary 2003 Lake Roosevelt fisheries investigations indicate hatchery/net pen stocking significantly contributed to harvestable rainbow trout and kokanee salmon fisheries. An increase in kokanee harvest was primarily owing to new release strategies. Walleye predation, early maturity and entrainment through Grand Coulee Dam continues to

  19. Morphological and molecular confirmation of Myxobolus cerebralis myxospores infecting wild‑caught and cultured trout in North Carolina (SE USA).

    Science.gov (United States)

    Ruiz, Carlos F; Rash, Jacob M; Arias, Cova R; Besler, Doug A; Orélis-Ribeiro, Raphael; Womble, Matthew R; Roberts, Jackson R; Warren, Micah B; Ray, Candis L; Lafrentz, Stacey; Bullard, Stephen A

    2017-11-21

    We used microscopy and molecular biology to provide the first documentation of infections of Myxobolus cerebralis (Myxozoa: Myxobolidae), the etiological agent of whirling disease, in trout (Salmonidae) from North Carolina (USA) river basins. A total of 1085 rainbow trout Oncorhynchus mykiss, 696 brown trout Salmo trutta, and 319 brook trout Salvelinus fontinalis from 43 localities across 9 river basins were screened. Myxospores were observed microscopically in pepsin-trypsin digested heads of rainbow and brown trout from the Watauga River Basin. Those infections were confirmed using the prescribed nested polymerase chain reaction (PCR; 18S rDNA), which also detected infections in rainbow, brown, and brook trout from the French Broad River Basin and the Yadkin Pee-Dee River Basin. Myxospores were 9.0-10.0 µm (mean ± SD = 9.6 ± 0.4; N = 119) long, 8.0-10.0 µm (8.8 ± 0.6; 104) wide, and 6.0-7.5 µm (6.9 ± 0.5; 15) thick and had polar capsules 4.0-6.0 µm (5.0 ± 0.5; 104) long, 2.5-3.5 µm (3.1 ± 0.3; 104) wide, and with 5 or 6 polar filament coils. Myxospores from these hosts and rivers were morphologically indistinguishable and molecularly identical, indicating conspecificity, and the resulting 18S rDNA and ITS-1 sequences derived from these myxospores were 99.5-100% and 99.3-99.8% similar, respectively, to published GenBank sequences ascribed to M. cerebralis. This report comprises the first taxonomic circumscription and molecular confirmation of M. cerebralis in the southeastern USA south of Virginia.

  20. Identifying potential virulence determinants in viral haemorrhagic septicaemia virus (VHSV) for rainbow trout

    DEFF Research Database (Denmark)

    Campbell, Scott; Collet, Bertrand; Einer-Jensen, Katja

    2009-01-01

    of an isolate recovered in 2000 from a viral haemorrhagic septicaemia disease episode in a marine rainbow trout farm in Sweden (SE-SVA-1033) was evaluated in juvenile rainbow trout via intraperitoneal injection and immersion challenge alongside 3 isolates recovered from wild-caught marine fish (DK-4p37, DK-5e59...... and UKMLA98/6HE1) suspected of being of low pathogenicity to trout. Mortality data revealed that isolate SE-SVA-1033 caused VHSV-specific mortality in both intraperitoneal and immersion challenges (75.0 and 15.4%, respectively). The remaining Genotype Ib isolates caused significantly lower mortalities using...

  1. Status of Oregon's Bull Trout.

    Energy Technology Data Exchange (ETDEWEB)

    Buchanan, David V.; Hanson, Mary L.; Hooton, Robert M.

    1997-10-01

    Limited historical references indicate that bull trout Salvelinus confluentus in Oregon were once widely spread throughout at least 12 basins in the Klamath River and Columbia River systems. No bull trout have been observed in Oregon's coastal systems. A total of 69 bull trout populations in 12 basins are currently identified in Oregon. A comparison of the 1991 bull trout status (Ratliff and Howell 1992) to the revised 1996 status found that 7 populations were newly discovered and 1 population showed a positive or upgraded status while 22 populations showed a negative or downgraded status. The general downgrading of 32% of Oregon's bull trout populations appears largely due to increased survey efforts and increased survey accuracy rather than reduced numbers or distribution. However, three populations in the upper Klamath Basin, two in the Walla Walla Basin, and one in the Willamette Basin showed decreases in estimated population abundance or distribution.

  2. Return of a giant: DNA from archival museum samples helps to identify a unique cutthroat trout lineage formerly thought to be extinct.

    Science.gov (United States)

    Peacock, Mary M; Hekkala, Evon R; Kirchoff, Veronica S; Heki, Lisa G

    2017-11-01

    Currently one small, native population of the culturally and ecologically important Lahontan cutthroat trout ( Oncorhynchus clarkii henshawi , LCT, Federally listed) remains in the Truckee River watershed of northwestern Nevada and northeastern California. The majority of populations in this watershed were extirpated in the 1940s due to invasive species, overharvest, anthropogenic water consumption and changing precipitation regimes. In 1977, a population of cutthroat trout discovered in the Pilot Peak Mountains in the Bonneville basin of Utah, was putatively identified as the extirpated LCT lacustrine lineage native to Pyramid Lake in the Truckee River basin based on morphological and meristic characters. Our phylogenetic and Bayesian genotype clustering analyses of museum specimens collected from the large lakes (1872-1913) and contemporary samples collected from populations throughout the extant range provide evidence in support of a genetically distinct Truckee River basin origin for this population. Analysis of museum samples alone identified three distinct genotype clusters and historical connectivity among water bodies within the Truckee River basin. Baseline data from museum collections indicate that the extant Pilot Peak strain represents a remnant of the extirpated lacustrine lineage. Given the limitations on high-quality data when working with a sparse number of preserved museum samples, we acknowledge that, in the end, this may be a more complicated story. However, the paucity of remnant populations in the Truckee River watershed, in combination with data on the distribution of morphological, meristic and genetic data for Lahontan cutthroat trout, suggests that recovery strategies, particularly in the large lacustrine habitats should consider this lineage as an important part of the genetic legacy of this species.

  3. Experimental infection of rainbow trout Oncorhynchus mykiss with viral haemorrhagic septicaemia virus isolates from European marine and farmed fishes

    DEFF Research Database (Denmark)

    Skall, Helle Frank; Slierendrecht, W.J.; King, J.A.

    2004-01-01

    The susceptibility of rainbow trout Oncorhynchus mykiss to infection with various isolates of viral haemorrhagic septicaemia virus (VHSV) was examined. A total of 8 experiments with rainbow trout ranging from 0.6 to 6.2 g was conducted for 139 isolates originating from wild marine fishes in Europ......The susceptibility of rainbow trout Oncorhynchus mykiss to infection with various isolates of viral haemorrhagic septicaemia virus (VHSV) was examined. A total of 8 experiments with rainbow trout ranging from 0.6 to 6.2 g was conducted for 139 isolates originating from wild marine fishes...... in European waters (115 isolates), farmed turbot from Scotland and Ireland (2 isolates), and farmed rainbow trout (22 isolates). The isolates were tested by immersion and/or intraperitoneal injection either as pooled or single isolates. The isolates from wild marine fishes did not cause mortality by immersion...... while some of the isolates caused mortality when injected. All VHSV isolates from farmed rainbow trout caused significant mortality by immersion. Currently, pathogenicity trials are the only way to differentiate VHSV isolates from wild marine fishes and farmed rainbow trout. The 2 farmed turbot isolates...

  4. Investigations of bull trout (Salvelinus confluentus), steelhead trout (Oncorhynchus mykiss), and spring chinook salmon (O. tshawytscha) interactions in Southeast Washington streams. Final report 1992; FINAL

    International Nuclear Information System (INIS)

    Underwood, K.D.; Martin, S.W.; Schuck, M.L.; Scholz, A.T.

    1995-01-01

    The goal of this two year study was to determine if supplementation with hatchery reared steelhead trout (Oncorhynchus mykiss) and spring chinook salmon (O. tshawytscha) negatively impacted wild native bull trout (Salvelinus confluentus) through competitive interactions. Four streams with varying levels of fish supplementation activity were sampled in Southeast Washington. Tasks performed during this study were population density, relative abundance, microhabitat utilization, habitat availability, diet analysis, bull trout spawning ground surveys, radio telemetry of adult bull trout, and growth analysis. Results indicate that bull trout overlapped geographically with the supplemented species in each of the study streams suggesting competition among species was possible. Within a stream, bull trout and the supplemented species utilized dissimilar microhabitats and microhabitat utilization by each species was the same among streams suggesting that there was no shifts in microhabitat utilization among streams. The diet of bull trout and O. mykiss significantly overlapped in each of the study streams. The stream most intensely supplemented contained bull trout with the slowest growth and the non-supplemented stream contained bull trout with the fastest growth. Conversely, the stream most intensely supplemented contain steelhead with the fastest growth and the non-supplemented stream contained steelhead with the slowest growth. Growth indicated that bull trout may have been negatively impacted from supplementation, although other factors may have contributed. At current population levels, and current habitat quantity and quality, no impacts to bull trout as a result of supplementation with hatchery reared steelhead trout and spring chinook salmon were detected. Project limitations and future research recommendations are discussed

  5. Identification of steelhead and resident rainbow trout progeny in the Deschutes River, Oregon, revealed with otolith microchemistry

    Science.gov (United States)

    Zimmerman, C.E.; Reeves, G.H.

    2002-01-01

    Comparisons of strontium:calcium (Sr:Ca) ratios in otolith primordia and freshwater growth regions were used to identify the progeny of steelhead Oncorhynchus mykiss (anadromous rainbow trout) and resident rainbow trout in the Deschutes River, Oregon. We cultured progeny of known adult steelhead and resident rainbow trout to confirm the relationship between Sr:Ca ratios in otolith primordia and the life history of the maternal parent. The mean (??SD) Sr:Ca ratio was significantly higher in the otolith primordia of the progeny of steelhead (0.001461 ?? 0.00029; n = 100) than in those of the progeny of resident rainbow trout (0.000829 ?? 0.000012; n = 100). We used comparisons of Sr:Ca ratios in the primordia and first-summer growth regions of otoliths to determine the maternal origin of unknown O. mykiss juveniles (n = 272) collected from rearing habitats within the main-stem Deschutes River and tributary rearing habitats and thus to ascertain the relative proportion of each life history morph in each rearing habitat. Resident rainbow trout fry dominated the bi-monthly samples collected from main-stem rearing habitats between May and November 1995. Steelhead fry dominated samples collected from below waterfalls on two tributaries in 1996 and 1998.

  6. Toxicity of potassium cyanide to trout. [Salmo gairdneri

    Energy Technology Data Exchange (ETDEWEB)

    Herbert, D W.M.; Merkens, J C

    1952-01-01

    The toxicity of KCN was tested on 50 rainbow trout using a flow through bioassay system. The system was designed to allow water conditions to remain constant throughout the test rather than change through metabolic activities of the fish. Results show: cyanide causes fish to loose equilibrium; cyanide resistance increases if the trout are allowed to acclimate to test temperatures before cyanides is added; young trout are more resistant to cyanide; and the distribution of trout survival times to cyanide concentration approximates a normal distribution. (14 references, 5 figures, 6 tables.

  7. Spokane Tribal Hatchery, 2005 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Peone, Tim L. (Spokane Tribe of Indians, Wellpinit, WA)

    2006-03-01

    Due to the construction and operation of Grand Coulee Dam (1939), anadromous salmon have been eradicated and resident fish populations permanently altered in the upper Columbia River region. Federal and private hydropower dam operations throughout the Columbia River system severely limits indigenous fish populations in the upper Columbia. Artificial production has been determined appropriate for supporting harvestable fisheries for kokanee salmon (Oncorhynchus nerka) and rainbow trout (Oncorhynchus mykiss) in Lake Roosevelt and Banks Lake (Grand Coulee Dam impoundments). The Spokane Tribe, Washington Department of Fish and Wildlife, Colville Confederated Tribes and Lake Roosevelt Development Association/Lake Roosevelt Volunteer Net Pen Project are cooperating in a comprehensive artificial production program to produce kokanee salmon (Oncorhynchus nerka) and rainbow trout (Oncorhynchus mykiss) for annual releases into the project area. The program consists of the Spokane Tribal Hatchery, Sherman Creek Hatchery, Ford Trout Hatchery and Lake Roosevelt Rainbow Trout Net Pen Rearing Projects. The Lake Roosevelt and Banks Lake Fisheries Evaluation Program monitor and evaluates release strategies and production methods for the aforementioned projects. Between 1985 and 2005 the projects have collectively produced up to 800,000 rainbow trout and 4 million kokanee salmon for release into Lake Roosevelt and 1.4 million kokanee fry for Banks Lake annually. In 2005, the annual release goal included 3.3 million kokanee fry, 475,000 kokanee yearlings and 500,000 rainbow trout yearlings. Fish produced by this project in 2005 to meet collective fish production and release goals included: 3,446,438 kokanee fingerlings, 347,730 rainbow trout fingerlings and 525,721 kokanee yearlings. Kokanee yearlings were adipose fin clipped before release. Stock composition consisted of Meadow Creek and Lake Whatcom kokanee, diploid-triploid Spokane Trout Hatchery (McCloud River) rainbow trout and

  8. Bull Trout Life History, Genetics, Habitat Needs, and Limiting Factors in Central and Northeast Oregon, Annual Report 2000.

    Energy Technology Data Exchange (ETDEWEB)

    Hemmingsen, Alan R.; Gunckel, Stephanie L.; Sankovich, Paul M.; Howell, Philip J.

    2001-11-01

    This section describes work accomplished in 2000 that continued to address two objectives of this project. These objectives are (1) determine the distribution of juvenile and adult bull trout Salvelinus confluentus and habitats associated with that distribution, and (2) determine fluvial and resident bull trout life history patterns. Completion of these objectives is intended through studies of bull trout in the Grande Ronde, Walla Walla, and John Day basins. These basins were selected because they provide a variety of habitats, from relatively degraded to pristine, and bull trout populations were thought to vary from relatively depressed to robust. In all three basins we continued to monitor the movements of bull trout with radio transmitters applied in 1998 (Hemmingsen, Bellerud, Gunckel and Howell 2001) and 1999 (Hemmingsen, Gunckel and Howell 2001). No new radio transmitters were applied to bull trout of the upper John Day River subbasin, Mill Creek (Walla Walla Basin), or the Grande Ronde Basin in 2000. We did implant radio transmitters in two bull trout incidentally captured in the John Day River near the confluence of the North Fork John Day River. In Mill Creek, we used traps to capture migrant bull trout to obtain data for the third successive year in this stream. With these traps, we intended to determine the timing of bull trout movements both upstream and downstream, and to determine the relative abundance, size and age of migrant fish. Because we captured migrant bull trout with traps for three years in the upper John Day River and its tributaries (Hemmingsen, Bellerud, Buchanan, Gunckel, Shappart and Howell 2001; Hemmingsen, Bellerud, Gunckel and Howell 2001; Hemmingsen, Gunckel and Howell 2001) and traps were no longer needed to capture bull trout for radio-tagging, no traps were operated in the John Day Basin in 2000.

  9. Effects of Experimental High Flow Releases and Increased Fluctuations in Flow from Glen Canyon Dam on Abundance, Growth, and Survival Rates of Early Life Stages of Rainbow Trout in the Lee's Ferry Reach of the Colorado River

    Science.gov (United States)

    Korman, Josh

    2010-05-01

    The abundance of adult fish populations is controlled by the growth and survival rates of early life stages. Evaluating the effects of flow regimes on early life stages is therefore critical to determine how these regimes affect the abundance of adult populations. Experimental high flow releases from Glen Canyon Dam, primarily intended to conserve fine sediment and improve habitat conditions for native fish in the Colorado River in Grand Canyon, AZ, have been conducted in 1996, 2004, and 2008. These flows potentially affect the Lee's Ferry reach rainbow trout population, located immediately downstream of the dam, which supports a highly valued fishery and likely influences the abundance of rainbow trout in Grand Canyon. Due to concerns about negative effects of high trout abundance on endangered native fish, hourly variation in flow from Glen Canyon Dam was experimentally increased between 2003 and 2005 to reduce trout abundance. This study reports on the effects of experimental high flow releases and fluctuating flows on early life stages of rainbow trout in the Lee's Ferry reach based on monthly sampling of redds (egg nests) and the abundance and growth of age-0 trout between 2003 and 2009. Data on spawn timing, spawning elevations, and intergravel temperatures were integrated in a model to estimate the magnitude and seasonal trend in incubation mortality resulting from redd dewatering due to fluctuations in flow. Experimental fluctuations from January through March promoted spawning at higher elevations where the duration of dewatering was longer and intergravel temperatures exceeded lethal thresholds. Flow-dependent incubation mortality rates were 24% (2003) and 50% (2004) in years with higher flow fluctuations, compared to 5-11% under normal operations (2006-2009). Spatial and temporal predictions of mortality were consistent with direct observations of egg mortality determined from the excavation of 125 redds. The amount of variation in backcalculated hatch

  10. Effects of prey abundance, distribution, visual contrast and morphology on selection by a pelagic piscivore

    Science.gov (United States)

    Hansen, Adam G.; Beauchamp, David A.

    2014-01-01

    Most predators eat only a subset of possible prey. However, studies evaluating diet selection rarely measure prey availability in a manner that accounts for temporal–spatial overlap with predators, the sensory mechanisms employed to detect prey, and constraints on prey capture.We evaluated the diet selection of cutthroat trout (Oncorhynchus clarkii) feeding on a diverse planktivore assemblage in Lake Washington to test the hypothesis that the diet selection of piscivores would reflect random (opportunistic) as opposed to non-random (targeted) feeding, after accounting for predator–prey overlap, visual detection and capture constraints.Diets of cutthroat trout were sampled in autumn 2005, when the abundance of transparent, age-0 longfin smelt (Spirinchus thaleichthys) was low, and 2006, when the abundance of smelt was nearly seven times higher. Diet selection was evaluated separately using depth-integrated and depth-specific (accounted for predator–prey overlap) prey abundance. The abundance of different prey was then adjusted for differences in detectability and vulnerability to predation to see whether these factors could explain diet selection.In 2005, cutthroat trout fed non-randomly by selecting against the smaller, transparent age-0 longfin smelt, but for the larger age-1 longfin smelt. After adjusting prey abundance for visual detection and capture, cutthroat trout fed randomly. In 2006, depth-integrated and depth-specific abundance explained the diets of cutthroat trout well, indicating random feeding. Feeding became non-random after adjusting for visual detection and capture. Cutthroat trout selected strongly for age-0 longfin smelt, but against similar sized threespine stickleback (Gasterosteus aculeatus) and larger age-1 longfin smelt in 2006. Overlap with juvenile sockeye salmon (O. nerka) was minimal in both years, and sockeye salmon were rare in the diets of cutthroat trout.The direction of the shift between random and non-random selection

  11. Age, growth, and maturity of the longnose sucker Catostomus catostomus, of western Lake Superior

    Science.gov (United States)

    Bailey, Merryll M.

    1969-01-01

    Studies of age, growth, and maturity were based on 1760 fish collected in western Lake Superior in 1964-65. The body:scale relation was curvilinear and the curve had an intercept of 1.65 inches on the length axis. The weight increased as the 2.85 power of the length. Some fish formed an annulus before May 18 in 1965; all had completed annuli by late September. Longnose suckers grew 3.6 inches the 1st year, reached 12 inches in the 6th year, and 18 inches in the 11th year. Fish from Pikes Bay grew faster than those from Gull Island Shoal. Over 6 years were required for weight to reach 1 lb and nearly 10 years to reach 2 lb. Minimum length at maturity was 10.5 inches for males and 11.5 inches for females. The youngest mature male belonged to age-group IV and the youngest mature female to age-group V. All males were mature at 14.5-14.9 inches (age-group VIII) and all females at 15.0-15.4 inches (age-group IX). Finclipped longnose suckers returned to spawn in the Brule River in successive years. One fish returned to spawn in 4 successive years. Many of the fish were not recaptured until 2 or 3 years after marking. The time of the Brule River spawning migration depended more on water temperature than on length of day. The average water temperature during the peak of the spawning runs of 1958-64 was 55.4 F. Larval suckers apparently spend little time in the Brule River and adjacent streams and drift downstream to the lake soon after hatching. The number of eggs in the ovaries of eight suckers ranged from 14 to 35 thousand and averaged 24 thousand for fish 13.9-17.7 inches long.

  12. Recovery of acidified mountain lakes in Norway as predicted by the MAGIC model

    Directory of Open Access Journals (Sweden)

    Bernard J. COSBY

    2004-02-01

    Full Text Available As part of the EU project EMERGE the biogeochemical model MAGIC was used to reconstruct acidification history and predict future recovery for mountain lakes in two regions of Norway. Central Norway (19 lakes receives low levels of acid deposition, most of the lakes have undergone only minor amounts of acidification, and all are predicted to recover in the future. Central Norway thus represents a reference area for more polluted regions in southern Norway and elsewhere in Europe. Southern Norway (23 lakes, on the other hand, receives higher levels of acid deposition, nearly all the studied lakes were acidified and had lost fish populations, and although some recovery has occurred during the period 1980-2000 and additional recovery is predicted for the next decades, the model simulations indicated that the majority of the lakes will not achieve water quality sufficient to support trout populations. Uncertainties in these predictions include possible future N saturation and the exacerbating effects of climate change. The mountain lakes of southern Norway are among the most sensitive in Europe. For southern Norway additional measures such as stricter controls of emissions of air pollutants will be required to obtain satisfactory water quality in the future.

  13. Lake sturgeon population characteristics in Rainy Lake, Minnesota and Ontario

    Science.gov (United States)

    Adams, W.E.; Kallemeyn, L.W.; Willis, D.W.

    2006-01-01

    Rainy Lake contains a native population of lake sturgeon Acipenser fulvescens that has been largely unstudied. The aims of this study were to document the population characteristics of lake sturgeon in Rainy Lake and to relate environmental factors to year-class strength for this population. Gill-netting efforts throughout the study resulted in the capture of 322 lake sturgeon, including 50 recaptures. Lake sturgeon in Rainy Lake was relatively plump and fast growing compared with a 32-population summary. Population samples were dominated by lake sturgeon between 110 and 150 cm total length. Age–structure analysis of the samples indicated few younger (<10 years) lake sturgeon, but the smallest gill net mesh size used for sampling was 102 mm (bar measure) and would not retain small sturgeon. Few lake sturgeon older than age 50 years were captured, and maximum age of sampled fish was 59 years. Few correlations existed between lake sturgeon year-class indices and both annual and monthly climate variables, except that mean June air temperature was positively correlated with year-class strength. Analysis of Rainy Lake water elevation and resulting lake sturgeon year-class strength indices across years yielded consistent but weak negative correlations between late April and early June, when spawning of lake sturgeon occurs. The baseline data collected in this study should allow Rainy Lake biologists to establish more specific research questions in the future.

  14. Effects of temperature and body size on radiocaesium retention in brown trout, Salmo trutta

    International Nuclear Information System (INIS)

    Ugedal, O.; Jonsson, B.; Njastad, O.; Naeumann, R.

    1992-01-01

    The elimination rate of radiocaesium in brown trout Salmo trutta L. was determined in the laboratory at four water temperatures (range 4.4 -15.6 0 C). In the experiments three or four homogeneous size-groups of fish (mean weights 23-496g) were studied at each temperature. The brown trout received acute oral doses of 134 Cs and were killed at intervals for radioactivity counting. The retention versus time curves were composed of two distinct exponential components. The long-lived component was quantitatively the most important for retention of radiocaesium. Elimination rate increased with increasing water temperature and decreased with increasing body weight. The biological half-life of 134 Cs (T b , days) was related to fresh body weight (W, g) and water temperature (t, 0 C) by the equation: T b = 290 x W 0.176 x e -0.106 x t . The elimination rate of Cs could be predicted from weight-specific metabolic rate as given by Elliott's equations for brown trout. (author)

  15. Holocene glacier fluctuations inferred from lacustrine sediment, Emerald Lake, Kenai Peninsula, Alaska

    Science.gov (United States)

    LaBrecque, Taylor S.; Kaufman, Darrell S.

    2016-01-01

    Physical and biological characteristics of lacustrine sediment from Emerald Lake were used to reconstruct the Holocene glacier history of Grewingk Glacier, southern Alaska. Emerald Lake is an ice-marginal threshold lake, receiving glaciofluvial sediment when Grewingk Glacier overtops the topographic divide that separates it from the lake. Sub-bottom acoustical profiles were used to locate core sites to maximize both the length and resolution of the sedimentary sequence recovered in the 4-m-long cores. The age model for the composite sequence is based on 13 14C ages and a 210Pb profile. A sharp transition from the basal inorganic mud to organic-rich mud at 11.4 ± 0.2 ka marks the initial retreat of Grewingk Glacier below the divide of Emerald Lake. The overlaying organic-rich mud is interrupted by stony mud that records a re-advance between 10.7 ± 0.2 and 9.8 ± 0.2 ka. The glacier did not spill meltwater into the lake again until the Little Ice Age, consistent with previously documented Little Ice Ages advances on the Kenai Peninsula. The retreat of Grewingk Glacier at 11.4 ka took place as temperature increased following the Younger Dryas, and the subsequent re-advance corresponds with a climate reversal beginning around 11 ka across southern Alaska.

  16. Fish production and some traits of meat quality in rainbow trout (Oncorhynchus mykiss farmed in different production systems

    Directory of Open Access Journals (Sweden)

    St. Stoyanova

    2016-12-01

    Full Text Available Abstract. The rainbow trout (Oncorhynchus mykiss, an important species in Bulgarian aquaculture, is farmed in different production systems as raceways, net cages etc. The aim of the present study was to evaluate the effect of two different rearing systems on fish production, survival rate, meat chemical, mineral composition and farming economic efficiency of culticated rainbow trout (Oncorhynchus mykiss. The information from a survey on fish production and economic efficiency traits was collected from two national rainbow trout farms using the two commonest fish farming systems: in raceways, Happy Fish Ltd fish farm and in net cages, Forest Group Ltd fish farm. The average individual weight gain (g, total weight gain (kg, feed conversion ratio, production costs of 1 kg fish and the economic efficiency coefficients were determined for the two studied fish farms. The final live weight of rainbow trout in net cages was 0.30 kg vs 0.35 kg in raceways. The average individual weight gain was higher in raceways farming system (0.30 kg than in net cages farm (0.26 kg. The mortality rate of fish in raceways was considerably lower: only 1% as compared to that in net cages (4%. The feed conversion ratio at the end of the experiment showed identical values for trout in both farms 1.01. The meat water content of fish reared in raceways and net cages was 77.46±0.65% and 74.52±0.52% respectively (P≤0.01.The protein content of fish meat was higher in fish farmed in net cages 18.84±0.29% as compared to fish cultivated in raceways 17.60±0.49% (P 0.05. Meat fat content of rainbow trout, reared in the net cage system was also considerably higher (5.26±0.30% than the respective parameter in fish farmed in ponds (3.60±0.15% (P≤0.001. The content of Ca and P was higher in rainbow trouts reared in raceways (138.96±1.12 mg.kg and 2844.32±39.31 mg.kg 1 -1 -1 compared with the values of these parameters of fish in net cages (134.46±1.96 mg.kg and 2690.31±42

  17. Spokane Tribal Hatchery, 2004 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Peone, Tim L. (Spokane Tribe of Indians, Wellpinit, WA)

    2005-03-01

    Due to the construction and operation of Grand Coulee Dam (1939), anadromous salmon have been eradicated and resident fish populations permanently altered in the upper Columbia River region. Federal and private hydropower dam operations throughout the Columbia River system severely limits indigenous fish populations in the upper Columbia. Artificial production has been determined appropriate for supporting a harvestable fishery for kokanee salmon (Oncorhynchus nerka) and rainbow trout (Oncorhynchus mykiss) in Lake Roosevelt and Banks Lake (Grand Coulee Dam impoundments). A collaborative multi-agency artificial production program for the Lake Roosevelt and Banks Lake fisheries exists consisting of the Spokane Tribal Hatchery, Sherman Creek Hatchery, Ford Trout Hatchery and the Lake Roosevelt Kokanee and Rainbow Trout Net Pen Rearing Projects. These projects operate complementary of one another to target an annual release of 1 million yearling kokanee and 500,000 yearling rainbow trout for Lake Roosevelt and 1.4 million kokanee fry/fingerlings for Banks Lake. Fish produced by this project in 2004 to meet collective fish production and release goals included: 1,655,722 kokanee fingerlings, 537,783 rainbow trout fingerlings and 507,660 kokanee yearlings. Kokanee yearlings were adipose fin clipped before release. Stock composition consisted of Lake Whatcom kokanee, 50:50 diploid-triploid Spokane Trout Hatchery (McCloud River) rainbow trout and Phalon Lake red-band rainbow trout. All kokanee were marked with either thermal, oxytetracyline or fin clips prior to release. Preliminary 2004 Lake Roosevelt fisheries investigations indicate hatchery/net pen stocking significantly contributed to harvestable rainbow trout and kokanee salmon fisheries. An increase in kokanee harvest was primarily owing to new release strategies. Walleye predation, early maturity and entrainment through Grand Coulee Dam continues to have a negative impact on adult kokanee returns and limits the

  18. The Prodigies of The Albano Lake During Roman Age and Natural Hazard Assessment At Roma, Italy.

    Science.gov (United States)

    Funiciello, R.; Giordano, G.; de Rita, D.

    Roma is built just 20 km to the northwest of the Pleistocene Colli Albani volcano, but is believed not exposed to relevant natural hazards, except for the Tiber river flood- ings, and local amplification of seismic waves from distal earthquakes. This belief has generally induced modern historians and geologists to discard as SmythologicalT the & cedil;many references to natural prodigies that are reported by many Roman-age historians. Recent studies have demonstrated that the Albano maar, the youngest volcanic cen- tre of the Colli Albani volcano and presently filled by a 175 m deep lake, protracted its activity to the Holocene triggering several catastrophic lahar events, likely related to lake withdrawal, the deposits of which are exposed to the southwest of Roma and reach its periphery. This finding youngs the history of the volcano and makes it rele- vant to pre-historic settlements, which ScarefullyT avoided the Albano maar slopes up & cedil;to the Bronze age. What is still unknown, though, is whether the lake experienced such fluctuations and overspills during historic times. Several Roman authors such as Ti- tus Livius, Dionigi d'Alicarnasso, Plutarco, Germanico, and many others wrote about the then well known 398 BC prodigious event, when, during the war between Roma and the Etruscan city of Veio, the gods anger caused the sudden rise and overspill of the Albano lake, reported as unrelated to climatic events, and the destructive flooding of the countryside. After that event Romans actually built a tunnel-drain which still operates regulating the lake level at 293 m a.s.l., 70 m below the maar rim elevation. Should those chronicles be truthful, we can join the geologic observation of Holocene lahar deposits from lake withdrawal with historical lake withdrawals, reassessing the natural hazard for the city of Roma under a point of view never explored before. This paper carefully explores the historical credibility of the 398 BC lake overspill event and its

  19. Voluntary feed intake in rainbow trout is regulated by diet-induced differences in oxygen use.

    Science.gov (United States)

    Saravanan, Subramanian; Geurden, Inge; Figueiredo-Silva, A Cláudia; Kaushik, Sadasivam; Verreth, Johan; Schrama, Johan W

    2013-06-01

    This study investigated the hypothesis that the voluntary feed intake in fish is regulated by diet-induced differences in oxygen use. Four diets were prepared with a similar digestible protein:digestible energy ratio (18 mg/kJ), but which differed in the composition of nonprotein energy source. This replacement of fat (F) by starch (S) was intended to create a diet-induced difference in oxygen use (per unit of feed): diets F30-S70, F50-S50, F65-S35, and F80-S20 with digestible fat providing 28, 49, 65, and 81% of the nonprotein digestible energy (NPDE), respectively. Each diet was fed to satiation to triplicate groups of 20 rainbow trout for 6 wk. As expected, diet-induced oxygen use decreased linearly (R(2) = 0.89; P digestible and metabolizable energy intakes of trout slightly increased with increasing NPDE as fat (i.e., decreasing starch content) (R(2) = 0.30, P = 0.08; and R(2) = 0.34, P = 0.05, respectively). Oxygen consumption of trout fed to satiation declined with increasing dietary NPDE as fat (R(2) = 0.48; P = 0.01). The inverse relation between digestible energy intake of trout and the diet-induced oxygen use (R(2) = 0.33; P = 0.05) suggests a possible role of diet-induced oxygen use in feed intake regulation as shown by the replacement of dietary fat by starch.

  20. The trout fishery in Shenandoah National Park

    Science.gov (United States)

    Lennon, Robert E.

    1961-01-01

    Populations of brook trout in streams of Shenandoah National Park were reduced drastically early in the past decade by a succession of unusually severe droughts and floods. The drying of stream beds, predation, and scouring were principal factors in the loss of fish. The park was closed to fishing in 1954 and 1955 to protect survivors. The small numbers of survivors quickly repopulated the streams after drought conditions abated. The stocking of hatchery-reared fingerling trout in selected waters failed to augment the recovery of populations. Survival and growth of young, wild trout were especially good. Their redistribution through miles of previously dry streams was rapid. The park was opened again to fishing in 1956 under regulations which restrict the take but afford an increase in sporting opportunity. Two streams were placed under fishing-for-fun-only regulations in 1961.The welfare of the trout populations is dependent mostly on the weather cycle . Fish may be abundant in wet years but very scarc e in dry ones. Thus, the stream must be managed a s marginal for trout.

  1. Biology and management of threatened and endangered western trouts

    Science.gov (United States)

    R. J. Behnke; Mark Zarn

    1976-01-01

    Discusses taxonomy, reasons for decline, life history and ecology, and suggestions for preservation and management of six closely related trouts native to western North America: Colorado River cutthroat, Salmo clarki pleuriticus; greenback trout, S. c. stomias; Lahontan cutthroat, S. c. henshawi; Paiute trout,...

  2. Novel molecular markers differentiate Oncorhynchus mykiss (rainbow trout and steelhead) and the O. clarki (cutthroat trout) subspecies

    Science.gov (United States)

    Ostberg, C.O.; Rodriguez, R.J.

    2002-01-01

    A suite of 26 PCR-based markers was developed that differentiates rainbow (Oncorhynchus mykiss) and coastal cutthroat trout (O. clarki clarki). The markers also differentiated rainbow from other cutthroat trout subspecies (O. clarki), and several of the markers differentiated between cutthroat trout subspecies. This system has numerous positive attributes, including: nonlethal sampling, high species-specificity and products that are easily identified and scored using agarose gel electrophoresis. The methodology described for developing the markers can be applied to virtually any system in which numerous markers are desired for identifying or differentiating species or subspecies.

  3. Ecosystem transformations of the Laurentian Great Lake Michigan by nonindigenous biological invaders.

    Science.gov (United States)

    Cuhel, Russell L; Aguilar, Carmen

    2013-01-01

    Lake Michigan, a 58,000-km(2) freshwater inland sea, is large enough to have persistent basin-scale circulation yet small enough to enable development of approximately balanced budgets for water, energy, and elements including carbon and silicon. Introduction of nonindigenous species-whether through invasion, intentional stocking, or accidental transplantation-has transformed the lake's ecosystem function and habitat structure. Of the 79 nonindigenous species known to have established reproductive populations in the lake, only a few have brought considerable ecological pressure to bear. Four of these were chosen for this review to exemplify top-down (sea lamprey, Petromyzon marinus), middle-out (alewife, Alosa pseudoharengus), and bottom-up (the dreissenid zebra and quagga mussels, Dreissena polymorpha and Dreissena rostriformis bugensis, respectively) transformations of Lake Michigan ecology, habitability, and ultimately physical environment. Lampreys attacked and extirpated indigenous lake trout, the top predator. Alewives outcompeted native planktivorous fish and curtailed invertebrate populations. Dreissenid mussels-especially quagga mussels, which have had a much greater impact than the preceding zebra mussels-moved ecosystem metabolism basin-wide from water column to bottom dominance and engineered structures throughout the lake. Each of these non indigenous species exerted devastating effects on commercial and sport fisheries through ecosystem structure modification.

  4. Digestibility in selected rainbow trout families and relation to growth and feed utilisation

    DEFF Research Database (Denmark)

    Rasmussen, Richard Skøtt; Jokumsen, Alfred

    2009-01-01

    Experiments have been carried out aimed at clarifying variations in the digestibility of dietary nutrients in rainbow trout families and studying how differences in digestibility may be related to growth and feed utilisation at various growth rates. The digestibility of protein, lipid...... the digestibility of protein, lipid, nitrogen-free extracts and dry matter was measured. Taken as a whole, our results indicate that selective breeding still offers a large potential for improved growth and feed utilisation in rainbow trout strains. In the first study, family Dc showed a higher specific growth rate......, carbohydrates (nitrogen-free extracts, NFE) and dry matter was analysed in two experiments involving eight rainbow trout families [Ab, Ba, Cd, Dc (first study); V, X, Y, Z (second study)]. In the first experiment rainbow trout were reared for 128 days at 13.0A degrees C, and in the second experiment, they were...

  5. Hungry Horse Mitigation : Flathead Lake : Annual Progress Report 2008.

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Barry; Evarts, Les [Confederated Salish and Kootenai Tribes

    2009-08-06

    . Monitoring, for example, includes a spring gillnetting series conducted annually in Flathead Lake and builds on an existing data set initiated in 1981. Monitoring of the experimental kokanee reintroduction was a primary activity of this project between 1992 and 1997. Lake trout, whose high densities have precluded successful mitigation of losses of other species in Flathead Lake, have been monitored since 1996 to measure several biological parameters. Results of this work have utility in determining the population status of this key predator in Flathead Lake. The project has also defined the baseline condition of the Flathead Lake fishery in 1992-1993 and has conducted annual lakewide surveys since 1998. The restoration component of the project has addressed several stream channel, riparian, and fish passage problems, and suppression of non-native fish. The research component of the project began in FY 2000 and measured trophic linkages between M. relicta and other species to assist in predicting the results of our efforts to suppress lake trout. Only Work Element A in the Statement of Work is funded entirely by Hungry Horse Mitigation funds. Additional funds are drawn from other sources to assist in completion of all remaining Work Elements.

  6. Hungry Horse Mitigation : Flathead Lake : Annual Progress Report 2007.

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Barry; Evarts, Les [Confederated Salish and Kootenai Tribes

    2008-12-22

    . Monitoring, for example, includes a spring gillnetting series conducted annually in Flathead Lake and builds on an existing data set initiated in 1981. Monitoring of the experimental kokanee reintroduction was a primary activity of this project between 1992 and 1997. Lake trout, whose high densities have precluded successful mitigation of losses of other species in Flathead Lake, have been monitored since 1996 to measure several biological parameters. Results of this work have utility in determining the population status of this key predator in Flathead Lake. The project has also defined the baseline condition of the Flathead Lake fishery in 1992-1993 and has conducted annual lakewide surveys since 1998. The restoration component of the project has addressed several stream channel, riparian, and fish passage problems, and suppression of non-native fish. The research component of the project began in FY 2000 and measured trophic linkages between M. relicta and other species to assist in predicting the results of our efforts to suppress lake trout. Only Work Element A in the Statement of Work is funded entirely by Hungry Horse Mitigation funds. Additional funds are drawn from other sources to assist in completion of all remaining Work Elements.

  7. Bull trout life history, genetics, habitat needs, and limiting fact in central and northeast Oregon, annual report 2000.; ANNUAL

    International Nuclear Information System (INIS)

    Hemmingsen, Alan R.

    2001-01-01

    This section describes work accomplished in 2000 that continued to address two objectives of this project. These objectives are (1) determine the distribution of juvenile and adult bull trout Salvelinus confluentus and habitats associated with that distribution, and (2) determine fluvial and resident bull trout life history patterns. Completion of these objectives is intended through studies of bull trout in the Grande Ronde, Walla Walla, and John Day basins. These basins were selected because they provide a variety of habitats, from relatively degraded to pristine, and bull trout populations were thought to vary from relatively depressed to robust. In all three basins we continued to monitor the movements of bull trout with radio transmitters applied in 1998 (Hemmingsen, Bellerud, Gunckel and Howell 2001) and 1999 (Hemmingsen, Gunckel and Howell 2001). No new radio transmitters were applied to bull trout of the upper John Day River subbasin, Mill Creek (Walla Walla Basin), or the Grande Ronde Basin in 2000. We did implant radio transmitters in two bull trout incidentally captured in the John Day River near the confluence of the North Fork John Day River. In Mill Creek, we used traps to capture migrant bull trout to obtain data for the third successive year in this stream. With these traps, we intended to determine the timing of bull trout movements both upstream and downstream, and to determine the relative abundance, size and age of migrant fish. Because we captured migrant bull trout with traps for three years in the upper John Day River and its tributaries (Hemmingsen, Bellerud, Buchanan, Gunckel, Shappart and Howell 2001; Hemmingsen, Bellerud, Gunckel and Howell 2001; Hemmingsen, Gunckel and Howell 2001) and traps were no longer needed to capture bull trout for radio-tagging, no traps were operated in the John Day Basin in 2000

  8. Overwintering of sea trout (Salmo trutta) in freshwater

    DEFF Research Database (Denmark)

    Thomsen, Dennis; Koed, Anders; Nielsen, Christian

    2007-01-01

    Brown trout (Salmo trutta) show large phenotypic plasticity. Juveniles may reside in their native freshwater habitat until maturation or migrate into the ocean as 1- to 3-year-old smolts. Sea-going fish (sea trout) reside at sea for 2-3 years until migrating back to their native stream for reprod......Brown trout (Salmo trutta) show large phenotypic plasticity. Juveniles may reside in their native freshwater habitat until maturation or migrate into the ocean as 1- to 3-year-old smolts. Sea-going fish (sea trout) reside at sea for 2-3 years until migrating back to their native stream...... for reproduction. However, immature fish may leave the ocean during their first or second winter at sea and overwinter in freshwater. The question is why does this occur? We tested the hypothesis that hypo-osmoregulatory capacity is compromised by low temperature in two coastal sea trout populations, one...... representing high salinity and the other, low salinity. Immature sea-run trout were caught in lower parts of two rivers during winter and acclimated to laboratory conditions. Subgroups were challenged with high salinity or low water temperature or both, and their osmoregulatory performance was investigated...

  9. Geology and environments of subglacial Lake Vostok.

    Science.gov (United States)

    Leitchenkov, German L; Antonov, Anton V; Luneov, Pavel I; Lipenkov, Vladimir Ya

    2016-01-28

    The reconstruction of the geological (tectonic) structure and environments of subglacial Lake Vostok is based on geophysical surveys and the study of mineral particles found in cores of accreted ice and frozen lake water (sampled after the lake was unsealed). Seismic reflection and refraction investigations conducted in the southern part of Lake Vostok show very thin (200-300 m) sedimentary cover overlying a crystalline basement. Most of this thin veneer is thought to have been deposited during temperate-glacial conditions in Oligocene to Middle Miocene time (ca 34-14 Ma). The composition of the lake-bottom sediments can be deduced from mineral inclusions found in cores of accreted ice. Inclusions are represented by soft aggregates consisting mainly of clay-mica minerals and micrometre-sized quartz grains. Some of these inclusions contain subangular to semi-rounded rock clasts (siltstones and sandstones) ranging from 0.3 to 8 mm in size. In total, 31 zircon grains have been identified in two rock clasts and dated using SHRIMP-II. The ages of the studied zircons range from 0.6 to 2.0 Ga with two distinct clusters between 0.8 and 1.15 Ga and between 1.6 and 1.8 Ga. Rock clasts obviously came from the western lake shore, which is thus composed of terrigenous strata with an age of not older than 600 Ma. The sedimentary nature of the western lake shore is also confirmed by seismic refraction data showing seismic velocities there of 5.4-5.5 km s(-1) at the bedrock surface. After Lake Vostok was unsealed, its water (frozen and sampled next season) was also studied with scanning electron microscopy and X-ray microprobe analysis. This study showed the existence of calcium carbonate and silica microparticles (10-20 μm across) in frozen water. © 2015 The Author(s).

  10. Age, growth, and maturity of round whitefish of the Apostle Islands and Isle Royale Regions, Lake Superior

    Science.gov (United States)

    Bailey, Merryll M.

    1963-01-01

    The round whitefish has been of some commercial importance in the upper Great Lakes but production in Lake Superior has generally been small; the United States average was 26,600 pounds for 1929-59. This study is based on 1,173 fish collected in the Apostle Islands in 1958-60 and 103 collected at Isle Royale in 1958 and 1960. The average age of 6.0 years at Isle Royale was concluded to be significantly higher than the mean of 4.2 years in the Apostle Islands. The body-scale relation is a straight line with an intercept of 1.1 inches on the length axis. Weight of Apostle Islands round whitefish captured in several months increased as the 3.22 power of the length. Growth in length was relatively slow; nearly or fully 7 years were required to reach an acceptable commercial length of 14 inches in both the Apostle Islands and at Isle Royale. The calculated weights at the end of the seventh year were 12.6 ounces in the Apostle Islands and 13.8 ounces at Isle Royale. Minimum length at maturity of male round whitefish (7.0-7.4 inches) was less than that of females (8.5-8.9 inches). At age-group II, 11.1 percent of male round whitefish, but only 1.5 percent of the females were mature. All males were mature as age-group V and all females as age-group VI. Males dominated the younger age groups but females were more numerous in the older ones. Estimates of the number of eggs in 37 round whitefish ovaries yielded an average of 5,330 eggs for fish 10.5-17.4 inches long.

  11. Body temperature change characteristics of Lake Michigan fishes

    International Nuclear Information System (INIS)

    Spigarelli, S.A.; Thommes, M.M.; Beitinger, T.L.

    1974-01-01

    Body temperature change rate experiments were conducted on alewife, brown trout, rainbow trout, brook trout, and carp collected from the discharge flumes and inshore areas near the Point Beach Nuclear Plant. Test fish were exposed to immediate water temperature changes of up to 10.6 0 C by transfer between ambient and discharge water holding tanks. Results showed that the temperature change rate was related to fish size, species, and direction of change, suggesting that rapid temperature changes would have a more pronounced effect on smaller fish

  12. Aspects Regarding the Influence of Growth Technology Concerning the Performances Production of the Rainbow Trout (Oncorhynchus Mykiss

    Directory of Open Access Journals (Sweden)

    Daniel Cocan

    2012-10-01

    Full Text Available Experiments were conducted throughout 2009 and 2010. At the beginning of experiments, both in 2009 and in 2010, were formed two groups (M-control group; E-experimental group, each group far 600 rainbow trout (Oncorhynchus mykiss. Control group M has been exploited in the Fiad trout farm, Bistriţa-Năsăud County, and the experimental group E was operated in a recirculating system arranged in Cluj-Napoca. Experiments were conducted over 210 days, both in 2009 and in 2010. Initial body weight of the specimens was 22.70±0.40 g – group M, and 22.68±0.39 – group E, in 2009. In the second experimental series (2010, the initial body weight of the rainbow trout specimens was 22.69±0.28 g – group M, respectively 22.56±0.31 g – group E. As factors which influencing directly the growth dynamic of rainbow trout, were monitored the physico-chemical parameters of water from the two locations, and feed consumption. Production performances of the trout from the two experimental groups, were assessed using as indicators total weight gain (TWG and specific growth rate (SGR. In 2009, TWG=370.92±4.37 g – group E vs. 79.59±1.09 g – group M (p<0.001, and SGR=1.55±0.01 g/day – group E vs. 0.33±0.005 g/day – group M (p<0.001. In 2010, TWG=377.85±3.97 g – group E vs. 103.78±1.28 g – group M (p<0.001, and SGR=1.57±0.01 g/day – group E vs. 0.43±0.005 g/day – group M. Analyzing the two indicators (TWG and SGR, we can conclude that due to optimal environmental conditions provided by the recirculating system, the production performances of rainbow trout in both experimental series, were significantly higher in group E compared with group M.

  13. Great Lakes prey fish populations: a cross-basin overview of status and trends based on bottom trawl surveys, 1978-2013

    Science.gov (United States)

    Gorman, Owen T.; Weidel, Brian C.

    2014-01-01

    Lake Michigan. In general, trends in year-class strengths were less concordant across the basin and only coregonids showed statistical agreement across the upper Great Lakes. The appearance of strong and moderate year-classes of Bloater in Lake Huron in 2005- 2011 countered the trend of continuing weak year-classes of coregonids in Lakes Michigan and Superior. Not shown in our analysis is the appearance of the 2013 year-class of Bloater in Huron, the largest to date. There was no agreement in cross-basin trends in year-class strengths for Rainbow Smelt and Alewife, although there was agreement between pairs of lakes. Although there was statistical agreement in trends of age-0 and older Round Goby biomass among lakes where this species has successfully invaded (Michigan, Huron, Erie and Ontario), temporal patterns of biomass in each lake were different. Round Goby may be approaching equilibrium in Lake Erie, peaking in Lake Huron, and expanding in Lake Michigan. The trend in Lake Ontario remains unclear. Declining abundance in Lake Erie has corresponded with evidence that Round Goby have become increasingly incorporated into piscivore diets, e.g., Lake Trout, Walleye, Smallmouth Bass, Yellow Perch, and Burbot in Lakes Michigan, Huron, Erie, and Ontario. Round Goby continue to be absent from spring bottom trawl assessments in Lake Superior, but their presence in the harbors and embayments of Duluth and Thunder Bay (U.S. Geological Survey and Ontario Ministry of Natural Resources, unpublished data), suggests that there is potential for future colonization.

  14. Lake Michigan Mass Balance Study Post Audit: Integrated, Multi-media PCB Modeling and Forecasting for Lake Trout

    Science.gov (United States)

    The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

  15. Age- and weight-dependent susceptibility of rainbow trout Oncorhynchus mykiss to isolates of infectious haematopoietic necrosis virus (IHNV) of varying virulence

    DEFF Research Database (Denmark)

    Bergmann, S.M.; Fichtner, D.; Skall, Helle Frank

    2003-01-01

    The virulence of 5 European and 1 North American isolate of infectious haematopoietic necrosis virus (IHNV) was compared by infecting female sibling rainbow trout ('lsle of Man' strain) of different weights and ages (2, 20 and 50 g). The fish were exposed to 104 TCID50 IHNV per ml of water...... by immersion, and the mortality was recorded for 28 d. Two new IHNV isolates from Germany were included in the investigation. One was isolated from European eels kept at 23degreesC (+/-2degreesC) and the other was not detectable by immunofluorescence with commercially available monoclonal antibodies...

  16. A Citizen Science Program for Monitoring Lake Stages in Northern Wisconsin

    Science.gov (United States)

    Kretschmann, A.; Drum, A.; Rubsam, J.; Watras, C. J.; Cellar-Rossler, A.

    2011-12-01

    Historical data indicate that surface water levels in northern Wisconsin are fluctuating more now than they did in the recent past. In the northern highland lake district of Vilas County, Wisconsin, concern about record low lake levels in 2008 spurred local citizens and lake associations to form a lake level monitoring network comprising citizen scientists. The network is administered by the North Lakeland Discovery Center (NLDC, a local NGO) and is supported by a grant from the Citizen Science Monitoring Program of the Wisconsin Department of Natural Resources (WDNR). With technical guidance from limnologists at neighboring UW-Madison Trout Lake Research Station, citizen scientists have installed geographic benchmarks and staff gauges on 26 area lakes. The project engages citizen and student science participants including homeowners, non-profit organization member-participants, and local schools. Each spring, staff gauges are installed and referenced to fixed benchmarks after ice off by NLDC and dedicated volunteers. Volunteers read and record staff gauges on a weekly basis during the ice-free season; and maintain log books recording lake levels to the nearest 0.5 cm. At the end of the season, before ice on, gauges are removed and log books are collected by the NLDC coordinator. Data is compiled and submitted to a database management system, coordinated within the Wisconsin Surface Water Integrated Monitoring System (SWIMS), a statewide information system managed by the WDNR in Madison. Furthermore, NLDC is collaborating with the SWIMS database manager to develop data entry screens based on records collected by citizen scientists. This program is the first of its kind in Wisconsin to utilize citizen scientists to collect lake level data. The retention rate for volunteers has been 100% over the three years since inception, and the program has expanded from four lakes in 2008 to twenty-six lakes in 2011. NLDC stresses the importance of long-term monitoring and the

  17. Seasonal comparison of wild and farmed brown trout (Salmo trutta forma fario L., 1758): crude lipid, gonadosomatic index and fatty acids.

    Science.gov (United States)

    Kaya, Yalçin; Erdem, Mehmet Emіn

    2009-08-01

    Brown trout is one of the most preferred wild freshwater fish species in the east Black Sea region (Turkey) due to its nutritional value and palatable aroma as well as being popular for sport fishing. In this research, seasonal variations in the crude lipid, gonadosomatic index and fatty acid composition of wild and farmed brown trout were investigated. The spawning period of wild and farmed brown trout appears to be from August to October and from October to January, respectively. The mean crude lipid content in farmed brown trout (3.62%) was significantly higher (P≤0.05) than that of wild brown trout (2.80%). Significant seasonal differences (P≤0.05) in crude lipid content were observed in both fish. The percentage of total saturated fatty acids was similar (P≥0.05) in both fish. Total polyunsaturated fatty acids were higher (P≤0.05) in the wild brown trout compared with the farmed brown trout, while its total monounsaturated fatty acids content was lower (P≤0.05). The muscle lipids of wild fish contained significantly (P≤0.05) higher percentages of C16:1n-7, C17:1n-7, C18:3n-3, C20:2n-6, C20:4n-6, C20:5n-3 and C22:2n-6 fatty acids and contained lower percentages of C14:0, C18:1n-9, C18:2n-6, C20:1n-9, C24:1n-9 and C22:6n-3 fatty acids than farmed fish. The total amounts of n-3 fatty acids in wild fish were higher than in farmed fish, but total amounts of n-6 fatty acids in farmed fish were higher than in wild fish. The n3/n6 proportion in wild fish was higher than that of farmed fish.

  18. Trout in the Classroom

    Science.gov (United States)

    Heath, Thomas

    2014-05-01

    Trout in the Classroom (TIC) is a conservation-oriented environmental education program for elementary, middle, and high school students. During the year each teacher tailors the program to fit his or her curricular needs. Therefore, each TIC program is unique. TIC has interdisciplinary applications in science, social studies, mathematics, language arts, fine arts, and physical education. In the program, students and teachers raise trout from fertilized eggs supplied by Virginia Department of Game and Inland Fisheries (VGIF) hatcheries, in aquariums equipped with special chillers designed to keep the water near 50 degrees F. The students make daily temperature measurements, and monitor pH, dissolved oxygen, conductivity, and ammonia levels. They record their data, plot trends, and make sure that the water quality is sufficient to support trout development. The fingerlings, which hatch in late October, are almost an inch and a half long by mid-January. And towards the end of the school year, students will release the fry into VGIF approved watersheds. TIC programs have been in place all across the country for more than 20 years, and are the result of numerous collaborations between teachers, volunteers, government agencies, and local organizations like Trout Unlimited. The programs were designed specifically for teachers who wanted to incorporate more environmental education into their curriculum. While the immediate goal of Trout in the Classroom is to increase student knowledge of water quality and cold water conservation, its long-term goal is to reconnect an increasingly urbanized population of youth to the system of streams, rivers, and watersheds that sustain them. Successful programs have helped: connect students to their local environments and their local watersheds; teach about watershed health and water quality, and; get students to care about fish and the environment. In Virginia, the TIC program is now in its 8th year. Over the past year, the program

  19. METHYLMERCURY BIOACCUMULATION DEPENDENCE ON NORTHERN PIKE AGE AND SIZE IN TWENTY MINNESOTA LAKES

    Science.gov (United States)

    Mercury accumulation in northern pike muscle tissue (fillets) was found to be directly related to fish age and size. Measurements were made on 173 individual northern pike specimens from twenty lakes across Minnesota. Best fit regressions of mercury fillet concentration (wet wt.)...

  20. Contaminant Monitoring Strategy for Henrys Lake, Idaho

    Energy Technology Data Exchange (ETDEWEB)

    John S. Irving; R. P. Breckenridge

    1992-12-01

    Henrys Lake, located in southeastern Idaho, is a large, shallow lake (6,600 acres, {approx} 17.1 feet maximum depth) located at 6,472 feet elevation in Fremont Co., Idaho at the headwaters of the Henrys Fork of the Snake River. The upper watershed is comprised of high mountains of the Targhee National Forest and the lakeshore is surrounded by extensive flats and wetlands, which are mostly privately owned. The lake has been dammed since 1922, and the upper 12 feet of the lake waters are allocated for downriver use. Henrys Lake is a naturally productive lake supporting a nationally recognized ''Blue Ribbon'' trout fishery. There is concern that increasing housing development and cattle grazing may accelerate eutrophication and result in winter and early spring fish kills. There has not been a recent thorough assessment of lake water quality. However, the Department of Environmental Quality (DEQ) is currently conducting a study of water quality on Henrys Lake and tributary streams. Septic systems and lawn runoff from housing developments on the north, west, and southwest shores could potentially contribute to the nutrient enrichment of the lake. Many houses are on steep hillsides where runoff from lawns, driveways, etc. drain into wetland flats along the lake or directly into the lake. In addition, seepage from septic systems (drainfields) drain directly into the wetlands enter groundwater areas that seep into the lake. Cattle grazing along the lake margin, riparian areas, and uplands is likely accelerating erosion and nutrient enrichment. Also, cattle grazing along riparian areas likely adds to nutrient enrichment of the lake through subsurface flow and direct runoff. Stream bank and lakeshore erosion may also accelerate eutrophication by increasing the sedimentation of the lake. Approximately nine streams feed the lake (see map), but flows are often severely reduced or completely eliminated due to irrigation diversion. In addition, subsurface

  1. Growth and survival of Apache Trout under static and fluctuating temperature regimes

    Science.gov (United States)

    Recsetar, Matthew S.; Bonar, Scott A.; Feuerbacher, Olin

    2014-01-01

    Increasing stream temperatures have important implications for arid-region fishes. Little is known about effects of high water temperatures that fluctuate over extended periods on Apache Trout Oncorhynchus gilae apache, a federally threatened species of southwestern USA streams. We compared survival and growth of juvenile Apache Trout held for 30 d in static temperatures (16, 19, 22, 25, and 28°C) and fluctuating diel temperatures (±3°C from 16, 19, 22 and 25°C midpoints and ±6°C from 19°C and 22°C midpoints). Lethal temperature for 50% (LT50) of the Apache Trout under static temperatures (mean [SD] = 22.8 [0.6]°C) was similar to that of ±3°C diel temperature fluctuations (23.1 [0.1]°C). Mean LT50 for the midpoint of the ±6°C fluctuations could not be calculated because survival in the two treatments (19 ± 6°C and 22 ± 6°C) was not below 50%; however, it probably was also between 22°C and 25°C because the upper limb of a ±6°C fluctuation on a 25°C midpoint is above critical thermal maximum for Apache Trout (28.5–30.4°C). Growth decreased as temperatures approached the LT50. Apache Trout can survive short-term exposure to water temperatures with daily maxima that remain below 25°C and midpoint diel temperatures below 22°C. However, median summer stream temperatures must remain below 19°C for best growth and even lower if daily fluctuations are high (≥12°C).

  2. Immune responses to methanolic extract of black cumin (Nigella sativa) in rainbow trout (Oncorhynchus mykiss).

    Science.gov (United States)

    Celik Altunoglu, Yasemin; Bilen, Soner; Ulu, Ferhat; Biswas, Gouranga

    2017-08-01

    The immune stimulating effects of the methanolic extract of black cumin (Nigella sativa) in rainbow trout (Oncorhynchus mykiss) was evaluated. Variable concentrations of black cumin methanolic extract [0 (Control), 0.1 and 0.5 g kg -1 of feed] were individually added to the basal diet and rainbow trout was fed for 30 days to assess the innate immune responses and growth performance. Feed conversion ratio significantly decreased in the group fed with 0.5 g kg -1 black cumin extract. Respiratory burst activity was observed to be the highest in the 0.5 g kg -1 black cumin extract fed group. Lysozyme and myeloperoxidase activities were significantly increased in fish of experimental groups compared to control (P  0.05) after challenged with Aeromonas hydrophila. The results indicate that the methanolic extract of black cumin is a stimulator of some innate humoral immune responses, but it is ineffective for cytokine-related gene trancriptions in rainbow trout. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Mink predation on brown trout in a Black Hills stream

    Science.gov (United States)

    Davis, Jacob L.; Wilhite, Jerry W.; Chipps, Steven R.

    2016-01-01

    In the early 2000’s, declines in the brown trout (Salmo trutta) fishery in Rapid Creek, South Dakota, caused concern for anglers and fisheries managers. We conducted a radio telemetry study in 2010 and 2011 to identify predation mortality associated with mink, using hatchery-reared (2010) or wild (2011) brown trout. Estimated predation rates by mink (Mustela vison) on radio-tagged brown trout were 30% for hatchery fish and 32% for wild fish. Size frequency analysis revealed that the size distribution of brown trout lost to predation was similar to that of other, radio-tagged brown trout. In both years, a higher proportion of predation mortality (83–92%) occurred during spring, consistent with seasonal fish consumption by mink. Predation by mink appeared to be a significant source of brown trout mortality in our study.

  4. MORPHOMETRIC CHARACTERISTICS OF THE REPLACEMENT-BROOD STOCK OF RAINBOW TROUT (ONCORHYNCHUS MYKISS (WALBAUM, 1792 REARED IN THE CONDITIONS OF THE INDUSTRIAL FISH FARM "SLOBODA-BANYLIV”

    Directory of Open Access Journals (Sweden)

    P. Mendrishora

    2017-09-01

    Full Text Available Purpose. To analyze the results of morphometric measurements and dates of aquaculture-biological characteristics of the young-of-the-year and age-1+ rainbow trout reared under industrial technology at instable conditions of the fish farm “Sloboda-Banyliv”. Methodology. The study has been performed at the industrial fish farm “Sloboda-Banyliv”, Chernivtsi region. The materials for the study were young-of-the-year and age-1+ rainbow trout obtained from the eggs of autumn-spawning form rainbow trout. The young-of-the-year were reared in a 216 m2 tank with stocking density of 255 ind./m2, age-1+ fish were reared in 108 m2 tank with a stocking density of 33 ind./m2 according to generally accepted methods in trout culture. Morphometric measurements of fish were performed according to I.F. Pravdin. Statistical processing of data was carried out in Microsoft Office Excel (2003. The analysis of values was done in the system of absolute values. The analyzed criteria of the measured parameters were their mean values and standard errors (M±m, deviation (σ, variability coefficient (Cv. Fish were fed with the artificial feed with high protein content manufactured by “Biomar” (Denmark. Findings. The studies on rainbow trout rearing under industrial conditions showed that fish body proportions did not change with age, however, the length of their fins decreased. The slenderness coefficient in age-1+ fish decreased insignificantly that is typical with increasing body depth. Despite instable rearing conditions, both young-of-the-year and age-1+ fish were characterized by moderate growth rate and high feed-conversion efficiency. Originality. For the first time, in conditions of Ukraine, a study on the formation of rainbow trout brood stocks in a fish farm with instable rearing conditions was performed with the use of the analysis of phenotypical and productive features. Practical value. The results of the performed work will provide an opportunity to

  5. Bull trout (Salvelinus confluentus) movement in relation to water temperature, season, and habitat features in Arrowrock Reservoir, Idaho, 2012

    Science.gov (United States)

    Maret, Terry R.; Schultz, Justin E.

    2013-01-01

    Acoustic telemetry was used to determine spring to summer (April–August) movement and habitat use of bull trout (Salvelinus confluentus) in Arrowrock Reservoir (hereafter “Arrowrock”), a highly regulated reservoir in the Boise River Basin of southwestern Idaho. Water management practices annually use about 86 percent of the reservoir water volume to satisfy downstream water demands. These practices might be limiting bull trout habitat and movement patterns. Bull trout are among the more thermally sensitive coldwater species in North America, and the species is listed as threatened throughout the contiguous United States under the Endangered Species Act. Biweekly water-temperature and dissolved-oxygen profiles were collected by the Bureau of Reclamation at three locations in Arrowrock to characterize habitat conditions for bull trout. Continuous streamflow and water temperature also were measured immediately upstream of the reservoir on the Middle and South Fork Boise Rivers, which influence habitat conditions in the riverine zones of the reservoir. In spring 2012, 18 bull trout ranging in total length from 306 to 630 millimeters were fitted with acoustic transmitters equipped with temperature and depth sensors. Mobile boat tracking and fixed receivers were used to detect released fish. Fish were tagged from March 28 to April 20 and were tracked through most of August. Most bull trout movements were detected in the Middle Fork Boise River arm of the reservoir. Fifteen individual fish were detected at least once after release. Water surface temperature at each fish detection location ranged from 6.0 to 16.2 degrees Celsius (°C) (mean=10.1°C), whereas bull trout body temperatures were colder, ranging from 4.4 to 11.6°C (mean=7.3°C). Bull trout were detected over deep-water habitat, ranging from 8.0 to 42.6 meters (m) (mean=18.1 m). Actual fish depths were shallower than total water depth, ranging from 0.0 to 24.5 m (mean=6.7 m). The last bull trout was

  6. Principles of lake sedimentology

    International Nuclear Information System (INIS)

    Janasson, L.

    1983-01-01

    This book presents a comprehensive outline on the basic sedimentological principles for lakes, and focuses on environmental aspects and matters related to lake management and control-on lake ecology rather than lake geology. This is a guide for those who plan, perform and evaluate lake sedimentological investigations. Contents abridged: Lake types and sediment types. Sedimentation in lakes and water dynamics. Lake bottom dynamics. Sediment dynamics and sediment age. Sediments in aquatic pollution control programmes. Subject index

  7. Instream cover and shade mediate avian predation on trout in semi-natural streams

    Science.gov (United States)

    Penaluna, Brooke E.; Dunham, Jason B.; Noakes, David L. G.

    2015-01-01

    Piscivory by birds can be significant, particularly on fish in small streams and during seasonal low flow when available cover from predators can be limited. Yet, how varying amounts of cover may change the extent of predation mortality from avian predators on fish is not clear. We evaluated size-selective survival of coastal cutthroat trout (Oncorhynchus clarkii clarkii) in replicated semi-natural stream sections. These sections provided high (0.01 m2 of cover per m2 of stream) or low (0.002 m2 of cover per m2 of stream) levels of instream cover available to trout and were closed to emigration. Each fish was individually tagged, allowing us to track retention of individuals during the course of the 36-day experiment, which we attributed to survival from predators, because fish had no other way to leave the streams. Although other avian predators may have been active in our system and not detected, the only predator observed was the belted kingfisher Megaceryle alcyon, which is known to prey heavily on fish. In both treatments, trout >20.4 cm were not preyed upon indicating an increased ability to prey upon on smaller individuals. Increased availability of cover improved survival of trout by 12% in high relative to low cover stream sections. Trout also survived better in stream sections with greater shade, a factor we could not control in our system. Collectively, these findings indicate that instream cover and shade from avian predators can play an important role in driving survival of fish in small streams or during periods of low flow.

  8. Terrestrial CDOM in Lakes of Yamal Peninsula: Connection to Lake and Lake Catchment Properties

    Directory of Open Access Journals (Sweden)

    Yury Dvornikov

    2018-01-01

    Full Text Available In this study, we analyze interactions in lake and lake catchment systems of a continuous permafrost area. We assessed colored dissolved organic matter (CDOM absorption at 440 nm (a(440CDOM and absorption slope (S300–500 in lakes using field sampling and optical remote sensing data for an area of 350 km2 in Central Yamal, Siberia. Applying a CDOM algorithm (ratio of green and red band reflectance for two high spatial resolution multispectral GeoEye-1 and Worldview-2 satellite images, we were able to extrapolate the a(λCDOM data from 18 lakes sampled in the field to 356 lakes in the study area (model R2 = 0.79. Values of a(440CDOM in 356 lakes varied from 0.48 to 8.35 m−1 with a median of 1.43 m−1. This a(λCDOM dataset was used to relate lake CDOM to 17 lake and lake catchment parameters derived from optical and radar remote sensing data and from digital elevation model analysis in order to establish the parameters controlling CDOM in lakes on the Yamal Peninsula. Regression tree model and boosted regression tree analysis showed that the activity of cryogenic processes (thermocirques in the lake shores and lake water level were the two most important controls, explaining 48.4% and 28.4% of lake CDOM, respectively (R2 = 0.61. Activation of thermocirques led to a large input of terrestrial organic matter and sediments from catchments and thawed permafrost to lakes (n = 15, mean a(440CDOM = 5.3 m−1. Large lakes on the floodplain with a connection to Mordy-Yakha River received more CDOM (n = 7, mean a(440CDOM = 3.8 m−1 compared to lakes located on higher terraces.

  9. Factors Affecting Mercury Stable Isotopic Distribution in Piscivorous Fish of the Laurentian Great Lakes.

    Science.gov (United States)

    Lepak, Ryan F; Janssen, Sarah E; Yin, Runsheng; Krabbenhoft, David P; Ogorek, Jacob M; DeWild, John F; Tate, Michael T; Holsen, Thomas M; Hurley, James P

    2018-03-06

    Identifying the sources of methylmercury (MeHg) and tracing the transformations of mercury (Hg) in the aquatic food web are important components of effective strategies for managing current and legacy Hg sources. In our previous work, we measured stable isotopes of Hg (δ 202 Hg, Δ 199 Hg, and Δ 200 Hg) in the Laurentian Great Lakes and estimated source contributions of Hg to bottom sediment. Here, we identify isotopically distinct Hg signatures for Great Lakes trout ( Salvelinus namaycush) and walleye ( Sander vitreus), driven by both food-web and water-quality characteristics. Fish contain high values for odd-isotope mass independent fractionation (MIF) with averages ranging from 2.50 (western Lake Erie) to 6.18‰ (Lake Superior) in Δ 199 Hg. The large range in odd-MIF reflects variability in the depth of the euphotic zone, where Hg is most likely incorporated into the food web. Even-isotope MIF (Δ 200 Hg), a potential tracer for Hg from precipitation, appears both disconnected from lake sedimentary sources and comparable in fish among the five lakes. We suggest that similar to the open ocean, water-column methylation also occurs in the Great Lakes, possibly transforming recently deposited atmospheric Hg deposition. We conclude that the degree of photochemical processing of Hg is controlled by phytoplankton uptake rather than by dissolved organic carbon quantity among lakes.

  10. Dietary acidification enhances phosphorus digestibility but decreases H+/K+-ATPase expression in rainbow trout.

    Science.gov (United States)

    Sugiura, Shozo H; Roy, Prabir K; Ferraris, Ronaldo P

    2006-10-01

    Oxynticopeptic cells of fish stomach are thought to secrete less acid than the specialized parietal cells of mammalian stomach. Gastric acidity, however, has not been directly compared between fish and mammals. We therefore fed rainbow trout and rats the same meal, and found that the lowest postprandial pH of trout stomach was 2.7, which was only transiently sustained for 1 h, whereas that of rat stomach was 1.3, which was sustained for 3 h. Postprandial pH of the small intestine was slightly higher in trout (approximately 8.0) than in rats (approximately 7.6), but pH of the large intestine was similar (approximately 8.0). Addition of acids to fish feeds, in an attempt to aid the weak acidity of fish stomach, has been known to improve phosphorus digestibility, but its physiological effect on fish stomach is not known. Exogenous acids did improve phosphorus digestibility but also decreased steady-state mRNA expression of trout H(+)/K(+)-ATPase (ATP4A, the proton pump) as well as Na(+)/bicarbonate cotransporter (NBC), and had no effect on gastrin-like mRNA and somastostatin (SST) mRNA abundance. Gastrin-like mRNA and SST-2 mRNA were equally distributed between corpus and antrum. ATP4A mRNA and NBC mRNA were in the corpus, whereas SST-1 mRNA was in the antrum. Trout gastrin-like EST had modest homology to halibut and pufferfish gastrin, whereas trout ATP4A mRNA had > or = 95% amino acid homology with mammalian, Xenopus and flounder ATP4A. Although ATP4A seems highly conserved among vertebrates, gastric acidity is much less in trout than in rats, explaining the low digestibility of bone phosphorus, abundant in fish diets. Dietary acidification does not reduce acidity enough to markedly improve phosphorus digestibility, perhaps because exogenous acids may inhibit endogenous acid production.

  11. Rearing environment influences boldness and prey acquisition behavior, and brain and lens development of bull trout

    Science.gov (United States)

    Brignon, William R.; Pike, Martin M.; Ebbesson, Lars O.E.; Schaller, Howard A.; Peterson, James T.; Schreck, Carl B.

    2018-01-01

    Animals reared in barren captive environments exhibit different developmental trajectories and behaviors than wild counterparts. Hence, the captive phenotypes may influence the success of reintroduction and recovery programs for threatened and endangered species. We collected wild bull trout embryos from the Metolius River Basin, Oregon and reared them in differing environments to better understand how captivity affects the bull trout Salvelinus confluentusphenotype. We compared the boldness and prey acquisition behaviors and development of the brain and eye lens of bull trout reared in conventional barren and more structurally complex captive environments with that of wild fish. Wild fish and captive reared fish from complex habitats exhibited a greater level of boldness and prey acquisition ability, than fish reared in conventional captive environments. In addition, the eye lens of conventionally reared bull trout was larger than complex reared captive fish or same age wild fish. Interestingly, we detected wild fish had a smaller relative cerebellum than either captive reared treatment. Our results suggest that rearing fish in more complex captive environments can create a more wild-like phenotype than conventional rearing practices. A better understanding of the effects of captivity on the development and behavior of bull trout can inform rearing and reintroduction programs though prediction of the performance of released individuals.

  12. Studies on the levels of Cs-137 originating from the Chernobyl accident in salmonid fish, its prey organisms and environment, in some alpine lakes of northern Sweden

    International Nuclear Information System (INIS)

    Hammar, J.; Neumann, G.; Notter, M.

    1988-01-01

    Fallout from the Chernobyl accident resulted in heavy surface contamination in areas of middle and northern Sweden. One of the most heavily affected regions was an approx. 5000 km 2 alpine district at the border to Norway. Shortly after the accident, the levels of Cs-137 and other radionuclides began to rise in two dominating fish species of the region, the brown trout (Salmo trutta L.) and the Arctic char (Salvelinus alpinus L. In July 1986 a research program started with the ultimate goal of understanding the mechanisms of transport for radionuclides through the food chain to fish, and, if possible, to give a forecast of the future development of the Cs-137 contamination. It comprises measurements of mainly Cs-137, Cs-134 and K-40 in 8 lakes within the area. The measurements have been performed at five occasions during the period July 1986 until October 1987. The preliminary results concerning Cs-137 show: - A large increase in levels of bottom sediments. A decrease in levels of water. A strong decrease in levels of phytoplankton, zooplankton, Gammarus and Mysis during autumn 1986, and a stabilization during 1987. In same lakes, however, another increase was recorded during 1987. That Mysis originally has the highest levels of all food items. That the levels of brown trout and Arctic char increased steadily during 1986 and showed a tendency of stabilization or slight decrease during 1987. That brown trout generally show higher levels than Arctic char and reaches its highest levels in lakes with introduced Mysis

  13. Evaluation of dietary soy sensitivity in snake river cutthroat trout

    Science.gov (United States)

    Hatchery-cultured cutthroat trout fed some commercially available rainbow trout feeds display slow growth and increased mortality. Feed characteristics such as buoyancy and texture alter feed acceptance in some fish species but their effects have not been adequately addressed in cutthroat trout. Th...

  14. Utilization of dietary urea in rainbow trout.

    Science.gov (United States)

    Kaushik, S J; Dabrowski, K R; Dabrowska, H; Olah, E; Luquet, P

    1983-01-01

    Experiments were conducted to examine the potential utilization of dietary urea by rainbow trout. A control diet and two diets supplemented with 1 and 3% of urea were fed to fish. Postprandial levels of urea and ammonia in blood plasma, and postprandial excretion of these metabolites were followed during 24 h. Apparent digestibility of urea in rainbow trout was very high (greater than 98%). Maximum values of urea levels in plasma were reached 6 h (32.3 +/- 10.2 micrograms/ml) after a meal in the control fish and respectively 6 h (83.4 +/- 18.4 micrograms/ml) and 8 h (250.3 +/- 96.1 micrograms/ml) after a meal in trout fed 1 and 3% urea diets. Peaks of urea excretion rates appeared 7-9 h after meal, coinciding with the highest circulating urea concentration. Total daily urea excretion amounted to 5.53, 10.43 and 33.80 mg urea N/100 mg N intake in trout fed the control, 1 and 3% urea diets, respectively. It is concluded that the dietary urea is readily absorbed in the digestive tract of trout but is totally excreted thus leading to no beneficial effect on nitrogen balance. This excretion of urea also takes place passively without any increase in energy demands.

  15. The problem of sampling families rather than populations: Relatedness among individuals in samples of juvenile brown trout Salmo trutta L

    DEFF Research Database (Denmark)

    Hansen, Michael Møller; Eg Nielsen, Einar; Mensberg, Karen-Lise Dons

    1997-01-01

    In species exhibiting a nonrandom distribution of closely related individuals, sampling of a few families may lead to biased estimates of allele frequencies in populations. This problem was studied in two brown trout populations, based on analysis of mtDNA and microsatellites. In both samples mt......DNA haplotype frequencies differed significantly between age classes, and in one sample 17 out of 18 individuals less than 1 year of age shared one particular mtDNA haplotype. Estimates of relatedness showed that these individuals most likely represented only three full-sib families. Older trout exhibiting...

  16. Multiscale hydrogeomorphic influences on bull trout (Salvelinus confluentus) spawning habitat

    Science.gov (United States)

    Bean, Jared R; Wilcox, Andrew C.; Woessner, William W.; Muhlfeld, Clint C.

    2015-01-01

    We investigated multiscale hydrogeomorphic influences on the distribution and abundance of bull trout (Salvelinus confluentus) spawning in snowmelt-dominated streams of the upper Flathead River basin, northwestern Montana. Within our study reaches, bull trout tended to spawn in the finest available gravel substrates. Analysis of the mobility of these substrates, based on one-dimensional hydraulic modeling and calculation of dimensionless shear stresses, indicated that bed materials in spawning reaches would be mobilized at moderate (i.e., 2-year recurrence interval) high-flow conditions, although the asynchronous timing of the fall–winter egg incubation period and typical late spring – early summer snowmelt high flows in our study area may limit susceptibility to redd scour under current hydrologic regimes. Redd occurrence also tended to be associated with concave-up bedforms (pool tailouts) with downwelling intragravel flows. Streambed temperatures tracked stream water diurnal temperature cycles to a depth of at least 25 cm, averaging 6.1–8.1 °C in different study reaches during the spawning period. Ground water provided thermal moderation of stream water for several high-density spawning reaches. Bull trout redds were more frequent in unconfined alluvial valley reaches (8.5 versus 5.0 redds·km−1 in confined valley reaches), which were strongly influenced by hyporheic and groundwater – stream water exchange. A considerable proportion of redds were patchily distributed in confined valley reaches, however, emphasizing the influence of local physical conditions in supporting bull trout spawning habitat. Moreover, narrowing or “bounding” of these alluvial valley segments did not appear to be important. Our results suggest that geomorphic, thermal, and hydrological factors influence bull trout spawning occurrence at multiple spatial scales.

  17. Fine Sediment Effects on Brook Trout Eggs in Laboratory Streams

    Science.gov (United States)

    David G. Argent; Patricia A. Flebbe

    1999-01-01

    This study was designed to determine effects of different fine sediments (0.43-0.85 mm in diameter) on survival of brook trout (Salvelinus fontinalis) eggs during early developmental stages under laboratory conditions. Intragravel permeability and dissolved oxygen declined