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.

Fish impingement at Lake Michigan power plants

International Nuclear Information System (INIS)

Sharma, R.K.; Freeman, R.F.; Spigarelli, S.A.

1976-01-01

A study was initiated in 1974 to survey the magnitude and to evaluate the impact of fish impingement at 20 power plants on the Great Lakes. Data on impingement rates, site characteristics, intake designs and operational features have been collected and analyzed. Interpretive analyses of these data are in progress. The objectives of this study were: to summarize fish impingement data for Lake Michigan (16/20 plants surveyed are on Lake Michigan); to assess the significance of total and source-related mortalities on populations of forage and predator species; and to expand the assessment of power plant impingement to include all water intakes on Lake Michigan. Data are tabulated

Haff disease associated with the ingestion of the freshwater fish Mylossoma duriventre (pacu-manteiga).

Science.gov (United States)

Tolesani Júnior, Oswaldo; Roderjan, Christian Nejm; do Carmo Neto, Edgard; Ponte, Micheli Mikaeli; Seabra, Mariana Cristina Pelli; Knibel, Marcos Freitas

2013-01-01

Haff disease associated rhabdomyolysis is correlated with the ingestion of certain freshwater fish and shellfish and is caused by an unidentified toxin. We report the case of a patient who experienced rhabdomyolysis approximately 2 hours after ingestion of the freshwater fish Mylossoma duriventre (pacu-manteiga) approximately 3 years after an outbreak had been reported in Manaus, Brazilian Amazon.

Effects of fish removal in the Furnas Lake, Azores

Directory of Open Access Journals (Sweden)

Bio, A.

2008-01-01

Full Text Available The Furnas Lake is a small volcanic, monomitic and increasingly eutrophised water body. Next to agricultural nutrient inputs, high densities of herbivorous fish are thought to contribute to high levels of turbidity in the lake, through zooplankton consumption and re suspension of the nutrients accumulated in the sediment. According to the alternative state hypothesis a shift from turbid to clear water conditions is favoured by reduction of nutrient concentrations, increased light availability and reduction of planktivorous and benthos-feeding fish stock. To improve water quality in the Furnas Lake, a substantial part of the bottom-feeding fish population (62% of the estimated common carp population, Cyprinus carpio, and 5% of the estimated roach population, Rutilus rutilus was removed. Effects of fish removal on turbidity and associated trophic state were analysed next to post-manipulation chlorophyll a concentration, zooplankton and macrophytes densities. Results suggest that fish removal was not enough to change lake conditions towards a lasting clear state dominated by macrophytes. Excessive nutrient load, in water and sediments, nutrient input from the lake basin and fish recruitment causing enhanced zooplankton grazing are appointed causes. Any further biomanipulation efforts should be associated to nutrient reduction; and continued monitoring of water quality, fish stock, macrophytes and zooplankton is needed.

Morphometry and Lens of Eyes Bilih Fish (mystacoleucus padangensis, Bleeker) from Lake Toba, North Sumatra and Lake Singkarak, West Sumatra

Science.gov (United States)

Razak, A.

2018-04-01

This research has been carried out 2015. Bilih fish today need conservation and attention for sustainability. Habitat this fish is treated by human activities in Lake Singkarak, West Sumatera and Lake Toba in North Sumatera. The objectives of the research are describes morphometry of the body and relation with lens of eyes. The methods of the reasearch for measure all parts of surface body fish according www.fishbase.org. For measure and chemical composition of lens of eyes Bilih Fish (M. padangensis) are according Razak (2005). T he result of the research are indicated the size of morphology body Bilih Fish from Lake Toba and from Lake Singkarak is diffrent. Furthermore, diameter of lens is trend linier follow the growth of the body Bilih Fish from Lake Singkarak and Lake Toba. The chemical composition of lens of eyes Bilih Fish from Lake Singkarak contains Sulfur until 73.77% per 100 ppm, another substances like Calcium, Silicone, Magnesium, Phosporus 4.09%-4.83% per 100 ppm. The chemical composition of lens of eyes Bilih Fish from Lake Toba contains Sulfur only 50.08% per 100 ppm, another substances like Kalium, Calcium, Silicone, Magnesium, Phosporus 1.09%-10.43% per 100 ppm. Kalium substance only found in lens of eyes Bilih Fish from Lake Toba. As conclusion, morphometry body Bilih Fish from Lake Toba is bigger better than Bilih Fish from Lake Singkarak and chemical composition lens of eyes Bilih Fish from Lake Toba is influenced by environmental waters factors.

Depth as an organizer of fish assemblages in floodplain lakes

Science.gov (United States)

Miranda, L.E.

2011-01-01

Depth reduction is a natural process in floodplain lakes, but in many basins has been accelerated by anthropogenic disturbances. A diverse set of 42 floodplain lakes in the Yazoo River Basin (Mississippi, USA) was examined to test the hypothesis of whether depth reduction was a key determinant of water quality and fish assemblage structure. Single and multiple variable analyses were applied to 10 commonly monitored water variables and 54 fish species. Results showed strong associations between depth and water characteristics, and between depth and fish assemblages. Deep lakes provided less variable environments, clearer water, and a wider range of microhabitats than shallow lakes. The greater environmental stability was reflected by the dominant species in the assemblages, which included a broader representation of large-body species, species less tolerant of extreme water quality, and more predators. Stability in deep lakes was further reflected by reduced among-lake variability in taxa representation. Fish assemblages in shallow lakes were more variable than deep lakes, and commonly dominated by opportunistic species that have early maturity, extended breeding seasons, small adult size, and short lifespan. Depth is a causal factor that drives many physical and chemical variables that contribute to organizing fish assemblages in floodplain lakes. Thus, correlations between fish and water transparency, temperature, oxygen, trophic state, habitat structure, and other environmental descriptors may ultimately be totally or partly regulated by depth. In basins undergoing rapid anthropogenic modifications, local changes forced by depth reductions may be expected to eliminate species available from the regional pool and could have considerable ecological implications. ?? 2010 Springer Basel AG (outside the USA).

Occurrence and amount of microplastic ingested by fishes in watersheds of the Gulf of Mexico.

Science.gov (United States)

Phillips, Melissa B; Bonner, Timothy H

2015-11-15

Ingestion of microplastics by fishes could be an emerging environmental crisis because of the proliferation of plastic pollution in aquatic environments. Microplastics in marine ecosystems are well documented, however only one study has reported percent occurrence of microplastics in freshwater fishes. The purpose of this study was to quantify the occurrences and types of microplastics ingested by fishes within several freshwater drainages of the Gulf of Mexico and an estuary of the Gulf of Mexico. Among 535 fishes examined in this study, 8% of the freshwater fishes and 10% of the marine fishes had microplastics in their gut tract. Percentage occurrence of microplastics ingested by fishes in non-urbanized streams (5%) was less than that of one of the urbanized streams (Neches River; 29%). Percent occurrence of microplastics by habitat (i.e., benthic, pelagic) and trophic guilds (herbivore/omnivore, invertivore, carnivore) were similar. Low but widespread occurrences among drainages, habitat guilds, and trophic guilds indicate proliferation of plastic pollution within watersheds of the Gulf of Mexico, but consequences to fish health are unknown at this time. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of Mercury, Selenium, Methylmercury in Consumed Fish from Shkodra Lake

OpenAIRE

, S. Fejzo; , K. Korro; , A. Alia

2016-01-01

In the present study, mercury and selenium levels were evaluated in fish tissues and fish organs from Shkodra Lake. 45 species of fish exists in this lake where 12 are migrate species. Some of the main types of fish that grow up in this lake are: crap, mullet, buy, carsi, cubla etc. Also the Shkodra Lake contains a very rich biota of microalgae, about 700 species with 250 algae type’s which grow up to 3 meter depth. These constitute a good environment food, but from the other side exist like ...

Cormorant predation on PIT-tagged lake fish

DEFF Research Database (Denmark)

Skov, Christian; Jepsen, Niels; Baktoft, Henrik

2014-01-01

The present study use data from recovered PIT (Passive Integrated Transponder) tags to explore species-and size-specific annual predation rates by cormorants on three common lacustrine fishes (size range 120-367 mm) in a European lake; roach (Rutilus rutilus), common bream (Abramis brama) and perch...... (Perca fluviatilis). In addition, we quantify the level of age/size truncation that cormorant predation could introduce in a population of perch, an important fish for recreational angling as well as for trophic interactions and ecosystem function in European lakes. Based on three years of PIT tagging...... of fish in Lake Viborg and subsequent recoveries of PIT tags from nearby cormorant roosting and breeding sites, we show that cormorants are major predators of roach, bream and perch within the size groups we investigated and for all species larger individuals had higher predation rates. Perch appear...

Ecological risk of methylmercury to piscivorous fish of the Great Lakes region.

Science.gov (United States)

Sandheinrich, Mark B; Bhavsar, Satyendra P; Bodaly, R A; Drevnick, Paul E; Paul, Eric A

2011-10-01

Contamination of fish populations with methylmercury is common in the region of the Laurentian Great Lakes as a result of atmospheric deposition and methylation of inorganic mercury. Using fish mercury monitoring data from natural resource agencies and information on tissue concentrations injurious to fish, we conducted a screening-level risk assessment of mercury to sexually mature female walleye (Sander vitreus), northern pike (Esox lucius), smallmouth bass (Micropterus dolomieu), and largemouth bass (Micropterus salmoides) in the Great Lakes and in interior lakes, impoundments, and rivers of the Great Lakes region. The assessment included more than 43,000 measurements of mercury in fish from more than 2000 locations. Sexually mature female fish that exceeded threshold-effect tissue concentrations of 0.20 μg g(-1) wet weight in the whole body occurred at 8% (largemouth bass) to 43% (walleye) of sites. Fish at 3% to 18% of sites were at risk of injury and exceeded 0.30 μg g(-1) where an alteration in reproduction or survival is predicted to occur. Most fish at increased risk were from interior lakes and impoundments. In the Great Lakes, no sites had sexually mature fish that exceeded threshold-effect concentrations. Results of this screening-level assessment indicate that fish at a substantive number of locations within the Great Lakes region are potentially at risk from methylmercury contamination and would benefit from reduction in mercury concentrations.

Selecting fish-based metrics responding to human pressures in French natural lakes and reservoirs: towards the development of a fish-based index (FBI) for French lakes

OpenAIRE

Launois, L.; Veslot, J.; Irz, P.; Argillier, C.

2010-01-01

1.Fish-based indices of biotic integrity (IBI) have been developed for many lotic systems but remain scarce for lakes. The goal of the present study was to assess the responses of lentic fish assemblages to anthropogenic pressures when environmental variability was controlled for, and to compare them between French natural lakes and reservoirs. 2.Environmental features, catchment-scale anthropogenic descriptors and fish data were collected from 30 natural lakes and 59 reservoirs throughout...

Regime shifts in shallow lakes: the importance of seasonal fish migration

DEFF Research Database (Denmark)

Brönmark, Christer; Brodersen, Jakob; Chapman, Ben B.

2010-01-01

. Our earlier research shows that a large proportion of zooplanktivorous fish populations in shallow lakes undertake seasonal migrations where they leave the lake during winter and migrate back to the lake in spring. Based on our past research, we propose a number of scenarios of how feedback processes...... properties, including piscivore abundance and zooplankton productivity, affect the individual state of zooplanktivorous fish, such as growth rate or condition. Individual state, in turn, affects the relative proportion and timing of migrating zooplanktivorous fish. This change, in turn, may stabilize states...... between the individual and ecosystem levels may affect stability of alternative stable states in shallow lakes when mediated by fish migration. Migration effects on shallow lakes result from processes at different scales, from the individual to the ecosystem. Our earlier research has shown that ecosystem...

The offshore fish community in southern Lake Ontario, 1972-1998

Science.gov (United States)

Owens, Randall W.; O'Gorman, Robert; Eckert, Thomas H.; Lantry, Brian F.; Munawar, M.

2003-01-01

The authors document the status of Lake Ontario's open-water fish community in 1972, near the beginning of an era of massive fish stocking and when phosphorus levels in the lake from anthropogenic inputs, were near their peak. They then describe changes that occurred in the fish community in 1978-98. This was a period when large numbers of young salmonid piscivores were released annually, sea lamprey control continued to improve, and phosphorus levels were declining due to successful nutrient abatement programs. Coincident with the above, the lower food web was changed by the addition of new exotic invertebrates, the zooplankter Bythotrephes cederstroemi and particularly the zebra mussel, Dreissena polymorpha, and quagga mussel, D. bugensis. The picture of the fish community structure is drawn from records of catches in bottom trawls and gill nets during surveys of southern Lake Ontario conducted the the U.S. Geological Survey (USGS) and the New York Department of Environmental Conservation (NYDEC), from records of fish stocked in Lake Ontario by the NYDEC, and from a creel census of boat anglers returning to southern Lake Ontario ports conducted by the NYDEC.

The major and trace element chemistry of fish and lake water within ...

African Journals Online (AJOL)

Chemical elements in lake water are incorporated into fish tissues through bioconcentration and biomagnification. Lake water and fish tissue samples from 23 lakes, located within 4 major South African catchments, were analysed to investigate the link between element concentrations in lake water and otolith, fin spine, ...

Lake variability: Key factors controlling mercury concentrations in New York State fish

International Nuclear Information System (INIS)

Simonin, Howard A.; Loukmas, Jefferey J.; Skinner, Lawrence C.; Roy, Karen M.

2008-01-01

A 4 year study surveyed 131 lakes across New York State beginning in 2003 to improve our understanding of mercury and gather information from previously untested waters. Our study focused on largemouth and smallmouth bass, walleye and yellow perch, common piscivorous fish shown to accumulate high mercury concentrations and species important to local fisheries. Fish from Adirondack and Catskill Forest Preserve lakes generally had higher mercury concentrations than those from lakes in other areas of the state. Variability between nearby individual lakes was observed, and could be due to differences in water chemistry, lake productivity or the abundance of wetlands in the watershed. We found the following factors impact mercury bioaccumulation: fish length, lake pH, specific conductivity, chlorophyll a, mercury concentration in the water, presence of an outlet dam and amount of contiguous wetlands. - Lake water chemistry variables, dams, and wetlands play major roles in determining fish mercury concentrations

2010 Great Lakes Human Health Fish Tissue Study Fish Tissue Data Dictionary

Science.gov (United States)

The Office of Science and Technology (OST) is providing the fish tissue results from the 2010 Great Lakes Human Health Fish Tissue Study (GLHHFTS). This document includes the “data dictionary” for Mercury, PFC, PBDE and PCBs.

LIMNOLOGICAL CONDITION AND ESTIMATION OF POTENTIAL FISH PRODUCTION OF KERINCI LAKE JAMBI, SUMATRA

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Samuel Samuel

2015-06-01

Full Text Available Kerinci Lake is a type of tectonic lakes located in a protected forest area of National Park of Kerinci Sebelat and a source of various fish species important for local people for their dayly food comsumption and income. However, few information is available on limnological condition and fish resources. Field research observing the limnological condition and estimating the potential fish production was conducted four times in April, June, August and October 2013. The research is aimed to describe the condition of limnology and estimate the potential fish production of the lake. Limnological aspect included the physico-chemical and biological parameters, namely: temperature, water transparency, depth, substrate, conductivity, pH, dissolved oxygen, alkalinity, ammonia, nitrate, phosphate, total phosphorus, chlorophyll-a and trophic state. Potential fish production was calculated by using the biological parameter levels of chlorophyll-a. The results show that the euphotic layer of the lake waters was still feasible for fish life. Water condition of the bottom layer was less supportable for fish life due to low dissolved oxygen content. Trophic state index (TSI values, either measured by temporal and spatial ways, had TSI with an average of 61.75. From these index, the lake is classified as a lake at the high productivity level (eutrophic. Annual fish production was an average of 307 kg/ha/year. By taking account the average of fish production and the total area of lake of around 4,200 ha, the potential fish production of Kerinci Lake is estimated about ± 1,287 tons/year.

Wandering Fish Bone: a Case of Pelvic Abscess due to Rectum Perforation Resulting from an Accidental Fish Bone Ingestion

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Sirous Abbasi

2010-09-01

Full Text Available Fish bone is the most common foreign body that is ingested accidentally and can be caused gastrointestinal complications such as perforation, abstraction, and abscess. We describe a 75-year-old man who suffered from constipation, diarrhea, and fever and chills for 3 months. He had mild tenderness in hypogasteric region and also mild tenderness and swelling on anterior rectal wall and prostate upon clinical examination. The abdominal and pelvic sonography and CT scan findings suggested existence of abscess in the space of between bladder and rectum. The patient underwent laparotomy to drainage the pelvic abscess. The surgeon found a 6-cm fish bone which was embedded in the abscess. The presented case indicated the importance of accidental fish bone ingestion and its possible complications. In addition, the patients with abdominal pain, GI bleeding, and fever of unknown origin living in the seaside regions, the wandering fish bone as a differential diagnosis should be kept in mind.

Transfer of Chernobyl-derived 137Cs into fishes in some Finnish lakes

International Nuclear Information System (INIS)

Saxen, R.; Koskelainen, U.; Alatalo, M.

2000-09-01

This report summarises STUK's work for the hydrological modelling (WG 4) in RODOS C, a project co-ordinated by the EU, in 1996-1999. The role of STUK in the project was to provide a data set on the radio-caesium contents in different types of fish and lakes in northern European environmental conditions for the development of a dynamic regional model describing radio-caesium transfer into fish. The co-operating institute, Technical Research Centre of Finland (VTT), was responsible for the modelling work in this project. Besides the analysed data on 137 Cs in the various fish species in the lakes, background information was produced on lakes and their drainage areas that might affect radio-caesium transfer into fish, which was needed for the development of fish, lake and drainage basin models. The role of STUK included also providing another, independent data set for the validation of the model. The proposals and needs of the co-operating institute, VTT, were taken into account. One of the factors strongly affecting the transfer of 137 Cs into fish is the nutrition level of the lake. The average transfer of 137 Cs in predators at the time of maximum activity concentrations in oligotrophic lakes was found to be up to 0.10 m 2 /kg, implying that approximately 10% of the amount of 137 Cs deposited on one square metre is transferred into 1 kg of fish. The corresponding transfer in eutrophic lakes was clearly lower,.i.e. 3- 4%, at the time of maximum concentrations, which usually occurred 1- 3 years after the deposition, depending on the fish species. These time-dependent transfer coefficients can be regarded as a kind of a lake-specific model. If deposition to the lake is known, the activity concentrations in fish can be estimated within specific uncertainty limits, by multiplying the deposition value by the transfer coefficient at a certain time point. Temporal changes in annual averages of transfer coefficients with variation for a certain set of lakes and for three

Characteristics of fatty acid composition of Gammarus lacustris inhabiting lakes with and without fish.

Science.gov (United States)

Makhutova, O N; Sharapova, T A; Kalachova, G S; Shulepina, S P; Gladyshev, M I

2016-01-01

The effect of a biotic factor--the presence of predatory fish in water--on the composition and content of fatty acids in crustaceans was studied in the populations of the lake amphipod Gammarus lacustris from two lakes with fish and three lakes without fish. It was found that, at an overall increase in the quantity and quality of food resources (namely, increase in the content of eicosapentaenoic acid and docosahexaenoic acid (DHA) in the biomass), the relative rate of DHA accumulation in gammarids in the lakes without fish is higher than in the lake with fish.

Ingested plastic transfers hazardous chemicals to fish and induces hepatic stress

Science.gov (United States)

Rochman, Chelsea M.; Hoh, Eunha; Kurobe, Tomofumi; Teh, Swee J.

2013-01-01

Plastic debris litters aquatic habitats globally, the majority of which is microscopic (plastic and accumulated pollutants are largely unknown. Here, we show that fish, exposed to a mixture of polyethylene with chemical pollutants sorbed from the marine environment, bioaccumulate these chemical pollutants and suffer liver toxicity and pathology. Fish fed virgin polyethylene fragments also show signs of stress, although less severe than fish fed marine polyethylene fragments. We provide baseline information regarding the bioaccumulation of chemicals and associated health effects from plastic ingestion in fish and demonstrate that future assessments should consider the complex mixture of the plastic material and their associated chemical pollutants. PMID:24263561

Total mercury concentration in common fish species of Lake Victoria ...

African Journals Online (AJOL)

Total mercury (THg) concentration was analysed in muscles of common fish species of Lake Victoria in the eastern and southern parts of the lake using cold vapour Atomic Absorption Spectrophotometric technique. Mercury concentration in all fish species was generally lower than the WHO maximum allowable ...

Short report: persistent bradycardia caused by ciguatoxin poisoning after barracuda fish eggs ingestion in southern Taiwan.

Science.gov (United States)

Hung, Yao-Min; Hung, Shih-Yuan; Chou, Kang-Ju; Huang, Neng-Chyan; Tung, Chung-Ni; Hwang, Deng-Fwu; Chung, Hsiao-Min

2005-12-01

We report an outbreak of ciguatoxin poisoning after barracuda fish ingestion in southern Taiwan. Three members of a family developed nausea, vomiting, watery diarrhea, and myalgias about 1 hour after eating three to ten eggs of a barracuda fish. Numbness of the lips and extremities followed the gastrointestinal symptoms about 2 hours after ingestion. Other manifestations included hyperthermia, hypotension, bradycardia, and hyperreflexia. Bradycardia persisted for several days, and one patient required a continuous infusion of intravenous atropine totaling 40 mg over 2 days. Further follow-up of the patients disclosed improvement of neurologic sequelae and bradycardia, but sensory abnormalities resolved several months later. In conclusion, ciguatoxin poisoning causes mainly gastrointestinal and neurologic effects of variable severity. In two patients with ciguatoxin poisoning after barracuda fish egg ingestion, persistent bradycardia required prolonged atropine infusion.

Management of an ingested fish bone in the lung using video-assist thoracic surgery: a case report.

Science.gov (United States)

Tan, Sichuang; Tan, Sipin; Peng, Muyun; Yu, Fenglei

2015-06-01

We report a case of lung abscess caused by an ingested fish bone that was successfully treated by minimally invasive surgery. Although cases of ingested foreign body abscess are well reported, lung abscess caused by ingested fish bone is extremely rare. To date, less than 10 similar cases have been reported in the literature. To the best of our knowledge, the case presented in this case report is the first report of this kind that was successfully treated by video-assist thoracic surgery (VATS). A 47-year-old man was admitted to department of thoracic surgery with the complaint of continues dry cough and fever. The patient accidentally swallowed a long sharp-blade-shaped fish bone 20 days before, which perforated the upper thoracic esophagus on the right and embedded in the right upper lobe.The diagnosis was verified by computed tomography scan and a video-assist thoracic surgery procedure was successfully performed to treat the patient. The patient survived the esophageal perforation fortunately without involvement of great vessel injury and probable mediastinitis. This report may provide additional experience on lung abscess caused by ingested fish bones. However, it is also important to educate the public of the risks of trying to force an ingested object down into the stomach.

Review of fish diversity in the Lake Huron basin

Science.gov (United States)

Roseman, E.F.; Schaeffer, J.S.; Steen, P.J.

2009-01-01

Lake Huron has a rich aquatic habitat diversity that includes shallow embayments, numerous tributaries, shallow mid-lake reef complexes, archipelagos, and profundal regions. These habitats provide support for warm, cool, and cold water fish communities. Diversity of fishes in Lake Huron reflects post-glaciation colonization events, current climate conditions, accidental and intentional introductions of non-indigenous species, and extinctions. Most extinction events have been largely associated with habitat alterations, exploitation of fisheries, and interactions with non-indigenous species. The most recent historical survey of extirpated and imperiled species conducted in the late 1970s identified 79 fish species in Lake Huron proper and about 50 additional species in tributaries. Of those 129 species, 20 are now considered extirpated or imperiled. Extirpated species include Arctic grayling, paddlefish, weed shiner, deepwater cisco, blackfin cisco, shortnose cisco, and kiyi. Six species have declined appreciably due to loss of clear-water stream habitat: the river redhorse, river darter, black redhorse, pugnose shiner, lake chubsucker, redside dace, eastern sand darter, and channel darter. While numerous agencies, universities, and other organizations routinely monitor nearshore and offshore fish distribution and abundance, there is a need for more rigorous examination of the distribution and abundance of less-common species to better understand their ecology. This information is critical to the development of management plans aimed at ecosystem remediation and restoration.

FISHING ACTIVITIES AND FISHERMEN INCOME IN RANAU LAKE, SOUTH SUMATRA

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Dina Muthmainah

2015-06-01

Full Text Available Fish resources contribute to the socio-economic development for people who live surrounding the waters. The fishermen of Ranau Lake, South Ogan Komering Ulu Regency, South Sumatra Province and West Lampung Regency, Lampung Province are the prime stakeholder and direct interest in fish resources, because they depend on it for their livelihoods or they are directly involved in its exploitation in some ways. However, to well manage these resources, it needs data and information about fish utilization and fishing activity. The objectives of this work are to assess fishing activities such as the fishing craft and gears, catch composition, fish yield, catch per unit of effort (CPUE and to estimate the fihermen income with economical parameter such as cost and price. Field surveys were conducted from February to November 2014. Fishing activities data were collected from field survey and interview. The results showed that fish resources utilization in Ranau Lake was categorized as traditional and small scale fisheries using different selective fishing gears such gillnet, harpoon, net trap and basket trap with the fish catch in average of 696.66 g/day; 205.03 g/day; 1.584.06 g/day and 123.67 g/day, respectively. Fisherman income (IDR 2,163,300 means the fishermen in Ranau Lake reach standard Indonesian welfare.

Jellyfish Distribution and Habitat - Fishing Special Regulation Lakes (Polygons)

Data.gov (United States)

NSGIC Education | GIS Inventory — This layer contains the lakes that are part of the Pennsylvania Fish and Boat Commission Fisheries Resource Database. These include lakes that are currently or have...

Correlates of mercury in fish from lakes near Clyde Forks, Ontario, Canada

International Nuclear Information System (INIS)

Ethier, A.L.M.; Scheuhammer, A.M.; Bond, D.E.

2008-01-01

Subsurface soils near Clyde Forks, Ontario, Canada, can have naturally high concentrations of mercury (Hg) from local geological sources. To investigate Hg in local aquatic food webs, Hg was measured in fish dorsal muscle (mainly yellow perch [YP] and pumpkinseed sunfish [PS]) and surface sediments from 10 regional lakes. Water chemistry, along with fork length, weight, and stable isotopes (δ 15 N, δ 13 C, δ 34 S) in fish were also measured. No lake sediments had elevated (>0.3 μg/g dw) Hg, and average Hg concentrations in fish were not sufficiently high ( 13 C), and certain lake variables (e.g., pH for YP). PS with more pelagic feeding habits had higher δ 34 S and Hg than those with more littoral feeding habits. Potential biological linkages between fish Hg and δ 34 S, a parameter that may be related to the lake sulphate-reducing bacteria activity, requires further investigation. - Fish from lakes near a localized geological Hg source do not have elevated Hg concentrations

Transfer of Chernobyl-derived {sup 137}Cs into fishes in some Finnish lakes

Energy Technology Data Exchange (ETDEWEB)

Saxen, R.; Koskelainen, U.; Alatalo, M

2000-09-01

This report summarises STUK's work for the hydrological modelling (WG 4) in RODOS C, a project co-ordinated by the EU, in 1996-1999. The role of STUK in the project was to provide a data set on the radio-caesium contents in different types of fish and lakes in northern European environmental conditions for the development of a dynamic regional model describing radio-caesium transfer into fish. The co-operating institute, Technical Research Centre of Finland (VTT), was responsible for the modelling work in this project. Besides the analysed data on {sup 137}Cs in the various fish species in the lakes, background information was produced on lakes and their drainage areas that might affect radio-caesium transfer into fish, which was needed for the development of fish, lake and drainage basin models. The role of STUK included also providing another, independent data set for the validation of the model. The proposals and needs of the co-operating institute, VTT, were taken into account. One of the factors strongly affecting the transfer of {sup 137}Cs into fish is the nutrition level of the lake. The average transfer of {sup 137}Cs in predators at the time of maximum activity concentrations in oligotrophic lakes was found to be up to 0.10 m{sup 2}/kg, implying that approximately 10% of the amount of {sup 137}Cs deposited on one square metre is transferred into 1 kg of fish. The corresponding transfer in eutrophic lakes was clearly lower,.i.e. 3- 4%, at the time of maximum concentrations, which usually occurred 1- 3 years after the deposition, depending on the fish species. These time-dependent transfer coefficients can be regarded as a kind of a lake-specific model. If deposition to the lake is known, the activity concentrations in fish can be estimated within specific uncertainty limits, by multiplying the deposition value by the transfer coefficient at a certain time point. Temporal changes in annual averages of transfer coefficients with variation for a certain

Lake Superior Coastal Wetland Fish Assemblages and ...

Science.gov (United States)

The role of the coastal margin and the watershed context in defining the ecology of even very large lakes is increasingly being recognized and examined. Coastal wetlands are both important contributors to the biodiversity and productivity of large lakes and important mediators of the lake-basin connection. We explored wetland-watershed connections and their relationship to wetland function and condition using data collected from 37 Lake Superior wetlands spanning a substantial geographic and geomorphic gradient. While none of these wetlands are particularly disturbed, there were nevertheless clear relationships between watershed landuse and wetland habitat and biota, and these varied consistently across wetland type categories that reflected the strength of connection to the watershed. For example, water clarity and vegetation structure complexity declined with decreasing percent natural land cover, and these effects were strongest in riverine wetlands (having generally large watersheds and tributary-dominated hydrology) and weakest in lagoon wetlands (having generally small watersheds and lake-dominate hydrology). Fish abundance and species richness both increased with decreasing percent natural land cover while species diversity decreased, and again the effect was strongest in riverine wetlands. Lagoonal wetlands, which lack any substantial tributary, consistently harbored the fewest species of fish and a composition different from the more watershed-lin

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

MERGANSER: an empirical model to predict fish and loon mercury in New England lakes.

Science.gov (United States)

Shanley, James B; Moore, Richard; Smith, Richard A; Miller, Eric K; Simcox, Alison; Kamman, Neil; Nacci, Diane; Robinson, Keith; Johnston, John M; Hughes, Melissa M; Johnston, Craig; Evers, David; Williams, Kate; Graham, John; King, Susannah

2012-04-17

MERGANSER (MERcury Geo-spatial AssessmeNtS for the New England Region) is an empirical least-squares multiple regression model using mercury (Hg) deposition and readily obtainable lake and watershed features to predict fish (fillet) and common loon (blood) Hg in New England lakes. We modeled lakes larger than 8 ha (4404 lakes), using 3470 fish (12 species) and 253 loon Hg concentrations from 420 lakes. MERGANSER predictor variables included Hg deposition, watershed alkalinity, percent wetlands, percent forest canopy, percent agriculture, drainage area, population density, mean annual air temperature, and watershed slope. The model returns fish or loon Hg for user-entered species and fish length. MERGANSER explained 63% of the variance in fish and loon Hg concentrations. MERGANSER predicted that 32-cm smallmouth bass had a median Hg concentration of 0.53 μg g(-1) (root-mean-square error 0.27 μg g(-1)) and exceeded EPA's recommended fish Hg criterion of 0.3 μg g(-1) in 90% of New England lakes. Common loon had a median Hg concentration of 1.07 μg g(-1) and was in the moderate or higher risk category of >1 μg g(-1) Hg in 58% of New England lakes. MERGANSER can be applied to target fish advisories to specific unmonitored lakes, and for scenario evaluation, such as the effect of changes in Hg deposition, land use, or warmer climate on fish and loon mercury.

Factors affecting fish biodiversity in floodplain lakes of the Mississippi Alluvial Valley

Science.gov (United States)

Miranda, Leandro E.; Dembkowski, Daniel J.

2012-01-01

River-floodplain ecosystems offer some of the most diverse and dynamic environments in the world. Accordingly, floodplain habitats harbor diverse fish assemblages. Fish biodiversity in floodplain lakes may be influenced by multiple variables operating on disparate scales, and these variables may exhibit a hierarchical organization depending on whether one variable governs another. In this study, we examined the interaction between primary variables descriptive of floodplain lake large-scale features, suites of secondary variables descriptive of water quality and primary productivity, and a set of tertiary variables descriptive of fish biodiversity across a range of floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas (USA). Lakes varied considerably in their representation of primary, secondary, and tertiary variables. Multivariate direct gradient analyses indicated that lake maximum depth and the percentage of agricultural land surrounding a lake were the most important factors controlling variation in suites of secondary and tertiary variables, followed to a lesser extent by lake surface area. Fish biodiversity was generally greatest in large, deep lakes with lower proportions of watershed agricultural land. Our results may help foster a holistic approach to floodplain lake management and suggest the framework for a feedback model wherein primary variables can be manipulated for conservation and restoration purposes and secondary and tertiary variables can be used to monitor the success of such efforts.

Environmental variables measured at multiple spatial scales exert uneven influence on fish assemblages of floodplain lakes

Science.gov (United States)

Dembkowski, Daniel J.; Miranda, Leandro E.

2014-01-01

We examined the interaction between environmental variables measured at three different scales (i.e., landscape, lake, and in-lake) and fish assemblage descriptors across a range of over 50 floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas. Our goal was to identify important local- and landscape-level determinants of fish assemblage structure. Relationships between fish assemblage structure and variables measured at broader scales (i.e., landscape-level and lake-level) were hypothesized to be stronger than relationships with variables measured at finer scales (i.e., in-lake variables). Results suggest that fish assemblage structure in floodplain lakes was influenced by variables operating on three different scales. However, and contrary to expectations, canonical correlations between in-lake environmental characteristics and fish assemblage structure were generally stronger than correlations between landscape-level and lake-level variables and fish assemblage structure, suggesting a hierarchy of influence. From a resource management perspective, our study suggests that landscape-level and lake-level variables may be manipulated for conservation or restoration purposes, and in-lake variables and fish assemblage structure may be used to monitor the success of such efforts.

Helminthiasis and gram negative enteric bacteria in freshwater fish from selected lakes of Haramaya District, Ethiopia

Science.gov (United States)

Microbiological and helminthiasis examination of fish from Tinike and Adelle Lakes were conducted at Haramaya District, Ethiopia. The types of fish available in the lakes were also assessed. Adelle Lake has only Clarias gariepinus while the Tinike Lake has only Oreochromis niloticus fish species. Te...

A dynamic model of caesium transport in lakes and their catchments

Energy Technology Data Exchange (ETDEWEB)

McDougall, Sandra; Jenkins, Alan (Institute of Hydrology, Wallingford (UK)); Hilton, John (Institute of Freshwater Ecology, Ambleside (UK). Windermere Lab.)

1991-04-01

A mathematical model has been developed to predict radiocaesium concentrations over time within individual compartments of the lake and its catchment. The lake has been divided into five compartments; catchment, lake water (epilimnion and hypolimnion during stratification), lake sediment and fish. Radiocaesium enters the lake via contaminated rainfall and catchment runoff. A proportion of this radiocaesium absorbs onto suspended solids in the lake. This proportion is represented by a distribution coefficient. Sedimentation of the suspended solids occurs at a rate defined by the areal removal coefficient and results in increased caesium concentrations in the sediment. The ingestion of radiocaesium by either water column or benthic feeding fish is described by transfer functions. The model has been tested against data collected from Esthwaite water and Windermere shortly after the Chernobyl reactor accident from May 1986 to December 1987. The model simulates observed radiocaesium concentrations in Esthwaite lake water and sediment and also in lake water, sediment and fish in Windermere. The model could form the basis of a valuable management tool for the water industry should a major airborne pollution event occur again. (author).

A dynamic model of caesium transport in lakes and their catchments

International Nuclear Information System (INIS)

McDougall, Sandra; Jenkins, Alan; Hilton, John

1991-01-01

A mathematical model has been developed to predict radiocaesium concentrations over time within individual compartments of the lake and its catchment. The lake has been divided into five compartments; catchment, lake water (epilimnion and hypolimnion during stratification), lake sediment and fish. Radiocaesium enters the lake via contaminated rainfall and catchment runoff. A proportion of this radiocaesium absorbs onto suspended solids in the lake. This proportion is represented by a distribution coefficient. Sedimentation of the suspended solids occurs at a rate defined by the areal removal coefficient and results in increased caesium concentrations in the sediment. The ingestion of radiocaesium by either water column or benthic feeding fish is described by transfer functions. The model has been tested against data collected from Esthwaite water and Windermere shortly after the Chernobyl reactor accident from May 1986 to December 1987. The model simulates observed radiocaesium concentrations in Esthwaite lake water and sediment and also in lake water, sediment and fish in Windermere. The model could form the basis of a valuable management tool for the water industry should a major airborne pollution event occur again. (author)

A RAD-based phylogenetics for Orestias fishes from Lake Titicaca.

Science.gov (United States)

Takahashi, Tetsumi; Moreno, Edmundo

2015-12-01

The fish genus Orestias is endemic to the Andes highlands, and Lake Titicaca is the centre of the species diversity of the genus. Previous phylogenetic studies based on a single locus of mitochondrial and nuclear DNA strongly support the monophyly of a group composed of many of species endemic to the Lake Titicaca basin (the Lake Titicaca radiation), but the relationships among the species in the radiation remain unclear. Recently, restriction site-associated DNA (RAD) sequencing, which can produce a vast number of short sequences from various loci of nuclear DNA, has emerged as a useful way to resolve complex phylogenetic problems. To propose a new phylogenetic hypothesis of Orestias fishes of the Lake Titicaca radiation, we conducted a cluster analysis based on morphological similarities among fish samples and a molecular phylogenetic analysis based on RAD sequencing. From a morphological cluster analysis, we recognised four species groups in the radiation, and three of the four groups were resolved as monophyletic groups in maximum-likelihood trees based on RAD sequencing data. The other morphology-based group was not resolved as a monophyletic group in molecular phylogenies, and some members of the group were diverged from its sister group close to the root of the Lake Titicaca radiation. The evolution of these fishes is discussed from the phylogenetic relationships. Copyright © 2015 Elsevier Inc. All rights reserved.

Determinism in fish assemblages of floodplain lakes of the vastly disturbed Mississippi Alluvial Valley

Science.gov (United States)

Miranda, L.E.; Lucas, G.M.

2004-01-01

The Mississippi Alluvial Valley between southern Illinois and southern Louisiana contains hundreds of floodplain lakes, most of which have been adversely affected by landscape modifications used to control flooding and support agriculture. We examined fish assemblages in lakes of this region to determine whether deterministic patterns developed in relation to prominent abiotic lake characteristics and to explore whether relevant abiotic factors could be linked to specific assemblage structuring mechanisms. The distributions of 14 taxa in 29 lakes were governed primarily by two gradients that contrasted assemblages in terms of lake area, lake elongation, and water clarity. The knowledge of whether a lake was clear or turbid, large or small, and long or short helped determine fish assemblage characteristics. Abiotic factors influenced fish assemblage structures, plausibly through limitations on foraging and physiological tolerances. Determinism in assemblage organization of floodplain lakes relative to recurrence in physicochemical features has been documented for unaltered rivers. Whereas the Mississippi Alluvial Valley has been subjected to vast anthropogenic disturbances and is not a fully functional floodplain river, fish assemblages in its floodplain lakes remain deterministic and organized by the underlying factors that also dictate assemblages in unaltered rivers. In advanced stages of lake aging, fish assemblages in these lakes are expected to largely include species that thrive in turbid, shallow systems with few predators and low oxygen concentrations. The observed patterns related to physical characteristics of these lakes suggest three general conservation foci, including (1) watershed management to control erosion, (2) removal of sediments or increases in water level to alleviate depth reductions and derived detriments to water physicochemistry, and (3) management of fish populations through stockings, removals, and harvest regulations.

Lake Michigan Fish Acoustic Data from 2011 to 2016

Data.gov (United States)

Department of the Interior — Each line in the file “Lake Michigan fish acoustic data from 2011 to 2016.csv” represents the acoustic data and estimated fish density for a single depth layer of...

Benthic prey fish assessment, Lake Ontario 2013

Science.gov (United States)

Weidel, Brian C.; Walsh, Maureen; Connerton, Michael J.

2014-01-01

The 2013 benthic fish assessment was delayed and shortened as a result of the U.S. Government shutdown, however the assessment collected 51 of the 62 planned bottom trawls. Over the past 34 years, Slimy Sculpin abundance in Lake Ontario has fluctuated, but ultimately decreased by two orders of magnitude, with a substantial decline occurring in the past 10 years. The 2013 Slimy Sculpin mean bottom trawl catch density (0.001 ind.·m-2, s.d.= 0.0017, n = 52) and mean biomass density (0.015 g·m-2 , s.d.= 0.038, n = 52) were the lowest recorded in the 27 years of sampling using the original bottom trawl design. From 2011-2013, the Slimy Sculpin density and biomass density has decreased by approximately 50% each year. Spring bottom trawl catches illustrate Slimy Sculpin and Round Goby Neogobius melanostoma winter habitat overlaps for as much as 7 months out of a year, providing opportunities for competition and predation. Invasive species, salmonid piscivory, and declines in native benthic invertebrates are likely all important drivers of Slimy Sculpin population dynamics in Lake Ontario. Deepwater Sculpin Myoxocephalus thompsonii, considered rare or absent from Lake Ontario for 30 years, have generally increased over the past eight years. For the first time since they were caught in this assessment, Deepwater Sculpin density and biomass density estimates declined from the previous year. The 2013 abundance and density estimates for trawls covering the standard depths from 60m to 150m was 0.0001 fish per square meter and 0.0028 grams per square meter. In 2013, very few small (recruitment. Nonnative Round Gobies were first detected in the USGS/NYSDEC Lake Ontario spring Alewife assessment in 2002. Since that assessment, observations indicate their population has expanded and they are now found along the entire south shore of Lake Ontario, with the highest densities in U.S. waters just east of the Niagara River confluence. In the 2013 spring-based assessment, both the

Mechanisms driving recruitment variability in fish: comparisons between the Laurentian Great Lakes and marine systems

Science.gov (United States)

Pritt, Jeremy J.; Roseman, Edward F.; O'Brien, Timothy P.

2014-01-01

In his seminal work, Hjort (in Fluctuations in the great fisheries of Northern Europe. Conseil Parmanent International Pour L'Exploration De La Mar. Rapports et Proces-Verbaux, 20: 1–228, 1914) observed that fish population levels fluctuated widely, year-class strength was set early in life, and egg production by adults could not alone explain variability in year-class strength. These observations laid the foundation for hypotheses on mechanisms driving recruitment variability in marine systems. More recently, researchers have sought to explain year-class strength of important fish in the Laurentian Great Lakes and some of the hypotheses developed for marine fisheries have been transferred to Great Lakes fish. We conducted a literature review to determine the applicability of marine recruitment hypotheses to Great Lakes fish. We found that temperature, interspecific interactions, and spawner effects (abundance, age, and condition of adults) were the most important factors in explaining recruitment variability in Great Lakes fish, whereas relatively fewer studies identified bottom-up trophodynamic factors or hydrodynamic factors as important. Next, we compared recruitment between Great Lakes and Baltic Sea fish populations and found no statistical difference in factors driving recruitment between the two systems, indicating that recruitment hypotheses may often be transferable between Great Lakes and marine systems. Many recruitment hypotheses developed for marine fish have yet to be applied to Great Lakes fish. We suggest that future research on recruitment in the Great Lakes should focus on forecasting the effects of climate change and invasive species. Further, because the Great Lakes are smaller and more enclosed than marine systems, and have abundant fishery-independent data, they are excellent candidates for future hypothesis testing on recruitment in fish.

Invasive alien freshwater fishes in the Wilderness Lakes System, a ...

African Journals Online (AJOL)

Invasive alien freshwater fishes in the Wilderness Lakes System, a wetland of international importance in the Western Cape Province, South Africa. ... A total of 87 893 fish comprising 16 species were caught. In addition to confirming the ... Key words: freshwater fish, invasive alien fishes, estuary, RAMSAR site, diversity.

A Research for Massive Fish Kills in Lake Bafa (Turkey

Directory of Open Access Journals (Sweden)

Murat Yabanlı

2011-06-01

Full Text Available As there were massive fish kills in Lake Bafa which is a lagoon situated in Southwestern Turkey in October, 2006, water and fish samples were taken from the region. Water samples were analysed physicochemically, toxicologically and microbiologically and fish samples were subjected to toxicological analysis. The analyses of lake water revealed on oxygen value of approximately 5.0 mg/L, salinity 16.2 ‰, nitrogen from ammonia 0.1 mg/L, nitrogen nitrite 0.013 mg/L, and total organic carbon 13 mg/L. Total coliform count was 1100 MPN/100 ml and faecal coliform count was 28 MPN/100 ml. There was no detection of any pesticide residues in fish and water samples. Massive fish kills are thought to be due to the decrease in water quality.

Turbidity as a factor in the decline of Great Lakes fishes with special reference to Lake Erie

Science.gov (United States)

Van Oosten, John

1948-01-01

Fish live and thrive in water with turbidities that range above 400 p.p.m. and average 200 p.p.m. The waters of the Great Lakes usually are clear except in Lake Erie where the turbidities of the inshore areas averaged 37 p.p.m.; the turbidities of the offshore waters averaged less. Lake Erie waters were no clearer 50 years ago than they are now. In fact, the turbidity values are less now than they were in the earlier years; the annual average of the inshore waters dropped from 44 p.p.m. before 1930 to 32 p.p.m. in 1930 and later, and the April-May values decreased from 72 p.p.m. to 46 p.p.m. Any general decline in the Lake Erie fishes cannot be attributed to increased turbidities. Furthermore, these turbidities averaged well below 100 p.p.m. and, therefore, were too low to affect fishes adversely.

Ingested Fish Bone: An Unusual Mechanism of Duodenal Perforation and Pancreatic Trauma

Directory of Open Access Journals (Sweden)

Dimitrios Symeonidis

2012-01-01

Full Text Available Ingestion of gastrointestinal foreign bodies represents a challenging clinical scenario. Increased morbidity is the price for the delayed diagnosis of complications and timely treatment. We present a case of 57-year-old female patient which was admitted in the emergency room department complaining of a mid-epigastric pain over the last twenty-four hours. Based on the patient's history, physical examination and elevated serum amylase levels, a false diagnosis of pancreatitis, was initially adopted. However, a CT scan confirmed the presence of a radiopaque foreign body in the pancreatic head and the presence of air bubbles outside the intestinal lumen. The patient was unaware of the ingestion of the foreign body. At laparotomy, after an oblique duodenotomy, a fish bone pinned in the pancreatic head after the penetration of the medial aspect of the second portion of the duodenal wall was identified and successfully removed. The patient had an uneventful postoperative recovery. Wide variation in clinical presentation characterizes the complicated fish bone ingestions. The strategically located site of penetration in the visceral wall is responsible for the often extraordinary gastrointestinal tract injury patterns. Increased level of suspicion is of paramount importance for the timely diagnosis and treatment.

Impact of Fish Oil Supplementation and Interruption of Fructose Ingestion on Glucose and Lipid Homeostasis of Rats Drinking Different Concentrations of Fructose

Science.gov (United States)

Sulis, Paola M.; Motta, Katia; Barbosa, Amanda M.; Besen, Matheus H.; da Silva, Julia S.; Nunes, Everson A.

2017-01-01

Background. Continuous fructose consumption may cause elevation of circulating triacylglycerol. However, how much of this alteration is reverted after the removal of fructose intake is not known. We explored this question and compared the efficacy of this approach with fish oil supplementation. Methods. Male Wistar rats were divided into the following groups: control (C), fructose (F) (water intake with 10% or 30% fructose for 9 weeks), fish oil (FO), and fructose/fish oil (FFO). Fish oil was supplemented only for the last 33 days of fructose ingestion. Half of the F group remained for additional 8 weeks without fructose ingestion (FR). Results. Fructose ingestion reduced food intake to compensate for the increased energy obtained through water ingestion, independent of fructose concentration. Fish oil supplementation exerted no impact on these parameters, but the removal of fructose from water recovered both ingestion behaviors. Plasma triacylglycerol augmented significantly during the second and third weeks (both fructose groups). Fish oil supplementation did not attenuate the elevation in triacylglycerol caused by fructose intake, but the interruption of sugar consumption normalized this parameter. Conclusion. Elevation in triacylglyceridemia may be recovered by removing fructose from diet, suggesting that it is never too late to repair improper dietary habits. PMID:28929113

Adirondack lakes survey: An interpretive analysis of fish communities and water chemistry, 1984--1987

Energy Technology Data Exchange (ETDEWEB)

Baker, J.P. (Baker (Joan P.), Raleigh, NC (USA)); Gherini, S.A.; Munson, R.K. (Tetra Tech, Inc., Pasadena, CA (USA)); Christensen, S.W. (Oak Ridge National Lab., TN (USA)); Driscoll, C.T. (Syracuse Univ., NY (USA)); Gallagher, J. (Adirondack Lakes Survey Corp., Ray Brook, NY (USA)); Newton, R.M. (Smith Coll., Northampton, MA (USA)); Reckhow, K.H. (Duke Univ., Durham, NC (USA)); Schofield, C.L. (Co

1990-01-01

The Adirondack Lakes Survey Corporation (ALSC) was formed as a cooperative effort of the New York State Department of Environmental Conservation and the Empire State Electric Energy Research Corporation to better characterize the chemical and biological status of Adirondack lakes. Between 1984 and 1987, the ALSC surveyed 1469 lakes within the Adirondack ecological zone. As a follow-up to the survey, the ALSC sponsored a series of interpretive analyses of the ALSC data base. The primary objectives of these analyses were as follows: Evaluate the influence of mineral acids (from acidic deposition) and nonmineral acids (natural organic acids) on lake pH levels; classify Adirondack lakes according to lake and watershed features expected to influence their responsiveness to changes in acidic deposition; evaluate the sensitivity of Adirondack lakes to changes in environmental conditions, such as changes in mineral acids or dissolved organic carbon concentrations; identify lake characteristics important in explaining the observed present-day status of fish communities in Adirondack lakes, in particular the relative importance of lake acidity; evaluate changes that have occurred over time in Adirondack fish communities and probable causes for these trends by using the available historical data on fish communities in the Adirondacks and the ALSC data base; and determine the degree to which the existing fish resource might be at risk from continued acidic deposition, or might recover if acidity levels were reduced. The basic approach examined relationships observed in the ALSC data base among watershed characteristics, lake chemistry, and fish status. Individual reports are processed separately for the data bases.

Great Lakes prey fish populations: A cross-basin overview of status and trends in 2008

Science.gov (United States)

Gorman, Owen T.; Bunnell, David B.

2009-01-01

Assessments of prey fishes in the Great Lakes have been conducted annually since the 1970s by the Great Lakes Science Center, sometimes assisted by partner agencies. Prey fish assessments differ among lakes in the proportion of a lake covered, seasonal timing, bottom trawl gear used, sampling design, and the manner in which the trawl is towed (across or along bottom contours). Because each assessment is unique in one or more important aspects, a direct comparison of prey fish catches among lakes is problematic. All of the assessments, however, produce indices of abundance or biomass that can be standardized to facilitate comparisons of trends among lakes and to illustrate present status of the populations. We present indices of abundance for important prey fishes in the Great Lakes standardized to the highest value for a time series within each lake: cisco (Coregonus artedi), bloater (C. hoyi), rainbow smelt (Osmerus mordax), and alewife (Alosa pseudoharengus). We also provide indices for round goby (Neogobius melanostomus), an invasive fish presently spreading throughout the basin. Our intent is to provide a short, informal report emphasizing data presentation rather than synthesis; for this reason we intentionally avoid use of tables and cited references.For each lake, standardized relative indices for annual biomass and density estimates of important prey fishes were calculated as the fraction relative to the largest value observed in the times series. To determine whether basin-wide trends were apparent for each species, we first ranked standardized index values within each lake. When comparing ranked index values from three or more lakes, we calculated the Kendall coefficient of concordance (W), which can range from 0 (complete discordance or disagreement among trends) to 1 (complete concordance or agreement among trends). The P-value for W provides the probability of agreement across the lakes. When comparing ranked index values from two lakes, we calculated

Urbanization is a major influence on microplastic ingestion by sunfish in the Brazos River Basin, Central Texas, USA

International Nuclear Information System (INIS)

Peters, Colleen A.; Bratton, Susan P.

2016-01-01

Microplastics, degraded and weathered polymer-based particles, and manufactured products ranging between 50 and 5000 μm in size, are found within marine, freshwater, and estuarine environments. While numerous peer-reviewed papers have quantified the ingestion of microplastics by marine vertebrates, relatively few studies have focused on microplastic ingestion by freshwater organisms. This study documents microplastic and manufactured fiber ingestion by bluegill (Lepomis macrochirus) and longear (Lepomis megalotis) sunfish (Centrarchidae) from the Brazos River Basin, between Lake Whitney and Marlin, Texas, USA. Fourteen sample sites were studied and categorized into urban, downstream, and upstream areas. A total of 436 sunfish were collected, and 196 (45%) stomachs contained microplastics. Four percent (4%) of items sampled were debris on the macro size scale (i.e. >5 mm) and consisted of masses of plastic, metal, Styrofoam, or fishing material, while 96% of items sampled were in the form of microplastic threads. Fish length was statistically correlated to the number of microplastics detected (p = 0.019). Fish collected from urban sites displayed the highest mean number of microplastics ingested, followed by downstream and upstream sites. Microplastics were associated with the ingestion of other debris items (e.g. sand and wood) and correlated to the ingestion of fish eggs, earthworms, and mollusks, suggesting that sunfish incidentally ingest microplastics during their normal feeding methods. The high frequency of microplastic ingestion suggest that further research is needed to determine the residence time of microplastics within the stomach and gut, potential for food web transfer, and adverse effects on wildlife and ecosystemic health. - Highlights: • Sunfish ingest microplastics and manufactured materials at significant levels. • Local urbanization influences microplastic ingestion. • Sunfish incidentally ingest microplastics during their normal

Phytoplankton productivity in newly dug fish ponds within Lake ...

African Journals Online (AJOL)

The declining Lake Victoria fisheries resource led to a growing recognition of aquaculture as a source of livelihood to riparian communities. Finger ponds speculated to naturally stock fish during flooding and retain them during dry seasons were introduced within the lake's wetlands. In order to develop a

Interactions between fishes and the structure of fish communities in Dutch shallow, eutrophic lakes

NARCIS (Netherlands)

Lammens, E.

1986-01-01

This thesis describes the structure of fish communities in Tjeukemeer (21 km ²) and some other surrounding very eutrophic lakes and emphasizes the interactions of the fishes with each other and their food organisms (predation and (exploitative) competition). It is a compilation of seven

Fish assemblages, connectivity, and habitat rehabilitation in a diked Great Lakes coastal wetland complex

Science.gov (United States)

Kowalski, Kurt P.; Wiley, Michael J.; Wilcox, Douglas A.

2014-01-01

Fish and plant assemblages in the highly modified Crane Creek coastal wetland complex of Lake Erie were sampled to characterize their spatial and seasonal patterns and to examine the implications of the hydrologic connection of diked wetland units to Lake Erie. Fyke netting captured 52 species and an abundance of fish in the Lake Erie–connected wetlands, but fewer than half of those species and much lower numbers and total masses of fish were captured in diked wetland units. Although all wetland units were immediately adjacent to Lake Erie, there were also pronounced differences in water quality and wetland vegetation between the hydrologically isolated and lake-connected wetlands. Large seasonal variations in fish assemblage composition and biomass were observed in connected wetland units but not in disconnected units. Reestablishment of hydrologic connectivity in diked wetland units would allow coastal Lake Erie fish to use these vegetated habitats seasonally, although connectivity does appear to pose some risks, such as the expansion of invasive plants and localized reductions in water quality. Periodic isolation and drawdown of the diked units could still be used to mimic intermediate levels of disturbance and manage invasive wetland vegetation.

ECONOMETRIC MODELLING OD THE INFLUENCE OF LAKE WATER QUALITY CHANGES ON FISHING ECONOMY

Directory of Open Access Journals (Sweden)

Marek Antoni Ramczyk

2017-06-01

Full Text Available The econometric model can be a precise instrument for the analysis of the impact of the natural environment's degradation on fishing economy. This paper aims at analysing the influence of the water quality changes in lake Charzykowskie on the fishing economy. This dissertation present the results of a research on the lake water pollution's impact on fishing economy. The economic-ecological models have been constructed, explaining the changes of economic effects of the lake fishery in the conditions of an increasing water pollution in the epilimnion on the example of the catch of Rutilus rutilus, Abramis brama, Blicca bjoerkna, Coregonus albula, Coregonus lavaretus, Anguilla anguilla and Esox lucius in Lake Charzykowskie. Performed empirical research looked into the influence of the environmental factors on the size of fish catch. Calculations and analysis show clearly that though the habitat factors do influence the catch size of each studied fish species, they do it with different intensity and in various combinations. Both lake water quality and climate factors changes cause measurable effects on fishing industry of lake Charzykowskie. Among all the examined Rutilus rutilus, Abramis brama and Blicca bjoerkna the highest environmental requirements concerning water quality has Blicca bjoerkna. Whereas Abramis brama has slightly higher environmental requirements than Rutilus rutilus. Empirical calculations showed as well that Coregonus albula and Coregonus lavaretus have considerably higher water cleanness requirements than Rutilus rutilus, Abramis brama and Blicca bjoerkna. While when talking about Rutilus rutilus, Abramis brama and Blicca bjoerkna, most water characteristics still rather stimulated these species' development, when it comes to Coregonus albula and Coregonus lavaretus, in general they suppressed their development. The model has also proved quite high habitat requierements of Anquilla anquilla and correctness of the thesis that

Challenges for Sustainable Use of the Fish Resources from Lake Balkhash, a Fragile Lake in an Arid Ecosystem

Directory of Open Access Journals (Sweden)

Steven G. Pueppke

2018-04-01

Full Text Available Lake Balkhash is the largest water body in Central Asia. More than three-quarters of its inflow comes from the Ili River, which is under increasing strain due to the diversion of water for energy and food production. Commercial fishing in Lake Balkhash began in 1929 and is currently in a state of crisis. The construction of the Balkhash dam and reservoir in the late 1960s reduced Ili River flows into the lake and upset the natural cycle of spring floods, which greatly reduced spawning and feeding areas for carp (Cyprinus carpio. Carp populations were consequently reduced by more than 90% during the filling of the reservoir and have not recovered, even though the lake’s level subsequently rose. Catches of carp and freshwater bream (Abramis brama orientalis have shown an inverse relationship since the 1960s, and the age structure of freshwater bream is changing. Historically, most captured fish of this species were 4- to 7-years-old, but smaller, 3- to 5-year-old fish have dominated recent catches. The total fish harvest from Lake Balkhash is currently at near historical lows, not just because of environmental factors, but also because of structural changes triggered by the collapse of the Soviet Union. Poaching, government disinterest, lack of enforcement of fishing regulations, and the economic challenges faced by today’s small fishing enterprises all contribute to the problem.

Local fish extinction in a small tropical lake in Brazil

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Paulo dos Santos Pompeu

Full Text Available Lagoa Santa is a shallow permanent lake, located in Belo Horizonte metropolitan region, Brazil. In this study, the loss in fish diversity of the lake over the past 150 years is evaluated. Local extinction of almost 70% of the original fish fauna is described. Probably, the main causes of this richness loss were: obstruction of natural communication with rio das Velhas, non-native species introduction, change in the water level, organic pollution, and elimination of littoral and submerged vegetation.

Water quality and fish dynamics in forested wetlands associated with an oxbow lake

Science.gov (United States)

Andrews, Caroline S.; Miranda, Leandro E.; Kroger, Robert

2015-01-01

Forested wetlands represent some of the most distinct environments in the Lower Mississippi Alluvial Valley. Depending on season, water in forested wetlands can be warm, stagnant, and oxygen-depleted, yet may support high fish diversity. Fish assemblages in forested wetlands are not well studied because of difficulties in sampling heavily structured environments. During the April–July period, we surveyed and compared the water quality and assemblages of small fish in a margin wetland (forested fringe along a lake shore), contiguous wetland (forested wetland adjacent to a lake), and the open water of an oxbow lake. Dissolved-oxygen levels measured hourly 0.5 m below the surface were higher in the open water than in either of the forested wetlands. Despite reduced water quality, fish-species richness and catch rates estimated with light traps were greater in the forested wetlands than in the open water. The forested wetlands supported large numbers of fish and unique fish assemblages that included some rare species, likely because of their structural complexity. Programs developed to refine agricultural practices, preserve riparian zones, and restore lakes should include guidance to protect and reestablish forested wetlands.

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

Transactional sex in the fishing communities along Lake Victoria ...

African Journals Online (AJOL)

The study describes the nature, context and implications of a unique form of transactional sexual relationships in the fishing communities along Lake Victoria in Kisumu County, Kenya. We conducted 12 focus group discussions and 17 key informant interviews among fishermen, fishmongers and fish transporters in Kisumu.

Methylmercury exposure in a subsistence fishing community in Lake Chapala, Mexico: an ecological approach

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Abercrombie Mary I

2010-01-01

Full Text Available Abstract Background Elevated concentrations of mercury have been documented in fish in Lake Chapala in central Mexico, an area that is home to a large subsistence fishing community. However, neither the extent of human mercury exposure nor its sources and routes have been elucidated. Methods Total mercury concentrations were measured in samples of fish from Lake Chapala; in sections of sediment cores from the delta of Rio Lerma, the major tributary to the lake; and in a series of suspended-particle samples collected at sites from the mouth of the Lerma to mid-Lake. A cross-sectional survey of 92 women ranging in age from 18-45 years was conducted in three communities along the Lake to investigate the relationship between fish consumption and hair mercury concentrations among women of child-bearing age. Results Highest concentrations of mercury in fish samples were found in carp (mean 0.87 ppm. Sediment data suggest a pattern of moderate ongoing contamination. Analyses of particles filtered from the water column showed highest concentrations of mercury near the mouth of the Lerma. In the human study, 27.2% of women had >1 ppm hair mercury. On multivariable analysis, carp consumption and consumption of fish purchased or captured from Lake Chapala were both associated with significantly higher mean hair mercury concentrations. Conclusions Our preliminary data indicate that, despite a moderate level of contamination in recent sediments and suspended particulate matter, carp in Lake Chapala contain mercury concentrations of concern for local fish consumers. Consumption of carp appears to contribute significantly to body burden in this population. Further studies of the consequences of prenatal exposure for child neurodevelopment are being initiated.

MERGANSER - A Predictive Model of Mercury in Fish and Loons in New England Lakes

Science.gov (United States)

Moore, R. B.; Shanley, J. B.; Smith, R. A.; Miller, E. K.; Simcox, A.; Kamman, N. C.; Nacci, D. E.; Robinson, K. W.; Johnston, J. M.; Hughes, M.; Johnston, C. M.; Williams, K.; Graham, J.; King, S.

2010-12-01

MERGANSER (MERcury Geo-spatial AssessmeNtS for the New England Region) is an empirical least squares multiple regression model using atmospheric deposition of mercury (Hg) and readily obtainable lake and watershed features to predict fish and common loon Hg in New England lakes. We modeled lakes larger than 8 ha and with drainage area completely within the USA (4404 lakes), using 3827 fish (12 species) and loon Hg values from 420 lakes. MERGANSER predictor variables included Hg deposition, watershed alkalinity, percent wetlands, percent forest canopy, percent agriculture, drainage area, population, mean annual temperature and watershed slope. The model returns fish tissue or loon blood Hg for user-entered species and length. MERGANSER explained 63% of the variance in fish fillet and loon Hg concentrations. MERGANSER predicted that 32-cm small mouth bass had a median Hg concentration of 0.53 µg g-1 and exceeded EPA’s maximum contaminant level (MCL) of 0.3 µg/g Hg in 90% of New England lakes. Common loon had a median Hg concentration of 1.07 µg g-1 and was in the moderate or higher risk category of >1 µg/g Hg in 58% of New England lakes.

Radiocaesium in lake fishes - pre and post Chernobyl evaluation of transfer factors from deposition

International Nuclear Information System (INIS)

Dominici, G.; Malvicini, A.

1991-01-01

The amounts and concentration of radiocaesium in fishes and in lake water, taken from major lakes in the Varese region for the periods pre and post Chernobyl are reported. Some relationships are obtained which permit to forecast the intake on behalf of the fishes knowing the quantity of radioactivity entering into the lake bed. (15 tabs; 18 figs)

Hierarchy in factors affecting fish biodiversity in floodplain lakes of the Mississippi Alluvial Valley

Science.gov (United States)

Dembkowski, D.J.; Miranda, L.E.

2012-01-01

River-floodplain ecosystems offer some of the most diverse and dynamic environments in the world. Accordingly, floodplain habitats harbor diverse fish assemblages. Fish biodiversity in floodplain lakes may be influenced by multiple variables operating on disparate scales, and these variables may exhibit a hierarchical organization depending on whether one variable governs another. In this study, we examined the interaction between primary variables descriptive of floodplain lake large-scale features, suites of secondary variables descriptive of water quality and primary productivity, and a set of tertiary variables descriptive of fish biodiversity across a range of floodplain lakes in the Mississippi Alluvial Valley of Mississippi and Arkansas (USA). Lakes varied considerably in their representation of primary, secondary, and tertiary variables. Multivariate direct gradient analyses indicated that lake maximum depth and the percentage of agricultural land surrounding a lake were the most important factors controlling variation in suites of secondary and tertiary variables, followed to a lesser extent by lake surface area. Fish biodiversity was generally greatest in large, deep lakes with lower proportions of watershed agricultural land. Our results may help foster a holistic approach to floodplain lake management and suggest the framework for a feedback model wherein primary variables can be manipulated for conservation and restoration purposes and secondary and tertiary variables can be used to monitor the success of such efforts. ?? 2011 Springer Science+Business Media B.V.

A Bottom-Up Understanding of Illegal, Unreported, and Unregulated Fishing in Lake Victoria

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Joseph Luomba

2016-10-01

Full Text Available Illegal, unreported, and unregulated (IUU fishing is a major concern in fisheries management around the world. Several measures have been taken to address the problem. In Lake Victoria, the alleviation of IUU fishing is implemented through the Regional Plan of Action (RPOA-IUU, which restricts use of certain fishing gear, as well as prohibits fishing in closed areas and during closed seasons. Despite the long-term efforts to monitor and control what goes on in the fisheries, IUU fishing has persisted in Lake Victoria. Inspired by interactive governance theory, this paper argues that the persistence of IUU fishing could be due to different images that stakeholders have about the situation, rather than the lack of management competency. Through structured interviews with 150 fisheries stakeholders on Ijinga Island in the southeastern part of Lake Victoria, Tanzania, using paired comparison questionnaires, the study elicits stakeholders’ perspective about the severity of different locally-pertinent fishing-related activities. The results show that while fisheries stakeholder groups agree on their judgments about certain fishing gears, some differences are also apparent. For instance, fisheries managers and scientists do not always agree with fishing people about what activities cause the most damage to fisheries resources and ecosystem. Further, they tend to consider some IUU fishing-related activities less damaging than some non-IUU fishing. Such disparity creates governability challenges, pointing to the need to revisit relevant regulatory measures and to make them consistent with the knowledge and judgments of all stakeholders. Based on these findings, we discuss governing interventions that may contribute to addressing IUU fishing in Lake Victoria and elsewhere.

Urbanization is a major influence on microplastic ingestion by sunfish in the Brazos River Basin, Central Texas, USA.

Science.gov (United States)

Peters, Colleen A; Bratton, Susan P

2016-03-01

Microplastics, degraded and weathered polymer-based particles, and manufactured products ranging between 50 and 5000 μm in size, are found within marine, freshwater, and estuarine environments. While numerous peer-reviewed papers have quantified the ingestion of microplastics by marine vertebrates, relatively few studies have focused on microplastic ingestion by freshwater organisms. This study documents microplastic and manufactured fiber ingestion by bluegill (Lepomis macrochirus) and longear (Lepomis megalotis) sunfish (Centrarchidae) from the Brazos River Basin, between Lake Whitney and Marlin, Texas, USA. Fourteen sample sites were studied and categorized into urban, downstream, and upstream areas. A total of 436 sunfish were collected, and 196 (45%) stomachs contained microplastics. Four percent (4%) of items sampled were debris on the macro size scale (i.e. >5 mm) and consisted of masses of plastic, metal, Styrofoam, or fishing material, while 96% of items sampled were in the form of microplastic threads. Fish length was statistically correlated to the number of microplastics detected (p = 0.019). Fish collected from urban sites displayed the highest mean number of microplastics ingested, followed by downstream and upstream sites. Microplastics were associated with the ingestion of other debris items (e.g. sand and wood) and correlated to the ingestion of fish eggs, earthworms, and mollusks, suggesting that sunfish incidentally ingest microplastics during their normal feeding methods. The high frequency of microplastic ingestion suggest that further research is needed to determine the residence time of microplastics within the stomach and gut, potential for food web transfer, and adverse effects on wildlife and ecosystemic health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of microcystins in lake water and fish (Mugilidae, Liza sp.) in the largest Spanish coastal lake.

Science.gov (United States)

Romo, Susana; Fernández, Francisca; Ouahid, Youness; Barón-Sola, Ángel

2012-01-01

Cyanobacteria dominance and cyanotoxin production can become major threats to humans and aquatic life, especially in warm shallow lakes, which are often dominated by cyanobacteria. This study investigates the occurrence and distribution of microcystins (MCYST) in water, cell-bound and in the tissues of the commercial mugilid Liza sp. in the largest, coastal, Spanish Mediterranean lake (Albufera of Valencia). This is the first report concerning microcystin accumulation in tissues of mugilid fish species. Considerable amounts of microcystins were found in the water and seston, which correlated with development of Microcystis aeruginosa populations in the lake. The MCYST concentrations found in Lake Albufera (mean 1.7 and 17 μg/L and maximum 16 and 120 μg/L in water and seston, respectively) exceeded by one to two orders of magnitude the guideline levels proposed by the World Health Organization and were higher than that reported in other lakes of the Mediterranean zone. The presence of MCYST was found in all the fishes studied and accumulated differently among tissues of the commercial species Liza sp. Toxin accumulation in fish tissues showed that although the target organ for MCYST was the liver, high concentrations of microcystins were also found in other analysed tissues (liver>intestine>gills>muscle). Human tolerable daily intake for microcystins is assessed relative to the WHO guidelines, and potential toxicological risks for humans, wildlife and related ecosystems of the lake are discussed.

Fish otolith geochemistry, environmental conditions and human occupation at Lake Mungo, Australia

Science.gov (United States)

Long, Kelsie; Stern, Nicola; Williams, Ian S.; Kinsley, Les; Wood, Rachel; Sporcic, Katarina; Smith, Tegan; Fallon, Stewart; Kokkonen, Harri; Moffat, Ian; Grün, Rainer

2014-03-01

Fish otoliths from the Willandra Lakes Region World Heritage Area (south-western New South Wales, Australia) have been analysed for oxygen isotopes and trace elements using in situ techniques, and dated by radiocarbon. The study focused on the lunettes of Lake Mungo, an overflow lake that only filled during flooding events and emptied by evaporation, and Lake Mulurulu, which was part of the running Willandra Creek system. Samples were collected from two different contexts: from hearths directly associated with human activity, and isolated surface finds. AMS radiocarbon dating constrains the human activity documented by five different hearths to a time span of less than 240 years around 19,350 cal. BP. These hearths were constructed in aeolian sediments with alternating clay and sand layers, indicative of fluctuating lake levels and occasional drying out. The geochemistry of the otoliths confirms this scenario, with shifts in Sr/Ca and Ba/Ca marking the entry of the fish into Lake Mungo several years before their death, and a subsequent increase in the δ18O by ˜4‰ indicating increasing evaporation of the lake. During sustained lake-full conditions there are considerably fewer traces of human presence. It seems that the evaporating Lake Mungo attracted people to harvest fish that might have become sluggish through oxygen starvation in an increasingly saline water body (easy prey hypothesis). In contrast, surface finds have a much wider range in radiocarbon age as a result of reworking, and do not necessarily indicate evaporative conditions, as shown by comparison with otoliths from upstream Lake Mulurulu.

The impact of fish predation and cyanobacteria on zooplankton size structure in 96 subtropical lakes.

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Jing Zhang

Full Text Available Zooplankton are relatively small in size in the subtropical regions. This characteristic has been attributed to intense predation pressure, high nutrient loading and cyanobacterial biomass. To provide further information on the effect of predation and cyanobacteria on zooplankton size structure, we analyzed data from 96 shallow aquaculture lakes along the Yangtze River. Contrary to former studies, both principal components analysis and multiple regression analysis showed that the mean zooplankton size was positively related to fish yield. The studied lakes were grouped into three types, namely, natural fishing lakes with low nutrient loading (Type1, planktivorous fish-dominated lakes (Type 2, and eutrophic lakes with high cyanobacterial biomass (Type 3. A marked difference in zooplankton size structure was found among these groups. The greatest mean zooplankton size was observed in Type 2 lakes, but zooplankton density was the lowest. Zooplankton abundance was highest in Type 3 lakes and increased with increasing cyanobacterial biomass. Zooplankton mean size was negatively correlated with cyanobacterial biomass. No obvious trends were found in Type 1 lakes. These results were reflected by the normalized biomass size spectrum, which showed a unimodal shape with a peak at medium sizes in Type 2 lakes and a peak at small sizes in Type 3 lakes. These results indicated a relative increase in medium-sized and small-sized species in Types 2 and 3 lakes, respectively. Our results suggested that fish predation might have a negative effect on zooplankton abundance but a positive effect on zooplankton size structure. High cyanobacterial biomass most likely caused a decline in the zooplankton size and encouraged the proliferation of small zooplankton. We suggest that both planktivorous fish and cyanobacteria have substantial effects on the shaping of zooplankton community, particularly in the lakes in the eastern plain along the Yangtze River where

Mercury Dynamics in Aquatic Food Webs of the Finger Lakes, New York

Science.gov (United States)

Cleckner, L.; Razavi, N. R.; Halfman, J. D.; Cushman, S. F.; Foust, J.; Gilman, B.

2016-12-01

Mercury (Hg) contamination of fish is a global concern due to the deleterious health effects in humans and wildlife associated with ingesting fish with elevated concentrations. A key to understanding elevated fish Hg concentrations is to examine methyl Hg dynamics at the base of food webs, including algae and zooplankton. Predicting determinants of methyl Hg concentrations in lower trophic level biota remains an active area of research. This study was conducted to assess Hg concentrations in biota of the Finger Lakes (New York, USA), a region where fisheries are an important economic driver, but where no comprehensive assessment of food web Hg dynamics has been completed to date. Sources of Hg in the region include atmospheric pollution from an active coal-fired power plant. The objectives of this study were to: 1) determine if fish Hg concentrations were of concern, 2) assess differences in Hg accumulation among lakes and determine predictors of fish Hg concentrations, and 3) evaluate the predictive power of monthly zooplankton methyl Hg concentrations on fish Hg concentrations. From May - October 2015, suspended particulate matter, zooplankton, and benthos were sampled monthly in five of the Finger Lakes (Honeoye, Canandaigua, Seneca, Cayuga, and Owasco Lakes). Fish were sampled once over the same study period and species were targeted from all trophic levels. Results for top predatory fish including Lake Trout (Salvelinus namaycush), Largemouth Bass (Micropterus salmoides), and Walleye (Sander vitreus) showed significant differences among lakes, and elevated concentrations are above US Environmental Protection Agency's screening value (300 ng/g wet weight). No clear pattern in Hg levels among lakes was evident in lower trophic level fishes such as Yellow Perch (Perca flavescens) and Golden Shiner (Notemigonus crysoleucas), but concentrations were low. Benthivorous Brown Bullhead (Ameiurus nebulosus) exhibited significant differences in Hg among lakes with

Ecology, fish and fishery of Lake Liambezi, a recently refilled ...

African Journals Online (AJOL)

Lake Liambezi (300 km2) refilled in 2009 after a prolonged 22-year dry period. Its aquatic macrophyte populations, fish fauna and fishery shortly after refilling are described. The emergent aquatic macrophyte Phragmites australis formed dense stands covering large parts of the lake, while extensive beds of submerged ...

Metal bioavailability and toxicity to fish in low-alkalinity lakes: A critical review

Science.gov (United States)

Spry, D.J.; Wiener, James G.

1991-01-01

Fish in low-alkalinity lakes having pH of 6·0–6·5 or less often have higher body or tissue burdens of mercury, cadmium, and lead than do fish in nearby lakes with higher pH. The greater bioaccumulation of these metals in such waters seems to result partly from the greater aqueous abundances of biologically available forms (CH3 Hg+, Cd2+, and Pb2+) at low pH. In addition, the low concentrations of aqueous calcium in low-alkalinity lakes increase the permeability of biological membranes to these metals, which in fish may cause greater uptake from both water and food. Fish exposed to aqueous inorganic aluminum in the laboratory and field accumulate the metal in and on the epithelial cells of the gills; however, there is little accumulation of aluminum in the blood or internal organs. In low-pH water, both sublethal and lethal toxicity of aluminum has been clearly demonstrated in both laboratory and field studies at environmental concentrations. In contrast, recently measured aqueous concentrations of total mercury, methylmercury, cadmium, and lead in low-alkalinity lakes are much lower than the aqueous concentrations known to cause acute or chronic toxicity in fish, although the vast majority of toxicological research has involved waters with much higher ionic strength than that in low-alkalinity lakes. Additional work with fish is needed to better assess (1) the toxicity of aqueous metals in low-alkalinity waters, and (2) the toxicological significance of dietary methylmercury and cadmium.

Remedial measures against high levels of radioactive cesium in Swedish lake fish

International Nuclear Information System (INIS)

Andersson, T.; Nilsson, Aa.; Haakanson, L.; Kvarnaes, H.

1991-01-01

The Swedish Radiation Protection Institute (SSI) has provided funds for the testing of methods to reduce the concentration of radioactive cesium in fish. The main purpose of this report is to present to remedies tested and to give an account of the effect they had on the concentration of Cs-137 in fish. In addition, analyses are made of the lake-specific factors contributing to the Cs-uptake in fish in the tested lakes. The time interval between the remedies adopted and the latest fish analyses (about 2 years on average) is not sufficient to statistically establish the small effects of the remedies. A longer time series of data is required for this

Mercury in sediment, water, and fish in a managed tropical wetland-lake ecosystem.

Science.gov (United States)

Malczyk, Evan A; Branfireun, Brian A

2015-08-15

Mercury pollution has not been well documented in the inland lakes or fishes of Mexico, despite the importance of freshwater fish as a source of protein in local diets. Total mercury and methylmercury in waters, sediments, and the commercial fish catch were investigated in Lake Zapotlán, Mexico. Concentrations of total and methylmercury were very high in runoff and wastewater inputs, but very low in sediments and surface waters of the open water area of the lake. Concentrations of total mercury in tilapia and carp were very low, consistent with the low concentrations in lake water and sediments. Particle settling, sorption, the biogeochemical environment, and/or bloom dilution are all plausible explanations for the significant reductions in both total mercury and methylmercury. Despite very high loading of mercury, this shallow tropical lake was not a mercury-impaired ecosystem, and these findings may translate across other shallow, alkaline tropical lakes. Importantly, the ecosystem services that seemed to be provided by peripheral wetlands in reducing mercury inputs highlight the potential for wetland conservation or restoration in Mexico. Copyright © 2015. Published by Elsevier B.V.

Women's independent access to productive resources: fish ponds in the Oxbow Lakes Project, Bangladesh.

Science.gov (United States)

Nathan, D; Apu, N A

1998-01-01

This article analyzes the experiences of women in acquiring user rights to fish ponds on government owned lands in the Oxbow Lakes Project in Bangladesh. The analysis describes the significance, functioning, and problems of women in fish farming. The field reports were based on the authors' involvement in implementation of the extension of fishing rights to women during 6 weeks/year over 4 years. Analysis was based on observations and discussions during project implementation and on a survey conducted in March 1997. The project involved land reforms that transferred rights to a group of poor people. Most of the lakes had been overfished. The poor fishers were organized into Lake Fishing Teams (LFTs) with the right to culture and harvest fish in lakes that were under common property management. In late 1994, at least 50% of the women were included in the Fish Farming Groups (FFGs) to manage fish culture in ponds constructed in shallow areas of the lake shore. The proportion of women was increased to 75% in 1994-95 and favored women-headed households. By March 1997, there were 510 members of FFGs, of whom 84% were single, poor women. Women had low participation in fish sales and netting and guarding the harvest. Women in mixed gender groups complained that men dominated the key decision-making and financial areas. Production averaged 1500 kg/hectare in 1995-96. FFGs had higher expenses for feed and fertilizer than LFTs. This endeavor earned higher per capita income than poultry raising. All women groups performed better than mixed groups. These groups increased assertiveness and self-confidence.

A synthesis of ecological and fish-community changes in Lake Ontario, 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.

2005-01-01

We assessed stressors associated with ecological and fishcommunity changes in Lake Ontario since 1970, when the first symposium on Salmonid Communities in Oligotrophic Lakes (SCOL I) was held (J. Fish. Res. Board Can. 29: 613-616). Phosphorus controls implemented in the early 1970s were undeniably successful; lower food-web studies showed declines in algal abundance and epilimnetic zooplankton production and a shift in pelagic primary productivity toward smaller organisms. Stressors on the fish community prior to 1970 such as exploitation, sea lamprey (Petromyzon marinus) predation, and effects of nuisance populations of alewife (Alosa pseudoharengus) were largely ameliorated by the 1990s. The alewife became a pivotal species supporting a multi-million-dollar salmonid sport fishery, but alewife-induced thiamine deficiency continued to hamper restoration and sustainability of native lake trout (Salvelinus namaycush). Expanding salmonine populations dependent on alewife raised concerns about predator demand and prey supply, leading to reductions in salmonine stocking in the early 1990s. Relaxation of the predation impact by alewives and their shift to deeper water allowed recovery of native fishes such as threespine stickleback (Gasterosteus aculeatus) and emerald shiner (Notropis atherinoides). The return of the Lake Ontario ecosystem to historical conditions has been impeded by unplanned introductions. Establishment of Dreissena spp. led to increased water clarity and increased vectoring of lower trophic-level production to benthic habitats and contributed to the collapse of Diporeia spp. populations, behavioral modifications of key fish species, and the decline of native lake whitefish (Coregonus clupeaformis). Despite reduced productivity, exotic-species introductions, and changes in the fish community, offshore Mysis relicta populations remained relatively stable. The effects of climate and climate change on the population abundance and dynamics of Lake Ontario

Long-term effects of extreme weather events and eutrophication on the fish community of shallow Lake Peipsi (Estonia/Russia

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Külli Kangur

2013-06-01

Full Text Available The fish kill in lake Peipsi (Estonia/Russia during the extraordinarily hot summer of 2010 evoked an investigation into the effects of environmental extremes and long-term eutrophication on the fish community of the lake. Current data on lake Peipsi indicate that temperature extremes and synergistic interactions with eutrophication have led to a radical restructuring of the fish community. Commercial landings of lake smelt, Osmerus eperlanus eperlanus m. spirinchus (Pallas, the previous dominant species of the fish community, have decreased dramatically since the 1930s, these declines being coupled with summer heat waves coinciding with low water levels. Gradual decline in smelt stock and catches was significantly related to a decline of near-bottom oxygen conditions and to a decrease in water transparency. The first documented fish kill in 1959 occurred only in the southern, most shallow and eutrophic lake (lake Pihkva. Recently, summer fish kill have become more frequent, involving larger areas of the lake. In addition to the cold-water species, e.g. smelt and vendace Coregonus albula (L., the abundance of bottom-dwelling fishes such as ruffe Gymnocephalus cernuus (L. and juvenile fish have significantly decreased after the 2010 heat wave probably due to hypoxia and warm water temperatures. This study showed that fish community structure in large shallow lakes may be very vulnerable to water temperature increases, especially temperature extremes in combination with eutrophication.

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.

Size Distribution and Growth of Young Payangka Fish, Ophieleotris Aporos (Bleeker) From Lake Tondano

OpenAIRE

Susanto, Mayangsari Kimberli; Bataragoa, Nego E; Moningkey, Ruddy D

2017-01-01

The research was conducted at the location of Lake Tondano, Minahasa District.The young payangka fish, locally known as nike fish by fishermen of the area. This study aims to determine the size distribution, length-weight relationships and to know the captivity growth in the aquarium. The research is expected to be a source of information about the fish of young payangka (Nike) and be able to contribute on the efforts of nike fish management in Lake Tondano for the future. Sampling is done by...

Impact of cooling systems on Lake Michigan fishes

International Nuclear Information System (INIS)

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

1976-01-01

A comparison of data on fish mortalities due to impingement at thermal power plant water intakes on Lake Michigan with available estimates of standing crop biomass, commercial and sport fishery catches, and estimated predation mortality is presented. The striking features of these data are the proportions of total mortality due to predation and the lack of accurate basic population statistics such as standing crop biomass and natural mortality for important forage and human food fishes in Lake Michigan. Although this preliminary assessment would indicate that power plant and total impingement losses constitute an insignificant fraction of total forage biomass, the potentially unstable forage-predator ratios and the apparent high degree of annual fluctuations (year-classes) in alewife, smelt, and perch indicate the need for a more detailed assessment of cooling-system related impact on selected populations

Assessment methodology for new cooling lakes. Volume 2. Development of empirical multivariate relationships for evaluating fish communities in new cooling lakes. Final report

International Nuclear Information System (INIS)

Grieb, T.M.; Porcella, D.B.; Ginn, T.C.; Lorenzen, M.W.

1983-02-01

Numerical classification techniques were used to define groups of lakes with distinct fish community attributes. Simple linear and multiple regression were then used to identify the important environmental variables affecting the fish communities. Next, the multivariate statistical technique of discriminant analysis was tested and shown to predict the groups of lakes (defined in the initial step of classification) using the identified environmental variables. Classification equations derived in the discriminant analysis enable the user to predict fish community characteristics of a new lake. The equations combine the information from nine limnological parameters into a single index of classification. Based on the value of this index, the lake is classified into one of four distinct groups. The fishery characteristics of the indicated group are then used to predict fish community structure and recreational fishery use. Angler-use estimates for the group are used to project multiple use benefits

Temporal and spatial variation of fish assemblages in Dianshan Lake, Shanghai, China

Science.gov (United States)

Hu, Zhongjun; Wang, Siqing; Wu, Hao; Chen, Qingjiang; Ruan, Renliang; Chen, Liqiao; Liu, Qigen

2014-07-01

Using multi-mesh gillnets and trawls, the fish communities in Dianshan Lake at 6 stations from Oct. 2009 to Jul. 2010 were investigated seasonally to reveal the biodiversity and its spatial and temporal distribution patterns. The long-term changes in their structural characteristics were then analyzed to identify the main influencing factors and several measures for lake restoration were put forward. Thirty six species, belonging to 9 family and 30 genera, were collected, amongst which, the order Cypriniformes accounted for 61.1% of the total species number. In terms of importance value, Cypriniformes was the predominant group, Coilia nasus the dominant species, while Cyprinus carpio and Rhinogobius giurinus were the subdominant taxa. The community types did not differ among stations, but between seasons. There were no significant differences between seasons and among stations in species diversity, but richness differed both spatially and seasonally. Along with the process of eutrophication and the drastic reduction of the area colonized by macrophytes from 1959 to 2009-2010, the fish diversity declined markedly, and species numbers of herbivores and piscivores declined proportionately more than those of invertivores, omnivores, and planktivores. The decline of potamophilus and river-lake migratory fish was more marked than those of sedentary, river-sea migratory, and estuarine fishes. Eutrophication concomitant with sharp reduction of macrophyte area and overfishing may be the main reasons for the decline in fish diversity in Dianshan Lake.

Disentangling the effects of a century of eutrophication and climate warming on freshwater lake fish assemblages.

Directory of Open Access Journals (Sweden)

Peter C Jacobson

Full Text Available Eutrophication and climate warming are profoundly affecting fish in many freshwater lakes. Understanding the specific effects of these stressors is critical for development of effective adaptation and remediation strategies for conserving fish populations in a changing environment. Ecological niche models that incorporated the individual effects of nutrient concentration and climate were developed for 25 species of fish sampled in standard gillnet surveys from 1,577 Minnesota lakes. Lake phosphorus concentrations and climates were hindcasted to a pre-disturbance period of 1896-1925 using existing land use models and historical temperature data. Then historical fish assemblages were reconstructed using the ecological niche models. Substantial changes were noted when reconstructed fish assemblages were compared to those from the contemporary period (1981-2010. Disentangling the sometimes opposing, sometimes compounding, effects of eutrophication and climate warming was critical for understanding changes in fish assemblages. Reconstructed abundances of eutrophication-tolerant, warmwater taxa increased in prairie lakes that experienced significant eutrophication and climate warming. Eutrophication-intolerant, warmwater taxa abundance increased in forest lakes where primarily climate warming was the stressor. Coolwater fish declined in abundance in both ecoregions. Large changes in modeled abundance occurred when the effects of both climate and eutrophication operated in the same direction for some species. Conversely, the effects of climate warming and eutrophication operated in opposing directions for other species and dampened net changes in abundance. Quantifying the specific effects of climate and eutrophication will allow water resource managers to better understand how lakes have changed and provide expectations for sustainable fish assemblages in the future.

Contaminants in fish tissue from US lakes and reservoirs: A national probabilistic study

Science.gov (United States)

An unequal probability design was used to develop national estimates for 268 persistent, bioaccumulative, and toxic chemicals in fish tissue from lakes and reservoirs of the conterminous United States (excluding the Laurentian Great Lakes and Great Salt Lake). Predator (fillet) ...

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.

Mitigation options for fish kills in L Lake and Pond C

International Nuclear Information System (INIS)

Paller, M.H.

1989-11-01

This report concerns mitigation options for reducing or eliminating the fish kills that occur in L Lake and Pond C as a result of reactor operations. These kills occur when fish that have entered the discharge areas during outages are killed by the rapid rises in temperature that follow reactor re-starts. Factors that have been observed to influence the severity of the kills include the length of the outage, season during which the outage occurs, reactor power level, and size of the fish in the discharge area. Without mitigation, fish kills can be expected to occur in Pond C with approximately the same frequency and severity as in the past. Even in the absence of mitigation, however, it is unlikely that future fish kills in L Lake will be as severe as the large kill that occurred in December 1986. Fish abundance in Region 2 of L Lake (where severe kills occurred in the past) has declined over 90% since 1986, largely due to a reduction in the abundance of juvenile sunfish (which constituted approximately 99% of past kills). There are basically three categories of mitigation options: changes in reactor operations, methods to exclude fish from time discharge areas, and methods to promote the escapement of fish from the discharge area. These options vary in approach, scope, and anticipated expense. Most would need to be researched in greater depth before it would be possible to predict their effectiveness more definitively. While the options have the potential to greatly reduce mortalities, none can totally eliminate mortalities. The only way of ensuring the elimination of all mortalities is to reduce effluent temperatures to sublethal levels with properly designed and operated cooling technology. 18 refs., 2 figs., 1 tab

Non-indigenous invertebrates, fish and macrophytes in Lake Garda (Italy

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Cristina CAPPELLETTI

2011-08-01

Full Text Available As observed in many countries, lakes are involved in an important process of colonization by non-indigenous species (NIS. Since 1725, 37 species of non-indigenous fish, invertebrates and macrophytes have been recorded in Lake Garda, the largest Italian lake. This phenomenon is particularly important for invertebrates and macrophytes, as their pathways of introduction are accidental. Recently among the 100 Worst Invasive Alien Species in Europe, the invertebrates Corbicula fluminea, Dikerogammarus villosus and Procambarus clarkii, and the macrophytes Lagarosiphon major, Elodea nuttallii and Elodea canadensis have been recorded in Lake Garda. In order to define the present status of non-indigenous species in Lake Garda, published and unpublished data were reviewed.

Herbivory of Omnivorous Fish Shapes the Food Web Structure of a Chinese Tropical Eutrophic Lake: Evidence from Stable Isotope and Fish Gut Content Analyses

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Jian Gao

2017-01-01

Full Text Available Studies suggest that, unlike the situation in temperate lakes, high biomasses of omnivorous fish are maintained in subtropical and tropical lakes when they shift from a turbid phytoplankton-dominated state to a clear water macrophyte-dominated state, and the predation pressure on large-bodied zooplankton therefore remains high. Whether this reflects a higher degree of herbivory in warm lakes than in temperate lakes is debatable. We combined food web studies using stable isotopes with gut content analyses of the most dominant fish species to elucidate similarities and differences in food web structure between a clear water macrophyte-dominated basin (MDB and a turbid phytoplankton-dominated basin (PDB of Huizhou West Lake, a shallow tropical Chinese lake. The δ13C–δ15N biplot of fish and invertebrates revealed community-wide differences in isotope-based metrics of the food webs between MDB and PDB. The range of consumer δ15N (NR was lower in MDB than in PDB, indicating shorter food web length in MDB. The mean nearest neighbor distance (MNND and standard deviation around MNND (SDNND were higher in MDB than in PDB, showing a markedly low fish trophic overlap and a more uneven packing of species in niches in MDB than in PDB. The range of fish δ13C (CR of consumers was more extensive in MDB than in PDB, indicating a wider feeding range for fish in MDB. Mixing model results showed that macrophytes and associated periphyton constituted a large fraction of basal production sources for the fish in MDB, while particulate organic matter (POM contributed a large fraction in PDB. In MDB, the diet of the dominant fish species, crucian carp (Carassius carassius, consisted mainly of vegetal matter (macrophytes and periphyton and zooplankton, while detritus was the most important food item in PDB. Our results suggest that carbon from macrophytes with associated periphyton may constitute an important food resource for omnivorous fish, and this may strongly

Histopathology of feral fish from a PCB-contaminated freshwater lake

Energy Technology Data Exchange (ETDEWEB)

Koponen, Kari; Ritola, Ossi; Huuskonen, Sirpa E.; Lindstroem-Seppae, Pirjo [Univ. of Kuopio (Finland). Dept. of Physiology; Myers, Mark S. [National Oceanic and Atmospheric Administration, Seattle, WA (United States). National Marine Fisheries Service

2001-05-01

The purpose of this study was to evaluate the potential toxic effects of chronic sublethal polychlorinated biphenyl (PCB) exposure on feral fish, using histopathology as an endpoint. Histopathological study of bream (Abramis brama) and asp (Aspius aspius) living in a PCB-polluted freshwater lake revealed abnormal cellular changes in the renal corpuscle of both species. Dilation of glomerular capillaries (DGC), mesangial edema (ME), an adhesion between visceral and parietal layers of Bowman's capsule (ABC), and filling of Bowman's space (FBS), were highly prevalent features in lake fish. The prevalence of each of these lesions was significantly lower, or totally absent in fish caught from reference locations. Cellular alterations in liver, gill, gonads, spleen, and intestine were all linked to seasonal changes. The results suggest that some of the observed histopathological changes in renal glomeruli, particularly DGC and ME, could possibly indicate a prolonged chemical stress caused by PCBs and related compounds. It is also possible that chronic PCB exposure may have suppressed and weakened the immuno systems of exposed fish making them more vulnerable to secondary parasitic infection.

Interconnectedness during high water maintains similarity in fish assemblages of island floodplain lakes in the Amazonian Basin

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Carlos Edwar de C. Freitas

2010-01-01

Full Text Available We conducted a study to test the hypothesis that interconnectedness among island floodplain lakes and the adjacent Solimões River during the flood stage of the hydrologic cycle is enough to maintain similarity in fish species assemblages. Gill net samples were collected during high and low water periods for three consecutive years (July 2004 to July 2006 in four lakes on Paciência Island. Two lakes, Piranha and Ressaca, are connected to the river all year, and the other two, Preto and Cacau, which are in the center of the island, are isolated during low water periods. The abundance, species richness and evenness of the fish assemblages in these lakes did not differ according to their relative positions or the season of the hydrological cycle, which confirmed our hypothesis. However, fish abundance during the dry season was greater than in the flood season. Apparently, the short period of full connection between the lakes is enough to allow the colonization of all fish species, but not to cause similar abundances. Our study indicates that persistence of the species composition of island floodplain lakes is primarily due to the annual replenishment of fish to the lakes during the flood season.

Fishing for improvements: managing fishing by boat on New York City water supply reservoirs and lakes

Science.gov (United States)

Nicole L. Green; Jennifer A. Cairo

2008-01-01

In 2003, the New York City Department of Environmental Protection Bureau of Water Supply undertook a 5-year initiative to improve fishing by boat on its water supply reservoirs and controlled lakes in upstate New York. The project includes: revising administrative procedures; cleaning up boat fishing areas on reservoir shores; improving two-way communication with...

Mercury in fish from three rift valley lakes (Turkana, Naivasha and Baringo), Kenya, East Africa

Energy Technology Data Exchange (ETDEWEB)

Campbell, L.M.; Osano, O.; Hecky, R.E.; Dixon, D.G

2003-09-01

Mercury concentrations in Kenyan fish vary with tropic position but, in general, do not pose an unacceptable risk to human consumers of wildlife. -Total mercury (THg) concentrations were measured for various fish species from Lakes Turkana, Naivasha and Baringo in the rift valley of Kenya. The highest THg concentration (636 ng g{sup -1} wet weight) was measured for a piscivorous tigerfish Hydrocynus forskahlii from Lake Turkana. THg concentrations for the Perciformes species, the Nile perch Lates niloticus from Lake Turkana and the largemouth bass Micropterus salmoides from Lake Naivasha ranged between 4 and 95 ng g{sup -1}. The tilapiine species in all lakes, including the Nile tilapia Oreochromis niloticus, had consistently low THg concentrations ranging between 2 and 25 ng g{sup -1}. In Lake Naivasha, the crayfish species, Procambrus clarkii, had THg concentrations similar to those for the tilapiine species from the same lake, which is consistent with their shared detritivore diet. THg concentrations in all fish species were usually consistent with their known trophic position, with highest concentrations in piscivores and declining in omnivores, insectivores and detritivores. One exception is the detritivore Labeo cylindricus from Lake Baringo, which had surprisingly elevated THg concentrations (mean=75 ng g{sup -1}), which was similar to those for the top trophic species (Clarias and Protopterus) in the same lake. Except for two Hydrocynus forskahlii individuals from Lake Turkana, which had THg concentrations near or above the international marketing limit of 500 ng g{sup -1}, THg concentrations in the fish were generally below those of World Health Organization's recommended limit of 200 ng g{sup -1} for at-risk groups.

Selenium poisoning of fish by coal ash wastewater in Herrington Lake, Kentucky.

Science.gov (United States)

Lemly, A Dennis

2018-04-15

Selenium pollution from the E.W. Brown Electric Generating Station was investigated in Herrington Lake, KY. Coal ash wastewater is discharged as surface water overflow from ash disposal ponds into the lake via a National Pollutant Discharge Elimination System permit issued by the Kentucky Division of Water, but the permit does not restrict or limit the amount of selenium released. Unpermitted discharges occur from seeps and drainage through leaks in ash pond dams. Together, these discharges have resulted in selenium concentrations in water, sediment, benthic macroinvertebrates, and fish that are 2-9 times the level that is toxic for fish reproduction and survival. A large proportion (12.2%, or 25 times background) of juvenile largemouth bass (Micropterus salmoides, the only species examined) exhibited spinal and/or craniofacial malformations that are consistent with selenium poisoning. Teratogenic Deformity Index values indicated a 3.05% population-level impact on the bass fishery, with total selenium-induced mortality (including pre-swimup mortality) estimated to be in excess of 25% per year. These findings confirm that coal ash discharges into Herrington Lake are contributing selenium to the Lake that is poisoning fish. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Nile perch fish processing waste along Lake Victoria in East Africa ...

African Journals Online (AJOL)

In East Africa, Nile perch fish processing into chilled fish fillet for export along Lake Victoria generate large proportions of both solid and liquid wastes. However, no thorough auditing and characterization of the waste has been done that would guide potential value addition through bioconversions and waste management.

Fish abundance and distribution near three heated effluents to Lake Michigan

International Nuclear Information System (INIS)

Spigarelli, S.A.; Goldstein, R.M.; Prepejchal, W.; Thommes, M.M.

1982-01-01

A combined echo location-temperature mapping technique was used to determine the abundance and distribution of fish with depth and temperature in locally heated and unheated areas of Lake Michigan. Surveys were conducted between April and October at two adjacent power plants in the southern basin and at one plant in the northern basin of the lake. Fish densities in plume and reference areas differed seasonally. Densities typically differed by a factor of 2-4 although on one occasion plume area density was 90 times greater. Highest plume densities occurred during late spring when alewife (Alosa pseudoharengus) were spawning inshore. Consistently dense congregations of fish were found downstream of the interfaces between ambient shore-parallel currents and discharge flows. The general distribution of fish with depth was similar in all areas. Differences between plume and reference areas were related to the discharge type: at canal discharges fish tended to congregate inshore while at the offshore discharge they congregated in deeper zones. Fish also tended to occupy shallower depth strata in all plume areas. Positive correlation between fish density and increasing temperature was common at both plume and reference areas during all three seasons, but more frequent at plume areas. Temperatures selected by fish in plume areas were 1-3 0 C higher than maximum ambient temperatures

Spatial Complexity, Resilience, and Policy Diversity: Fishing on Lake-rich Landscapes

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Stephen R. Carpenter

2004-06-01

Full Text Available The dynamics of and policies governing spatially coupled social-ecological mosaics are considered for the case of fisheries in a lake district. A microeconomic model of households addresses agent decisions at three hierarchic levels: (1 selection of the lake district from among a larger set of alternative places to live or visit, (2 selection of a base location within the lake district, and (3 selection of a portfolio of ecosystem services to use. Ecosystem services are represented by dynamics of fish production subject to multiple stable domains and trophic cascades. Policy calculations show that optimal policies will be highly heterogeneous in space and fluid in time. The diversity of possible outcomes is illustrated by simulations for a hypothetical lake district based loosely on the Northern Highlands of the State of Wisconsin. Lake districts are frequently managed as if lakes were independent, similar, endogenously regulating systems. Our findings contradict that view. One-size-fits-all (OSFA policies erode ecological and social resilience. If regulations are too stringent, social resilience declines because of the potential rewards of overharvesting. If regulations are too lax, ecological resilience is diminished by overharvesting in some lakes. In either case, local collapses of fish populations evoke spatial shifts of angling effort that can lead to serial collapses in neighboring fisheries and degraded fisheries in most or all of the lakes. Under OSFA management, the natural resources of the entire landscape become more vulnerable to transformation because of changes in, e.g., human population, the demand for resources, or fish harvesting technology. Multiplicity of management regimes can increase the ecological resilience, social resilience, and inclusive value of a spatially heterogeneous social-ecological system. Because of the complex interactions of mobile people and multistable ecosystems, management regimes must also be flexible

Bottom trawl assessment of Lake Ontario prey fishes

Science.gov (United States)

Weidel, Brian C.; Connerton, Michael J.; Holden, Jeremy

2018-01-01

Managing Lake Ontario fisheries in an ecosystem-context requires prey fish community and population data. Since 1978, multiple annual bottom trawl surveys have quantified prey fish dynamics to inform management relative to published Fish Community Objectives. In 2017, two whole-lake surveys collected 341 bottom trawls (spring: 204, fall: 137), at depths from 8-225m, and captured 751,350 fish from 29 species. Alewife were 90% of the total fish catch while Deepwater Sculpin, Round Goby, and Rainbow Smelt comprised the majority of the remaining total catch (3.8, 3.1, and 1.1% respectively). The adult Alewife abundance index for US waters increased in 2017 relative to 2016, however the index for Canadian waters declined. Adult Alewife condition, assessed by the predicted weight of a 165 mm fish (6.5 inches), declined in 2017 from record high values observed in spring 2016. Spring 2017 Alewife condition was slightly less than the 10-year average, but the fall value was well below the 10-year average, likely due to increased Age-1 Alewife abundance. The Age-1 Alewife abundance index was the highest observed in 40 years, and 8-times higher than the previous year. The Age-1 index estimates Alewife reproductive success the preceding year. The warm summer and winter of 2016 likely contributed to the large year class. In contrast the relatively cool 2017 spring and cold winter may result in a lower than average 2017 year class. Abundance indices for Rainbow Smelt, Cisco, and Emerald Shiner either declined or remained at low levels in 2017. Pelagic prey fish diversity continues to be low since a single species, Alewife, dominates the catch. Deepwater Sculpin were the most abundant benthic prey fish in 2017 because Round Goby abundance declined sharply from 2016. Slimy Sculpin density continued to decline and the 2017 biomass index for US waters was the lowest ever observed. Prior to Round Goby proliferation, juvenile Slimy Sculpin comprised ~10% of the Slimy Sculpin catch, but

Climate warming reduces fish production and benthic habitat in Lake Tanganyika, one of the most biodiverse freshwater ecosystems

Science.gov (United States)

Cohen, Andrew S.; Gergurich, Elizabeth L.; Kraemer, Benjamin M.; McGlue, Michael M.; McIntyre, Peter B.; Russell, James M.; Simmons, Jack D.; Swarzenski, Peter W.

2016-01-01

Warming climates are rapidly transforming lake ecosystems worldwide, but the breadth of changes in tropical lakes is poorly documented. Sustainable management of freshwater fisheries and biodiversity requires accounting for historical and ongoing stressors such as climate change and harvest intensity. This is problematic in tropical Africa, where records of ecosystem change are limited and local populations rely heavily on lakes for nutrition. Here, using a ∼1,500-y paleoecological record, we show that declines in fishery species and endemic molluscs began well before commercial fishing in Lake Tanganyika, Africa’s deepest and oldest lake. Paleoclimate and instrumental records demonstrate sustained warming in this lake during the last ∼150 y, which affects biota by strengthening and shallowing stratification of the water column. Reductions in lake mixing have depressed algal production and shrunk the oxygenated benthic habitat by 38% in our study areas, yielding fish and mollusc declines. Late-20th century fish fossil abundances at two of three sites were lower than at any other time in the last millennium and fell in concert with reduced diatom abundance and warming water. A negative correlation between lake temperature and fish and mollusc fossils over the last ∼500 y indicates that climate warming and intensifying stratification have almost certainly reduced potential fishery production, helping to explain ongoing declines in fish catches. Long-term declines of both benthic and pelagic species underscore the urgency of strategic efforts to sustain Lake Tanganyika’s extraordinary biodiversity and ecosystem services.

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.

Fish communities of the Wilderness Lakes System in the southern Cape, South Africa

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Alexis A. Olds

2016-08-01

Full Text Available The Wilderness Lakes System, a temporarily open and closed estuary with three associated lakes situated in the southern Cape region of South Africa, was sampled using a range of sampling gears to assess the fish community. A total of 25 species were sampled throughout the system, with the highest diversity in the Touw Estuary (23 species and the lowest in Langvlei (11 species. Estuary-associated marine species (13 species dominated species richness with smaller proportions of estuarine resident (7 species, freshwater (3 species and catadromous species (2 species. Estuarine resident species dominated the catch numerically. The size–class distribution of euryhaline marine species indicated that upon entering the Touw Estuary as juveniles, the fish move up the system towards Rondevlei where they appear to remain. Three freshwater species were recorded in the system, all of which are alien to the Wilderness Lakes System. Decreasing salinity in the upper lakes appears to be a driving factor in the distribution and increasing abundance of the freshwater fishes. Sampling followed a drought, with the system experiencing substantially increased levels of mouth closure compared to a similar study conducted in the 1980s. The timing of mouth opening and the degree of connectivity between the lakes influence the nursery function of the system as a whole. Management actions need to focus on improving ecological functioning of this system, in particular how mouth opening is managed, to facilitate nursery function and limit the establishment of invasive species. Conservation implications: Key management actions are required to improve fish recruitment potential into and within the system. These include maintenance of adequate marine inflow through adherence to artificial mouth breaching protocols and improving connectivity between the lakes through sediment removal from localised deposition points within the connecting channels.

Rapid ecological shift following piscivorous fish introduction to increasingly eutrophic and warmer Lake Furnas (Azores Archipelago, Portugal): A paleoecological approach

DEFF Research Database (Denmark)

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

2011-01-01

Lake ecosystems are nowadays often subjected to multi-stressors, such as eutrophication, climate change, and fish manipulations, the effects of which can be difficult to disentangle, not least from the usual short-term limnological time-series that are available. However, multi-proxy paleoecologi......Lake ecosystems are nowadays often subjected to multi-stressors, such as eutrophication, climate change, and fish manipulations, the effects of which can be difficult to disentangle, not least from the usual short-term limnological time-series that are available. However, multi......, meteorological forcing, and fish species introduction for recent lake ecosystem development in Lake Furnas on the island of Sa˜o Miguel, the Azores. The lake was stocked with cyprinids in the late nineteenth century and recently also with piscivorous fish, and has been affected by increasing agricultural......, and cryptophytes. The composition of microbial and algal assemblages changed rapidly after Daphnia appearance, and the covariance between fish stocking, nutrient loading, and enhanced temperatures captured most of the variability in algae accumulation, and thus likely in lake primary production as well. Thus, lake...

The effect of pesticides on fish fauna of Bhopal lower lake (M. P. ...

African Journals Online (AJOL)

Pesticides significantly affect the early life stages of fishes. Toxic effects of pesticides vary in different organs of the fish. Liver, gill, kidney are tissues that can accumulate high level of pollutants as well as other factors, such as salinity temperature, hardness, etc. Key words: Bhopal lower lake, fishes, pesticides, toxicity.

Expansion of Dreissena into offshore waters of Lake Michigan and potential impacts on fish populations

Science.gov (United States)

Bunnell, D.B.; Madenjian, C.P.; Holuszko, J.D.; Adams, J.V.; French, J. R. P.

2009-01-01

Lake Michigan was invaded by zebra mussels (Dreissena polymorpha) in the late 1980s and then followed by quagga mussels (D. bugensis) around 1997. Through 2000, both species (herein Dreissena) were largely restricted to depths less than 50??m. Herein, we provide results of an annual lake-wide bottom trawl survey in Lake Michigan that reveal the relative biomass and depth distribution of Dreissena between 1999 and 2007 (although biomass estimates from a bottom trawl are biased low). Lake-wide mean biomass density (g/m2) and mean depth of collection revealed no trend between 1999 and 2003 (mean = 0.7??g/m2 and 37??m, respectively). Between 2004 and 2007, however, mean lake-wide biomass density increased from 0.8??g/m2 to 7.0??g/m2, because of increased density at depths between 30 and 110??m, and mean depth of collection increased from 42 to 77??m. This pattern was confirmed by a generalized additive model. Coincident with the Dreissena expansion that occurred beginning in 2004, fish biomass density (generally planktivores) declined 71% between 2003 and 2007. Current understanding of fish population dynamics, however, indicates that Dreissena expansion is not the primary explanation for the decline of fish, and we provide a species-specific account for more likely underlying factors. Nonetheless, future sampling and research may reveal a better understanding of the potential negative interactions between Dreissena and fish in Lake Michigan and elsewhere.

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

Fish Lake, Utah - a promising long core site straddling the Great Basin to Colorado Plateau transition zone

Science.gov (United States)

Marchetti, D. W.; Abbott, M. B.; Bailey, C.; Wenrich, E.; Stoner, J. S.; Larsen, D. J.; Finkenbinder, M. S.; Anderson, L.; Brunelle, A.; Carter, V.; Power, M. J.; Hatfield, R. G.; Reilly, B.; Harris, M. S.; Grimm, E. C.; Donovan, J.

2015-12-01

Fish Lake (~7x1.5 km and 2696 m asl) is located on the Fish Lake Plateau in central Utah. The Lake occupies a NE-striking tectonic graben; one of a suite of grabens on the Plateau that cut 21-26 Ma volcanic rocks. The lake outflows via Lake Creek to the NE where it joins Sevenmile Creek to become the Fremont River, a tributary to the Colorado River. A bathymetric survey reveals a mean depth of 27 m and a max depth of 37.2 m. The lake bottom slopes from NW to SE with the deepest part near the SE wall, matching the topographic expression of the graben. Nearby Fish Lake Hightop (3545 m) was glaciated with an ice field and outlet glaciers. Exposure ages indicate moraine deposition during Pinedale (15-23 ka) and Bull Lake (130-150 ka) times. One outlet glacier at Pelican Canyon deposited moraines and outwash into the lake but the main basin of the lake was never glaciated. Gravity measurements indicate that lake sediments thicken toward the SE side of the lake and the thickest sediment package is modeled to be between 210 and 240 m. In Feb 2014 we collected cores from Fish Lake using a 9-cm diameter UWITECH coring system in 30.5 m of water. A composite 11.2-m-long core was constructed from overlapping 2 m drives that were taken in triplicate to ensure total recovery and good preservation. Twelve 14C ages and 3 tephra layers of known age define the age model. The oldest 14C age of 32.3±4.2 cal ka BP was taken from 10.6 m. Core lithology, CT scans, and magnetic susceptibility (ms) reveal three sediment packages: an organic-rich, low ms Holocene to post-glacial section, a fine-grained, minerogenic glacial section with high ms, and a short section of inferred pre-LGM sediment with intermediate composition. Extrapolating the age model to the maximum estimated sediment thicknesses suggest sediments may be older than 500-700 ka. Thus Fish Lake is an ideal candidate for long core retrieval as it likely contains paleoclimatic records extending over multiple glacial cycles.

A study on the levels of radioactivity in fish samples from the experimental lakes area in Ontario, Canada

International Nuclear Information System (INIS)

Chen, Jing; Rennie, Michael D.; Sadi, Baki; Zhang, Weihua; St-Amant, Nadereh

2016-01-01

To better understand background radiation levels in country foods, a total of 125 fish samples were collected from three lakes (Lake 226, Lake 302 and Lake 305) in the Experimental Lakes Area (ELA) in Ontario of Canada during the summer of 2014. Concentrations of naturally occurring radionuclides ("2"2"6Ra, "2"1"0Pb and "2"1"0Po) as well as anthropogenic radionuclides ("1"3"4Cs and "1"3"7Cs) were measured. This study confirmed that "2"1"0Po is the dominant contributor to radiation doses resulting from fish consumption. While concentrations of "2"1"0Pb and "2"2"6Ra were below conventional detection limits, "2"1"0Po was measured in almost all fish samples collected from the ELA. The average concentration was about 1.5 Bq/kg fresh weight (fw). None of the fish samples analysed in this study contained any detectable levels of "1"3"4Cs. An average "1"3"7Cs level of 6.1 Bq/kg fw was observed in freshwater fishes harvested in the ELA, almost twice that of samples measured in the National Capital Region of Canada in 2014 and more than 20 times higher than the levels observed in marine fish harvested from the Canadian west coast in 2013 and 2014. However, it is important to note that the concentrations of "1"3"7Cs in fish samples from these inland lakes are considered very low from a radiological protection perspective. The resulting radiation dose for people from fish consumption would be a very small fraction of the annual dose from exposure to natural background radiation in Canada. The results indicate that fishes from inland lakes do not pose a radiological health concern. - Highlights: • "2"1"0Po is the dominant radionuclide measured in a total of 125 fish samples. The average activity concentration was 1.5 Bq/kg fresh weight (fw). • Activity concentration of "2"1"0Po in fish showed a negative dependency on fish size. • While an average "1"3"7Cs level of 6.1 Bq/kg fw was observed, none of the fish samples analysed in this study contained any detectable

Lake fish as the main contributor of internal dose to lakeshore residents in the Chernobyl contaminated area

International Nuclear Information System (INIS)

Travnikova, I.G.; Bazjukin, A.N.; Bruk, G.Ja.; Shutov, V.N.; Balonov, M.I.; Skuterud, L.; Mehli, H.; Strand, P.

2004-01-01

Two field expeditions in 1996 studied 137 Cs intake patterns and its content in the bodies of adult residents from the village Kozhany in the Bryansk region, Russia, located on the shore of a drainless peat lake in an area subjected to significant radioactive contamination after the 1986 Chernobyl accident. The 137 Cs contents in lake water and fish were two orders of magnitude greater than in local rivers and flow-through lakes, 10 years after Chernobyl radioactive contamination, and remain stable. The 137 Cs content in lake fish and a mixture of forest mushrooms was between approximately 10-20 kBq/kg, which exceeded the temporary Russian permissible levels for these products by a factor of 20-40. Consumption of lake fish gave the main contribution to internal doses (40-50%) for Kozhany village inhabitants Simple countermeasures, such as Prussian blue doses for dairy cows and pre-boiling mushrooms and fish before cooking, halved the 137 Cs internal dose to inhabitants, even 10 years after the radioactive fallout

A National Probabilistic Study of Polybrominated Diphenyl Ethers in Fish from US Lakes and Reservoirs

Science.gov (United States)

National estimates were developed for polybrominated diphenyl ethers (PBDEs) in fish from lakes and reservoirs of the conterminous United States (excluding the Laurentian Great Lakes and Great Salt Lake) using an unequal probability design. Predator (fillet) and bottom-dweller (w...

[Species composition, diversity and density of small fishes in two different habitats in Niushan Lake].

Science.gov (United States)

Ye, Shao-Wen; Li, Zhong-Jie; Cao, Wen-Xuan

2007-07-01

This paper studied the spatial distribution of small fishes in a shallow macrophytic lake, Niushan Lake in spring 2003, and its relations with habitat heterogeneity. Based on the macrophyte cover condition, distance from lake shore and water depth, two representative habitat types in the lake were selected. Habitat A was near the shore with dense submersed macrophyte, while habitat B was far from the shore with sparse submersed macrophyte. Small fishes were sampled quantitatively by block net (180 m2), and their densities within the net area were estimated by multiple mark-recapture or Zippin's removal method. The results showed that there were some differences in species composition, biodiversity measurement, and estimated density of small fishes between the two habitats: 1) the catches in habitat A consisted of 14 small fish species from 5 families, among which, benthopelagic species Rhodeus ocellatus, Paracheilognathus imberbis and Pseudorasbora parva were considered as dominant species, while those in habitat B consisted of 9 small fish species from 3 families, among which, bottom species Rhinogobius giurinus and Micropercops swinhonis were dominant; 2) the Bray-Curtis index between the two small fish communities was 0.222, reflecting their low structure similarity, and no significant difference was observed between their rank/ abundance distributions, both of which belonged to log series distribution; 3) the total density of 9 major species in habitat A was 8.71 ind x m(-2), while that of 5 major species in habitat B was only 3.54 ind x m(-2). The fact that the spatial distribution of the small fishes differed with habitats might be related to their habitat need for escaping predators, feeding, and breeding, and thus, aquatic macrophyte habitat should be of significance in the rational exploitation of small fish resources as well as the conservation of fish resource diversity.

Freshwater fishes in Greek lakes: Species richness and body size patterns

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Anthi Oikonomou

2015-11-01

Full Text Available Freshwater ecosystems are widely recognised as hotspots of biodiversity and endemism; thus they are of great value for conservation biogeography. Amongst the taxa found in freshwater ecosystems, fish are the ideal biological model for testing biogeographical patterns and have often been used in large-scale ecological and biogeographical analyses. Lakes of Greece provide a unique opportunity to test biogeographical theories, however, biogeographical studies in Greece at broader, regional, scales, based on the distribution of freshwater species, species richness and endemism, are scarce. The aim of the current study is to test the effect of key environmental factors and spatial variables on species richness of lacustrine fishes and to test their effect on species’ size distributions. We assembled datasets of species richness and body size and environmental (predictor factors for 13 Greek lakes. Model selection procedures revealed that fish species richness increased with ecosystem area and decreased with altitude. In addition, our results showed that latitude per se is a good predictor of body size. Indeed, the mean size of lacustrine communities in the northern and southern lake ecosystems differed significantly. These patterns reflect the biogeographical history of these areas and highlight the crucial role connectivity plays in communities’ species composition.

Impact of metal pollution, food availability, and excessive fishing on Rhabdosargus haffara stock (family: Sparidae) in Timsah lake.

Science.gov (United States)

Mehanna, Sahar F; Abd El-Azim, Hoda; Belal, Aisha A

2016-08-01

The lakes' fisheries play an important role in Egyptian economy. In 1980s, they provided more than 50 % of harvested fish in Egypt but now their contribution to the Egypt fish production decreased to only 12.5 % in 2012. Lake Timsah, one of the Suez Canal lakes, faced many challenges that lead to serious changes in its water and fish quality, fish production, as well as the catch composition. The present work investigated the impact of pollution, food availability, and excessive fishing mortality on the haffara production in lake Timsah. The distribution of four heavy metals (Pb, Zn, Ni, and Fe) was detected seasonally in water and in muscles, gills, and livers of Rhabdosargus haffara, during 2012 through 2013. Fe and Zn were presented by high values in liver, while Pb and Ni in gills. Generally, the lowest concentrations of all metals were found in muscles. The recorded crustacean organisms (the main food of haffara) decreased from 12 species and 32,079 organisms⁄m(2) in 2012 to only 7 species and 7290 organisms⁄m(2) in 2013 while the amphipods completely disappeared. This serious change was due to the severe pollution in the lake. A logistic surplus production model was fitted to the catch per unit effort indices, to estimate the maximum sustainable yield and the optimum level of fishing effort. The results revealed that haffara stock at lake Timsah is overfished, and the estimated precautionary target reference points advised the reduction of fishing effort by about 30-50 %.

Projected shifts in fish species dominance in Wisconsin lakes under climate change.

Science.gov (United States)

Hansen, Gretchen J A; Read, Jordan S; Hansen, Jonathan F; Winslow, Luke A

2017-04-01

Temperate lakes may contain both coolwater fish species such as walleye (Sander vitreus) and warmwater fish species such as largemouth bass (Micropterus salmoides). Recent declining walleye and increasing largemouth bass populations have raised questions regarding the future trajectories and management actions for these species. We developed a thermodynamic model of water temperatures driven by downscaled climate data and lake-specific characteristics to estimate daily water temperature profiles for 2148 lakes in Wisconsin, US, under contemporary (1989-2014) and future (2040-2064 and 2065-2089) conditions. We correlated contemporary walleye recruitment and largemouth bass relative abundance to modeled water temperature, lake morphometry, and lake productivity, and projected lake-specific changes in each species under future climate conditions. Walleye recruitment success was negatively related and largemouth bass abundance was positively related to water temperature degree days. Both species exhibited a threshold response at the same degree day value, albeit in opposite directions. Degree days were predicted to increase in the future, although the magnitude of increase varied among lakes, time periods, and global circulation models (GCMs). Under future conditions, we predicted a loss of walleye recruitment in 33-75% of lakes where recruitment is currently supported and a 27-60% increase in the number of lakes suitable for high largemouth bass abundance. The percentage of lakes capable of supporting abundant largemouth bass but failed walleye recruitment was predicted to increase from 58% in contemporary conditions to 86% by mid-century and to 91% of lakes by late century, based on median projections across GCMs. Conversely, the percentage of lakes with successful walleye recruitment and low largemouth bass abundance was predicted to decline from 9% of lakes in contemporary conditions to only 1% of lakes in both future periods. Importantly, we identify up to 85

Connectedness of land use, nutrients, primary production, and fish assemblages in oxbow lakes

Science.gov (United States)

Miranda, Leandro E.; Andrews, Caroline S.; Kroger, Robert

2013-01-01

We explored the strength of connectedness among hierarchical system components associated with oxbow lakes in the alluvial valley of the Lower Mississippi River. Specifically, we examined the degree of canonical correlation between land use (agriculture and forests), lake morphometry (depth and size), nutrients (total nitrogen and total phosphorus), primary production (chlorophyll-a), and various fish assemblage descriptors. Watershed (p < 0.01) and riparian (p = 0.02) land use, and lake depth (p = 0.05) but not size (p = 0.28), were associated with nutrient concentrations. In turn, nutrients were associated with primary production (p < 0.01), and primary production was associated with sunfish (Centrarchidae) assemblages (p < 0.01) and fish biodiversity (p = 0.08), but not with those of other taxa and functional guilds. Multiple chemical and biological components of oxbow lake ecosystems are connected to landscape characteristics such as land use and lake depth. Therefore, a top-down hierarchical approach can be useful in developing management and conservation plans for oxbow lakes in a region impacted by widespread landscape changes due to agriculture.

Spatial distribution of pelagic fish larvae in the northern main basin of Lake Huron

Science.gov (United States)

Roseman, Edward F.; O'Brien, Timothy P.

2013-01-01

Larval fish occurrence in inshore and offshore zones in the northern main basin of Lake Huron was assessed during 2007 as part of a larger ecological examination of Lake Huron foodwebs and habitats. Day and night collections using neuston and conical nets at inshore (1.5–15 m depths) and offshore (37 and 91 m depths) locations at De Tour and Hammond Bay to assess the abundance, phenology, and spatial distribution of pelagic ichthyoplankton during spring and early summer were made. In general, densities of larval fishes were higher at De Tour than Hammond Bay during daytime neuston net collections, with the exception of Longnose Sucker, which were only collected at Hammond Bay. Lake Whitefish, Burbot, and Rainbow Smelt dominated inshore catches in early spring with Cisco, Deepwater Sculpin, Emerald Shiner, Bloater, Slimy Sculpin, Ninespine Stickleback, and Yellow Perch larvae also collected.Nighttime nearshore and offshore sampling revealed that Rainbow Smelt and Burbot larvae were present in relatively high abundances compared to inshore densities. Concentrations of larvae of deepwater demersal fishes such as Lake Whitefish and Deepwater Sculpin suggest that inshore zones in northern Lake Huron are important nursery habitats emphasizing a critical production and recruitment linkage between inshore and deepwater zones.

Status and trends in the fish community of Lake Superior, 2012

Science.gov (United States)

Gorman, Owen T.; Evrard, Lori M.; Cholwek, Gary A.; Vinson, Mark

2012-01-01

The Great Lakes Science Center has conducted daytime nearshore bottom trawl surveys of Lake Superior (15-80 m bathymetric depth zone) each spring since 1978 and an offshore survey (>80 m) since 2011 to provide long-term trends of relative abundance and biomass of the fish community. In 2012, 72 nearshore and 34 offshore stations were sampled with a 12-m Yankee bottom trawl.

Patterns of lake occupancy by fish indicate different adaptations to life in a harsh Arctic environment

Science.gov (United States)

Haynes, Trevor B.; Rosenberger, Amanda E.; Lindberg, Mark S.; Whitman, Matthew; Schmutz, Joel A.

2014-01-01

Summary For six fish species sampled from 86 lakes on the Arctic Coastal Plain, Alaska, we examined whether lake occupancy was related to variables representing lake size, colonisation potential and/or the presence of overwintering habitat.

Mercury transfer from fish carcasses to scavengers in boreal lakes: the use of stable isotopes of mercury

International Nuclear Information System (INIS)

Sarica, Jose; Amyot, Marc; Hare, Landis; Blanchfield, Paul; Bodaly, R.A.; Hintelmann, Holger; Lucotte, Marc

2005-01-01

Scavengers play an important role in the flow of energy, matter and pollutants through food webs. For methylmercury (MeHg), which biomagnifies along food chains, the movement of this metal from fish carcasses to aquatic scavengers has never been demonstrated. We measured the transfer of MeHg from fish carcasses to scavenging leeches in two lakes and in the laboratory. The results of a field experiment indicated that leeches were attracted to fish carcasses and that their Hg concentrations increased by as much as a factor of 5 during the time that Hg-rich fish were available for consumption. Under controlled conditions, we exposed leeches to 202 Hg-labelled fish that had been marked in situ following a whole lake 202 Hg addition. Leeches rapidly accumulated Hg from carcasses, and within two weeks assumed the isotopic signature of the carcasses. Necrophagous invertebrates could therefore return Hg from fish carcasses to other trophic levels in lakes. - Scavengers such as leeches accumulate mercury from fish carcasses which then may return into the food web

Influence of intensive fishing on the partitioning of mercury and methylmercury in three lakes of Northern Quebec

Energy Technology Data Exchange (ETDEWEB)

Surette, Celine [COMERN, Universite du Quebec a Montreal, c.p. 8888, succ. Centre-Ville, Montreal, Quebec, H3C 3P8 (Canada)]. E-mail: surettc@umoncton.ca; Lucotte, Marc [COMERN, Universite du Quebec a Montreal, c.p. 8888, succ. Centre-Ville, Montreal, Quebec, H3C 3P8 (Canada); Tremblay, A. [Environment Unit, Dams and Environment Direction, Hydro-Quebec Production 75 Rene-Levesque West, 10th floor, Montreal, Quebec, H2Z 1A4 (Canada)

2006-09-01

It has been demonstrated that intensive fishing, i.e., removing more than 25% of the fish biomass, can reduce mercury levels in predator fish in a lake. We test here the hypothesis that, by removing an important part of the fish biomass from a lake, a significant amount of methylmercury can be eliminated, therefore reducing the mercury available to the remaining biota, at least in the short term. A mass burden approach is used to evaluate the partitioning of total mercury and methylmercury in natural lake ecosystems. Three small natural lakes from the James Bay territory, in northern Quebec, Canada, were selected for intensive fishing. Mercury (Hg) and methylmercury (MeHg) concentrations were evaluated for sediments, water column (dissolved fraction and suspended particulate matter), plankton, aquatic invertebrates, and fish. Biomasses were determined for fish, plankton, and aquatic invertebrates. Two case scenarios are presented using different mercury contributions from the sediment component (1 cm depth, and no sediment). Our results for the scenario including the sediment contribution show that lake sediments represent over 98% of the total mercury while the biotic components represent less than 0.1% of the same burden. For methylmercury, fish account for up to 5% of the burden, while sediments make up 84.6% to 93.1%. If we put aside the sediment contribution, the methylmercury in fish partitioning can represent up to 48%. As for invertebrates, they can account for up to 48% of the total MeHg burden. We do not observe any change in the partitionings or the quantities of Hg and MeHg before and after fishing in either of the two case scenarios even when we do not take into account dynamics of the ecosystems. This will be all the more the case when the dynamics of the system are included in the analyses. Therefore, biological parameters such as growth rates or fish diet must be considered.

Influence of intensive fishing on the partitioning of mercury and methylmercury in three lakes of Northern Quebec

International Nuclear Information System (INIS)

Surette, Celine; Lucotte, Marc; Tremblay, A.

2006-01-01

It has been demonstrated that intensive fishing, i.e., removing more than 25% of the fish biomass, can reduce mercury levels in predator fish in a lake. We test here the hypothesis that, by removing an important part of the fish biomass from a lake, a significant amount of methylmercury can be eliminated, therefore reducing the mercury available to the remaining biota, at least in the short term. A mass burden approach is used to evaluate the partitioning of total mercury and methylmercury in natural lake ecosystems. Three small natural lakes from the James Bay territory, in northern Quebec, Canada, were selected for intensive fishing. Mercury (Hg) and methylmercury (MeHg) concentrations were evaluated for sediments, water column (dissolved fraction and suspended particulate matter), plankton, aquatic invertebrates, and fish. Biomasses were determined for fish, plankton, and aquatic invertebrates. Two case scenarios are presented using different mercury contributions from the sediment component (1 cm depth, and no sediment). Our results for the scenario including the sediment contribution show that lake sediments represent over 98% of the total mercury while the biotic components represent less than 0.1% of the same burden. For methylmercury, fish account for up to 5% of the burden, while sediments make up 84.6% to 93.1%. If we put aside the sediment contribution, the methylmercury in fish partitioning can represent up to 48%. As for invertebrates, they can account for up to 48% of the total MeHg burden. We do not observe any change in the partitionings or the quantities of Hg and MeHg before and after fishing in either of the two case scenarios even when we do not take into account dynamics of the ecosystems. This will be all the more the case when the dynamics of the system are included in the analyses. Therefore, biological parameters such as growth rates or fish diet must be considered

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)

Great lakes prey fish populations: a cross-basin overview of status and trends based on bottom trawl surveys, 1978-2012

Science.gov (United States)

Gorman, Owen T.

2012-01-01

The assessment of prey fish stocks in the Great Lakes have been conducted annually with bottom trawls since the 1970s by the Great Lakes Science Center, sometimes assisted by partner agencies. These stock assessments provide data on the status and trends of prey fish that are consumed by important commercial and recreational fishes. Although all these annual surveys are conducted using bottom trawls, they differ among the lakes in the proportion of the lake covered, seasonal timing, bottom trawl gear used, and the manner in which the trawl is towed (across or along bottom contours). Because each assessment is unique in one or more important aspects, direct comparison of prey fish catches among lakes is not straightforward. However, all of the assessments produce indices of abundance or biomass that can be standardized to facilitate comparisons of status and trends across all the Great Lakes. In this report, population indices were standardized to the highest value for a time series within each lake for the following principal prey species: cisco (Coregonus artedi), bloater (C. hoyi), rainbow smelt (Osmerus mordax), and alewife (Alosa pseudoharengus). Indices were also provided for round goby (Neogobius melanostomus), an invasive fish that has proliferated throughout the basin over the past 18 years. These standardized indices represent the best available long-term indices of relative abundance for these fishes across all of the Great Lakes. In this report, standardized indices are presented in graphical form along with synopses to provide a short, informal cross-basin summary of the status and trends of principal prey fishes. In keeping with this intent, tables, references, and a detailed discussion were omitted.

Assemblage patterns of fish functional groups relative to habitat connectivity and conditions in floodplain lakes

Science.gov (United States)

Miyazono, S.; Aycock, J.N.; Miranda, L.E.; Tietjen, T.E.

2010-01-01

We evaluated the influences of habitat connectivity and local environmental factors on the distribution and abundance patterns of fish functional groups in 17 floodplain lakes in the Yazoo River Basin, USA. The results of univariate and multivariate analyses showed that species-environmental relationships varied with the functional groups. Species richness and assemblage structure of periodic strategists showed strong and positive correlations with habitat connectivity. Densities of most equilibrium and opportunistic strategists decreased with habitat connectivity. Densities of certain equilibrium and opportunistic strategists increased with turbidity. Forested wetlands around the lakes were positively related to the densities of periodic and equilibrium strategists. These results suggest that decreases in habitat connectivity, forested wetland buffers and water quality resulting from environmental manipulations may cause local extinction of certain fish taxa and accelerate the dominance of tolerant fishes in floodplain lakes. ?? 2010 John Wiley & Sons A/S.

Parasites and non-fish predators of tilapia with particular reference to the sustainable management of fisheries of Lake Kainji Nigeria

OpenAIRE

Okaeme, A.N.; Olufemi, B.E.; Obiekezie, A.

2001-01-01

The fisheries of Lake Kainji, Nigeria, experienced a boom year following impoundment, then decline post impoundment and now is in a period of stabilisation of the fish resources. Several reasons have been advanced on factors responsible for these changes, but two outstanding factors are those of nutritional status and fishing methods of the lake. Two important fish families however continue to dominate the lake fisheries in daily fisherman catches: Clupeidae and Cichlidae (tilapias). Recent s...

Rapid sympatric ecological differentiation of crater lake cichlid fishes within historic times

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Harrod Chris

2010-05-01

Full Text Available Abstract Background After a volcano erupts, a lake may form in the cooled crater and become an isolated aquatic ecosystem. This makes fishes in crater lakes informative for understanding sympatric evolution and ecological diversification in barren environments. From a geological and limnological perspective, such research offers insight about the process of crater lake ecosystem establishment and speciation. In the present study we use genetic and coalescence approaches to infer the colonization history of Midas cichlid fishes (Amphilophus cf. citrinellus that inhabit a very young crater lake in Nicaragua-the ca. 1800 year-old Lake Apoyeque. This lake holds two sympatric, endemic morphs of Midas cichlid: one with large, hypertrophied lips (~20% of the total population and another with thin lips. Here we test the associated ecological, morphological and genetic diversification of these two morphs and their potential to represent incipient speciation. Results Gene coalescence analyses [11 microsatellite loci and mitochondrial DNA (mtDNA sequences] suggest that crater lake Apoyeque was colonized in a single event from the large neighbouring great lake Managua only about 100 years ago. This founding in historic times is also reflected in the extremely low nuclear and mitochondrial genetic diversity in Apoyeque. We found that sympatric adult thin- and thick-lipped fishes occupy distinct ecological trophic niches. Diet, body shape, head width, pharyngeal jaw size and shape and stable isotope values all differ significantly between the two lip-morphs. The eco-morphological features pharyngeal jaw shape, body shape, stomach contents and stable isotopes (δ15N all show a bimodal distribution of traits, which is compatible with the expectations of an initial stage of ecological speciation under disruptive selection. Genetic differentiation between the thin- and thick-lipped population is weak at mtDNA sequence (FST = 0.018 and absent at nuclear

Predicting Great Lakes fish yields: tools and constraints

Science.gov (United States)

Lewis, C.A.; Schupp, D.H.; Taylor, W.W.; Collins, J.J.; Hatch, Richard W.

1987-01-01

Prediction of yield is a critical component of fisheries management. The development of sound yield prediction methodology and the application of the results of yield prediction are central to the evolution of strategies to achieve stated goals for Great Lakes fisheries and to the measurement of progress toward those goals. Despite general availability of species yield models, yield prediction for many Great Lakes fisheries has been poor due to the instability of the fish communities and the inadequacy of available data. A host of biological, institutional, and societal factors constrain both the development of sound predictions and their application to management. Improved predictive capability requires increased stability of Great Lakes fisheries through rehabilitation of well-integrated communities, improvement of data collection, data standardization and information-sharing mechanisms, and further development of the methodology for yield prediction. Most important is the creation of a better-informed public that will in turn establish the political will to do what is required.

Mercury concentrations of fish in Southern Indian Lake and Issett Lake, Manitoba 1975-88: The effect of lake impoundment and Churchill River diversion

International Nuclear Information System (INIS)

Strange, N.E.; Bodaly, R.A.; Fudge, R.J.P.

1991-01-01

Southern Indian and Issett Lakes in northern Manitoba were flooded in 1976 as part of Manitoba Hydro's Churchill River diversion project. Fish were collected from 1975 to 1988 from five regional sites on the lakes to examine the effects of impoundment and river diversion on muscle mercury concentrations. Raw data for individual fish caught in 1987 and 1988 are presented, along with means and analyses calculated over the entire 1975-1988 study period. Mercury concentrations in whitefish, pike, and walleye increased significantly after impoundment. Whitefish mercury levels peaked in 1978 and have since declined to near pre-flooding levels. Northern pike and walleye mercury levels were much higher than for whitefish. Pike mercury concentrations showed no indication of declining after 12 years of impoundment, but walleye mercury levels at 2 of the 5 Southern Indian Lake sites declined from maximum recorded levels. Significant variability in fish mercury concentrations was noted both from year to year and among the sites. It is suggested that site-to-site variations are due to varying conditions in the reservoir which stimulate mercury methylation. Since there appears to be an ongoing long-term source of mercury and organic material from the eroding shorelines, pike and walleye mercury concentrations are expected to remain high for many years. 25 refs., 7 figs., 20 tabs

Fish abundance in the Wilderness and Swartvlei lake systems ...

African Journals Online (AJOL)

A longer duration tidal phase in the Swartvlei system during 1992 and 1993, compared to the Wilderness lake system, did not result in greater abundance of fish sampled. There appears to be no justification for the artificial maintenance of permanently tidal conditions in the Swartvlei and Touw River estuaries on the ...

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.

Repeated Fish Removal to Restore Lakes: Case Study of Lake Væng, Denmark—Two Biomanipulations during 30 Years of Monitoring

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Martin Søndergaard

2017-01-01

Full Text Available Biomanipulation by fish removal has been used in many shallow lakes as a method to improve lake water quality. Here, we present and analyse 30 years of chemical and biological data from the shallow and 16 ha large Lake Væng, Denmark, which has been biomanipulated twice with a 20-year interval by removing roach (Rutilus rutilus and bream (Abramis brama. After both biomanipulations, Lake Væng shifted from a turbid, phytoplankton-dominated state to a clear, water macrophyte-dominated state. Chlorophyll a was reduced from 60–80 μg·L−1 to 10–30 μg·L−1 and the coverage of submerged macrophytes, dominated by Elodea canadensis, increased from <0.1% to 70%–80%. Mean summer total phosphorus was reduced from about 0.12 to 0.07 mg·L−1 and total nitrogen decreased from 1.0 to 0.4 mg·L−1. On a seasonal scale, phosphorus and chlorophyll concentrations changed from a summer maximum during turbid conditions to a winter maximum under clear conditions. The future of Lake Væng is uncertain and a relatively high phosphorus loading via the groundwater, and the accumulation of a mobile P pool in the sediment make it likely that the lake eventually will return to turbid conditions. Repeated fish removals might be a relevant management strategy to apply in shallow lakes with a relatively high external nutrient loading.

Comparison of fish assemblages in two disjoined segments of an oxbow lake in relation to connectivity

Science.gov (United States)

Dembkowski, Daniel J.; Miranda, Leandro E.

2011-01-01

Disconnection between adjacent habitat patches is one of the most notable factors contributing to the decreased biotic integrity of global ecosystems. Connectivity is especially threatened in river–floodplain ecosystems in which channel modifications have disrupted the lateral links between the main river channel and floodplain lakes. In this study, we examined the interaction between the interconnectedness of floodplain lakes and main river channels and fish assemblage descriptors. Fish assemblages in two segments of an oxbow lake, one connected to and the other isolated from the Yazoo River, Mississippi, were estimated with daytime boat electrofishing during 2007–2010. The frequency of connection for the connected segment ranged from zero to seven individual events per year (mean, ∼2). The timing of most connection events reflected regional precipitation patterns. Greater species richness, diversity, and evenness were observed in the connected segment. Additionally, the connected segment had a greater abundance of piscivores and periodic life history strategists. All fishes collected solely in the connected segment were typically riverine in nature, whereas fishes collected only in the disconnected segment were more lacustrine adapted. These results suggest that periodic connection and the associated habitat heterogeneity that it provides are important for maintaining fish species richness and diversity in large-river floodplain lakes. We suggest that maintenance or restoration of connection be an integral part of fluvial ecosystem management plans.

Cesium-137 activities in fish residing in thermal discharges to Lake Michigan

International Nuclear Information System (INIS)

Spigarelli, S.A.

1976-01-01

The results of a study of 137 Cs activity in brown and rainbow trout and chinook salmon found in the thermal discharges from power plant sites on Lake Michigan, are reported. The objectives of the investigation were: (1) to compare 137 Cs activities in plume 'resident' fish with those in fish collected from reference (unheated) areas; (2) to compare the residence effect on the three sport fishes; and (3) to evaluate the radioecological significance of thermal discharge residence on temporal trends in 137 Cs accumulation by these fishes. Plume resident fish were identified and the residence time of these individuals estimated by the use of temperature-sensitive fish tags. Results are shown tabulated. (U.K.)

Cesium-137 activities in fish residing in thermal discharges to Lake Michigan

Energy Technology Data Exchange (ETDEWEB)

Spigarelli, S A [Argonne National Lab., Ill. (USA)

1976-05-01

The results of a study of /sup 137/Cs activity in brown and rainbow trout and chinook salmon found in the thermal discharges from power plant sites on Lake Michigan, are reported. The objectives of the investigation were: (1) to compare /sup 137/Cs activities in plume 'resident' fish with those in fish collected from reference (unheated) areas; (2) to compare the residence effect on the three sport fishes; and (3) to evaluate the radioecological significance of thermal discharge residence on temporal trends in /sup 137/Cs accumulation by these fishes. Plume resident fish were identified and the residence time of these individuals estimated by the use of temperature-sensitive fish tags. Results are shown tabulated.

MERGANSER - An Empirical Model to Predict Fish and Loon Mercury in New England Lakes

Science.gov (United States)

MERGANSER (MERcury Geo-spatial AssessmeNtS for the New England Region) is an empirical least-squares multiple regression model using mercury (Hg) deposition and readily obtainable lake and watershed features to predict fish (fillet) and common loon (blood) Hg in New England lakes...

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.

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.

Mercury bioaccumulation in fishes from subalpine lakes of the Wallowa-Whitman National Forest, northeastern Oregon and western Idaho

Science.gov (United States)

Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

2013-01-01

Mercury (Hg) is a globally distributed pollutant that poses considerable risks to human and wildlife health. Over the past 150 years since the advent of the industrial revolution, approximately 80 percent of global emissions have come from anthropogenic sources, largely fossil fuel combustion. As a result, atmospheric deposition of Hg has increased by up to 4-fold above pre-industrial times. Because of their isolation, remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited Hg through freshwater food webs, as well as for evaluating the relative importance of Hg loading versus landscape influences on Hg bioaccumulation. The increase in Hg deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in Hg emissions may propagate to changes in Hg bioaccumulation and ecological risk. In this study, we evaluated Hg concentrations in fishes of high-elevation, sub-alpine lakes in the Wallowa-Whitman National Forest in northeastern Oregon and western Idaho. Our goals were to (1) assess the magnitude of Hg contamination in small-catchment lakes to evaluate the risk of atmospheric Hg to human and wildlife health, (2) quantify the spatial variability in fish Hg concentrations, and (3) determine the ecological, limnological, and landscape factors that are best correlated with fish total mercury (THg) concentrations in these systems. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. Importantly, our top statistical model explained 87 percent of the variability in fish THg concentrations among lakes with four key landscape and limnological variables— catchment conifer density (basal area of conifers within a lake’s catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. The basal area of conifers

Trophodynamics of Organic Pollutants in Pelagic and Benthic Food Webs of Lake Dianchi: Importance of Ingested Sediment As Uptake Route.

Science.gov (United States)

Fan, Senrong; Wang, Beili; Liu, Hang; Gao, Shixiong; Li, Tong; Wang, Shuran; Liu, Yong; Liu, Xueqin; Wan, Yi

2017-12-19

Habitat is of great importance in determining the trophic transfer of pollutants in freshwater ecosystems; however, the major factors influencing chemical trophodynamics in pelagic and benthic food webs remain unclear. This study investigated the levels of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), polycyclic aromatic hydrocarbons (PAHs), and substituted PAHs (s-PAHs) in 2 plankton species, 6 invertebrate species, and 10 fish species collected from Lake Dianchi in southern China. Relatively high concentrations of PAHs and s-PAHs were detected with total concentrations of 11.4-1400 ng/g wet weight (ww) and 5.3-115 ng/g ww, respectively. Stable isotope analysis and stomach content analysis were applied to quantitatively determine the trophic level of individual organisms and discriminate between pelagic and benthic pathways, and the trophodynamics of the detected compounds in the two food webs were assessed. P,p'-DDE was found to exhibit relatively higher trophic magnification rate in the pelagic food web than in the benthic food web. In contrast, PAHs and s-PAHs exhibited greater dilution rates along the trophic levels in the pelagic food web. The lower species differences of pollutants accumulated in benthic organisms compared to pelagic organisms is attributable to extra uptake via ingested sediment in benthos. The average uptake proportions of PAHs and s-PAHs via ingested sediment in benthic biotas were estimated to be 31-77%, and that of p,p'-DDE was 46%. The uptake routes are of importance for assessing the trophic magnification potentials of organic pollutants, especially in eutrophic freshwater ecosystems.

Perfluorinated compounds in fish and blood of anglers at Lake Möhne, Sauerland area, Germany.

Science.gov (United States)

Hölzer, Jürgen; Göen, Thomas; Just, Paul; Reupert, Rolf; Rauchfuss, Knut; Kraft, Martin; Müller, Johannes; Wilhelm, Michael

2011-10-01

Perfluorinated compounds (PFCs) were measured in fish samples and blood plasma of anglers in a cross-sectional study at Lake Möhne, Sauerland area, Germany. Human plasma and drinking water samples were analyzed by solid phase extraction, high-performance liquid chromatography (HPLC), and tandem mass spectrometry (MS/MS). PFCs in fish fillet were measured by ion pair extraction followed by HPLC and MS/MS. PFOS concentrations in 44 fish samples of Lake Möhne ranged between 4.5 and 150 ng/g. The highest median PFOS concentrations have been observed in perches (median: 96 ng/g) and eels (77 ng/g), followed by pikes (37 ng/g), whitefish (34 ng/g), and roaches (6.1 ng/g). In contrast, in a food surveillance program only 11% of fishes at retail sale contained PFOS at detectable concentrations. One hundred five anglers (99 men, 6 women; 14-88 years old; median 50.6 years) participated in the human biomonitoring study. PFOS concentrations in blood plasma ranged from 1.1 to 650 μg/L (PFOA: 2.1-170 μg/L; PFHxS: 0.4-17 μg/L; LOD: 0.1 μg/L). A distinct dose-dependent relationship between fish consumption and internal exposure to PFOS was observed. PFOS concentrations in blood plasma of anglers consuming fish 2-3 times per month were 7 times higher compared to those without any fish consumption from Lake Möhne. The study results strongly suggest that human internal exposure to PFC is distinctly increased by consumption of fish from PFC-contaminated sites.

Consumption dynamics of the adult piscivorous fish community in Spirit Lake, Iowa

Science.gov (United States)

Liao, H.; Pierce, C.L.; Larscheid, J.G.

2004-01-01

At Spirit Lake, one of Iowa's most important fisheries, walleye Sander vitreus (formerly Stizostedion vitreum) is one of the most popular species with anglers. Despite a century of walleye stocking and management in Spirit Lake, walleye growth rate, size structure, and angler harvest continue to decline. Our purpose was to determine the magnitude and dynamics of walleye population consumption relative to those of other piscivorous species in Spirit Lake, which would allow managers to judge the feasibility of increasing the abundance, growth rate, and size structure of the walleye population. We quantified food consumption by the adult piscivorous fish community in Spirit Lake over a 3-year period. Data on population dynamics, diet, energy density, and water temperature from 1995 to 1997 were used in bioenergetics models to estimate total consumption by walleye, yellow perch Perca flavescens, smallmouth bass Micropterus dolomieu, largemouth bass Micropterus salmoides, black crappie Pomoxis nigromaculatus, and northern pike Esox lucius. Estimated annual consumption by the piscivorous community varied roughly fourfold, ranging from 154,752 kg in 1995 to 662,776 kg in 1997. Walleyes dominated total consumption, accounting for 68, 73, and 90% (1995-1997, respectively) of total food consumption. Walleyes were also the dominant consumers of fish, accounting for 76, 86, and 97% of piscivorous consumption; yellow perch followed, accounting for 16% of piscivorous consumption in 1995 and 12% in 1996. Yellow perch were the predominant fish prey species in all 3 years, accounting for 68, 52, and 36% of the total prey consumed. Natural reproduction is weak, so high walleye densities are maintained by intensive stocking. Walleye stocking drives piscivorous consumption in Spirit Lake, and yearly variation in the cannibalism of stocked walleye fry may be an important determinant of walleye year-class strength and angler success. Reducing walleye stocking intensity, varying stocking

Variation in fish community structure, richness, and diversity in 56 Danish lakes with contrasting depth, size, and trophic state: does the method matter?

DEFF Research Database (Denmark)

Menezes, Rosemberg; Borchsenius, Finn; Svenning, J.-C.

2013-01-01

a better understanding of fish communities. We compare fish community composition, richness, and diversity in 56 Danish lakes using data obtained by gillnetting in different lake zones and near-shore electrofishing, respectively. On average, electrofishing captured more species than offshore gillnets......, but not more than littoral gillnets. Overall, the different fish sampling methods showed consistency as to fish community structure, but noticeable differences in community–environment relationships. Lake area was the best predictor for fish species richness in the littoral samplings, while it was poor...... community, as all methods miss some important species that other methods capture. However, electrofishing seems to be a fast alternative to gillnets for monitoring fish species richness and composition in littoral habitats of Danish lakes....

Estimating exposure of piscivorous birds and sport fish to mercury in California lakes using prey fish monitoring: a predictive tool for managers

Science.gov (United States)

Ackerman, Joshua T.; Hartman, C. Alex; Eagles-Smith, Collin A.; Herzog, Mark P.; Davison, Jay; Ichikawa, Gary; Bonnema, Autumn

2015-01-01

Numerous water bodies in California are listed under the Clean Water Act as being impaired due to mercury (Hg) contamination. The Surface Water Ambient Monitoring Program (SWAMP), via the Bioaccumulation Oversight Group (BOG), has recently completed statewide surveys of contaminants in sport fish tissue from more than 250 lakes and rivers in California and throughout coastal waters. This effort focused on human health issues but did not include beneficial uses by wildlife. Many piscivorous birds such as grebes, terns, cormorants, and mergansers eat fish smaller than those that were sampled by BOG, and sport fish Hg concentrations are not always indicative of wildlife exposure to Hg; therefore, the BOG surveys could not address whether wildlife were at risk due to Hg-induced reproductive impairment in these lakes.

A review of the influence of biogeography, riverine linkages, and marine connectivity on fish assemblages in evolving lagoons and lakes of coastal southern Africa.

Science.gov (United States)

Whitfield, Alan K; Weerts, Steven P; Weyl, Olaf L F

2017-09-01

The Holocene evolution of eight South African coastal lakes and lagoons is examined and related to changes in fish composition over that period. Historical and current connectivity with riverine and marine environments are the primary determinants of present-day fish assemblages in these systems. A small and remarkably consistent group of relict estuarine species have persisted in these coastal lakes and lagoons. The loss or reduction of connectivity with the sea has impacted on the diversity of marine fishes in all eight study systems, with no marine fishes occurring in those water bodies where connectivity has been completely broken (e.g. Sibaya, Groenvlei). In systems that have retained tenuous linkages with the sea (e.g., Verlorenvlei, Wilderness lakes), elements of the marine fish assemblage have persisted, especially the presence of facultative catadromous species. Freshwater fish diversity in coastal lakes and lagoons is a function of historical and present biogeography and salinity. From a freshwater biogeography perspective, the inflowing rivers of the four temperate systems reviewed here contain three or fewer native freshwater fishes, while the subtropical lakes that are fed by river systems contain up to 40 freshwater fish species. Thus, the significantly higher fish species diversity in subtropical versus temperate coastal lakes and lagoons comes as no surprise. Fish species diversity has been increased further in some systems (e.g., Groenvlei) by alien fish introductions. However, the impacts of fish introductions and translocations have not been studied in the coastal lakes and lagoons of South Africa. In these closed systems, it is probable that predation impacts on small estuarine fishes are significant. The recent alien fish introductions is an example of the growing threats to these systems during the Anthropocene, a period when human activities have had significant negative impacts and show potential to match the changes recorded during the

Lake Sturgeon, Lake Whitefish, and Walleye egg deposition patterns with response to fish spawning substrate restoration in the St. Clair–Detroit River system

Science.gov (United States)

Fischer, Jason L.; Pritt, Jeremy J.; Roseman, Edward; Prichard, Carson G.; Craig, Jaquelyn M.; Kennedy, Gregory W.; Manny, Bruce A.

2018-01-01

Egg deposition and use of restored spawning substrates by lithophilic fishes (e.g., Lake Sturgeon Acipenser fulvescens, Lake Whitefish Coregonus clupeaformis, and Walleye Sander vitreus) were assessed throughout the St. Clair–Detroit River system from 2005 to 2016. Bayesian models were used to quantify egg abundance and presence/absence relative to site-specific variables (e.g., depth, velocity, and artificial spawning reef presence) and temperature to evaluate fish use of restored artificial spawning reefs and assess patterns in egg deposition. Lake Whitefish and Walleye egg abundance, probability of detection, and probability of occupancy were assessed with detection-adjusted methods; Lake Sturgeon egg abundance and probability of occurrence were assessed using delta-lognormal methods. The models indicated that the probability of Walleye eggs occupying a site increased with water velocity and that the rate of increase decreased with depth, whereas Lake Whitefish egg occupancy was not correlated with any of the attributes considered. Egg deposition by Lake Whitefish and Walleyes was greater at sites with high water velocities and was lower over artificial spawning reefs. Lake Sturgeon eggs were collected least frequently but were more likely to be collected over artificial spawning reefs and in greater abundances than elsewhere. Detection-adjusted egg abundances were not greater over artificial spawning reefs, indicating that these projects may not directly benefit spawning Walleyes and Lake Whitefish. However, 98% of the Lake Sturgeon eggs observed were collected over artificial spawning reefs, supporting the hypothesis that the reefs provided spawning sites for Lake Sturgeon and could mitigate historic losses of Lake Sturgeon spawning habitat.

Local and regional variability in fish community structure, richness and diversity of 56 Danish lakes with contrasting depth and trophic state

DEFF Research Database (Denmark)

Menezes, Rosemberg; Borchsenius, Finn; Svenning, J.-C.

Habitat distribution of fish might be influenced by food availability, competition, predation,composition of aquatic plants and water clarity. It has been found that a shift from a turbid to a clear water state in a lake lead to higher proportion of piscivorous fish and a habitat shift of prey fish...... oligotrophic lakes due to high turbidity leading to loss of submerged macrophytes and thus habitat variability. Also the influence of piscivorous birds on the fish distribution in the littoral zone may differ between lake types leading to a more homogeneous distribution along the littoral area in eutrophic...

Energy density of lake whitefish Coregonus clupeaformis in Lakes Huron and Michigan

Science.gov (United States)

Pothoven, S.A.; Nalepa, T.F.; Madenjian, C.P.; Rediske, R.R.; Schneeberger, P.J.; He, J.X.

2006-01-01

We collected lake whitefish Coregonus clupeaformis off Alpena and Tawas City, Michigan, USA in Lake Huron and off Muskegon, Michigan USA in Lake Michigan during 2002–2004. We determined energy density and percent dry weight for lake whitefish from both lakes and lipid content for Lake Michigan fish. Energy density increased with increasing fish weight up to 800 g, and then remained relatively constant with further increases in fish weight. Energy density, adjusted for weight, was lower in Lake Huron than in Lake Michigan for both small (≤800 g) and large fish (>800 g). Energy density did not differ seasonally for small or large lake whitefish or between adult male and female fish. Energy density was strongly correlated with percent dry weight and percent lipid content. Based on data from commercially caught lake whitefish, body condition was lower in Lake Huron than Lake Michigan during 1981–2003, indicating that the dissimilarity in body condition between the lakes could be long standing. Energy density and lipid content in 2002–2004 in Lake Michigan were lower than data for comparable sized fish collected in 1969–1971. Differences in energy density between lakes were attributed to variation in diet and prey energy content as well as factors that affect feeding rates such as lake whitefish density and prey abundance.

Spatially explicit measures of production of young alewives in Lake Michigan: Linkage between essential fish habitat and recruitment

Science.gov (United States)

Hook, Tomas O.; Rutherford, Edward S.; Brines, Shannon J.; Mason, Doran M.; Schwab, David J.; McCormick, Michael; Desorcie, Timothy J.

2003-01-01

The identification and protection of essential habitats for early life stages of fishes are necessary to sustain fish stocks. Essential fish habitat for early life stages may be defined as areas where fish densities, growth, survival, or production rates are relatively high. To identify critical habitats for young-of-year (YOY) alewives (Alosa pseud oharengus) in Lake Michigan, we integrated bioenergetics models with GIS (Geographic Information Systems) to generate spatially explicit estimates of potential population production (an index of habitat quality). These estimates were based upon YOY alewife bioenergetic growth rate potential and their salmonine predators’ consumptive demand. We compared estimates of potential population production to YOY alewife yield (an index of habitat importance). Our analysis suggested that during 1994–1995, YOY alewife habitat quality and yield varied widely throughout Lake Michigan. Spatial patterns of alewife yield were not significantly correlated to habitat quality. Various mechanisms (e.g., predator migrations, lake circulation patterns, alternative strategies) may preclude YOY alewives from concentrating in areas of high habitat quality in Lake Michigan.

Cormorant predation overlaps with fish communities and commercial-fishery interest in a Swedish lake

DEFF Research Database (Denmark)

Ovegård, K. M.; Öhman, K.; Mikkelsen, Jørgen Skole

2017-01-01

The increase of the fish-eating cormorant (Phalacrocorax carbo sinensis) in Europe has resulted in conflicts with fisheries. In Lake Roxen, Sweden, cormorants are blamed for causing a decrease in fishery catches. To study and describe the potential effects that cormorants may have had on fish in ...

Ecomorphological correlates of twenty dominant fish species of Amazonian floodplain lakes

Directory of Open Access Journals (Sweden)

F. K. Siqueira-Souza

Full Text Available Abstract Fishes inhabiting Amazonian floodplain lakes exhibits a great variety of body shape, which was a key advantage to colonize the several habitats that compose these areas adjacent to the large Amazon rivers. In this paper, we did an ecomorphological analysis of twenty abundant species, sampled in May and August 2011, into two floodplain lakes of the lower stretch of the Solimões River. The analysis detected differences among species, which could be probably associated with swimming ability and habitat use preferences.

Acute thermal tolerance of tropical estuarine fish occupying a man-made tidal lake, and increased exposure risk with climate change

Science.gov (United States)

Waltham, Nathan J.; Sheaves, Marcus

2017-09-01

Understanding acute hyperthermic exposure risk to animals, including fish in tropical estuaries, is increasingly necessary under future climate change. To examine this hypothesis, fish (upper water column species - glassfish, Ambassis vachellii; river mullet, Chelon subviridis; diamond scale mullet, Ellochelon vaigiensis; and ponyfish, Leiognathus equulus; and lower water bottom dwelling species - whiting Sillago analis) were caught in an artificial tidal lake in tropical north Queensland (Australia), and transported to a laboratory tank to acclimate (3wks). After acclimation, fish (between 10 and 17 individuals each time) were transferred to a temperature ramping experimental tank, where a thermoline increased (2.5 °C/hr; which is the average summer water temperature increasing rate measured in the urban lakes) tank water temperature to establish threshold points where each fish species lost equilibrium (defined here as Acute Effect Temperature; AET). The coolest AET among all species was 33.1 °C (S. analis), while the highest was 39.9 °C (A. vachellii). High frequency loggers were deployed (November and March representing Austral summer) in the same urban lake where fish were sourced, to measure continuous (20min) surface (0.15 m) and bottom (0.1 m) temperature to derive thermal frequency curves to examine how often lake temperatures exceed AET thresholds. For most fish species examined, water temperature that could be lethal were exceeded at the surface, but rarely, if ever, at the bottom waters suggesting deep, cooler, water provides thermal refugia for fish. An energy-balance model was used to estimate daily mean lake water temperature with good accuracy (±1 °C; R2 = 0.91, modelled vs lake measured temperature). The model was used to predict climate change effects on lake water temperature, and the exceedance of thermal threshold change. A 2.3 °C climate warming (based on 2100 local climate prediction) raised lake water temperature by 1.3 °C. However

Fishing Farmers or Farming Fishers? Fishing Typology of Inland Small-Scale Fishing Households and Fisheries Management in Singkarak Lake, West Sumatra, Indonesia

Science.gov (United States)

Yuerlita; Perret, Sylvain Roger; Shivakoti, Ganesh P.

2013-07-01

Technical and socio-economic characteristics are known to determine different types of fishers and their livelihood strategies. Faced with declining fish and water resources, small-scale fisheries engage into transformations in livelihood and fishing practices. The paper is an attempt to understand these changes and their socio-economic patterns, in the case of Singkarak Lake in West Sumatra, Indonesia. Based upon the hypothesis that riparian communities have diverse, complex yet structured and dynamic livelihood systems, the paper's main objective is to study, document and model the actual diversity in livelihood, practices and performance of inland small-scale fisheries along the Singkarak Lake, to picture how households are adapted to the situation, and propose an updated, workable model (typology) of those for policy. Principal component analysis and cluster analysis were used to develop a typology of fishing households. The results show that small-scale fishers can be classified into different types characterized by distinct livelihood strategies. Three household types are identified, namely "farming fishers" households (type I, 30 %), "fishing farmers" households (type II, 30 %), and "mainly fishers" households (type III, 40 %). There are significant differences among these groups in the number of boats owned, annual fishing income, agriculture income and farming experience. Type I consists of farming fishers, well equipped, with high fishing costs and income, yet with the lowest return on fishing assets. They are also landowners with farming income, showing the lowest return on land capital. Type II includes poor fishing farmers, landowners with higher farming income; they show the highest return on land asset. They have less fishing equipment, costs and income. Type III (mainly fishers) consists of poorer, younger fishers, with highest return on fishing assets and on fishing costs. They have little land, low farming income, and diversified livelihood

A survey of ichthyofauna of Lake Kanyaboli and other small waterbodies in Kenya: alternative refugia for endangered fish species

OpenAIRE

Maithya, J.

1998-01-01

In 1988, the World Conservation Union (WCU) Red Book of Endangered Species listed hundreds of endemic fishes of Lake Victoria under a single heading - "ENDANGERED". Most of the endemic native food fishes are either endangered or extinct. However, a survey of the fauna of Lake Kanyaboli, revealed that a few remaining samples of these native fishes are actually thriving. These include several unidentified Haplochromis spp., Oreochromis esculentus and Oreochromis variabilis. As a resul...

Activity concentration and population dose from natural occurring radionuclide (40K) due to consumption of fresh water fish

International Nuclear Information System (INIS)

Jha, M.K.; Patra, A.K.; Jaison, T.J.; Ravi, P.M.; Tripathi, R.M.

2015-01-01

The objective of this study was to measure the concentration of natural occurring radionuclide ( 40 K) in different fresh water fish collected from Moticher lake near Kakrapar, Gujarat. The three types of commonly available fresh water fish in Moticher lake are Notopterus sps, Ophiocephalus sps. and Tor sps. The 40 K activity (Bq/kg flesh wt.) was found to be in the range of 38-100 (Notopterus sps.), 33-123 (Ophiocephalus sps.) and 80-116 (Tor sps.) respectively. The ingestion dose (μSv/y) to the adult population around Kakrapar was estimated due to the consumption of fresh water fish and found to be in the range of 7.7-20.5 (Notopterus sps.), 6.8-25.0 (Ophiocephalus sps.) and 16.0-24.0 (Tor sps.) respectively. (author)

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.

FishVis, A regional decision support tool for identifying vulnerabilities of riverine habitat and fishes to climate change in the Great Lakes Region

Science.gov (United States)

Stewart, Jana S.; Covert, S. Alex; Estes, Nick J.; Westenbroek, Stephen M.; Krueger, Damon; Wieferich, Daniel J.; Slattery, Michael T.; Lyons, John D.; McKenna, James E.; Infante, Dana M.; Bruce, Jennifer L.

2016-10-13

Climate change is expected to alter the distributions and community composition of stream fishes in the Great Lakes region in the 21st century, in part as a result of altered hydrological systems (stream temperature, streamflow, and habitat). Resource managers need information and tools to understand where fish species and stream habitats are expected to change under future conditions. Fish sample collections and environmental variables from multiple sources across the United States Great Lakes Basin were integrated and used to develop empirical models to predict fish species occurrence under present-day climate conditions. Random Forests models were used to predict the probability of occurrence of 13 lotic fish species within each stream reach in the study area. Downscaled climate data from general circulation models were integrated with the fish species occurrence models to project fish species occurrence under future climate conditions. The 13 fish species represented three ecological guilds associated with water temperature (cold, cool, and warm), and the species were distributed in streams across the Great Lakes region. Vulnerability (loss of species) and opportunity (gain of species) scores were calculated for all stream reaches by evaluating changes in fish species occurrence from present-day to future climate conditions. The 13 fish species included 4 cold-water species, 5 cool-water species, and 4 warm-water species. Presently, the 4 cold-water species occupy from 15 percent (55,000 kilometers [km]) to 35 percent (130,000 km) of the total stream length (369,215 km) across the study area; the 5 cool-water species, from 9 percent (33,000 km) to 58 percent (215,000 km); and the 4 warm-water species, from 9 percent (33,000 km) to 38 percent (141,000 km).Fish models linked to projections from 13 downscaled climate models projected that in the mid to late 21st century (2046–65 and 2081–2100, respectively) habitats suitable for all 4 cold-water species and 4

Prevalence and seasonality of parasites of fish in Agulu Lake ...

African Journals Online (AJOL)

Owner

2014-01-15

Jan 15, 2014 ... belonging to four families (Cichlidae, Bagridae, Hepsetidae and Channidae), seven genera and nine species were collected from the lake ... Fish oil contains omega-3-essential fatty acids necessary for the proper ... 7°01' and 7°03'E. The climate of the area shows two distinct seasons namely, rainy season ...

Environmental Assessment: Lake Yankton Fish Population Renovation Project Yankton County, South Dakota and Cedar County, Nebraska

Science.gov (United States)

2014-08-01

respiration in fish, mammals, birds, insects, reptiles , amphibians , and plants. However, at concentrations used in fisheries management, rotenone is...prey upon fish, rodents, and small game. Lake Yankton supports many species of fish, reptiles , and amphibians . The Preferred Alternative is not...3‐4  3.2.1.3.  Amphibians

Risk and toxicity assessments of heavy metals in sediments and fishes from the Yangtze River and Taihu Lake, China.

Science.gov (United States)

Fu, Jie; Hu, Xin; Tao, Xiancong; Yu, Hongxia; Zhang, Xiaowei

2013-11-01

Heavy metal pollution is one of the most serous environmental issues globally. To evaluate the metal pollution in Jiangsu Province of China, the total concentrations of heavy metals in sediments and fishes from the Yangtze River and Taihu Lake were analyzed. Ecological risk of sediments and human health risk of fish consumption were assessed respectively. Furthermore, toxicity of samples on expression of the stress responsive genes was evaluated using microbial live cell-array method. The results showed that the heavy metals concentrations in sediments from the Yangtze River were much higher than those in sediments from the Taihu Lake. However, the fishes from the Taihu Lake had higher concentrations of heavy metals than fishes from the Yangtze River. Ecological risk evaluation showed that the heavy metal contaminants in sediments from the Yangtze River posed higher risk of adverse ecological effects, while sediments from the study areas of Taihu Lake were relatively safe. Health risk assessment suggested that the heavy metals in fishes of both Yangtze River and Taihu Lake might have risk of adverse health effects to human. The toxicity assessment indicated that the heavy metals in these sediments and fishes showed transcriptional effects on the selected 21 stress responsive genes, which were involved in the pathways of DNA damage response, chemical stress, and perturbations of electron transport. Together, this field investigation combined with chemical analysis, risk assessment and toxicity bioassay would provide useful information on the heavy metal pollution in Jiangsu Province. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nile perch fish processing waste along Lake Victoria in East Africa ...

African Journals Online (AJOL)

Nile perch fish processing waste along Lake Victoria in East Africa: Auditing and characterization. ... African Journal of Environmental Science and Technology ... If you would like more information about how to print, save, and work with PDFs, Highwire Press provides a helpful Frequently Asked Questions about PDFs.

Coping with scarcity: Fishing adaptability and culture in lake Chapala

Directory of Open Access Journals (Sweden)

Carmen Pedroza Gutiérrez

2017-11-01

Full Text Available This paper examines different adaptive responses that lakeside communities develop when faced with environmental change. The focus lies particularly on rural towns near lake Chapala, Mexico, affected by water level fluctuations. These situations require social reorganization, especially among groups whose survival is directly dependent on the lake’s integrity, such as fishermen.Using an adaptation and adaptability framework, various historical and current strategies used to confront scarcity and lake stress in La Palma, Michoacán are contrasted. Our aim is to highlight the changing social position of the fishing trade, and its most influential cultural features that have allowed its continuity.

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.

Changes in the fish community and water quality during seven years of stocking piscivorous fish in a shallow lake

DEFF Research Database (Denmark)

Skov, Christian; Perrow, M.R.; Berg, Søren

2002-01-01

evaluated between predatory fish and potential prey and between zooplanktivorous or benthivorous fish and water quality parameters. In addition, potential consumption of piscivorous fishes was calculated. 3. The density of fish feeding on larger zooplankton or benthos (roach >15 cm, crucian carp >15 cm......1. Piscivores (annual stocking of 1000 individuals ha(-1) of 0+ pike and a single stocking of 30 kg ha(-1) of large 20-30 cm perch) were stocked in seven consecutive years in a shallow eutrophic lake in Denmark. The stocking programme aimed at changing food-web structure by reducing...... zooplanktivorous and benthivorous fish, with resultant effects on lower trophic levels and ultimately water quality. 2. The fish community and water quality parameters (Secchi depth, concentrations of total phosphorus, chlorophyll a and suspended solids) were monitored between 1996 and 2000 and relationships were...

FISH PRODUCTION ESTIMATES FOR GBEDIKERE LAKE, BASSA, KOGI STATE, NIGERIA

Directory of Open Access Journals (Sweden)

Samuel Olusegun Adeyemi

2013-10-01

Full Text Available Annual estimates of the fish caught by local fishermen in randomly selected fishing villages adjacent to Gbedikere Lake were determined using Catch Assessment (CAS. The studies were carried out within two seasons of low water (February and high water (September periods between 2006 to 2008. Annual fish catch varied from 537.4 mts to 576.9 mts at high water. Mean catch per boat ranged from 7.40 kg to 10.60 kg among the landing sites. A total of 12 fish species were identified belonging to ten families. The catches were dominated by the cichlids with Orechromis niloticus dominating the overall catch compositions. Production estimate was compared with the catches obtained through experimental gill-net sampling and potential fish yield estimates using Ryder’s Morpho - Edaphic Index (MEI as modified by Henderson and Welcomme (1974. Contributions of the gears in use were also done with cast nets ranking above others (29%, followed by the set net (25%, hook and lines (16.6%, traps (16.6%, clap net (8.3%. Management measures were suggested.

Impacts of climate warming on lake fish community structure and potential effects on ecosystem function

NARCIS (Netherlands)

Jeppesen, E.; Meerhoff, M.; Holmgren, K.; González-Bergonzoni, I.; Teixeira-de Mello, F.; Declerck, Steven A.J.; De Meester, L.; Søndergaard, M.; Lauridsen, T.; Bjerring, R.; Conde-Porcuna, J-M.; Mazzeo, N.; Iglesias, C.; Reizenstein, M.; Malmquist, H.J.; Liu, Z.; Balayla, D.; Lazzaro, X.

2010-01-01

Fish play a key role in the trophic dynamics of lakes, not least in shallow systems. With climate warming, complex changes in fish community structure may be expected owing to the direct and indirect effects of temperature, and indirect effects of eutrophication, water-level changes and salinisation

heavy metal contamination of clarias gariepinus from a lake and fish ...

African Journals Online (AJOL)

Adult Clarias gariepinus (African Catfish) were purchased from Eleiyele Lake and Zartech fish farm in Ibadan. Water samples were also collected in February (dry season) and. June (rainy season), 2002. Gill, bone, intestine, muscle and water samples were analyzed for five metals: manganese, copper, zinc, iron, and ...

From "Duck Factory" to "Fish Factory": Climate induced changes in vertebrate communities of prairie pothole wetlands and small lakes

Science.gov (United States)

McLean, Kyle I.; Mushet, David M.; Stockwell, Craig A.

2016-01-01

The Prairie Pothole Region’s myriad wetlands and small lakes contribute to its stature as the “duck factory” of North America. The fishless nature of the region’s aquatic habitats, a result of frequent drying, freezing, and high salinity, influences its importance to waterfowl. Recent precipitation increases have resulted in higher water levels and wetland/lake freshening. In 2012–13, we sampled chemical characteristics and vertebrates (fish and salamanders) of 162 Prairie Pothole wetlands and small lakes. We used non-metric multidimensional scaling, principal component analysis, and bootstrapping techniques to reveal relationships. We found fish present in a majority of sites (84 %). Fish responses to water chemistry varied by species. Fathead minnows (Pimephales promelas) and brook sticklebacks (Culaea inconstans) occurred across the broadest range of conditions. Yellow perch (Perca flavescens) occurred in a smaller, chemically defined, subset. Iowa darters (Etheostoma exile) were restricted to the narrowest range of conditions. Tiger salamanders (Ambystoma mavortium) rarely occurred in lakes with fish. We also compared our chemical data to similar data collected in 1966–1976 to explore factors contributing to the expansion of fish into previously fishless sites. Our work contributes to a better understanding of relationships between aquatic biota and climate-induced changes in this ecologically important area.

PARENTAL CONSUMPTION OF CONTAMINATED SPORT FISH FROM LAKE ONTARIO AND PREDICTED FECUNDABILITY

Science.gov (United States)

Wildlife studies suggest that consumption of contaminated fish from the Great Lakes may expose humans to polychlorinated biphenyls and persistent chlorinated pesticides. To assess whether time to pregnancy or fecundability is affected, we conducted a telephone survey in 1993 with...

Fishes from Lake Yaxhá, Mayan Biosphere Reserve, Petén, Guatemala

OpenAIRE

Barrientos, Christian; Elías, Diego; Quintana, Yasmín

2015-01-01

The Mayan Biosphere Reserve is the largest protected area in Guatemala. Lake Yaxhá is located inside the core zone. Using electrofishing, seines and gillnets we assessed the fish richness and community in 2011. We collected 18 species distributed in seven families, with Cichlidae (seven species) and Poecilidae (five species) the most specious. We evaluated the effectiveness of electrofishing to sample the most important fish in the artisanal fishery in Petén, Petenia splendida, with September...

Acid rain recovery may help to mitigate the impacts of climate change on thermally sensitive fish in lakes across eastern North America.

Science.gov (United States)

Warren, Dana R; Kraft, Clifford E; Josephson, Daniel C; Driscoll, Charles T

2017-06-01

From the 1970s to 1990s, more stringent air quality regulations were implemented across North America and Europe to reduce chemical emissions that contribute to acid rain. Surface water pH slowly increased during the following decades, but biological recovery lagged behind chemical recovery. Fortunately, this situation is changing. In the past few years, northeastern US fish populations have begun to recover in lakes that were historically incapable of sustaining wild fish due to acidic conditions. As lake ecosystems across the eastern United States recover from acid deposition, the stress to the most susceptible populations of native coldwater fish appears to be shifting from acidification effects to thermal impacts associated with changing climate. Extreme summer temperature events - which are expected to occur with increasing frequency in the coming century - can stress and ultimately kill native coldwater fish in lakes where thermal stratification is absent or highly limited. Based on data from northeastern North America, we argue that recovery from acid deposition has the potential to improve the resilience of coldwater fish populations in some lakes to impacts of climate change. This will occur as the amount of dissolved organic carbon (DOC) in the water increases with increasing lake pH. Increased DOC will reduce water clarity and lead to shallower and more persistent lake thermoclines that can provide larger areas of coldwater thermal refuge habitat. Recovery from acidification will not eliminate the threat of climate change to coldwater fish, but secondary effects of acid recovery may improve the resistance of coldwater fish populations in lakes to the effects of elevated summer temperatures in historically acidified ecosystems. This analysis highlights the importance of considering the legacy of past ecosystem impacts and how recovery or persistence of those effects may interact with climate change impacts on biota in the coming decades. © 2016 John

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

Bioaccumulation of PCB Contaminants in Five Fish Species in Utah Lake as Affected by Carp Removal

Science.gov (United States)

Sanjinez-Guzmán, V. A.; Cadet, E. L.; Crandall, T.; Chamberlain, T.; Rakotoarisaona, H.; Morris, P.

2017-12-01

State reports published by the Utah Department of Health (2005) and the Utah Department of Water Quality (2008) determined that there were elevated levels of PCBs (Polychlorinated biphenyls) that exceeded the EPA's cancer (0.02 𝑚𝑔 𝑘𝑔-1) and non-cancer screening levels (0.08 𝑚𝑔 𝑘𝑔-1) in two fish species from Utah Lake, the Common Carp (Cyprinus carpio) and the Channel Catfish (Ictalurus punctatus). Fish consumption advisories were issued for both of these fish species due to their health effects of PCBs. The Common Carp is a non-native predatory species that comprise 90% of the biomass in Utah Lake. As of September 2009, an extensive carp removal program was instituted by the Department of Natural Resources and began the removal of 75% of the carp population. The purpose of this study is to assess the impact of carp removal on PCB levels in five sport fish species consumed by Utah citizens. The fish being analyzed are the Common Carp (Cyprinus carpio), Channel Catfish (Ictalurus punctatus), Black Bullhead (Ameiurus melas), Walleye (Sander vitreus), and White Bass (Morone chrysops). One-hundred twenty (120) fish were collected from Utah Lake and subcategorized by their gender, tissue type (fillet and offal), weight, and size: small (under 33 cm), medium (33 cm - 43 cm), and large (greater than 43 cm). This was done in order to determine the variation of contaminant levels in each subcategory. PCB analysis was performed by Utility Testing Laboratory in Salt Lake City, Utah. Results show there has been a significant increase in PCB levels in all fish species in comparison with the state reports (2008). All fish species have exceeded the EPA cancer screening level, except for the fillet tissue of the White Bass species. In Common Carp fillet, and offal decreased concentrations of 11.80% and 23.72%, respectively. In Channel catfish: the PCB levels in the fillet increase by 87.93%, however, the offal levels

Po-210 and Pb-210 in water and fish from Taboshar uranium mining Pit Lake, Tajikistan

International Nuclear Information System (INIS)

Skipperud, L.; Jørgensen, A.G.; Heier, L.S.; Salbu, B.; Rosseland, B.O.

2013-01-01

Polonium-210 in water and 210 Pb and 210 Po in different fish organs from 3 different fish species in Taboshar Pit Lake (n = 13), located in the uranium mining area in Tajikistan, and in Kairakkum Reservoir (reference lake, n = 3), have been determined as part of a Joint project between Norway, Kazakhstan, Kyrgyzstan and Tajikistan. The average activity concentration of 210 Pb and 210 Po in liver, muscle and bone of Carassius auratus was higher than the concentration in similar tissues of C. carpio and Sander lucioperca from the reference site. The accumulation of 210 Po was higher than for 210 Pb, and the accumulation of 210 Po was highest in the liver of C. auratus (3673 ± 434 Bq kg −1 ww). Although the average activity concentration of 210 Pb in liver and bones of C. auratus from Pit Lake were fairly similar, a huge variation in the liver activity concentrations (25–327 Bq kg −1 ww) was found. The results confirm direct uptake of unsupported 210 Po into the liver, and that the distributions of 210 Po and 210 Pb in fish organs were different. The BCF (L/kg) for 210 Po in bone, liver and muscle clearly demonstrates high accumulation of 210 Po in C. auratus, especially in the liver. The average BCFs of liver, bone and muscle were >1.4 × 10 5 , >2.5 × 10 4 and >1.4 × 10 4 , respectively. All fish in the Pit Lake were found to be in the same trophic level, however, a linear correlation between log 210 Po in liver and δ 15 N could indicate biomagnification of 210 Po in liver of C. auratus. In regards to the recommended Annual Limit of Intake (ALI) for 210 Po, the concentration of 210 Po in muscle tissues of C. auratus is alarming, as there is a high probability for the local population at risk to exceed the recommended ALI through consumption of fish from Taboshar Pit Lake

Temporal variation in fish mercury concentrations within lakes from the western Aleutian Archipelago, Alaska.

Directory of Open Access Journals (Sweden)

Leah A Kenney

Full Text Available We assessed temporal variation in mercury (Hg concentrations of threespine stickleback (Gasterosteus aculeatus from Agattu Island, Aleutian Archipelago, Alaska. Total Hg concentrations in whole-bodied stickleback were measured at two-week intervals from two sites in each of two lakes from June 1 to August 10, 2011 during the time period when lakes were ice-free. Across all sites and sampling events, stickleback Hg concentrations ranged from 0.37-1.07 µg/g dry weight (dw, with a mean (± SE of 0.55 ± 0.01 µg/g dw. Mean fish Hg concentrations declined by 9% during the study period, from 0.57 ± 0.01 µg/g dw in early June to 0.52 ± 0.01 µg/g dw in mid-August. Mean fish Hg concentrations were 6% higher in Loon Lake (0.56 ± 0.01 µg/g dw than in Lake 696 (0.53 ± 0.01 µg/g dw, and 4% higher in males (0.56 ± 0.01 µg/g dw than in females (0.54 ± 0.01 µg/g dw. Loon Lake was distinguished from Lake 696 by the presence of piscivorous waterbirds during the breeding season. Mercury concentrations in stickleback from Agattu Island were higher than would be expected for an area without known point sources of Hg pollution, and high enough to be of concern to the health of piscivorous wildlife.

Temporal variation in fish mercury concentrations within lakes from the western Aleutian Archipelago, Alaska

Science.gov (United States)

Kenney, Leah A.; Eagles-Smith, Collin A.; Ackerman, Joshua T.; von Hippel, Frank A.

2014-01-01

We assessed temporal variation in mercury (Hg) concentrations of threespine stickleback (Gasterosteus aculeatus) from Agattu Island, Aleutian Archipelago, Alaska. Total Hg concentrations in whole-bodied stickleback were measured at two-week intervals from two sites in each of two lakes from June 1 to August 10, 2011 during the time period when lakes were ice-free. Across all sites and sampling events, stickleback Hg concentrations ranged from 0.37–1.07 µg/g dry weight (dw), with a mean (± SE) of 0.55±0.01 µg/g dw. Mean fish Hg concentrations declined by 9% during the study period, from 0.57±0.01 µg/g dw in early June to 0.52±0.01 µg/g dw in mid-August. Mean fish Hg concentrations were 6% higher in Loon Lake (0.56±0.01 µg/g dw) than in Lake 696 (0.53±0.01 µg/g dw), and 4% higher in males (0.56±0.01 µg/g dw) than in females (0.54±0.01 µg/g dw). Loon Lake was distinguished from Lake 696 by the presence of piscivorous waterbirds during the breeding season. Mercury concentrations in stickleback from Agattu Island were higher than would be expected for an area without known point sources of Hg pollution, and high enough to be of concern to the health of piscivorous wildlife.

Water-quality models to assess algal community dynamics, water quality, and fish habitat suitability for two agricultural land-use dominated lakes in Minnesota, 2014

Science.gov (United States)

Smith, Erik A.; Kiesling, Richard L.; Ziegeweid, Jeffrey R.

2017-07-20

Fish habitat can degrade in many lakes due to summer blue-green algal blooms. Predictive models are needed to better manage and mitigate loss of fish habitat due to these changes. The U.S. Geological Survey (USGS), in cooperation with the Minnesota Department of Natural Resources, developed predictive water-quality models for two agricultural land-use dominated lakes in Minnesota—Madison Lake and Pearl Lake, which are part of Minnesota’s sentinel lakes monitoring program—to assess algal community dynamics, water quality, and fish habitat suitability of these two lakes under recent (2014) meteorological conditions. The interaction of basin processes to these two lakes, through the delivery of nutrient loads, were simulated using CE-QUAL-W2, a carbon-based, laterally averaged, two-dimensional water-quality model that predicts distribution of temperature and oxygen from interactions between nutrient cycling, primary production, and trophic dynamics.The CE-QUAL-W2 models successfully predicted water temperature and dissolved oxygen on the basis of the two metrics of mean absolute error and root mean square error. For Madison Lake, the mean absolute error and root mean square error were 0.53 and 0.68 degree Celsius, respectively, for the vertical temperature profile comparisons; for Pearl Lake, the mean absolute error and root mean square error were 0.71 and 0.95 degree Celsius, respectively, for the vertical temperature profile comparisons. Temperature and dissolved oxygen were key metrics for calibration targets. These calibrated lake models also simulated algal community dynamics and water quality. The model simulations presented potential explanations for persistently large total phosphorus concentrations in Madison Lake, key differences in nutrient concentrations between these lakes, and summer blue-green algal bloom persistence.Fish habitat suitability simulations for cool-water and warm-water fish indicated that, in general, both lakes contained a large

Restoration of Shallow Lakes in Subtropical and Tropical China: Response of Nutrients and Water Clarity to Biomanipulation by Fish Removal and Submerged Plant Transplantation

Directory of Open Access Journals (Sweden)

Jinlei Yu

2016-10-01

Full Text Available Fish removal has been used to restore temperate lakes, and positive effects on ecological state and water clarity have frequently been recorded in many lakes. Recently, a supplementary measure, transplantation of submerged macrophytes after fish removal, has been applied to restore warm Chinese shallow lakes in order to compensate for the expected lack of increasing grazing control of phytoplankton after the biomanipulation. These measures have successfully shifted turbid warm lakes to a clear water state, but little is known about the responses to restoration of key physico-chemical variables. We analyzed the seasonal variation in nutrient concentrations in two subtropical and one tropical biomanipulated shallow Chinese lakes subjected to restoration. In all three lakes, a marked decline occurred in the concentrations of lake total nitrogen (TN, total phosphorus (TP, total suspended solids (TSS, and chlorophyll a (Chl a, while the transparency (SD:WD ratio, Secchi depth to water depth ratio increased. A clear water state was established, lasting so far for 7 to 23 months, and TN, TP, Chl a, and TSS levels in the three restored lakes decreased to, on average, 49%, 58%, 41%, and 18% of the level prior to restoration and/or the level in a reference lake, respectively, while the annual mean SD:WD ratio exhibited a 1.5–4 fold increase. In conclusion, lake restoration by transplantation of submerged macrophytes after fish removal had major positive effects on the physico-chemical variables in our study lakes. However, continuous control of omnivorous and herbivorous fish biomass is recommended as the fish typically present in warm, shallow lakes to some extent feed on submerged macrophytes, when available.

Bioaccumulation of organochlorine pollutants in the fish community in Lake Arungen, Norway

International Nuclear Information System (INIS)

Sharma, Chhatra Mani; Rosseland, Bjorn Olav; Almvik, Marit; Eklo, Ole Martin

2009-01-01

Organochlorine pollutants in the major fish species (pike Esox lucius, perch Perca fluviatilis, and roach Rutilus rutilus) of Lake Arungen, Norway, were investigated after an extensive removal of large pike in 2004. The organochlorine pollutants detected in fish liver samples in 2005 were dichlorodiphenyltrichloroethane (DDTs), polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and heptachlor epoxide (HCE). DDTs were the dominant among all analyzed OCs. ΣPCB and HCB, detected in fish from two clearly distinct trophic levels (prey and predators), give an indication of biomagnification. All OC concentrations in female pike were significantly lower compared to males, which might be due to the removal of high concentrations of pollutants in roe during spawning. - Organochlorine pollutants in fish tissues tend to magnify up the food chain

Effects of water quality and trophic status on helminth infections in the cyprinid fish, Schizothorax niger Heckel, 1838 from three lakes in the Kashmir Himalayas.

Science.gov (United States)

Zargar, U R; Yousuf, A R; Chishti, M Z; Ahmed, F; Bashir, H; Ahmed, F

2012-03-01

Water quality greatly influences the population density of aquatic biota, including parasites. In order to evaluate the relationship between fish parasites and water quality in Kashmir Himalayas, we assessed helminth parasite densities in Schizothorax niger Heckel, 1838 (an endemic cyprinid fish of Kashmir) from three lakes, namely Anchar, Manasbal and Dal, which reflected the varied stages of eutrophication. The overall prevalence of helminth infections was higher in the hypertrophic Anchar Lake (prevalence = 18.6%) compared to Manasbal Lake, which was the least eutrophied (prevalence = 6.4%). Furthermore, mean prevalence of monoxenous and heteroxenous parasites was higher in lakes containing higher levels of water degradation (Anchar and Dal). The mean number of helminth species per fish host was the highest in the hypertrophic lake (1.3 ± 0.3) in comparison to the least eutrophic lake (0.2 ± 1.5). Variability of calculated infection indices (prevalence, mean intensity and mean abundance) revealed that helminth parasite composition in the fish was affected by the lakes' environmental stress (degraded water quality). Therefore, data on the density of helminth parasites in fish can provide supplementary information on the pollution status of a water body.

trace metals in selected fish species from lakes awassa and ziway

African Journals Online (AJOL)

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were collected from six sampling stations in Lakes Awassa and Ziway, Ethiopia. The edible ... Concentrations of trace elements in the fishes ranged (µg element/g dry mass): Zn. 23.04–30.92; Fe ...... water and soil sediments from some fishponds. Int. J. Environ. ... radioactive contaminants in the aquatic environ- ment and ...

Recovery of a wild fish population from whole-lake additions of a synthetic estrogen.

Science.gov (United States)

Blanchfield, Paul J; Kidd, Karen A; Docker, Margaret F; Palace, Vince P; Park, Brad J; Postma, Lianne D

2015-03-03

Despite widespread recognition that municipal wastewaters contain natural and synthetic estrogens, which interfere with development and reproduction of fishes in freshwaters worldwide, there are limited data on the extent to which natural populations of fish can recover from exposure to these compounds. We conducted whole-lake additions of an active component of the birth control pill (17α-ethynylestradiol; EE2) that resulted in the collapse of the fathead minnow (Pimephales promelas) population. Here we quantify physiological, population, and genetic characteristics of this population over the 7 years after EE2 additions stopped to determine if complete recovery was possible. By 3 years post-treatment, whole-body vitellogenin concentrations in male fathead minnow had returned to baseline, and testicular abnormalities were absent. In the spring of the fourth year, adult size-frequency distribution and abundance had returned to pretreatment levels. Microsatellite analyses clearly showed that postrecovery fish were descendants of the original EE2-treated population. Results from this whole-lake experiment demonstrate that fish can recover from EE2 exposure at the biochemical through population levels, although the timelines to do so are long for multigenerational exposures. These results suggest that wastewater treatment facilities that reduce discharges of estrogens and their mimics can improve the health of resident fish populations in their receiving environments.

A new cichlid fish in the Sahara: The Ounianga Serir lakes (Chad), a biodiversity hotspot in the desert.

Science.gov (United States)

Trape, Sébastien

In the rare perennial bodies of water of the Sahara desert, only a few fish species have survived to increasing aridification since the end of the last humid period at the Holocene, approximately 5000 years BP. Here, I report the occurrence of an undescribed haplochomine cichlid fish in Lake Boukou, one of the seven Ounianga Serir lakes (Chad). These lakes are located in one of the most arid areas of the Sahara desert, but they persist by virtue of subsurface inflow of fresh groundwater from a large fossil aquifer. Astatotilapia tchadensis sp. nov. is characterized by a black bar between eye and corner of mouth, rounded orange spots on anal fin, scales ctenoid, lower limb of first gill arch with 7-8 gill rackers, dorsal fin with 13-14 spines and 9-11 soft rays, anal fin with 3 spines and 8-9 soft rays, 29 or 30 lateral line scales, and lower pharyngeal dentition with enlarged molariform teeth. The new species is easily distinguished from A. desfontainii and A. flaviijosephii, the northernmost haplochromine species currently isolated from its other group members, and appears close to an unnamed species of Lake Chad basin. Ounianga Serir lakes and especially Lake Boukou present a remarkable diversity of fish, the highest known in the Sahara desert with a total of at least six fish species belonging to six genera and three families. They also constitute an exceptional natural landscape inscribed on the UNESCO world heritage list in 2012 and a biodiversity hotspot for desert vertebrate species. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Comparing the Performance of Protected and Unprotected Areas in Conserving Freshwater Fish Abundance and Biodiversity in Lake Tanganyika, Tanzania

Directory of Open Access Journals (Sweden)

Emmanuel Andrew Sweke

2016-01-01

Full Text Available Marine protected areas have been shown to conserve aquatic resources including fish, but few studies have been conducted of protected areas in freshwater environments. This is particularly true of Lake Tanganyika, Tanzania. To better conserve the lake’s biodiversity, an understanding of the role played by protected areas in conserving fish abundance and diversity is needed. Sampling of fish and environmental parameters was performed within the Mahale Mountains National Park (MMNP and nearby unprotected areas at depths between 5 m and 10 m. Twelve replicates of fish sampling were performed at each site using gillnets set perpendicularly to the shore. Mann-Whitney tests were performed, and the total amount of species turnover was calculated. A total of 518 individual fish from 57 species were recorded in the survey. The fish weight abundance was fivefold greater in the MMNP than in the unprotected areas. Fish abundance and diversity were higher in the MMNP than in the unprotected areas and decreased with distance from it. Our findings confirmed the importance of the protected area in conserving fish resources in Lake Tanganyika. The study provides baseline information for management of the resources and guiding future studies in the lake and other related ecosystems. Management approaches that foster awareness and engage with communities surrounding the MMNP are recommended for successful conservation of the resources in the region.

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.

Occurrence of parasites of the genus Eustrongylides spp. (Nematoda: Dioctophymatidae in fish caught in Trasimeno lake, Italy

Directory of Open Access Journals (Sweden)

Raffaella Branciari

2016-11-01

Full Text Available Eustrongylides spp. is considered a freshwater fish zoonotic nematode. In the present study, the prevalence of Eustrongylides spp. in six edible fish (European perch - Perca fluviatilis, goldfish - Carassius auratus, largemouth black bass - Micropterus salmoides, tench- Tinca tinca, carp - Cyprinus carpio and sand smelt - Atherina boyeri of Trasimeno lake was surveyed. The investigations were conducted from October 2014 to September 2015 and 384 specimens per species for each season were caught in Trasimeno lake and examined for the presence of larvae in the abdominal cavity and muscle. The presence of nematodes in the abdominal cavity and musculature was revealed in three fish species. The prevalence of Eustrongylides spp. infection was 6.84, 1.89 and 0.13% in perch, largemouth black bass and sand smelt, respectively. The number of parasites per fish was only one in largemouth black bass and sand smelt and ranged from one up to three in perch. This study states that the European perch, largemouth black bass and sand smelt of Trasimeno lake are infected with zoonotic parasites; therefore, food business operators have to take appropriate measures to guarantee the health of consumers.

Assessment of committed effective dose due to the ingestion of 210Po and 210Pb in consumed Lebanese fish affected by a phosphate fertilizer plant

International Nuclear Information System (INIS)

Aoun, M.; El Samad, O.; Bou Khozam, R.; Lobinski, R.

2015-01-01

Ingestion of radionuclides through seafood intake is a one of the sources contributing to the internal effective dose in the human organism. In order to evaluate the internal exposure and potential risks due to 210 Po and 210 Pb associated with fish consumption, these radionuclides were measured in commonly consumed fish species from a clean area and an area subjected to the impact of a Lebanese phosphate fertilizer plant. The highest concentration of 210 Pb was 98.7 Bq/kg fresh weight while 210 Po activity concentrations varied from 3.6 Bq/kg to 140 Bq/kg. A supplementary radiation exposure was detected; the highest committed effective dose due to 210 Po and 210 Pb was found to be 1110 μSv/y and 450 μSv/y, respectively. Moreover, the average mortality and morbidity risks due to the fish consuming were estimated. - Highlights: • Enrichment in 210 Po and 210 Pb in fish affected by a phosphate fertilizer plant. • Significant human exposure associated with the ingestion of fish. • Estimation of potential risks due to 210 Po and 210 Pb via fish consumption

Bioaccumulation of persistent organic pollutants (POPs) in fish species from Lake Koka, Ethiopia: The influence of lipid content and trophic position

International Nuclear Information System (INIS)

Deribe, Ermias; Rosseland, Bjørn Olav; Borgstrøm, Reidar; Salbu, Brit; Gebremariam, Zinabu; Dadebo, Elias; Norli, Hans Ragnar; Eklo, Ole Martin

2011-01-01

The concentrations and bioaccumulation of persistent organic pollutants (POPs) were determined in four fish species from Lake Koka, Ethiopia, representing 2–3 levels in the food chain of the lake. Dichlorodiphenyltrichloroethanes (DDTs), endosulfans, polychlorinated biphenyls (PCBs) and chlorpyrifos were identified, with DDTs as the most predominant pesticide, with concentration ranging from 0.05 to 72.53 ng g −1 wet weight (ww). All fish tissue samples collected from different species of the lake contained residues of DDTs. The maximum level of DDTs was found in the fattiest, African sharptooth catfish (Clarias gariepinus) sampled from the lake, with a mean concentration of 15.15 ng g −1 ww. The significant (P 15 N indicates that DDTs biomagnified in the food web of the lake. The 4,4′-DDE to 4,4′-DDT ratio in Oreochromis niloticus (0.6) and Cyprinus carpio (0.5) were below 1, indicating ongoing use of DDTs in the study area and recent exposure of these fish species.

Constraints and motivations related to fishing along the Lake Ontario coast

Science.gov (United States)

Matthew P. Brincka; Diane M. Kuehn; Valerie Luzadis

2012-01-01

The number of nonresident anglers along the Lake Ontario coast has decreased over the past 15 years. Therefore, in order to sustain a strong sport fishing industry, local businesses and tourism promoters might want to tap into the large resident angler market group. This study examines resident anglers' social, environmental, and economic constraints/facilitators...

Assessment of fishing gear and catch rate in Oguta Lake, south ...

African Journals Online (AJOL)

This study was carried out in Oguta Lake, Imo State, Nigeria, from January, 2012 to December, 2013 at five stations (Onu Utu, Okposha, Ogbe Hausa, Osemotor and Ede Ngwugwu) to ascertain the percentage abundance and catch rate of gear and craft. The average weight of fish caught per canoe per day ranged between ...

Detection of Viral Hemorrhagic Septicemia Virus by Quantitative Reverse Transcription Polymerase Chain Reaction from Two Fish Species at Two Sites in Lake Superior

Science.gov (United States)

Cornwell, Emily R.; Eckerlin, Geofrey E.; Getchell, Rodman G.; Groocock, Geoffrey H.; Thompson, Tarin M.; Batts, William N.; Casey, Rufina N.; Kurath, Gael; Winton, James R.; Bowser, Paul R.; Bain, Mark B.; Casey, James W.

2011-01-01

Viral hemorrhagic septicemia virus (VHSV) was first detected in the Laurentian Great Lakes in 2005 during a mortality event in the Bay of Quinte, Lake Ontario. Subsequent analysis of archived samples determined that the first known isolation of VHSV in the Laurentian Great Lakes was from a muskellunge Esox masquinongy collected in Lake St. Clair in 2003. By the end of 2008, mortality events and viral isolations had occurred in all of the Laurentian Great Lakes except Lake Superior. In 2009, a focused disease surveillance program was designed to determine whether VHSV was also present in Lake Superior. In this survey, 874 fish from 7 sites along the U.S. shoreline of Lake Superior were collected during June 2009. Collections were focused on nearshore species known to be susceptible to VHSV. All fish were dissected individually by using aseptic techniques and were tested for the presence of VHSV genetic material by use of a quantitative reverse transcription (qRT) polymerase chain reaction (PCR) targeting the viral nucleoprotein gene. Seventeen fish from two host species at two different sites tested positive at low levels for VHSV. All attempts to isolate virus in cell culture were unsuccessful. However, the presence of viral RNA was confirmed independently in five fish by using a nested PCR that targeted the glycoprotein (G) gene. Partial G gene sequences obtained from three fish were identical to the corresponding sequence from the original 2003 VHSV isolate (MI03) from muskellunge. These detections represent the earliest evidence for the presence of VHSV in Lake Superior and illustrate the utility of the highly sensitive qRT-PCR assay for disease surveillance in aquatic animals.

The role of light for fish-zooplankton-phytoplankton interactions during winter in shallow lakes - a climate change perspective

DEFF Research Database (Denmark)

Bramm, Mette Elisabeth; Lassen, Majbritt Kjeldahl; Liboriussen, Lone

2009-01-01

in the life history of copepods. The strength of the fish effect on zooplankton biomass diminished with declining light and the effect of light was strongest in the presence of fish. 4. When fish were present, reduced light led to a shift from rotifers to calanoid copepods in the clear lake and from rotifers...... in winter light conditions are needed in order to have a significant effect on the plankton community. The change in light occurring when such plankton communities move northwards in response to global warming will mostly be of modest importance for this lake type, at least for the rest of this century...

Science support for evaluating natural recovery of polychlorinated biphenyl concentrations in fish from Crab Orchard Lake, Crab Orchard National Wildlife Refuge, Illinois

Science.gov (United States)

Kunz, Bethany K.; Hinck, Jo E.; Calfee, Robin D.; Linder, Greg L.; Little, Edward E.

2018-05-11

IntroductionCrab Orchard Lake in southern Illinois is one of the largest and most popular recreational lakes in the state. Construction of the nearly 7,000-acre reservoir in the late 1930s created employment opportunities through the Works Progress Administration, and the lake itself was intended to supply water, control flooding, and provide recreational opportunities for local communities (Stall, 1954). In 1942, the Department of War appropriated or purchased more than 20,000 acres of land around Crab Orchard Lake and constructed the Illinois Ordnance Plant, which manufactured bombs and anti-tank mines during World War II. After the war, an Act of Congress transferred the property to the U.S. Department of the Interior. Crab Orchard National Wildlife Refuge was established on August 5, 1947, for the joint purposes of wildlife conservation, agriculture, recreation, and industry. Production of explosives continued, but new industries also moved onsite. More than 200 tenants have held leases with Crab Orchard National Wildlife Refuge and have operated a variety of manufacturing plants (electrical components, plated metal parts, ink, machined parts, painted products, and boats) on-site. Soils, water, and sediments in several areas of the refuge were contaminated with hazardous substances from handling and disposal methods that are no longer acceptable environmental practice (for example, direct discharge to surface water, use of unlined landfills).Polychlorinated biphenyl (PCB) contamination at the refuge was identified in the 1970s, and a PCB-based fish-consumption advisory has been in effect since 1988 for Crab Orchard Lake. The present advisory covers common carp (Cyprinus carpio) and channel catfish (Ictalurus punctatus); see Illinois Department of Public Health (2017). Some of the most contaminated areas of the refuge were actively remediated, and natural ecosystem recovery processes are expected to further reduce residual PCB concentrations in the lake. The U

Detection of the spatiotemporal trends of mercury in Lake Erie fish communities: a Bayesian approach.

Science.gov (United States)

Azim, M Ekram; Kumarappah, Ananthavalli; Bhavsar, Satyendra P; Backus, Sean M; Arhonditsis, George

2011-03-15

The temporal trends of total mercury (THg) in four fish species in Lake Erie were evaluated based on 35 years of fish contaminant data. Our Bayesian statistical approach consists of three steps aiming to address different questions. First, we used the exponential and mixed-order decay models to assess the declining rates in four intensively sampled fish species, i.e., walleye (Stizostedion vitreum), yellow perch (Perca flavescens), smallmouth bass (Micropterus dolomieui), and white bass (Morone chrysops). Because the two models postulate monotonic decrease of the THg levels, we included first- and second-order random walk terms in our statistical formulations to accommodate nonmonotonic patterns in the data time series. Our analysis identified a recent increase in the THg concentrations, particularly after the mid-1990s. In the second step, we used double exponential models to quantify the relative magnitude of the THg trends depending on the type of data used (skinless-boneless fillet versus whole fish data) and the fish species examined. The observed THg concentrations were significantly higher in skinless boneless fillet than in whole fish portions, while the whole fish portions of walleye exhibited faster decline rates and slower rates of increase relative to the skinless boneless fillet data. Our analysis also shows lower decline rates and higher rates of increase in walleye relative to the other three fish species examined. The food web structural shifts induced by the invasive species (dreissenid mussels and round goby) may be associated with the recent THg trends in Lake Erie fish.

Diel vertical migration of major fish-species in Lake Victoria, East Africa

NARCIS (Netherlands)

Goudswaard, P.C.; Wanink, J.H.; Witte, F.; Katunzi, E.F.B.; Berger, M.R.; Postma, D.J.

2004-01-01

Understanding of migration patterns is essential in the interpretation of hydro-acoustic stock assessment data of partly demersal partly pelagic fish stocks. In this paper we provide this kind of information for some species that were common in the Mwanza Gulf of Lake Victoria in the 1980s, before

Diel vertical migration of major fish-species in Lake Victoria, East Africa.

NARCIS (Netherlands)

Goudswaard, KPC; Wanink, JH; Witte, F; Katunzi, EFB; Berger, MR; Postma, DJ

2004-01-01

Understanding of migration patterns is essential in the interpretation of hydro-acoustic stock assessment data of partly demersal partly pelagic fish stocks. In this paper we provide this kind of information for some species that were common in the Mwanza Gulf of Lake Victoria in the 1980s, before

Fish and crustaceans in northeast Greenland lakes with special emphasis on interactions between Arctic charr (Salvelinus alpinus), Lepidurus arcticus and benthic chydorids

DEFF Research Database (Denmark)

Jeppesen, E.; Christoffersen, K.; Landkildehus, F.

2001-01-01

We studied the trophic structure in the pelagial and crustacean remains in the surface 1 cm of the sediment of 13 shallow, high arctic lakes in northeast Greenland (74 N). Seven lakes were fishless, while the remaining six hosted a dwarf form of Arctic charr (Salvelinus alpinus). In fishless lakes...... sp. in lakes with Lepidurus, while they were abundant in lakes with fish. The low abundance in fishless lakes could not be explained by damage of crustacean remains caused by Lepidurus feeding in the sediment, because remains of the more soft-shelled, pelagic-living Daphnia were abundant...... in the sediment of these lakes. No significant differences between lakes with and without fish were found in chlorophyll a, total phosphorus, total nitrogen, conductivity or temperature, suggesting that the observed link between Lepidurus arcticus and the benthic crustacean community is causal. Consequently...

Polychlorinated dibenzo-p-dioxins, dibenzofurans, biphenyls, naphthalenes and polybrominated diphenyl ethers in the edible fish caught from the Baltic Sea and lakes in Finland

International Nuclear Information System (INIS)

Isosaari, Pirjo; Hallikainen, Anja; Kiviranta, Hannu; Vuorinen, Pekka J.; Parmanne, Raimo; Koistinen, Jaana; Vartiainen, Terttu

2006-01-01

A total of 156 fish composite samples were collected from five areas of the Baltic Sea and from three lakes and analysed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and polybrominated diphenyl ethers (PBDEs). The European Union's maximum permissible level for PCDD/Fs, 4 pg WHO-TEQ/g fresh weight (fw), was exceeded in salmon, river lamprey and Baltic herring. In other species from the Baltic Sea, the 90th percentile was 3.42 pg WHO PCDD/F -TEQ/g fw. In the lake fish, the concentrations of PCDD/Fs, PCBs and PCNs were only 29-46% of those in the same species caught from the Baltic Sea, whereas the concentrations of PBDEs in the lake fish were as high as in the Baltic Sea fish. Dioxin-like PCBs contributed to the total dioxin-like toxicity of PCBs and PCDD/Fs by 49 ± 12% in all the analysed samples. - Lake fish is less contaminated with dioxins, PCBs and chloronaphthalenes than Baltic Sea fish but similarly contaminated with polybrominated diphenyl ethers

Adaption of egg and larvae sampling techniques for lake sturgeon and broadcast spawning fishes in a deep river

Science.gov (United States)

Roseman, Edward F.; Kennedy, Gregory W.; Craig, Jaquelyn; Boase, James; Soper, Karen

2011-01-01

In this report we describe how we adapted two techniques for sampling lake sturgeon (Acipenser fulvescens) and other fish early life history stages to meet our research needs in the Detroit River, a deep, flowing Great Lakes connecting channel. First, we developed a buoy-less method for sampling fish eggs and spawning activity using egg mats deployed on the river bottom. The buoy-less method allowed us to fish gear in areas frequented by boaters and recreational anglers, thus eliminating surface obstructions that interfered with recreational and boating activities. The buoy-less method also reduced gear loss due to drift when masses of floating aquatic vegetation would accumulate on buoys and lines, increasing the drag on the gear and pulling it downstream. Second, we adapted a D-frame drift net system formerly employed in shallow streams to assess larval lake sturgeon dispersal for use in the deeper (>8 m) Detroit River using an anchor and buoy system.

Temporal variations in the food habits of some fish species in Lake ...

African Journals Online (AJOL)

Stomach contents of the 12 most abundant fish species in Lake Nokoué, Benin, collected between 2003 and 2005, were analysed for temporal variations in their diet. Several species showed seasonal shifts in their diets based on benthic prey abundance and biomass variation, which are influenced by physico-chemical ...

Bioaccumulation of persistent organic pollutants (POPs) in fish species from Lake Koka, Ethiopia: The influence of lipid content and trophic position

Energy Technology Data Exchange (ETDEWEB)

Deribe, Ermias, E-mail: ermias.weldemariam@umb.no [Norwegian University of Life Sciences, Department of Plant and Environmental Sciences, P.O. Box 5003, N-1432, As (Norway); Hawassa University, Faculty of Natural Sciences, Department of Applied Biology, P.O. Box 5, Awassa (Ethiopia); Rosseland, Bjorn Olav; Borgstrom, Reidar [Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432, As (Norway); Salbu, Brit [Norwegian University of Life Sciences, Department of Plant and Environmental Sciences, P.O. Box 5003, N-1432, As (Norway); Gebremariam, Zinabu [Higher Education Strategy Center (HESC) P.O. Box 32742, Addis Ababa (Ethiopia); Hawassa University, Faculty of Natural Sciences, Department of Applied Biology, P.O. Box 5, Awassa (Ethiopia); Dadebo, Elias [Hawassa University, Faculty of Natural Sciences, Department of Applied Biology, P.O. Box 5, Awassa (Ethiopia); Norli, Hans Ragnar [Norwegian Institute for Agricultural and Environmental Research, Plant Health and Plant Protection Division, Pesticide Chemistry Section, Hogskoleveien 7, N-1432 As (Norway); Eklo, Ole Martin [Norwegian University of Life Sciences, Department of Plant and Environmental Sciences, P.O. Box 5003, N-1432, As (Norway); Norwegian Institute for Agricultural and Environmental Research, Plant Health and Plant Protection Division, Pesticide Chemistry Section, Hogskoleveien 7, N-1432 As (Norway)

2011-12-01

The concentrations and bioaccumulation of persistent organic pollutants (POPs) were determined in four fish species from Lake Koka, Ethiopia, representing 2-3 levels in the food chain of the lake. Dichlorodiphenyltrichloroethanes (DDTs), endosulfans, polychlorinated biphenyls (PCBs) and chlorpyrifos were identified, with DDTs as the most predominant pesticide, with concentration ranging from 0.05 to 72.53 ng g{sup -1} wet weight (ww). All fish tissue samples collected from different species of the lake contained residues of DDTs. The maximum level of DDTs was found in the fattiest, African sharptooth catfish (Clarias gariepinus) sampled from the lake, with a mean concentration of 15.15 ng g{sup -1}ww. The significant (P < 0.05) relationship between concentrations of DDTs and {delta}{sup 15}N indicates that DDTs biomagnified in the food web of the lake. The 4,4 Prime -DDE to 4,4 Prime -DDT ratio in Oreochromis niloticus (0.6) and Cyprinus carpio (0.5) were below 1, indicating ongoing use of DDTs in the study area and recent exposure of these fish species.

A review of the influence of biogeography, riverine linkages, and marine connectivity on fish assemblages in evolving lagoons and lakes of coastal southern Africa

CSIR Research Space (South Africa)

Whitfield, AK

2017-09-01

Full Text Available lakes), elements of the marine fish assemblage have persisted, especially the presence of facultative catadromous species. Freshwater fish diversity in coastal lakes and lagoons is a function of historical and present biogeography and salinity. From a...

Food of forage fishes in western Lake Erie, 1975-76

Science.gov (United States)

Muth, Kenneth M.; Busch, Wolf-Dieter N.

1989-01-01

In western Lake Erie in the summer and fall of 1975–1976, food eaten by seven forage fishes—emerald shiner (Notropis atherinoides), spottail shiner (Notropis hudsonius), trout-perch (Percopsis omiscomaycus), andyoung-of-the-year (YOY) of alewife (Alosa pseudoharengus), gizzard shad (Dorosoma cepedianum), white bass (Morone chrysops), and freshwater drum (Aplodi-notus grunniens)—was divided among six major taxa: Cladocera, Copepoda, Diptera, Ostracoda, Amphipoda, and Algae. In addition, fish were eaten by YOY white bass, and Rotifera were consumed by YOY gizzard shad. Interspecies diet overlap indices, calculated to compare the food of the different species and to evaluate diet similarities, were usually highest for YOY white bass and YOY freshwater drum when compared with the other species and usually lowest between emerald shiners and all other forage fishes. Understanding the feeding interactions among fishes that could influence production at the forage-food level of the food web could provide insight into how cascading trophic interactions influence the production of piscivorous predators.

B chromosomes have a functional effect on female sex determination in Lake Victoria cichlid fishes.

Directory of Open Access Journals (Sweden)

Kohta Yoshida

2011-08-01

Full Text Available The endemic cichlid fishes in Lake Victoria are a model system for speciation through adaptive radiation. Although the evolution of the sex-determination system may also play a role in speciation, little is known about the sex-determination system of Lake Victoria cichlids. To understand the evolution of the sex-determination system in these fish, we performed cytogenetic analysis in 11 cichlid species from Lake Victoria. B chromosomes, which are present in addition to standard chromosomes, were found at a high prevalence rate (85% in these cichlids. In one species, B chromosomes were female-specific. Cross-breeding using females with and without the B chromosomes demonstrated that the presence of the B chromosomes leads to a female-biased sex ratio in this species. Although B chromosomes were believed to be selfish genetic elements with little effect on phenotype and to lack protein-coding genes, the present study provides evidence that B chromosomes have a functional effect on female sex determination. FISH analysis using a BAC clone containing B chromosome DNA suggested that the B chromosomes are derived from sex chromosomes. Determination of the nucleotide sequences of this clone (104.5 kb revealed the presence of several protein-coding genes in the B chromosome, suggesting that B chromosomes have the potential to contain functional genes. Because some sex chromosomes in amphibians and arthropods are thought to be derived from B chromosomes, the B chromosomes in Lake Victoria cichlids may represent an evolutionary transition toward the generation of sex chromosomes.

Respondent driven sampling in a biomonitoring study of refugees from Burma in Buffalo, New York who eat Great Lakes fish.

Science.gov (United States)

Liu, Ming; McCann, Molly; Lewis-Michl, Elizabeth; Hwang, Syni-An

2018-06-01

Refugees from Burma who consume fish caught from local waterbodies have increased risk of exposure to environmental contaminants. We used respondent driven sampling (RDS) to sample this hard-to-reach population for the first Biomonitoring of Great Lakes Populations program. In the current study, we examined the interview data and assessed the effectiveness of RDS to sample the unique population. In 2013, we used RDS to sample 205 Burmese refugees and immigrants residing in Buffalo, New York who consumed fish caught from Great Lakes waters. RDS-adjusted population estimates of sociodemographic characteristics, residential history, fish consumption related behaviors, and awareness of fish advisories were obtained. We also examined sample homophily and equilibrium to assess how well the RDS assumptions were met in the study. Our sample was diverse with respect to sex, age, years residing in Buffalo, years lived in a refugee camp, education, employment, and fish consumption behaviors, and each of these variables reached equilibrium by the end of recruitment. Burmese refugees in Buffalo consumed Great Lakes fish throughout the year; a majority of them consumed the fish more than two times per week during summer, and about one third ate local fish more than once per week in winter. An estimated 60% of Burmese refugees in Buffalo had heard about local fish advisories. RDS has the potential to be an effective methodology for sampling refugees and immigrants in conducting biomonitoring and environmental exposure assessment. Due to high fish consumption and limited awareness and knowledge of fish advisories, some refugee and immigrant populations are more susceptible to environmental contaminants. Increased awareness on local fish advisories is needed among these populations. Published by Elsevier GmbH.

Physiological and ecological effects of increasing temperature on fish production in lakes of Arctic Alaska

Science.gov (United States)

Carey, Michael P.; Zimmerman, Christian E.

2014-01-01

Lake ecosystems in the Arctic are changing rapidly due to climate warming. Lakes are sensitive integrators of climate-induced changes and prominent features across the Arctic landscape, especially in lowland permafrost regions such as the Arctic Coastal Plain of Alaska. Despite many studies on the implications of climate warming, how fish populations will respond to lake changes is uncertain for Arctic ecosystems. Least Cisco (Coregonus sardinella) is a bellwether for Arctic lakes as an important consumer and prey resource. To explore the consequences of climate warming, we used a bioenergetics model to simulate changes in Least Cisco production under future climate scenarios for lakes on the Arctic Coastal Plain. First, we used current temperatures to fit Least Cisco consumption to observed annual growth. We then estimated growth, holding food availability, and then feeding rate constant, for future projections of temperature. Projected warmer water temperatures resulted in reduced Least Cisco production, especially for larger size classes, when food availability was held constant. While holding feeding rate constant, production of Least Cisco increased under all future scenarios with progressively more growth in warmer temperatures. Higher variability occurred with longer projections of time mirroring the expanding uncertainty in climate predictions further into the future. In addition to direct temperature effects on Least Cisco growth, we also considered changes in lake ice phenology and prey resources for Least Cisco. A shorter period of ice cover resulted in increased production, similar to warming temperatures. Altering prey quality had a larger effect on fish production in summer than winter and increased relative growth of younger rather than older age classes of Least Cisco. Overall, we predicted increased production of Least Cisco due to climate warming in lakes of Arctic Alaska. Understanding the implications of increased production of Least Cisco to

Use of Fish Telemetry in Rehabilitation Planning, Management, and Monitoring in Areas of Concern in the Laurentian Great Lakes

Science.gov (United States)

Brooks, J. L.; Boston, C.; Doka, S.; Gorsky, D.; Gustavson, K.; Hondorp, D.; Isermann, D.; Midwood, J. D.; Pratt, T. C.; Rous, A. M.; Withers, J. L.; Krueger, C. C.; Cooke, S. J.

2017-12-01

Freshwater ecosystems provide many ecosystem services; however, they are often degraded as a result of human activity. To address ecosystem degradation in the Laurentian Great Lakes, Canada and the United States of America established the Great Lakes Water Quality Agreement (GLWQA). In 1987, 43 highly polluted and impacted areas were identified under the GLWQA as having one or more of 14 Beneficial Use Impairments (BUIs) to the physical and chemical habitat for fish, wildlife and humans, and were designated as Areas of Concern (AOC). Subnational jurisdictions combined with local stakeholders, with support from federal governments, developed plans to remediate and restore these sites. Biotelemetry (the tracking of animals using electronic tags) provides information on the spatial ecology of fish in the wild relevant to habitat management and stock assessment. Here, seven case studies are presented where biotelemetry data were directly incorporated within the AOC Remedial Action Plan (RAP) process. Specific applications include determining seasonal fish-habitat associations to inform habitat restoration plans, identifying the distribution of pollutant-indicator species to identify exposure risk to contamination sources, informing the development of fish passage facilities to enable fish to access fragmented upstream habitats, and assessing fish use of created or restored habitats. With growing capacity for fish biotelemetry research in the Great Lakes, we discuss the strengths and weaknesses of incorporating biotelemetry into AOC RAP processes to improve the science and practice of restoration and to facilitate the delisting of AOCs.

Physico-chemical thresholds in the distribution of fish species among French lakes

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Roubeix Vincent

2017-01-01

Full Text Available The management of lakes requires the definition of physico-chemical thresholds to be used for ecosystem preservation or restoration. According to the European Water Framework Directive, the limits between physico-chemical quality classes must be set consistently with biological quality elements. One way to do this consists in analyzing the response of aquatic communities to environmental gradients across monitoring sites and in identifying ecological community thresholds, i.e. zones in the gradients where the species turnover is the highest. In this study, fish data from 196 lakes in France were considered to derive ecological thresholds using the multivariate method of gradient forest. The analysis was performed on 25 species and 36 environmental parameters. The results revealed the highest importance of maximal water temperature in the distribution of fish species. Other important parameters included geographical factors, dissolved organic carbon concentration and water transparency, while nutrients appeared to have low influence. In spite of the diversity of species responses to the gradients, community thresholds were detected in the gradients of the most important physico-chemical parameters and of total phosphorus and nitrate concentrations as well. The thresholds identified in such macroecological study may highlight new patterns of species natural distribution and improve niche characterization. Moreover, when factors that may be influenced by human activities are involved, the thresholds could be used to set environmental standards for lake preservation.

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

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.

Sub-indicator: Prey fish

Science.gov (United States)

Weidel, Brian C.; Dunlop, Erin

2017-01-01

Prey fish communities across the Great Lakes continue to change, although the direction and magnitude of those changes are not consistent across the lakes. The metrics used to categorize prey fish status in this and previous periods are based on elements that are common among each of the lake’s Fish Community Objectives and include diversity and the relative role of native species in the prey fish communities. The diversity index categorized three of lakes as ‘fair’, while Superior and Erie were ‘good’ (Table 1). The short term trend, from the previous period (2008-2010) to the current period (2011-2014) found diversity in Erie and Superior to be unchanging, but the other three lakes to be ‘deteriorating’, resulting in an overall trend categorization of ‘undetermined’ (Table 1). The long term diversity trend suggested Lakes Superior and Erie have the most diverse prey communities although the index for those prey fish have been quite variable over time (Figure 1). In Lake Huron, where non-native alewife have substantially declined, the diversity index has also declined. The continued dominance of alewife in Lake Ontario (96% of the prey fish biomass) resulted in the lowest diversity index value (Figure 1). The proportion of native species within the community was judged as ‘good’ in Lakes Superior and Huron, ‘fair’ in Michigan and Erie and ‘poor’ in Ontario (Table 2). The short term trend was improving in in all lakes except Michigan (‘deteriorating’) and Ontario (‘unchanging’), resulting in an overall short term trend of ‘undetermined’ (Table 2). Over the current period, Lake Superior consistently had the highest proportion native prey fish (87%) while Lake Ontario had the lowest (1%) (Figure 2). Lake Michigan’s percent native has declined as round goby increase and comprises a greater proportion of the community. Native prey fish make up 51% of Lake Erie, although basin-specific values differed (Figure 2). Most notably

Catch per unit efforts and impacts of gears on fish abundance in an oxbow lake ecosystem in Eastern India

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Dipankar Ghosh

2017-05-01

Full Text Available Background: Oxbow lakes are abundant in indigenous fishes, but they are subject to unsustainable fishing practices, potential overexploitation, and indiscriminate use of fine-meshed fishing gear. To quantify the catch per unit effort (CPUE and impact of fishing gears on fish abundance, a survey was carried out in an oxbow lake in eastern India. Methods: The gear-wise CPUE for fish caught in per unit hour of operation was calculated by dividing the total sampling gear catch in biomass, which is the observed value of fish caught by a particular gear, by the total sampling effort hours. A value of P 71%. Cone-framed cast net hauled the maximum catch in biomass (31.51%, and gill nets contributed the maximum number of fish (64.92%. The lower CPUE values of line and hook, gill net, cone-framed cast net and long lines identified them as the most harmful among all gears. Conclusion: Indiscriminate use of gear, particularly line and hook, gill nets, cone-framed cast nets, and long lines, demands regulations and preventions concerning such gear to obtain higher fish abundance.

Spatial distribution of nearshore fish in the vicinity of two thermal generating stations, Nanticoke and Douglas Point, on the Great Lakes

International Nuclear Information System (INIS)

Minns, C.K.; Kelso, J.R.M.; Hyatt, W.

1978-01-01

At Nanticoke, Lake Erie, 1974, mean fish density varied considerably, range 162-14 204/10 000 m 3 , as estimated by digital acoustic fish enumeration. At Douglas Point, Lake Huron, 1975, mean density varied less, range 108-671/10 000 m 3 . At both sites fish densities were generally greatest in the shallowest, 3-5 m, depths. At Nanticoke, where the nearshore has low relief, there were no distinguishable communities. At Douglas Point, where depth increases rapidly offshore, there was evidence of benthic and pelagic communities. There was no evidence of altered fish distribution in relation to temperature. At Nanticoke there was no vertical variation in temperature and no vertical response was to be expected. At Douglas Point there was thermal stratification present in the summer and there was no apparent response. The influence of incident radiation was uncertain because of the effects of diurnal migrations. At both locations fish were clustered horizontally to varying degrees in the spring and fall, while in the summer fish were distributed more evenly. Densest clusters were usually in the vicinity of the turbulent discharge at both locations. The lack of temperature response and the similarity of Nanticoke with situations at nearby streams on Lake Erie suggest that the fish are responding to currents and perhaps topography. (author)

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.

Sampling little fish in big rivers: Larval fish detection probabilities in two Lake Erie tributaries and implications for sampling effort and abundance indices

Science.gov (United States)

Pritt, Jeremy J.; DuFour, Mark R.; Mayer, Christine M.; Roseman, Edward F.; DeBruyne, Robin L.

2014-01-01

Larval fish are frequently sampled in coastal tributaries to determine factors affecting recruitment, evaluate spawning success, and estimate production from spawning habitats. Imperfect detection of larvae is common, because larval fish are small and unevenly distributed in space and time, and coastal tributaries are often large and heterogeneous. We estimated detection probabilities of larval fish from several taxa in the Maumee and Detroit rivers, the two largest tributaries of Lake Erie. We then demonstrated how accounting for imperfect detection influenced (1) the probability of observing taxa as present relative to sampling effort and (2) abundance indices for larval fish of two Detroit River species. We found that detection probabilities ranged from 0.09 to 0.91 but were always less than 1.0, indicating that imperfect detection is common among taxa and between systems. In general, taxa with high fecundities, small larval length at hatching, and no nesting behaviors had the highest detection probabilities. Also, detection probabilities were higher in the Maumee River than in the Detroit River. Accounting for imperfect detection produced up to fourfold increases in abundance indices for Lake Whitefish Coregonus clupeaformis and Gizzard Shad Dorosoma cepedianum. The effect of accounting for imperfect detection in abundance indices was greatest during periods of low abundance for both species. Detection information can be used to determine the appropriate level of sampling effort for larval fishes and may improve management and conservation decisions based on larval fish data.

Seasonal and interannual effects of hypoxia on fish habitat quality in central Lake Erie

Science.gov (United States)

Arend, Kristin K.; Beletsky, Dmitry; DePinto, Joseph; Ludsin, Stuart A.; Roberts, James J.; Rucinski, Daniel K.; Scavia, Donald; Schwab, David J.; Höök, Tomas O.

2011-01-01

1. Hypoxia occurs seasonally in many stratified coastal marine and freshwater ecosystems when bottom dissolved oxygen (DO) concentrations are depleted below 2–3 mg O2 L-1. 2. We evaluated the effects of hypoxia on fish habitat quality in the central basin of Lake Erie from 1987 to 2005, using bioenergetic growth rate potential (GRP) as a proxy for habitat quality. We compared the effect of hypoxia on habitat quality of (i) rainbow smelt, Osmerus mordax mordax Mitchill (young-of-year, YOY, and adult), a cold-water planktivore, (ii) emerald shiner, Notropis atherinoides Rafinesque (adult), a warm-water planktivore, (iii) yellow perch, Perca flavescens Mitchill (YOY and adult), a cool-water benthopelagic omnivore and (iv) round goby Neogobius melanostomus Pallas (adult) a eurythermal benthivore. Annual thermal and DO profiles were generated from 1D thermal and DO hydrodynamics models developed for Lake Erie’s central basin. 3. Hypoxia occurred annually, typically from mid-July to mid-October, which spatially and temporally overlaps with otherwise high benthic habitat quality. Hypoxia reduced the habitat quality across fish species and life stages, but the magnitude of the reduction varied both among and within species because of the differences in tolerance to low DO levels and warm-water temperatures. 4. Across years, trends in habitat quality mirrored trends in phosphorus concentration and water column oxygen demand in central Lake Erie. The per cent reduction in habitat quality owing to hypoxia was greatest for adult rainbow smelt and round goby (mean: -35%), followed by adult emerald shiner (mean: -12%), YOY rainbow smelt (mean: -10%) and YOY and adult yellow perch (mean: -8.5%). 5. Our results highlight the importance of differential spatiotemporally interactive effects of DO and temperature on relative fish habitat quality and quantity. These effects have the potential to influence the performance of individual fish species as well as population dynamics

Methyl mercury concentrations in macroinvertebrates and fish from burned and undisturbed lakes on the Boreal Plain

Energy Technology Data Exchange (ETDEWEB)

Allen, E.W. [Alberta Univ., Edmonton, AB (Canada). Dept. of Biological Sciences; Prepas, E.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Biological Sciences; Lakehead Univ., Thunder Bay, ON (Canada). Faculty of Forest and the Forest Environment; Gabos, S.; Zhang, W. [Alberta Health and Wellness, Edmonton, AB (Canada); Strachan, W.M.J. [Environment Canada, Burlington, ON (Canada). National Water Research Inst.

2005-09-01

Methylmercury (MeHg) concentrations in macroinvertebrates and fish from 5 lakes in burned catchments in Alberta's Swan Hills region were compared with those from 5 reference lakes on the western Canadian Boreal Plain. The objective was to determine the effect of forest fire on the bioaccumulation of MeHg, a toxic pollutant. It was noted that lakes near the Alberta Special Waste Treatment Centre (ASWTC) have fish consumption advisories due to high mercury concentrations. In a separate comparison, MeHg concentrations in biota from a single lake were compared before and after a forest fire interrupted a prescribed timber harvest experiment. The affect of lake water chemistry, watershed characteristics, and trophic ecology on the bioaccumulation and biomagnification of MeHg in littoral food webs was also examined. The study area covered 2 ecoregions, the Boreal Foothills and the Boreal Mixedwood. Two years after the fire, MeHg concentrations in 5 of 6 aquatic taxa did not differ between burned and reference drainage basins in the Swan Hills. These results were in agreement with previous studies. Biomagnification of MeHg was negatively correlated with lake water chlorophyll 'a' concentration. Ecoregional variation in water chemistry seemed to influence MeHg concentrations in aquatic biota, which eluded comparisons of MeHg bioaccumulation between burned and reference drainage basins. MeHg concentrations in biota were negatively correlated with lake water pH, as well as with total phosphorous and dominant cation concentrations, all of which were higher in Mixedwood than in Foothills lakes. It was concluded that in the short-term, fire may lower MeHg concentrations in aquatic biota in a nutrient-rich setting by inducing an increase in lake productivity that dilutes MeHg at the base of the food web. 42 refs., 5 tabs., 7 figs.

Use of navigation channels by Lake Sturgeon: Does channelization increase vulnerability of fish to ship strikes?

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Darryl W Hondorp

Full Text Available Channelization for navigation and flood control has altered the hydrology and bathymetry of many large rivers with unknown consequences for fish species that undergo riverine migrations. In this study, we investigated whether altered flow distributions and bathymetry associated with channelization attracted migrating Lake Sturgeon (Acipenser fulvescens into commercial navigation channels, potentially increasing their exposure to ship strikes. To address this question, we quantified and compared Lake Sturgeon selection for navigation channels vs. alternative pathways in two multi-channel rivers differentially affected by channelization, but free of barriers to sturgeon movement. Acoustic telemetry was used to quantify Lake Sturgeon movements. Under the assumption that Lake Sturgeon navigate by following primary flow paths, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River were expected to choose navigation channels over alternative pathways and to exhibit greater selection for navigation channels than conspecifics in the less-channelized lower St. Clair River. Consistent with these predictions, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River selected the higher-flow and deeper navigation channels over alternative migration pathways, whereas in the less-channelized lower St. Clair River, individuals primarily used pathways alternative to navigation channels. Lake Sturgeon selection for navigation channels as migratory pathways also was significantly higher in the more-channelized lower Detroit River than in the less-channelized lower St. Clair River. We speculated that use of navigation channels over alternative pathways would increase the spatial overlap of commercial vessels and migrating Lake Sturgeon, potentially enhancing their vulnerability to ship strikes. Results of our study thus demonstrated an association between channelization and the path use of migrating Lake Sturgeon that could prove

Evolutionary history of Lake Tanganyika's scale-eating cichlid fishes.

Science.gov (United States)

Koblmüller, Stephan; Egger, Bernd; Sturmbauer, Christian; Sefc, Kristina M

2007-09-01

Although Lake Tanganyika is not the most species-rich of the Great East African Lakes it comprises by far the greatest diversity of cichlid fishes in terms of morphology, ecology, and breeding styles. Our study focuses on the Tanganyikan cichlid tribe Perissodini, which exhibits one of the most peculiar feeding strategies found in cichlids-scale-eating. Their evolutionary history was reconstructed from 1416 bp DNA sequence of two mitochondrial genes (ND2 and partial control region) and from 612 AFLP markers. We confirm the inclusion of the zooplanktivorous genus Haplotaxodon in the tribe Perissodini, and species status of Haplotaxodon trifasciatus. Within the Perissodini, the major lineages emerged within a short period roughly 1.5-2 MYA, which makes their radiation slightly younger than that of other Tanganyikan cichlid tribes. Most scale-eaters evolved in deep-water habitat, perhaps associated with the previously documented radiations of other deep-water dwelling cichlid lineages, and colonized the shallow habitat only recently.

Functional redundancy and sensitivity of fish assemblages in European rivers, lakes and estuarine ecosystems.

Science.gov (United States)

Teichert, Nils; Lepage, Mario; Sagouis, Alban; Borja, Angel; Chust, Guillem; Ferreira, Maria Teresa; Pasquaud, Stéphanie; Schinegger, Rafaela; Segurado, Pedro; Argillier, Christine

2017-12-14

The impact of species loss on ecosystems functioning depends on the amount of trait similarity between species, i.e. functional redundancy, but it is also influenced by the order in which species are lost. Here we investigated redundancy and sensitivity patterns across fish assemblages in lakes, rivers and estuaries. Several scenarios of species extinction were simulated to determine whether the loss of vulnerable species (with high propensity of extinction when facing threats) causes a greater functional alteration than random extinction. Our results indicate that the functional redundancy tended to increase with species richness in lakes and rivers, but not in estuaries. We demonstrated that i) in the three systems, some combinations of functional traits are supported by non-redundant species, ii) rare species in rivers and estuaries support singular functions not shared by dominant species, iii) the loss of vulnerable species can induce greater functional alteration in rivers than in lakes and estuaries. Overall, the functional structure of fish assemblages in rivers is weakly buffered against species extinction because vulnerable species support singular functions. More specifically, a hotspot of functional sensitivity was highlighted in the Iberian Peninsula, which emphasizes the usefulness of quantitative criteria to determine conservation priorities.

Is Fish Farming an Illusion for Lake Malawi Riparian Communities under Environmental Changes?

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Moses Majid Limuwa

2018-05-01

Full Text Available Global environmental changes have negatively affected many food systems while the demand for food has continued to rise. An urgent need exists to identify other sustainable means of producing food. This is a case in Malawi, where capture fisheries and agriculture are not supplying sufficient food. Fish farming food systems by communities who rely on inland fisheries have not been evaluated. Therefore, a study was conducted in two phases: January 2016 to May 2016 and in July 2017 to evaluate if fish farming could sustainably support livelihoods of Lake Malawi riparian communities. We used mixed methods to collect and analyze data. The data collection methods included explorative surveys, household survey interviews, focus group discussion and key informant interviews. Qualitative data was analyzed using content analysis for themes. This identified themes that were quantitatively analyzed using descriptive and inferential statistics. We observed that fish farming was dominated by men and also not the main occupation for the respondents despite owning fishponds. The respondents have water and land, which are prerequisite for any farming. The study also observed fish farming production challenges related to quality fingerlings, formulated diets, and extension services. Cases of food insecurity amongst the respondents were also prevalent due to lack of food to cover the entire year. Weak synergies existed between fish farming and agriculture restricting bio-resource flow and water usage between these two food systems, meaning the outcomes of the food systems provide unsustainable diets. Furthermore, water availability, money spent on food, and cassava cropping increased fish farming participation. Whereas operating a bicycle taxi, casual labor, former fish farming, as well as application of agricultural wastes negatively affected fish farming. On the other hand, extreme weather events (increased incidences of droughts and floods attributed to inter

Alien species of fish parasites in the coastal lakes and lagoons of the southern Baltic

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Jolanta Morozińska-Gogol

2009-03-01

Full Text Available Alien species are now found all over the world. New fish parasites have been unintentionally introduced with infected alien fish imported for aquaculture or have sometimes spread with their intermediate invertebrate hosts transported in the ballast waters of ships. Four alien fish parasites have been recorded in Polish coastal lakes and lagoons, all parasitising eels. Three were introduced with the final host - the Japanese eel - introduced for aquaculture (Anguillicola crassus, Pseudodactylogyrus anguillae and Pseudodactylogyrus bini and one (Paratenuisentis ambiguus with its sole intermediate host (Gammarus tigrinus.

Continental-scale patterns of nutrient and fish effects on shallow lakes: synthesis of a pan-European mesocosm experiment

NARCIS (Netherlands)

Moss, B.; Stephen, D.; Balayla, D.; Bécares, E.; Collings, S.E.; Fernández-Aláez, C.; Fernández-Aláez, M.; Ferriol, C.; García, P.; Gomá, J.; Gyllström, M.; Hansson, L-A.; Hietala, J.; Kairesalo, T.; Rosa Miracle, M.; Romo, S.; Rueda, J.; Russell, V.; Ståhl-Delbanco, A.; Svensson, M.; Vakkilainen, K.; Valentín, M.; van de Bund, W.; Van Donk, E.; Vicente, E.; Villena, M.J.

2004-01-01

1. Results are analysed from 11 experiments in which effects of fish addition and nutrient loading on shallow lakes were studied in mesocosms. The experiments, five in 1998, six in 1999, were carried out in six lakes, distributed from Finland to southern Spain, according to a standard protocol. 2.

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

The composition of fish communities of nine Ethiopian lakes along a north-south gradient: threats and possible solutions

NARCIS (Netherlands)

Vijverberg, J.; Dejen, E.; Getahun, A.; Nagelkerke, L.A.J.

2012-01-01

Fish populations of nine Ethiopian freshwater lakes were quantitatively sampled with a standardized protocol, using multi-mesh gill nets. In total, 27 species were identified, but only 14 species were common. Based on the common species, the fish communities showed large differences in their species

Planktivory in the changing Lake Huron zooplankton community: Bythotrephes consumption exceeds that of Mysis and fish

Science.gov (United States)

Bunnell, D.B.; Hunter, R. Douglas; Warner, D.M.; Chriscinske, M.A.; Roseman, E.F.

2011-01-01

Oligotrophic lakes are generally dominated by calanoid copepods because of their competitive advantage over cladocerans at low prey densities. Planktivory also can alter zooplankton community structure. We sought to understand the role of planktivory in driving recent changes to the zooplankton community of Lake Huron, a large oligotrophic lake on the border of Canada and the United States. We tested the hypothesis that excessive predation by fish (rainbow smelt Osmerus mordax, bloater Coregonus hoyi) and invertebrates (Mysis relicta, Bythotrephes longimanus) had driven observed declines in cladoceran and cyclopoid copepod biomass between 2002 and 2007. We used a field sampling and bioenergetics modelling approach to generate estimates of daily consumption by planktivores at two 91-m depth sites in northern Lake Huron, U.S.A., for each month, May-October 2007. Daily consumption was compared to daily zooplankton production. Bythotrephes was the dominant planktivore and estimated to have eaten 78% of all zooplankton consumed. Bythotrephes consumption exceeded total zooplankton production between July and October. Mysis consumed 19% of all the zooplankton consumed and exceeded zooplankton production in October. Consumption by fish was relatively unimportant - eating only 3% of all zooplankton consumed. Because Bythotrephes was so important, we explored other consumption estimation methods that predict lower Bythotrephes consumption. Under this scenario, Mysis was the most important planktivore, and Bythotrephes consumption exceeded zooplankton production only in August. Our results provide no support for the hypothesis that excessive fish consumption directly contributed to the decline of cladocerans and cyclopoid copepods in Lake Huron. Rather, they highlight the importance of invertebrate planktivores in structuring zooplankton communities, especially for those foods webs that have both Bythotrephes and Mysis. Together, these species occupy the epi-, meta- and

Use of fish telemetry in rehabilitation planning, management, and monitoring in Areas of Concern in the Laurentian Great Lakes

Science.gov (United States)

Brooks, J.L.; Boston, C.; Doka, Susan E.; Gorsky, Dimitry; Gustavson, K.; Hondorp, Darryl W.; Isermann, Daniel A.; Midwood, Jonathan D.; Pratt, T.C.; Rous, Andrew M.; Withers, J. L.; Krueger, C.C.; Cooke, S.J.

2017-01-01

Freshwater ecosystems provide many ecosystem services; however, they are often degraded as a result of human activity. To address ecosystem degradation in the Laurentian Great Lakes, Canada and the United States of America established the Great Lakes Water Quality Agreement (GLWQA). In 1987, 43 highly polluted and impacted areas were identified under the GLWQA as having one or more of 14 Beneficial Use Impairments (BUIs) to the physical and chemical habitat for fish, wildlife and humans, and were designated as Areas of Concern (AOC). Subnational jurisdictions combined with local stakeholders, with support from federal governments, developed plans to remediate and restore these sites. Biotelemetry (the tracking of animals using electronic tags) provides information on the spatial ecology of fish in the wild relevant to habitat management and stock assessment. Here, seven case studies are presented where biotelemetry data were directly incorporated within the AOC Remedial Action Plan (RAP) process. Specific applications include determining seasonal fish–habitat associations to inform habitat restoration plans, identifying the distribution of pollutant-indicator species to identify exposure risk to contamination sources, informing the development of fish passage facilities to enable fish to access fragmented upstream habitats, and assessing fish use of created or restored habitats. With growing capacity for fish biotelemetry research in the Great Lakes, we discuss the strengths and weaknesses of incorporating biotelemetry into AOC RAP processes to improve the science and practice of restoration and to facilitate the delisting of AOCs.

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.

Development of DNA-based Identification methods to track the species composition of fish larvae within nearshore areas of the Great Lakes

Science.gov (United States)

The ability to track the identity and abundance of larval fish, which are ubiquitous during spawning season, may lead to a greater understanding of fish species distributions in Great Lakes nearshore areas including early-detection of invasive fish species before they become esta...

Concentrations and compositions of organochlorine contaminants in sediments, soils, crustaceans, fishes and birds collected from Lake Tai, Hangzhou Bay and Shanghai city region, China

Energy Technology Data Exchange (ETDEWEB)

Nakata, Haruhiko [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan)]. E-mail: nakata@sci.kumamoto-u.ac.jp; Hirakawa, Yuko [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Kawazoe, Masahiro [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, (Japan); Nakabo, Tetsuji [Kyoto University Museum, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Arizono, Koji [Faculty of Environmental and Symbiotic Sciences, Kumamoto Prefectural University, 3-1-100 Tsukide, Kumamoto 862-8502 (Japan); Abe, Shin-Ichi [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Kitano, Takeshi [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Shimada, Hideaki [Faculty of Education, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Watanabe, Izumi [Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchuu-city, Tokyo 183-8509 (Japan); Li Weihua [Shanghai Institute of Planned Parenthood Research, 2140 Xie Tu road, Shanghai 200032 (China); Ding Xucheng [Shanghai Institute of Planned Parenthood Research, 2140 Xie Tu road, Shanghai 200032 (China)

2005-02-01

Contamination by persistent organochlorines (OCs), such as DDTs, hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs) were examined in sediments, soils, fishes, crustaceans, birds, and aquaculture feed from Lake Tai, Hangzhou Bay, and in the vicinity of Shanghai city in China during 2000 and 2001. OCs were detected in all samples analyzed, and DDT and its metabolites were the predominant contaminants in most sediments, soils and biota. Concentrations of p,p'-DDT and ratio of p,p'-DDT to {sigma}DDTs were significantly higher in marine fishes than those in freshwater fishes. While the use of DDTs has been officially banned in China since 1983, these results indicate a recent input of technical DDTs into the marine environment around Hangzhou Bay. Comparison of organochlorine concentrations in fishes collected from Lake Tai and Hangzhou Bay suggests the presence of local sources of HCHs, chlordanes and PCBs at Lake Tai. Higher proportions of penta- and hexa-PCB congeners in fishes at Lake Tai may suggest the use of highly chlorinated PCB product, such as PCB{sub 5}, around this lake. To our knowledge, this is a first comprehensive study to examine the present status of organochlorine contamination in various environmental media, such as sediments, soils and wildlife, in China. - Elevated concentrations of DDTs were detected in sediments, soils, and wildlife collected from China.

Changes in fish mercury concentrations over 20 years in an acidified lake subject to experimental liming

International Nuclear Information System (INIS)

Rask, Martti; Jones, Roger I.; Jaervinen, Marko; Paloheimo, Anna; Salonen, Maiju; Syvaeranta, Jari; Verta, Matti

2007-01-01

Lake Iso Valkjaervi (southern Finland, Europe) was divided in two with a plastic curtain in 1991. One half was neutralized with CaCO 3 , and the other acted as a control. Mercury concentrations of perch (Perca fluviatilis) and northern pike (Esox lucius) in the limed and control side of the lake were studied both before and after the treatment. Average Hg concentrations of perch and pike were 0.40 and 1.2 μg g -1 (ww) in the early 1980s and 0.25 and 0.72 μg g -1 (ww) a decade later at the time of liming. Ten years after the liming the Hg concentrations of perch in the limed and control sides of the lake were 0.21 and 0.28 μg g -1 (ww) and those of pike were 0.69 and 0.43 μg g -1 (ww), respectively. Nitrogen isotope ratios (δ 15 N) for perch in the sampling period 2002-2004 showed wide variation suggesting variable trophic positions for individual fish. Pike formed two groups according to their δ 15 N-values, suggesting that zoobenthos dominated the diet of pike around 20 cm in length and fish that of the larger pikes. Because the δ 15 N-values of fish were at similar levels in the limed and control sides of L. Iso Valkjaervi, differences in food web structure cannot account for the different fish Hg concentrations. A more likely explanation is water quality induced differences in the dynamics and bioavailability of Hg, leading to decreased formation of methyl Hg

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.

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

The assessment of Great Lakes prey fish stocks have been conducted annually with bottom trawls since the 1970s by the Great Lakes Science Center, sometimes assisted by partner agencies. These stock assessments provide data on the status and trends of prey fish that are consumed by important commercial and recreational fishes. Although all these annual surveys are conducted using bottom trawls, they differ among the lakes in the proportion of the lake covered, seasonal timing, trawl gear used, and the manner in which the trawl is towed (across or along bottom contours). Because each assessment is unique, population indices were standardized to the highest value for a time series within each lake for the following prey species: Cisco (Coregonus artedi), Bloater (C. hoyi), Rainbow Smelt (Osmerus mordax), Alewife (Alosa pseudoharengus), and Round Goby (Neogobius melanostomus). In this report, standardized indices are presented in graphical form along with synopses to provide a short, informal cross-basin summary of the status and trends of principal prey fishes. There was basin-wide agreement in the trends of age-1 and older biomass for all prey species, with the highest concordance occurring for coregonids and Rainbow Smelt, and weaker concordance for Alewife. For coregonids, the highest biomass occurred from the mid-1980s to the mid-1990s. Rainbow Smelt biomass declined slowly and erratically during the last quarter century. Alewife biomass was generally higher from the early 1980s through 1990s across the Great Lakes, but since the early 1990s, trends have been divergent across the lakes, though there has been a downward trend in all lakes since 2005. Recently, Lake Huron has shown resurgence in biomass of Bloater, achieving 75% of its maximum record in 2012 due to recruitment of a succession of strong and moderate year classes that appeared in 2005-2011. Also, strong recruitment of the 2010 year class of Alewife has led to a sharp increase in biomass of Alewife in

What is the influence of a reduction of planktivorous and benthivorous fish on water quality in temperate eutrophic lakes? A systematic review

DEFF Research Database (Denmark)

Bernes, Claes; Carpenter, Stephen R.; Gårdmark, Anna

2015-01-01

three years afterwards. Piscivore stocking alone has no significant effect. The response of chlorophyll a levels to biomanipulation is stronger in lakes where fish removal is intense, and in lakes which are small and/or have high pre-manipulation concentrations of total phosphorus. Conclusions: Our......Background: In recent decades, many attempts have been made to restore eutrophic lakes through biomanipulation. Reducing the populations of planktivorous and benthivorous fish (either directly or through stocking of piscivorous fish) may induce ecosystem changes that increase water transparency...... using inclusion criteria set out in an a priori protocol. To reduce the risk of bias, we then critically appraised the combined evidence found on each biomanipulation. Data were extracted on outcomes such as Secchi depth and chlorophyll a concentration before, during and/or after manipulation...

A compilation of empirical data and variations in data concerning radiocesium in water, sediments and fish in European lakes after Chernobyl

International Nuclear Information System (INIS)

Hakanson, L.

1999-01-01

This work concerns the variability of radiocesium within lakes. The focus is on a broad set of data concerning radiocesium after the Chernobyl accident in lake water, sediments and different species of fish. Data are available to the author from three European data bases. Basic questions are: Are there any general patterns to be found concerning the variability of 137 Cs in lakes? Is it possible to give any recommendations concerning CV values (coefficient of variation; CV=SD/MV; SD=standard deviation, MV=mean value) for radiocesium in lake water, sediments and different species of fish? The analysis can be summarised as: 1. The CV values for lake water vary around 0.3 and are rather independent of the time after fallout. 2. One can use a CV of 0.6 as a reference for the typical uncertainty in radiocesium concentration in surficial lake sediments. CV values are generally higher (up to CV=1) for bottom areas dominated by erosion and transport processes (for fine material following Stokes' law) and lower (CV approx. 0.2) for areas dominated by continuous sedimentation and fine deposits (accumulation areas). CV values for radiocesium in sediments are also likely to increase with contamination and the size of the lake. 3. A reference CV of 0.22 would be a reasonable general CV value for lake fish. CV values are typically larger just after fallout (CV approx. 0.3) and decrease with time after fallout (to about 0.15). CV values are likely to increase with trophic level, from about 0.1 for planktivores to about 0.3 for piscivores, but these CV are based on limited data and are quite uncertain. The benefit of general empirical CV values is evident in modelling, e.g., when empirical data are compared to modelled values. The CV values for water, sediments and fish can be used to set empirical uncertainty bands for model predictions to enable meaningful discussions about predictive success. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Lake whitefish diet, condition, and energy density in Lake Champlain and the lower four Great Lakes following dreissenid invasions

Science.gov (United States)

Herbst, Seth J.; Marsden, J. Ellen; Lantry, Brian F.

2013-01-01

Lake Whitefish Coregonus clupeaformis support some of the most valuable commercial freshwater fisheries in North America. Recent growth and condition decreases in Lake Whitefish populations in the Great Lakes have been attributed to the invasion of the dreissenid mussels, zebra mussels Dreissena polymorpha and quagga mussels D. bugensis, and the subsequent collapse of the amphipod, Diporeia, a once-abundant high energy prey source. Since 1993, Lake Champlain has also experienced the invasion and proliferation of zebra mussels, but in contrast to the Great Lakes, Diporeia were not historically abundant. We compared the diet, condition, and energy density of Lake Whitefish from Lake Champlain after the dreissenid mussel invasion to values for those of Lake Whitefish from Lakes Michigan, Huron, Erie, and Ontario. Lake Whitefish were collected using gill nets and bottom trawls, and their diets were quantified seasonally. Condition was estimated using Fulton's condition factor (K) and by determining energy density. In contrast to Lake Whitefish from some of the Great Lakes, those from Lake Champlain Lake Whitefish did not show a dietary shift towards dreissenid mussels, but instead fed primarily on fish eggs in spring, Mysis diluviana in summer, and gastropods and sphaeriids in fall and winter. Along with these dietary differences, the condition and energy density of Lake Whitefish from Lake Champlain were high compared with those of Lake Whitefish from Lakes Michigan, Huron, and Ontario after the dreissenid invasion, and were similar to Lake Whitefish from Lake Erie; fish from Lakes Michigan, Huron, and Ontario consumed dreissenids, whereas fish from Lake Erie did not. Our comparisons of Lake Whitefish populations in Lake Champlain to those in the Great Lakes indicate that diet and condition of Lake Champlain Lake Whitefish were not negatively affected by the dreissenid mussel invasion.

Importance of benthic production to fish populations in Lake Mead prior to the establishment of quagga mussels

Science.gov (United States)

Umek, John; Chandra, Sudeep; Rosen, Michael; Wittmann, Marion; Sullivan, Joe; Orsak, Erik

2010-01-01

Limnologists recently have developed an interest in quantifying benthic resource contributions to higher-level consumers. Much of this research focuses on natural lakes with very little research in reservoirs. In this study, we provide a contemporary snapshot of the food web structure of Lake Mead to evaluate the contribution of benthic resources to fish consumers. In addition, we document the available food to fishes on soft sediments and changes to the invertebrate community over 2 time periods. Benthic invertebrate food availability for fishes is greater in Las Vegas Bay than Overton Arm. Las Vegas Bay is dominated by oligochaetes, whose biomass increased with depth, while Overton Arm is dominated by chironomids, whose biomass did not change with depth. Diet and isotopic measurements indicate the fish community largely relies on benthic resources regardless of basin (Las Vegas Bay >80%; Overton Arm >92%); however, the threadfin shad likely contribute more to largemouth and striped bass production in Overton Arm versus Las Vegas Bay. A 2-time period analysis, pre and post quagga mussel establishment and during lake level declines, suggests there is no change in the density of benthic invertebrates in Boulder Basin, but there were greater abundances of select taxa in this basin by season and depth than in other basins. Given the potential of alterations as a result of the expansion of quagga mussel and the reliance of the fishery on benthic resources, future investigation of basin specific, benthic processes is recommended.

Identification of Cryptosporidium Species in Fish from Lake Geneva (Lac Léman) in France.

Science.gov (United States)

Certad, Gabriela; Dupouy-Camet, Jean; Gantois, Nausicaa; Hammouma-Ghelboun, Ourida; Pottier, Muriel; Guyot, Karine; Benamrouz, Sadia; Osman, Marwan; Delaire, Baptiste; Creusy, Colette; Viscogliosi, Eric; Dei-Cas, Eduardo; Aliouat-Denis, Cecile Marie; Follet, Jérôme

2015-01-01

Cryptosporidium, a protozoan parasite that can cause severe diarrhea in a wide range of vertebrates including humans, is increasingly recognized as a parasite of a diverse range of wildlife species. However, little data are available regarding the identification of Cryptosporidium species and genotypes in wild aquatic environments, and more particularly in edible freshwater fish. To evaluate the prevalence of Cryptosporidiumspp. in fish from Lake Geneva (Lac Léman) in France, 41 entire fish and 100 fillets (cuts of fish flesh) were collected from fishery suppliers around the lake. Nested PCR using degenerate primers followed by sequence analysis was used. Five fish species were identified as potential hosts of Cryptosporidium: Salvelinus alpinus, Esox lucius, Coregonus lavaretus, Perca fluviatilis, and Rutilus rutilus. The presence of Cryptosporidium spp. was found in 15 out of 41 fish (37%), distributed as follows: 13 (87%) C. parvum, 1 (7%) C. molnari, and 1 (7%) mixed infection (C. parvum and C. molnari). C. molnari was identified in the stomach, while C. parvum was found in the stomach and intestine. C. molnari was also detected in 1 out of 100 analyzed fillets. In order to identify Cryptosporidium subtypes, sequencing of the highly polymorphic 60-kDa glycoprotein (gp60) was performed. Among the C. parvum positive samples, three gp60 subtypes were identified: IIaA15G2R1, IIaA16G2R1, and IIaA17G2R1. Histological examination confirmed the presence of potential developmental stages of C. parvum within digestive epithelial cells. These observations suggest that C. parvum is infecting fish, rather than being passively carried. Since C. parvum is a zoonotic species, fish potentially contaminated by the same subtypes found in terrestrial mammals would be an additional source of infection for humans and animals, and may also contribute to the contamination of the environment with this parasite. Moreover, the risk of human transmission is strengthened by the

Identification of Cryptosporidium Species in Fish from Lake Geneva (Lac Léman in France.

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Gabriela Certad

Full Text Available Cryptosporidium, a protozoan parasite that can cause severe diarrhea in a wide range of vertebrates including humans, is increasingly recognized as a parasite of a diverse range of wildlife species. However, little data are available regarding the identification of Cryptosporidium species and genotypes in wild aquatic environments, and more particularly in edible freshwater fish. To evaluate the prevalence of Cryptosporidiumspp. in fish from Lake Geneva (Lac Léman in France, 41 entire fish and 100 fillets (cuts of fish flesh were collected from fishery suppliers around the lake. Nested PCR using degenerate primers followed by sequence analysis was used. Five fish species were identified as potential hosts of Cryptosporidium: Salvelinus alpinus, Esox lucius, Coregonus lavaretus, Perca fluviatilis, and Rutilus rutilus. The presence of Cryptosporidium spp. was found in 15 out of 41 fish (37%, distributed as follows: 13 (87% C. parvum, 1 (7% C. molnari, and 1 (7% mixed infection (C. parvum and C. molnari. C. molnari was identified in the stomach, while C. parvum was found in the stomach and intestine. C. molnari was also detected in 1 out of 100 analyzed fillets. In order to identify Cryptosporidium subtypes, sequencing of the highly polymorphic 60-kDa glycoprotein (gp60 was performed. Among the C. parvum positive samples, three gp60 subtypes were identified: IIaA15G2R1, IIaA16G2R1, and IIaA17G2R1. Histological examination confirmed the presence of potential developmental stages of C. parvum within digestive epithelial cells. These observations suggest that C. parvum is infecting fish, rather than being passively carried. Since C. parvum is a zoonotic species, fish potentially contaminated by the same subtypes found in terrestrial mammals would be an additional source of infection for humans and animals, and may also contribute to the contamination of the environment with this parasite. Moreover, the risk of human transmission is strengthened by

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.

Teratogenic effects and monetary cost of selenium poisoning of fish in Lake Sutton, North Carolina

Science.gov (United States)

A. Dennis Lemly

2014-01-01

Selenium pollution from coal ash waste water was investigated in Lake Sutton, NC. This lake has been continuously used as a cooling pond for a coal-fired power plant since 1972. Historic and recent levels of contamination in fish tissues (14–105 µg Se/g dry weight in liver, 24–127 in eggs, 4–23 in muscle,7–38 in whole-body) exceeded toxic thresholds and teratogenic...

Fish larvae assemblages in two floodplain lakes with different degrees of connection to the Paraná River, Brazil

Directory of Open Access Journals (Sweden)

Vanessa Salete Daga

Full Text Available The objective of this study was to assess the abundance, attributes of assemblages, and spatial and temporal distributions of fish larvae and their relationships with some abiotic variables in two floodplain lakes with different degrees of connection to the Paraná River in Ilha Grande National Park, PR, Brazil. Four sampling sites were chosen, two in each floodplain lake. Night samples were taken with plankton nets during three spawning seasons (monthly, from October to March from 2001 to 2005. The highest diversity and abundance were recorded at Saraiva Lake, with 25 taxa being identified. In Xambrê Lake, only sedentary species were captured, and the most abundant species were Plagioscion squamosissimus and Hypophthalmus edentatus. The greatest abundance of larvae was found in the second spawning season. In the Saraiva Lake, the most abundant species were Moenkhausia aff. intermedia, Hyphessobrycon sp., and Bryconamericus stramineus, but larvae of known migratory species were also documented. In this lake, the greatest abundance of larvae was found in the third spawning. Larvae abundance was influenced by water temperature and conductivity. The high diversity and abundance recorded in Saraiva Lake may be a result of its connectivity with the Paraná River, and the low diversity and abundance observed at Xambrê Lake are likely due to its isolation from the river. This work shows the importance of these lagoons for fish development, for both sedentary and migratory species. Both lagoons may be considered to have extreme ecological importance and they are also extremely susceptible to impacts, so any careless disturbance may cause irreversible damage.

Fish but Not Macroinvertebrates Promote Trophic Cascading Effects in High Density Submersed Plant Experimental Lake Food Webs in Two Contrasting Climate Regions

Directory of Open Access Journals (Sweden)

Carlos Iglesias

2017-07-01

Full Text Available Predators play a key role in the functioning of shallow lakes. Differences between the response of temperate and subtropical systems to fish predation have been proposed, but experimental evidence is scarce. To elucidate cascading effects produced by predators in contrasting climatic zones, we conducted a mesocosm experiment in three pairs of lakes in Uruguay and Denmark. We used two typical planktivorous-omnivorous fish species (Jenynsia multidentata + Cnesterodon decemmaculatus and Gasterosteus aculeatus + Perca fluviatilis and one littoral omnivorous-predatory macroinvertebrate (Palaemonetes argentinus and Gammarus lacustris, alone and combined, in numbers resembling natural densities. Fish predation on zooplankton increased phytoplankton biomass in both climate zones, whereas the effects of predatory macroinvertebrates on zooplankton and phytoplankton were not significant in either climate zone. Macroinvertebrates (that freely colonized the sampling devices were diminished by fish in both climate areas; however, periphyton biomass did not vary among treatments. Our experiments demonstrated that fish affected the structure of both planktonic and littoral herbivorous communities in both climate regions, with a visible positive cascading effect on phytoplankton biomass, but no effects on periphyton. Altogether, fish impacts appeared to be a strong driver of turbid water conditions in shallow lakes regardless of climatic zone by indirectly contributing to increasing phytoplankton biomass.

Distribution of Po-210 and Pb-210 in Arctic Char (Salvelinus alpinus) from an Arctic freshwater lake

Energy Technology Data Exchange (ETDEWEB)

Gwynn, J.P.; Rudolfsen, G. [Norwegian Radiation Protection Authority, The Fram Centre, Tromsoe (Norway)

2014-07-01

There is little information available with regard to the accumulation of Po-210 and Pb-210 by freshwater fish in natural freshwater systems despite the potential for relevant ingestion doses to man. This is maybe of particular pertinence for certain population groups where freshwater fish are an important dietary food item. Equally, it is important to understand the body distributions of these naturally occurring radionuclides to quantify the resulting doses to different tissues and organs of freshwater fish. With regard to the latter, it is important to consider not only the doses arising from bio-accumulated Po-210 and Pb-210 in various body compartments but additionally the internal dose from unabsorbed Po-210 and Pb-210 in the digestive tract. In this study, activity concentrations of Po-210 and Pb-210 were determined in muscle and various internal organs of Arctic Charr (Salvelinus alpinus) sampled from a lake in the Norwegian Arctic (69 deg. 4' N, 19 deg. 20' E). Observed activity concentrations of Po-210 and Pb-210 in different tissues will be discussed in relation to physiological parameters and ambient lake water activity concentrations. Results from this study will be compared to two similar studies conducted in freshwater systems where elevated activity concentrations of these radionuclides have been observed. Ingestion dose rates to man and effective absorbed dose rates to different tissues and organs of Arctic Charr from Po-210 and Pb-210 will be derived and compared to those from observed activity concentrations of the anthropogenic radionuclide Cs-137. (authors)

Spatial distribution and risk assessment of radioactivity and heavy metal levels of sediment, surface water and fish samples from Lake Van, Turkey

International Nuclear Information System (INIS)

Sema Erenturk; Zeyneb Camtakan

2014-01-01

In this study, radioactivity levels of 228 lake water samples, 63 upper and depth sediment samples and 12 fish samples from Lake Van were investigated from 2005 to 2008 and the distribution patterns of the radionuclides were presented. Analysis included gross alpha-beta and total radium isotopes activities and uranium concentrations of the water, and gross alpha and gross beta activities and relevant 238 U, 232 Th and 40 K activity of the sediment and fish samples of the lake. Mean gross alpha, gross beta and radium isotopes activities of lake water were found 0.74 ± 0.46, 0.02 ± 0.01 and 0.06 ± 0.04 Bq/L, respectively. Mean gross alpha and beta activities in upper and depth sediments were found to be 41 ± 6 and 1,514 ± 74 Bq/kg; 77 ± 5 and 394 ± 24 Bq/kg at a 95 % confidence level, respectively. Mean activities of 238 U, 232 Th and 40 K activity concentrations in upper and depth sediments were determined to be 225 ± 22, 70 ± 7 and 486 ± 39 Bq/kg; 174 ± 4, 63 ± 3 and 263 ± 25 Bq/kg, respectively. The mean gross alpha and beta, 238 U, 232 Th and 40 K activities in fish samples were established as 47 ± 18, 470 ± 12, 0.57 ± 0.220, 0.022 ± 0.006, 319 ± 11 Bq/kg, respectively. The transfer factor from lake water to fish tissues, annual intake by humans consuming fish, and annual committed effective doses were estimated and evaluated. (author)

Fatty acid composition of fish species with different feeding habits from an Arctic Lake.

Science.gov (United States)

Gladyshev, M I; Sushchik, N N; Glushchenko, L A; Zadelenov, V A; Rudchenko, A E; Dgebuadze, Y Y

2017-05-01

We compared the composition and content of fatty acids (FAs) in fish with different feeding habits (sardine (least) cisco Coregonus sardinella, goggle-eyed charr (pucheglazka) form of Salvelinus alpinus complex, humpback whitefish Coregonus pidschian, broad whitefish Coregonus nasus, boganid charr Salvelinus boganidae, and northern pike Esox lucius from an Arctic Lake. Feeding habits of the studied fish (planktivore, benthivore, or piscivore) significantly affected the composition of biomarker fatty acids and the ratio of stable isotopes of carbon and nitrogen in their biomass. The hypothesis on a higher content of eicosapentaenoic and docosahexaenoic acids in the fish of higher trophic level (piscivores) when compared within the same taxonomic group (order Salmoniformes) was confirmed.

Biota sediment concentration ratio (CRs-b) for fishes of Rana Pratap Sagar Lake, Rawatbhata

International Nuclear Information System (INIS)

Goyal, S.K.; Srivastava, A.P.; Jain, A.K.; Meenal, Balram; Tiwari, S.N.; Ravi, P.M.; Tripathi, R.M.

2018-01-01

Radionuclides dissolved in water can be adsorbed by bottom/shore sediment transferring it to the deep sediment layers. These adsorbed radionuclides can be remobilized and be available again for uptake by freshwater biota. The biota sediment concentration ratio (CR s-b ) is the ratio of the concentration of a radionuclide in an organism (C b ) on a fresh weight basis to the radionuclide concentration measured in the sediment (C sediment ). Using the data of 137 Cs activity in fish and shore sediment, CR s-b was calculated for fish samples of Rana Pratap Sagar (RPS) Lake, Rawatbhata. This value can be applied in predictive models to calculate radionuclide concentration in fish samples

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.

[Phytoplankton community in a recreational fishing lake, Brazil].

Science.gov (United States)

Matsuzaki, Mayla; Mucci, José Luiz Negrão; Rocha, Aristides Almeida

2004-10-01

The assessment of water quality and phytoplankton community in recreational environments allows to setting management programs aiming at preventing potential harm to human health. The purpose of the present study was to describe phytoplankton seasonal changes in a freshwater system and their relation to water quality. The recreational fishing lake is located in the southern area of the city of São Paulo, Brazil. Water samples were collected in three previously selected sites in the lake throughout a year and analyzed regarding floristic composition and physical and chemical parameters. The phytoplankton qualitative analysis revealed 91 taxa distributed among eight classes: Chlorophyceae, Cyanophyceae, Euglenophyceae, Zygnemaphyceae, Bacillariophyceae, Xantophyceae, Dinophyceae, and Chrysophyceae. Some physical and chemical parameters seemed to influence phytoplankton community behavior. Chlorophyceae development was favored by local conditions. Among the species of cyanobacteria identified, Microcystis paniformis, Cylindrospermopsis raciborskii, and Anabaena species were the most important due to their ability to produce toxins, posing a high risk to public health. Some physical and chemical parameters had an impact on the structure of phytoplankton community. The presence of Microcystis paniformis, Cylindrospermopsis raciborskii and Anabaena species indicates toxic potential and likelihood of public health problems unless there is constant monitoring. Further studies are recommended to prevent hazardous effects to the environment and public health.

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.

Early warning signs of endocrine disruption in adult fish from the ingestion of polyethylene with and without sorbed chemical pollutants from the marine environment

Energy Technology Data Exchange (ETDEWEB)

Rochman, Chelsea M., E-mail: cmrochman@ucdavis.edu; Kurobe, Tomofumi; Flores, Ida; Teh, Swee J.

2014-09-15

Plastic debris is associated with several chemical pollutants known to disrupt the functioning of the endocrine system. To determine if the exposure to plastic debris and associated chemicals promotes endocrine-disrupting effects in fish, we conducted a chronic two-month dietary exposure using Japanese medaka (Oryzias latipes) and environmentally relevant concentrations of microplastic (< 1 mm) and associated chemicals. We exposed fish to three treatments: a no-plastic (i.e. negative control), virgin-plastic (i.e. virgin polyethylene pre-production pellets) and marine-plastic treatment (i.e. polyethylene pellets deployed in San Diego Bay, CA for 3 months). Altered gene expression was observed in male fish exposed to the marine-plastic treatment, whereas altered gene expression was observed in female fish exposed to both the marine- and virgin-plastic treatment. Significant down-regulation of choriogenin (Chg H) gene expression was observed in males and significant down-regulation of vitellogenin (Vtg I), Chg H and the estrogen receptor (ERα) gene expression was observed in females. In addition, histological observation revealed abnormal proliferation of germ cells in one male fish from the marine-plastic treatment. Overall, our study suggests that the ingestion of plastic debris at environmentally relevant concentrations may alter endocrine system function in adult fish and warrants further research. - Highlights: • We saw down-regulation of Chg H in males exposed to marine plastic. • We saw down-regulation of Vtg I, Chg H and ERα in females exposed to plastic. • We saw abnormal proliferation of germ cells in a male exposed to marine plastic. • Our results suggest that the ingestion of plastic may alter endocrine system function.

Early warning signs of endocrine disruption in adult fish from the ingestion of polyethylene with and without sorbed chemical pollutants from the marine environment

International Nuclear Information System (INIS)

Rochman, Chelsea M.; Kurobe, Tomofumi; Flores, Ida; Teh, Swee J.

2014-01-01

Plastic debris is associated with several chemical pollutants known to disrupt the functioning of the endocrine system. To determine if the exposure to plastic debris and associated chemicals promotes endocrine-disrupting effects in fish, we conducted a chronic two-month dietary exposure using Japanese medaka (Oryzias latipes) and environmentally relevant concentrations of microplastic (< 1 mm) and associated chemicals. We exposed fish to three treatments: a no-plastic (i.e. negative control), virgin-plastic (i.e. virgin polyethylene pre-production pellets) and marine-plastic treatment (i.e. polyethylene pellets deployed in San Diego Bay, CA for 3 months). Altered gene expression was observed in male fish exposed to the marine-plastic treatment, whereas altered gene expression was observed in female fish exposed to both the marine- and virgin-plastic treatment. Significant down-regulation of choriogenin (Chg H) gene expression was observed in males and significant down-regulation of vitellogenin (Vtg I), Chg H and the estrogen receptor (ERα) gene expression was observed in females. In addition, histological observation revealed abnormal proliferation of germ cells in one male fish from the marine-plastic treatment. Overall, our study suggests that the ingestion of plastic debris at environmentally relevant concentrations may alter endocrine system function in adult fish and warrants further research. - Highlights: • We saw down-regulation of Chg H in males exposed to marine plastic. • We saw down-regulation of Vtg I, Chg H and ERα in females exposed to plastic. • We saw abnormal proliferation of germ cells in a male exposed to marine plastic. • Our results suggest that the ingestion of plastic may alter endocrine system function

Host records and tissue locations for Diplostomum mordax (metacercariae) inhabiting the cranial cavity of fishes from Lake Titicaca, Peru.

Science.gov (United States)

Heckmann, R A

1992-06-01

Metacercariae of Diplostomum mordax were found in the cranial cavity of Orestias agasii, Orestias olivaceous, Orestias luteus, and Basilichthys bonariensis, fishes from Lake Titicaca, Peru. Metacercariae were not found in Oncorhynchus mykiss introduced into the lake during 1939 and 1940. Compression of neural tissue within and on the surface of the brain was observed in all infected fishes. Metacercariae migrating into the cerebrum and cerebellum of the piscine host caused hemorrhaging, cell necrosis, inflammation, fiber formation, and nerve fiber disruption. The presence of D. mordax in B. bonariensis and the 3 species of Orestias constitute new host records. Infections in the cerebrum and cerebellum add new information on specific parasite location.

The last snapshot of natural pelagic fish assemblage in Lake Turkana, Kenya: A hydroacoustic study

Czech Academy of Sciences Publication Activity Database

Muška, Milan; Vašek, Mojmír; Modrý, David; Jirků, Miloslav; Ojwang, W. O.; Malala, J. O.; Kubečka, Jan

2012-01-01

Roč. 38, č. 1 (2012), s. 98-106 ISSN 0380-1330 R&D Projects: GA AV ČR(CZ) KJB600960813 Institutional support: RVO:60077344 Keywords : African lakes * acoustics * fish distribution * endorheic basin * lates Subject RIV: EH - Ecology, Behaviour Impact factor: 2.309, year: 2012

Sub-fossils of cladocerans in the surface sediment of 135 lakes as proxies for community structure of zooplankton, fish abundance and lake temperature

DEFF Research Database (Denmark)

Jeppesen, E.; Jensen, J. P.; Lauridsen, T. L.

2003-01-01

, which otherwise can be obtained only by long-term frequent contemporary sampling for several years. The contribution of Daphnia to the sum of Daphnia and Bosmina ephippia was negatively correlated with the abundance of fish expressed as catch per night in multi-mesh sized gill nets (CPUE). Yet, region...... to summer mean air temperature, and for Danish lakes also, albeit weakly, to fish CPUE but not to chlorophyll a. Apparently, temperature is the most important factor determining the ratio of parthenogenetic to ephippia producing specimens of Bosmina. We conclude that the sediment record of cladocerans...

Seasonal Variations in the Use of Profundal Habitat among Freshwater Fishes in Lake Norsjø, Southern Norway, and Subsequent Effects on Fish Mercury Concentrations

Directory of Open Access Journals (Sweden)

Tom Robin Olk

2016-11-01

Full Text Available This study is based on monthly sampling of fish from grates mounted at an industrial water intake, located at a depth of 50 m in Lake Norsjø (Southern Norway during the year 2014, to investigate seasonal variations in the use of the profundal habitat and subsequent variations in total Hg-concentrations in profundal fish. Data on various fish present in a cold and dark hypolimnion of a large, deep, dimictic lake within the upper temperate zone of the Northern Hemisphere are rare. While predominant species such as A. charr (Salvelinus alpinus and E. smelt (Osmerus eperlanus were continuously present in this habitat, whitefish (Coregonus lavaretus occupied this habitat primarily during wintertime, while other common species like brown trout (Salmo trutta, perch (Perca fluviatilis and northern pike (Esox lucius were almost absent. Besides stomach analyses (diet and biometry, stable isotope analyses (δ15N and δ13C and total mercury (Tot-Hg analyses were carried out on the caught fish. The δ13C signature and stomach analyses revealed a combined profundal-pelagic diet for all three species, A. charr with the most profundal-based diet. Length was the strongest predictor for Hg in whitefish and A. charr, while age was the strongest explanatory variable for Hg in E. smelt. A. charr was the only species exhibiting seasonal variation in Hg, highest during winter and spring.

Freshwater fish Fauna and Restock Fish Activities of Reservoir in the Dardanelles (Canakkale-Turkey

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Hüseyin SASI

2012-06-01

Full Text Available Turkey has, with geographic location including Istanbul and Çanakkale straits the system, 178,000 km in length streams, 906,000 ha of natural lakes, and 411,800 ha of dam lakes, and 28,000 ha of ponds due to richness inland waters which include freshwater fish. The fingerling fish (fry were restocked approximately 250,000,000 in natural lakes, dam lakes and ponds for fisheries between years of 1979 and 2005. Canakkale has rich freshwater potential with 7 major rivers (Büyükdere, Karamenderes stream, Kavak brook, Kocacay stream, Sarıcay stream, Tuzla brook, Umurbey brook, 7 Dam Lakes (Atikhisar, Zeytinlikoy, Bayramic, Bakacak, Tayfur, Umurbey and Yenice-Gönen Dam lakes. In the studies, it has been determined that 15 fish species belonging to 6 families (Anguillidae, Atherinidae, Salmonidae, Cobitidae, Cyprinidae and Poecilidae can be found in reservoirs. Fish restocking of the activities of the reservoir until today approximately 1,120,000 (Cyprinus carpio L., 1758 is introduced. In this study, the activity of Canakkale province in the fish restocking and reservoir exploiting possibilities were discussed in view of reservoir fisheries potential which is used insufficiently today.

Can pelagic forage fish and spawning cisco (Coregonus artedi) biomass in the western arm of Lake Superior be assessed with a single summer survey?

Science.gov (United States)

Yule, D.L.; Stockwell, J.D.; Schreiner, D.R.; Evrard, L.M.; Balge, M.; Hrabik, T.R.

2009-01-01

Management efforts to rehabilitate lake trout Salvelinus namaycush in Lake Superior have been successful and the recent increase in their numbers has led to interest in measuring biomass of pelagic prey fish species important to these predators. Lake Superior cisco Coregonus artedi currently support roe fisheries and determining the sustainability of these fisheries is an important management issue. We conducted acoustic and midwater trawl surveys of the western arm of Lake Superior during three periods: summer (July-August), October, and November 2006 to determine if a single survey can be timed to estimate biomass of both prey fish and spawning cisco. We evaluated our methods by comparing observed trawl catches of small (cisco increased substantially in November, while small bloater Coregonus hoyi biomass was lower. We compared our summer 2006 estimates of total fish biomass to the results of a summer survey in 1997 and obtained similar results. We conclude that the temporal window for obtaining biomass estimates of pelagic prey species in the western arm of Lake Superior is wide (July through October), but estimating spawning cisco abundance is best done with a November survey.

Predicting the locations of naturally fishless lakes

Science.gov (United States)

Schilling, Emily Gaenzle; Loftin, C.S.; Degoosh, K.E.; Huryn, Alexander D.; Webster, K.E.

2008-01-01

1. Fish have been introduced into many previously fishless lakes throughout North America over the past 100+ years. It is difficult to determine the historical distribution of fishless lakes, however, because these introductions have not always been well-documented. 2. Due to its glacial history and low human population density, the state of Maine (U.S.A.) may host the greatest number of naturally fishless lakes in the northeastern United States. However, less than one-quarter of Maine's 6000+ lakes have been surveyed for fish presence, and no accurate assessments of either the historical or current abundance and distribution of fishless lakes exist. 3. We developed methods to assess the abundance and distribution of Maine's naturally fishless lakes (0.6-10.1 ha). We hypothesized that the historical distribution of fishless lakes across a landscape is controlled by geomorphic and geographic conditions. 4. We used ArcGIS to identify landscape-scale geomorphic and geographic factors (e.g. connectivity, surrounding slope) correlated with fish absence in two geomorphic regions of Maine - the western and interior mountains and the eastern lowlands and foothills. By using readily available geographic information systems data our method was not limited to field-visited sites. We estimated the likelihood that a particular lake is fishless with a stepwise logistic regression model developed for each region. 5. The absence of fish from western lakes is related to altitude (+), minimum percent slope in the 500 m buffer (+), maximum percent slope in the 500 m buffer (+) and percent cover of herbaceous-emergent wetland in 1000 m buffer (-). The absence of fish from eastern lakes is related to the lack of a stream within 50 m of the lake. 6. The models predict that a total of 4% (131) of study lakes in the two regions were historically fishless, with the eastern region hosting a greater proportion than the western region. 7. We verified the model predictions with two

Lake-wide distribution of Dreissena in Lake Michigan, 1999

Science.gov (United States)

Fleischer, Guy W.; DeSorcie, Timothy J.; Holuszko, Jeffrey D.

2001-01-01

The Great Lakes Science Center has conducted lake-wide bottom trawl surveys of the fish community in Lake Michigan each fall since 1973. These systematic surveys are performed at depths of 9 to 110 m at each of seven index sites around Lake Michigan. Zebra mussel (Dreissena polymorpha) populations have expanded to all survey locations and at a level to sufficiently contribute to the bottom trawl catches. The quagga (Dreissena bugensis), recently reported in Lake Michigan, was likely in the catches though not recognized. Dreissena spp. biomass ranged from about 0.6 to 15 kg/ha at the various sites in 1999. Dreissenid mussels were found at depths of 9 to 82 m, with their peak biomass at 27 to 46 m. The colonization of these exotic mussels has ecological implications as well as potential ramifications on the ability to sample fish consistently and effectively with bottom trawls in Lake Michigan.

Fish community status in Norwegian lakes in relation to acidification: a comparison between interviews and actual catches by test fishing

Energy Technology Data Exchange (ETDEWEB)

Hesthagen, T.; Berger, H.M.; Larsen, B.M. (Norwegian Inst. for Nature Research, Trondheim (Norway)); Rosseland, B.O. (Norwegian Inst. for Water Research, Oslo (Norway))

1993-01-01

Inquiries are used to obtain information on fish community status in terms of unchanged, reduced and lost communities, to assess the effects of acidification in lakes. The aim of this paper was to investigate the validity of this method by comparing fish status with actual catches on standard gill net series (CPUE). Data from 230 test fishing incidents comprising 357 stocks of 7 different fish species are presented. We found significant differences in CPUE between perceived fish status categories for brown trout (Salmo trutta), arctic char (Salvelinus alpinus) and perch (Perca fluviatilis), for which sufficient data were available. A discriminant analysis revealed that for stocks reported as unchanged and lost, the predicted membership ranged between 60.0-72.1 % respectively. However, a dominant fraction (50.0-66.7 %) of stocks reported as reduced were assigned as lost. Stocks which have been declining for less than 10 years, had a significantly higher CPUE than stocks which have declined for a longer period of time. Another apparent change in population characteristics was an acidification induced increase in mean weight for fish affected stocks. It is suggested that interviews tend to overestimate the current fish status. This is discussed in relation to a time lag between the damage and the time when it became apparent to fishermen, and rapid decline in population numbers. 26 refs, 2 figs, 4 tabs

Refuge Lake Reclassification in 620 Minnesota Cisco Lakes under Future Climate Scenarios

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Liping Jiang

2017-09-01

Full Text Available Cisco (Coregonus artedi is the most common coldwater stenothermal fish in Minnesota lakes. Water temperature (T and dissolved oxygen (DO in lakes are important controls of fish growth and reproduction and likely change with future climate warming. Built upon a previous study, this study uses a modified method to identify which of 620 cisco lakes in Minnesota can still support cisco populations under future climate and therefore be classified as cisco refuge lakes. The previous study used oxythermal stress parameter TDO3, the temperature at DO of 3 mg/L, simulated only from deep virtual lakes to classify 620 cisco lakes. Using four categories of virtual but representative cisco lakes in modified method, a one-dimensional water quality model MINLAKE2012 was used to simulate daily T and DO profiles in 82 virtual lakes under the past (1961–2008 and two future climate scenarios. A multiyear average of 31-day largest TDO3 over variable benchmark (VB periods, AvgATDO3VB, was calculated from simulated T and DO profiles using FishHabitat2013. Contour plots of AvgATDO3VB for four categories of virtual lakes were then developed to reclassify 620 cisco lakes into Tier 1 (AvgATDO3VB < 11 °C or Tier 2 refuge lakes, and Tier 3 non-refuge lakes (AvgATDO3VB > 17 °C. About 20% of 620 cisco lakes are projected to be refuge lakes under future climate scenarios, which is a more accurate projection (improving the prediction accuracy by ~6.5% from the previous study since AvgATDO3VB was found to vary by lake categories.

Experimental whole-lake dissolved organic carbon increase alters fish diet and density but not growth or productivity

Science.gov (United States)

Koizumi, Shuntaro; Craig, Nicola; Zwart, Jacob A.; Kelly, Patrick T.; Ziegler, Jacob P.; Weidel, Brian C.; Jones, Stuart E.; Solomon, Christopher T.

2018-01-01

Negative relationships between dissolved organic carbon (DOC) concentration and fish productivity have been reported from correlative studies across lakes, but to date there have not been experimental tests of these relationships. We increased the DOC concentration in a lake by 3.4 mg L-1, using a before-after control-impact (BACI) design, to quantify the effects on the productivity and population structure of Largemouth Bass (Micropterus salmoides). Greater DOC reduced the volume of the epilimnion, the preferred habitat of Largemouth Bass, resulting in increased bass density. The likelihood that adult bass had empty diets decreased despite this increase in bass density; diet composition also changed. There was no apparent change in bass growth or condition. Overall, there was no net change in Largemouth Bass productivity. However, changes in YOY and juvenile recruitment and feeding success suggest the possibility that future effects could occur. Our results are the first to examine the effects of an increase in DOC on fish productivity through a five-year temporal lens, which demonstrates that the relationship between DOC and fish productivity is multi-dimensional and complex.

FISH DIVERSITY ALONG THE LONGITUDINAL GRADIENT IN A MAN–MADE LAKE OF WEST AFRICA, TAABO HYDROELECTRIC RESERVOIR, IVORY COAST

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N. G. Aliko

2010-04-01

Full Text Available Fish assemblage patterns in Taabo Reservoir, a hydroelectric lake of Ivory Coast, were studied and related to the longitudinal gradient (river–dam gradient composed of riverine, transitional, and lacustrine zones. Data were collected at 5 stations and each one was sampled during 5 surveys. Fish community structure was analysed using alpha and beta diversity indices. In total, 53 fish species were obtained in the whole ecosystem. Total species richness recorded at each ecological zone was 42, 43 and 45 species respectively in the riverine, transitional and lacustrine zones. Alpha diversity did not differed significantly along the longitudinal gradient but reached the highest value (33 species in the transitional zone and the lowest (18 species occurred in both the riverine and lacustrine zones. Temporal variability of Alpha diversity according to the hydrological regime of the lake differed with the zone. Beta diversity showed that fish assemblages similarity was higher between the transitional and the riverine zones (βw = 0.43 and lower between the riverine and the lacustrine zones (βw = 0.79.

Rapid Stable Isotope Turnover of Larval Fish in a Lake Superior Coastal Wetland: Implications for Diet and Life History Studies

Science.gov (United States)

Trophic linkages of larval fish in Lake Superior coastal wetlands, rivers and embayments can be identified using naturally occurring differences in the stable isotope ratios of nitrogen (15N:14N, ?15N) and carbon (13C:12C, ?13C). We sampled pelagic fish larvae weekly during sprin...

A comparison between benthic gillnet and bottom trawl for assessing fish assemblages in a shallow eutrophic lake near the Changjiang River estuary

Science.gov (United States)

Li, Yalei; Liu, Qigen; Chen, Liping; Zhao, Liangjie; Wu, Hao; Chen, Liqiao; Hu, Zhongjun

2018-03-01

Two fishing methods including gillnetting and trawling to estimate attributes of fish assemblage were compared in Dianshan Lake from August 2009 to July 2010. Species composition differed significantly between the gears, with four significant contributors in gillnet catches and one in trawl catches. Trawling collected more proportions of benthic species by number and biomass than gillnetting. Size distribution was significantly influenced by fishing technique; gillnetting captured relatively less small-sized fishes and trawling captured less large-sized individuals. Trawling produced species richness closer to the one expected than gillnetting. On the whole, trawl catch was a quadratic polynomial function of gillnet catch and a significantly negative correlation was found between them, both of which varied as different polynomial functions of temperature. However, trawl and gillnet catches were significantly correlated only in one of five month groups. It is concluded that single-gear-based surveys can be misleading in assessments of attributes of fish assemblages, bottom trawling is a more effective gear for assessing fish diversity than benthic gillnetting, and using gillnet catches as an indicator of fish density depends on fishing season in the lake.

Assessment of biological effects of pollutants in a hyper eutrophic tropical water body, Lake Beira, Sri Lanka using multiple biomarker responses of resident fish, Nile tilapia (Oreochromis niloticus).

Science.gov (United States)

Pathiratne, Asoka; Pathiratne, K A S; De Seram, P K C

2010-08-01

Biomarkers measured at the molecular and cellular level in fish have been proposed as sensitive "early warning" tools for biological effect measurements in environmental quality assessments. Lake Beira is a hypertrophic urban water body with a complex mixture of pollutants including polycyclic aromatic hydrocarbons (PAHs) and Microcystins. In this study, a suite of biomarker responses viz. biliary fluorescent aromatic compounds (FACs), hepatic ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST), brain and muscle cholinesterases (ChE), serum sorbitol dehydrogenase (SDH), and liver histology of Oreochromis niloticus, the dominant fish inhabiting this tropical Lake were evaluated to assess the pollution exposure and biological effects. Some fish sampled in the dry periods demonstrated prominent structural abnormalities in the liver and concomitant increase in serum SDH and reduction in hepatic GST activities in comparison to the control fish and the fish sampled in the rainy periods. The resident fish with apparently normal liver demonstrated induction of hepatic EROD and GST activities and increase in biliary FACs irrespective of the sampling period indicating bioavailability of PAHs. Muscle ChE activities of the resident fish were depressed significantly indicating exposure to anticholinesterase substances. The results revealed that fish populations residing in this Lake is under threat due to the pollution stress. Hepatic abnormalities in the fish may be mainly associated with the pollution stress due to recurrent exposure to PAHs and toxigenic Microcystis blooms in the Lake.

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.

Lake Afdera: a threatened saline lake in Ethiopia | Getahun | SINET ...

African Journals Online (AJOL)

Lake Afdera is a saline lake located in the Afar region, Northern Ethiopia. Because of its inaccessibility it is one of the least studied lakes of the country. It supports life including three species of fish of which two are endemic. Recently, reports are coming out that this lake is used for salt extraction. This paper gives some ...

Feeding patterns of migratory and non-migratory fourth instar larvae of two coexisting Chaoborus species in an acidic and metal contaminated lake: Importance of prey ingestion rate in predicting metal bioaccumulation

Science.gov (United States)

Croteau, M.-N.; Hare, L.; Marcoux, P.

2003-01-01

We studied diel variations in the feeding habits and migratory behaviors of two coexisting Chaoborus species in an acidic and metal contaminated lake (Lake Turcotte, QC, Canada). We found that although the zooplankton community was dominated by rotifers, both Chaoborus species fed mostly on chironomids and crustaceans despite the relatively low abundance of these prey types in the lake plankton. Chaoborus americanus larvae fed on those of Chaoborus punctipennis, but not vice versa. The non-migratory species (C. americanus) fed throughout the day and night whereas the migratory species (C. punctipennis) fed only at night while in the water column. The larger-bodied C. americanus consumed more prey and had a more diverse diet than did the smaller-bodied C. punctipennis. Differences in feeding habits between the Chaoborus species inhabiting Lake Turcotte (prey biomass, prey types) likely explain in part their ability to coexist. Attempts to predict Cd in the Chaoborus species using our measurements of Cd in their prey and their prey ingestion rates met with mixed success; although we correctly predicted higher Cd concentrations for C. americanus larvae than for C. punctipennis larvae, we under-predicted absolute Cd concentrations. We suggest that studies such as ours that are based on analyses of gut contents of larvae collected at intervals of 4h or longer likely underestimate prey ingestion rates.

Distributions of the endemic and threatened freshwater fish depik, Rasbora tawarensis Weber & de Beaufort, 1916 in Lake Laut Tawar, Aceh Province, Indonesia

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Zainal A. Muchlisin

2013-08-01

Full Text Available Depik fish, Rasbora tawarensis is an endemic and threatened species in Lake Laut Tawar (Central Aceh, Indonesia,and the population of depik has been decreased drastically over the last two decades. Information about distribution patternsis crucially needed in relation to plan better conservation strategies. Hence, the objective of present study was to evaluate thedistribution patterns (spatial and seasonal distribution based on catch per unit efforts and fish abundance data. Stratifiedrandom sampling was utilized in this study. Two fishing grounds were selected based on information from local fishermen,and a total of 14 fishing sites (seven sites per fishing ground were determined randomly. Sampling was conducted in differentseasons; dry and wet season. The Rasbora tawarensis is widespread in the lake but most abundant in shallow waters andthe near shore, however, the size is small on average for this area. In contrast, bigger fish was found in deep waters offshore,but with lower abundance. In conclusion, the distribution of depik is not seasonally dependent, but more spatially.

The Risk of Mercury Exposure to the People Consuming Fish from Lake Phewa, Nepal

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Devna Singh Thapa

2014-06-01

Full Text Available The risk of mercury exposure through consumption of fish from Lake Phewa, Nepal was investigated. A total of 170 people were surveyed to know their fish consumption levels. The weekly mercury (Hg intake in the form of methylmercury (MeHg through fish was calculated by using the data on average MeHg concentrations in fish, the average consumption of fish per week, and an average body weight of the people. Hotel owners were consuming significantly high amounts of fish, followed by fishermen, in comparison to the government staff, army/police, locals and others (visitors. Some individuals exceeded the Provisional Tolerable Weekly Intake (PTWI of 1.6 µg per kg body weight of MeHg (FAO/WHO. The minimum intake of MeHg (0.05 µg/kg/week was found in the visitors (others category, whereas the hotel owners had the maximum intake (3.71 µg/kg/week. In general, it was found that a person of 60 kg can consume at least 2 kg of fish per week without exceeding PTWI such that it does not pose any health risk associated with Hg poisoning at the present contamination level. Hg based PTWI values for Nepal has not been proposed yet in fishery resources so as to reduce health risk of the people.

Fatty acid composition of freshwater wild fish in subalpine lakes: a comparative study.

Science.gov (United States)

Vasconi, Mauro; Caprino, Fabio; Bellagamba, Federica; Busetto, Maria Letizia; Bernardi, Cristian; Puzzi, Cesare; Moretti, Vittorio Maria

2015-03-01

In this study, the proximate and fatty acid compositions of the muscle tissue of 186 samples of fish belonging to fifteen species of freshwater fish harvested in subalpine lakes (bleak, shad, crucian carp, whitefish, common carp, pike, black bullhead, burbot, perch, Italian roach, roach, rudd, wels catfish, chub and tench) were investigated. Most of the fish demonstrated a lipid content in the fillet lower than 2.0 g 100 g(-1) wet weight (range 0.6-9.7). A strong relationship between feeding behavior and fatty acid composition of the muscle lipids was observed. Planktivorous fish showed the lowest amounts of n-3 fatty acids (p fish showed the highest amounts of saturated fatty acids and n-3 fatty acids (p fish showed substantial proportions of n-3 fatty acids and the highest contents of n-6 fatty acids. Principal component analysis showed a distinct separation between fish species according to their feeding habits and demonstrated that the most contributing trophic markers were 18:1n-9, 18:3n-3, 22:6n-3 and 20:4n-6. The quantitative amounts n-3 polyunsaturated fatty acid in muscle tissues varied depending on the fish species, the lipid content and the feeding habits. Some species were very lean, and therefore would be poor choices for human consumption to meet dietary n-3 fatty acid requirements. Nevertheless, the more frequently consumed and appreciated fish, shad and whitefish, had EPA and DHA contents in the range 900-1,000 mg 100 g(-1) fresh fillet.

Levels and distribution of organohalogenated contaminants in 5 fish species from Sir Dam Lake, Kahramanmaras, Turkey

Energy Technology Data Exchange (ETDEWEB)

Erdogrul, Oe [Faculty of Agriculture, Kahramanmaras (Turkey). Dept. of Food Engineering; Covaci, A; Schepens, P [Antwerp Univ. (Belgium). Toxicological Center

2004-09-15

In Turkey, OCPs have been used since 1945, with large quantities of these chemicals being used during the 1960s and 1970s. Since 1983, the usage of OCPs has been severely restricted or banned. Only few studies have investigated the presence of OCPs in Turkish aquatic environment, where they have been evidenced in relatively high concentrations. The aim of this study was to investigate the levels and distribution of organohalogenated contaminants in several fish species from Syr Dam Lake (Kahramanmarab, Turkey), an artificial lake with great economical importance for the region.

Radiation dose and risk to recreational fishermen from ingestion of fish caught near eight oil platforms in the Gulf of Mexico

International Nuclear Information System (INIS)

Meinhold, A.F.; Holtzman, S.

1998-06-01

Offshore production of oil and gas is accompanied by a saline wastewater, called produced water. Produced water discharges to the Gulf of Mexico often contain elevated concentrations of radionuclides that occur naturally in the geologic reservoir along with the oil and gas. These radionuclides may accumulate in organisms that live near offshore oil and gas structures. Because recreational fishing in the Gulf of Mexico is concentrated near oil and gas platforms, there is the potential for increased risks to recreational fishermen from the ingestion of radionuclides in fish caught near produced water discharges. This analysis investigated the potential risk to recreational fishermen from radium and lead-210 in offshore produced water discharged to the Gulf of Mexico

Radiation dose and risk to recreational fishermen from ingestion of fish caught near eight oil platforms in the Gulf of Mexico

Energy Technology Data Exchange (ETDEWEB)

Meinhold, A.F.; Holtzman, S.

1998-06-01

Offshore production of oil and gas is accompanied by a saline wastewater, called produced water. Produced water discharges to the Gulf of Mexico often contain elevated concentrations of radionuclides that occur naturally in the geologic reservoir along with the oil and gas. These radionuclides may accumulate in organisms that live near offshore oil and gas structures. Because recreational fishing in the Gulf of Mexico is concentrated near oil and gas platforms, there is the potential for increased risks to recreational fishermen from the ingestion of radionuclides in fish caught near produced water discharges. This analysis investigated the potential risk to recreational fishermen from radium and lead-210 in offshore produced water discharged to the Gulf of Mexico.

Communities of gastrointestinal helminths of fish in historically connected habitats: habitat fragmentation effect in a carnivorous catfish Pelteobagrus fulvidraco from seven lakes in flood plain of the Yangtze River, China

Directory of Open Access Journals (Sweden)

Yao Wei J

2009-04-01

Full Text Available Abstract Background Habitat fragmentation may result in the reduction of diversity of parasite communities by affecting population size and dispersal pattern of species. In the flood plain of the Yangtze River in China, many lakes, which were once connected with the river, have become isolated since the 1950s from the river by the construction of dams and sluices, with many larger lakes subdivided into smaller ones by road embankments. These artificial barriers have inevitably obstructed the migration of fish between the river and lakes and also among lakes. In this study, the gastrointestinal helminth communities were investigated in a carnivorous fish, the yellowhead catfish Pelteobagrus fulvidraco, from two connected and five isolated lakes in the flood plain in order to detect the effect of lake fragmentation on the parasite communities. Results A total of 11 species of helminths were recorded in the stomach and intestine of P. fulvidraco from seven lakes, including two lakes connected with the Yangtze River, i.e. Poyang and Dongting lakes, and five isolated lakes, i.e. Honghu, Liangzi, Tangxun, Niushan and Baoan lakes. Mean helminth individuals and diversity of helminth communities in Honghu and Dongting lakes was lower than in the other five lakes. The nematode Procamallanus fulvidraconis was the dominant species of communities in all the seven lakes. No significant difference in the Shannon-Wiener index was detected between connected lakes (0.48 and isolated lakes (0.50. The similarity of helminth communities between Niushan and Baoan lakes was the highest (0.6708, and the lowest was between Tangxun and Dongting lakes (0.1807. The similarity was low between Dongting and the other lakes, and the similarity decreased with the geographic distance among these lakes. The helminth community in one connected lake, Poyang Lake was clustered with isolated lakes, but the community in Dongting Lake was separated in the tree. Conclusion The

A scientific basis for restoring fish spawning habitat in the St. Clair and Detroit Rivers of the Laurentian Great Lakes

Science.gov (United States)

Manny, Bruce A.; Roseman, Edward F.; Kennedy, Gregory W.; Boase, James C.; Craig, Jaquelyn; Bennion, David H.; Read, Jennifer; Vaccaro, Lynn; Chiotti, Justin A.; Drouin, Richard; Ellison, Roseanne

2015-01-01

Loss of functional habitat in riverine systems is a global fisheries issue. Few studies, however, describe the decision-making approach taken to abate loss of fish spawning habitat. Numerous habitat restoration efforts are underway and documentation of successful restoration techniques for spawning habitat of desirable fish species in large rivers connecting the Laurentian Great Lakes are reported here. In 2003, to compensate for the loss of fish spawning habitat in the St. Clair and Detroit Rivers that connect the Great Lakes Huron and Erie, an international partnership of state, federal, and academic scientists began restoring fish spawning habitat in both of these rivers. Using an adaptive management approach, we created 1,100 m2 of productive fish spawning habitat near Belle Isle in the Detroit River in 2004; 3,300 m2 of fish spawning habitat near Fighting Island in the Detroit River in 2008; and 4,000 m2 of fish spawning habitat in the Middle Channel of the St. Clair River in 2012. Here, we describe the adaptive-feedback management approach that we used to guide our decision making during all phases of spawning habitat restoration, including problem identification, team building, hypothesis development, strategy development, prioritization of physical and biological imperatives, project implementation, habitat construction, monitoring of fish use of the constructed spawning habitats, and communication of research results. Numerous scientific and economic lessons learned from 10 years of planning, building, and assessing fish use of these three fish spawning habitat restoration projects are summarized in this article.

Depth gradients in food-web processes linking habitats in large lakes: Lake Superior as an exemplar ecosystem

Science.gov (United States)

Sierszen, Michael E.; Hrabik, Thomas R.; Stockwell, Jason D.; Cotter, Anne M; Hoffman, Joel C.; Yule, Daniel L.

2014-01-01

In large lakes around the world, depth-based changes in the abundance and distribution of invertebrate and fish species suggest that there may be concomitant changes in patterns of resource allocation. Using Lake Superior of the Laurentian Great Lakes as an example, we explored this idea through stable isotope analyses of 13 major fish taxa.

Responses of phytoplankton to fish predation and nutrient loading in shallow lakes: a pan-European mesocosm experiment

NARCIS (Netherlands)

van de Bund, W.; Romo, S.; Villena, M.J.; Valentín, M.; Van Donk, E.; Vicente, E.; Vakkilainen, K.; Svensson, M.; Stephen, D.; Ståhl-Delbanco, A.; Rueda, J.; Moss, B.; Rosa Miracle, M.; Kairesalo, T.; Hansson, L-A.; Hietala, J.; Gyllström, M.; Goma, J.; García, P.; Fernández-Aláez, M.; Fernández-Aláez, C.; Ferriol, C.; Collings, S.E.; Bécares, E.; Balayla, D.; Alfonso, T.

2004-01-01

1. The impacts of nutrients (phosphorus and nitrogen) and planktivorous fish on phytoplankton composition and biomass were studied in six shallow, macrophyte-dominated lakes across Europe using mesocosm experiments. 2. Phytoplankton biomass was more influenced by nutrients than by densities of

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.

Mercury concentrations in fish from Canadian Great Lakes areas of concern: an analysis of data from the Canadian Department of Environment database

International Nuclear Information System (INIS)

Weis, I.M.

2004-01-01

The tissue mercury concentrations in six species of fish collected at the 17 Areas of Concern identified by the International Joint Commission on the Canadian side of the Great Lakes were analyzed using an Environment Canada database. A linear increase in mercury concentration with fish length was found, but slopes differed among locations. The temporal pattern over the period 1971-1997 differed across species in fish collected in Lake St. Clair; in at least two species there was evidence of increased mercury concentration during the 1990s that had been suggested in an earlier analysis. Areas of Concern differed significantly in observed tissue concentrations. Differences observed did not consistently parallel expectations associated with the historical presence of chlor-alkali plants in the vicinities of some locations. An attempt to correlate the fish tissue mercury concentration with the frequency of occurrence of infantile cerebral palsy at Areas of Concern was unsuccessful

Identifying temporal bottlenecks for the conservation of large-bodied fishes: Lake Sturgeon (Acipenser fulvescens show highly restricted movement and habitat use over-winter

Directory of Open Access Journals (Sweden)

Donnette Thayer

2017-04-01

Full Text Available The relationship between species’ size and home range size has been well studied. In practice, home range may provide a good surrogate of broad spatial coverage needed for species conservation, however, many species can show restricted movement during critical life stages, such as breeding and over-wintering. This suggests the existence of either a behavioral or habitat mediated ‘temporal bottleneck,’ where restricted or sedentary movement can make populations more susceptible to harm during specific life stages. Here, we study over-winter movement and habitat use of Lake Sturgeon (Acipenser fulvescens, the largest freshwater fish in North America. We monitored over-winter movement of 86 fish using a hydro-acoustic receiver array in the South Saskatchewan River, Canada. Overall, 20 fish remained within our study system throughout the winter. Lake Sturgeon showed strong aggregation and sedentary movement over-winter, demonstrating a temporal bottleneck. Movement was highly restricted during ice-on periods (ranging from 0.9 km/day in November and April to 0.2 km/day in mid-November to mid-March, with Lake Sturgeon seeking deeper, slower pools. We also show that Lake Sturgeon have strong aggregation behavior, where distance to conspecifics decreased (from 575 to 313 m in preparation for and during ice-on periods. Although the Lake Sturgeon we studied had access to 1100 kilometers of unfragmented riverine habitat, we show that during the over-winter period Lake Sturgeon utilized a single, deep pool (<0.1% of available habitat. The temporal discrepancy between mobile and sedentary behaviors in Lake Sturgeon suggest adaptive management is needed with more localized focus during periods of temporal bottlenecks, even for large-bodied species.

Variation in fish community structure, richness and diversity of 56 Danish lakes with contrasting depth and trophic state: Does the method matter?

DEFF Research Database (Denmark)

Menezes, Rosemberg

2011-01-01

The understanding of the variables that determine the structure and composition of fish communities is crucial for developing fish monitoring programs for lakes. Although electrofishing has long been recognized as an efficient method for quantitative investigations of fish populations, it has typ...... are not well caught in the gill nets such as eel, common carp (Carassius carassius) and stickleback (Gasterosteus aculeatus)....

The offshore benthic fish community

Science.gov (United States)

Lantry, Brian F.; Lantry, Jana R.; Weidel, Brian C.; Walsh, Maureen; Hoyle, James A.; Schaner, Teodore; Neave, Fraser B.; Keir, Michael

2014-01-01

Lake Ontario’s offshore benthic fish community includes primarily slimy sculpin, lake whitefish, rainbow smelt, lake trout, burbot, and sea lamprey. Of these, lake trout have been the focus of an international restoration effort for more than three decades (Elrod et al. 1995; Lantry and Lantry 2008). The deepwater sculpin and three species of deepwater ciscoes (Coregonus spp.) that were historically important in the offshore benthic zone became rare or were extirpated by the 1960s (Christie 1973; Owens et al. 2003; Lantry et al. 2007b; Roth et al. 2013). Ecosystem changes continue to influence the offshore benthic fish community, including the effects of dreissenid mussels, the near disappearance of burrowing amphipods (Diporeia spp.) (Dermott et al. 2005; Watkins et al. 2007), and the increased abundance and expanded geographic distribution of round goby (see Nearshore Fish Community chapter) (Lantry et al. 2007b). The fish-community objectives for the offshore benthic fish community, as described by Stewart et al. (1999), are:

Isolated contact urticaria caused by immunoglobulin E-mediated fish allergy.

Science.gov (United States)

Onesimo, Roberta; Giorgio, Valentina; Pill, Stefania; Monaco, Serena; Sopo, Stefano Miceli

2012-01-01

Fish is a common cause of food allergy. The reactions usually occur after its ingestion. In most immunoglobulin E-mediated reactions, the allergens are gastroresistant and heat-stable proteins of low molecularweight (parvalbumin). On the other hand, isolated contact urticaria following the handling of raw fish but without symptoms after its ingestion was found among cooks and professional fish handlers. In these cases, the fish allergens are gastrosensitive and thermolabile, as demonstrated by the decrease in the diameter of the wheal in the skin-prick test using cooked fish. To the best of our knowledge isolated fish contact urticaria in children has not been previously reported. We analyze the features of three pediatric cases of contact urticaria from cod (one of them was sensitized to parvalbumin), with tolerance after ingestion of this fish on oral food challenge.

Demography and genome divergence of lake and stream populations of an East African cichlid fish.

Science.gov (United States)

Egger, Bernd; Roesti, Marius; Böhne, Astrid; Roth, Olivia; Salzburger, Walter

2017-10-01

Disentangling the processes and mechanisms underlying adaptive diversification is facilitated by the comparative study of replicate population pairs that have diverged along a similar environmental gradient. Such a setting is realized in a cichlid fish from southern Lake Tanganyika, Astatotilapia burtoni, which occurs within the lake proper as well as in various affluent rivers. Previously, we demonstrated that independent lake and stream populations show similar adaptations to the two habitat regimes. However, little is known about the evolutionary and demographic history of the A. burtoni populations in question and the patterns of genome divergence among them. Here, we apply restriction site-associated DNA sequencing (RADseq) to examine the evolutionary history, the population structure and genomic differentiation of lake and stream populations in A. burtoni. A phylogenetic reconstruction based on genome-wide molecular data largely resolved the evolutionary relationships among populations, allowing us to re-evaluate the independence of replicate lake-stream population clusters. Further, we detected a strong pattern of isolation by distance, with baseline genomic divergence increasing with geographic distance and decreasing with the level of gene flow between lake and stream populations. Genome divergence patterns were heterogeneous and inconsistent among lake-stream population clusters, which is explained by differences in divergence times, levels of gene flow and local selection regimes. In line with the latter, we only detected consistent outlier loci when the most divergent lake-stream population pair was excluded. Several of the thus identified candidate genes have inferred functions in immune and neuronal systems and show differences in gene expression between lake and stream populations. © 2017 John Wiley & Sons Ltd.

Morfological Variation of Endemic Fish Rainbow Celebensis (Telmatherina celebensis Boulenger in Lake Towuti, South Sulawesi

Directory of Open Access Journals (Sweden)

S.H. Nasution

2007-08-01

Full Text Available Rainbow Celebensis (Telmatherina celebensis Boulenger is one of endemic fish is a part of richness of biodiversity and world heritage in Lake Towuti. Rainbow Celebensis have beautiful colour especially in male, so that it is an economically and potentially as ornamental freshwater fish. It should be protected from threats because to fear decrease offish population in nature. This research is to know morphological variation of endemic fish rainbow Celebensis based on standard morphometric character in several stations. This research is conducted in Lake Towuti, South Sulawesi from March 2002 until April 2003 in four stations were I: Bakara Cape, II: inlet of Lake Towuti for River Tominanga, III: Loeha Island, IV: outlet of Lake Towuti to River Hola-hola. Sample were collected using experimental gillnet sized of 3A, 1, lA, and VA inch. Measuring offish standard morphometric character to be down on Kottelat et al. (1993 with modification covering 14 characters. The result of univariate and multivariate analysis towards standard morphometric character, could be said that male and female at I, II, III, and IV station is same tendency or to be deacended from one fish population. The characteristic to have influence of male are body hight and length from mouth to first pectoral fin, whereas in female are forskal length, total length, and basic length of second pectoral fin. Key words: Morphological variation. Telmatherina celebensis, lake Towuti.   ABSTRAK Rainbow Selebensis adalah salah satu jenis ikan endemik dan merupakan bagian dari kekayaan sumberdaya hayati dan world heritage, yang terdapat di Danau Towuti. Rainbow Selebensis memiliki warna tubuh yang indah, terutama pada ikan jantan sehingga ikan tersebut berpotensi sebagai ikan hias air tawar yang bernilai ekonomis. Ikan ini perlu dilindungi dari ancaman kepunahan karena dikhawatirkan akan terjadi penurunan populasi ikan tersebut di alam. Penelitian ini bertujuan untuk melihat variasi

Commercial and game fish from the Dąbie lake (Poland and their infection of Paracoenogonimus ovatus (Digenea

Directory of Open Access Journals (Sweden)

Angelika Anna Linowska

2015-11-01

Full Text Available Paracoenogonimus ovatus is the parasite that infest wide definitive host range (predator birds and at least two intermediate hosts: molluscs (Viviparus viviparus, V. fasciatus and freshwater fish from eastern and central Europe. The larvae of the parasite (metacercariae go to the muscle and connective tissue, and at high intensity of infection to the internal organs and brain of fish. A total of 128 fishes were caught in autumn 2009 and 2014, by fishing boats operating in Lake Dąbie, which is one of the largest lakes in Poland. The species selected reflect the species structure of commercial and recreational catches. They were roach, bream, silver bream, crucian carp (Cyprinidae, ruffe, perch, zander (Percidae and pike (Esocidae. The fish were filleted, and the skinned muscle was compressed under a trichinoscope, what allowed to see and count metacercariae in the tissues. To facilitate parasite isolation from the cysts, the muscle tissues were subjected to a 0.1 % solution of activated pepsin and 5 % citric acid at a temperature of 20ºC. The free larvae were measured and identified under an Olympus BX 50 microscope coupled with a camera running AxioVs40 V 4.8.2.0 software. Metacercariae are grouped primarily at depths ranging from just beneath the skin to about 50% of fillet thickness. The infection prevalence of P. ovatus metacercariae in the fish analyzed was 78,5%. The density of infection per gram of muscle tissue mass in the fish infected was 8.85 (from 1 to 84 metacercariae. The highest density was noted in roach, bream and white bream (17.09, 11.14 and 9.58, respectively. Metacercariae occurred singly in pike, parasites were not found in the muscles of crucian carp, ruffe, and perch examined. The reason for such differences in infection is the availability and composition of food, as well as the behavior of the fish examined.

Avoidance reactions of fish in the trawl mouth opening in a shallow and turbid lake at night

Czech Academy of Sciences Publication Activity Database

Jůza, Tomáš; Rakowitz, G.; Draštík, Vladislav; Blabolil, Petr; Herzig, A.; Kratochvíl, Michal; Muška, Milan; Říha, Milan; Sajdlová, Zuzana; Kubečka, Jan

2013-01-01

Roč. 147, October (2013), s. 154-160 ISSN 0165-7836 R&D Projects: GA MŠk(CZ) EE2.3.20.0204 Institutional support: RVO:60077344 Keywords : Lake Neusiedl * trawl * DIDSON * fish abundance * biomass Subject RIV: EH - Ecology, Behaviour Impact factor: 1.843, year: 2013

Moses Lake Fishery Restoration Project; Factors Affecting the Recreational Fishery in Moses Lake Washington, Annual Report 2002-2003.

Energy Technology Data Exchange (ETDEWEB)

Burgess, Dave

2003-11-01

This annual report is a precursor to the final technical report we will be writing the next contract period. Consequently, this report, covering the period between September 27, 2002, and September 26, 2003, represents a progress report towards the final technical report we anticipate completing by September 26, 2004. Sample analysis and field work have progressed well and we anticipate no further delays. There are 4 objectives: (1) To quantify secondary production Moses Lake; (2) To quantify the influence of predation on target fishes in Moses Lake; (3) To quantify mortality of selected fished in Moses Lake; and (4) To assess effects of habitat changes from shoreline development and carp on the fish community in Moses Lake.

Evaluation of heavy metal uptake in micropterus salmoides (Largemouth Bass) of Lake Austin, TX by neutron activation analysis

International Nuclear Information System (INIS)

Weaver, J.; Wilson, W.H.; Biegalski, S.R.F.; O'Kelly, D.J.

2009-01-01

Neutron activation analysis was used to investigate and quantify the level of heavy metal uptake in the marine environment of Lake Austin in Austin, TX. Specifically, the samples studied were largemouth bass, or micropterus salmoides. The presence of heavy metals in the food chain presents multiple hazards, mostly as a food hazard for those species that ingest the fish, namely humans. To measure the concentrations of heavy metals in various fish samples, the nuclear analytical technique of neutron activation analysis (NAA) was used. Both epithermal and thermal irradiations were conducted for the NAA to look for short and long-lived radioisotopes, respectively. The samples themselves consisted of liver and tissue samples for each of the fish caught. Each sample was freeze-dried and homogenized before irradiation and spectrum acquisition. The results showed that all levels of heavy metals were not sufficient enough to make the fish unsafe for eating, with the highest levels being found for iron and zinc. Gold was found to be at much higher concentrations in the younger fish and virtually non-existent in the larger of the samples. (author)

Great Lakes Science Center

Data.gov (United States)

Federal Laboratory Consortium — Since 1927, Great Lakes Science Center (GLSC) research has provided critical information for the sound management of Great Lakes fish populations and other important...

Invasive fish species in the largest lakes of Scotland, Northern Ireland, Wales and England: the collective U.K. experience

OpenAIRE

Winfield, I.J.; Fletcher, J.M.; James, J.B.

2011-01-01

An invasive species is defined as an alien (or introduced or non-native) species whose establishment and spread threaten ecosystems, habitats or species with harm. Such threats to UK lake fish communities have long been appreciated and this review assembles case histories, including new data, from the largest lakes of Scotland, Northern Ireland, Wales and England to examine the hypothesis that at least some of these introductions have become invasive. Loch Lomond in Scotland has experienced s...

Ecological position of 'small barbs' and their potential for fisheries: an option to reduce fishing pressure on 'large barbs' of Lake Tana (Ethiopia)?

NARCIS (Netherlands)

Dejen, E.; Osse, J.W.M.; Sibbing, F.A.

2004-01-01

The two barbs, Barbus humilis and Barbus tanapelagius are important pelagic fish in Lake Tana. These 'small barb' species (<10 cm fork length) play a key role in the Lake's ecosystem as a link between zooplankton and the top predators, mostly 'large barbs'. This paper presents an overview on the

Mixed stock analysis of Lake Michigan's Lake Whitefish Coregonus clupeaformis commercial fishery

Science.gov (United States)

Andvik, Ryan; Sloss, Brian L.; VanDeHey, Justin A.; Claramunt, Randall M.; Hansen, Scott P.; Isermann, Daniel A.

2016-01-01

Lake whitefish (Coregonus clupeaformis) support the primary commercial fishery in Lake Michigan. Discrete genetic stocks of lake whitefish have been identified and tagging data suggest stocks are mixed throughout much of the year. Our objectives were to determine if (1) differential stock harvest occurs in the commercial catch, (2) spatial differences in genetic composition of harvested fish were present, and (3) seasonal differences were present in the harvest by commercial fisheries that operate in management zones WI-2 and WFM-01 (Green Bay, Lake Michigan). Mixed stock analysis was conducted on 17 commercial harvest samples (n = 78–145/sample) collected from various ports lake-wide during 2009–2010. Results showed significant mixing with variability in stock composition across most samples. Samples consisted of two to four genetic stocks each accounting for ≥ 10% the catch. In 10 of 17 samples, the stock contributing the largest proportion made up differences existed in the proportional stock contribution at a single capture location. Samples from Wisconsin's primary commercial fishing management zone (WI-2) were composed predominately of fish from the Big Bay de Noc (Michigan) stock as opposed to the geographically proximate, North–Moonlight Bay (Wisconsin) stock. These findings have implications for management and allocation of fish to various quotas. Specifically, geographic location of harvest, the current means of allocating harvest quotas, is not the best predictor of genetic stock harvest.

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...

Assessment of heavy metals and estimation of human health risk in Tilapia fish from Naik lake of Nagpur, India

Digital Repository Service at National Institute of Oceanography (India)

Giripunje, M.D.; Fulke, A.B.; Meshram, P.U.

/g dw respectively. These levels were above the maximum permissible limits of Food and Agriculture Organization (FAO)/World Health Organisation (WHO). The results confirmed that tilapia fish from Naik lake are not safe for human consumption. Further...

Artificial reefs and reef restoration in the Laurentian Great Lakes

Science.gov (United States)

McLean, Matthew W.; Roseman, Edward; Pritt, Jeremy J.; Kennedy, Gregory W.; Manny, Bruce A.

2015-01-01

We reviewed the published literature to provide an inventory of Laurentian Great Lakes artificial reef projects and their purposes. We also sought to characterize physical and biological monitoring for artificial reef projects in the Great Lakes and determine the success of artificial reefs in meeting project objectives. We found records of 6 artificial reefs in Lake Erie, 8 in Lake Michigan, 3 in Lakes Huron and Ontario, and 2 in Lake Superior. We found 9 reefs in Great Lakes connecting channels and 6 reefs in Great Lakes tributaries. Objectives of artificial reef creation have included reducing impacts of currents and waves, providing safe harbors, improving sport-fishing opportunities, and enhancing/restoring fish spawning habitats. Most reefs in the lakes themselves were incidental (not created purposely for fish habitat) or built to improve local sport fishing, whereas reefs in tributaries and connecting channels were more frequently built to benefit fish spawning. Levels of assessment of reef performance varied; but long-term monitoring was uncommon as was assessment of physical attributes. Artificial reefs were often successful at attracting recreational species and spawning fish; however, population-level benefits of artificial reefs are unclear. Stressors such as sedimentation and bio-fouling can limit the effectiveness of artificial reefs as spawning enhancement tools. Our investigation underscores the need to develop standard protocols for monitoring the biological and physical attributes of artificial structures. Further, long-term monitoring is needed to assess the benefits of artificial reefs to fish populations and inform future artificial reef projects.

Antibiotic and fermentative activity of bacteria found in water and digestive tract of fish from Lake Drukshiai at Ignalina Nuclear Power Plant

International Nuclear Information System (INIS)

Lubianskiene, V.; Jastiuginiene, R.

1996-01-01

The composition and antagonistic activity of microflora found in water and digestive tract of roaches - fish, which prevail in Lake Drukshiai, were investigated. The investigations revealed that unfavourable environmental conditions first of all gave rise to the changes in bacteria composition. It has been found that the bacteria of g. Vibrio, prevailed, their virulentic properties became more intense, antibiotical properties weakened, the prevailing microflora lost its ability to fight with pathogenic microorganisms. An increased lysozymic activity of g. Vibrio bacteria in the intestinal tract of fishes shows their resistance to phagocytosis and ability to stay for a long time in the digestive tract. The high antilysozymic activity of g. Vibrio bacteria in fishes digestive tract shows their ability to inactivate the lysozyme secreted by cells of organism reaction to pathogenic microflora. Antilysozymic and lysozymic activity of g. Vibrio bacteria is supposed to be one of the causes predetermining the predominance of this genus in biocenosis. The predominance of g. Vibrio bacteria in biocenosis of water and fish digestive tract bacteria, the strengthening of their virulentic properties speak for poor microecological conditions in the lake and lower immunological state of fish. 15 refs., 7 figs

Urbanization and the Level of Microplastic Ingestion by Fish: A Comparison of Freshwater Sunfish (Centrarchidae) from the Brazos River watershed, and Pinfish (Sparidae), from the Brazos Estuary and Inshore Marine Sites, Texas, USA

Science.gov (United States)

Rieper, K. B.; Peters, C. A.; Bratton, S. P.

2016-02-01

While previous research has documented ingestion of macro- and microplastics by aquatic fauna in both freshwater and marine ecosystems, relatively little is known of the environmental and ecological factors influencing the entry and diffusion of plastics and artificial polymers into aquatic foodwebs. Microplastics are defined as 50 μm to 5 mm in length. This study utilized stomach content analysis to compare the level of microplastic artificial polymer ingestion for fish collected from the Brazos River watershed, Brazos estuary, and inshore coastal waters of Texas, USA, in areas with varying levels of urbanization. We collected 318 bluegill (Lepomis macrochirus) and 118 longear sunfish (Lepomis megalotis) at 14 freshwater locales, and 11 samples of 298 pinfish (Lagodon rhomboides) at 6 saltwater locales. Sunfish averaged 12.6 cm in length, and pinfish averaged 14.9 cm. Sunfish averaged .807 microplastics per fish, and pinfish averaged 1.09. The maximum percentage for pinfish with microplastics present per sample (frequency) was 77%, compared to 75% for sunfish. Mean frequencies per sample were also similar: 45% for sunfish and 47% for pinfish. The Brazos River collections, however, had a greater percentage with frequencies of colors. Comparison with presence of natural food items suggests microplastic ingestion is predominantly incidental for these sentinel fish species.

Lake size and fish diversity in southern Brazil coastal lagoons

Directory of Open Access Journals (Sweden)

Lucia Ribeiro Rodrigues

2015-10-01

Full Text Available The coastal plain of Rio Grande do Sul, southern Brazil, presents a series of shallow lagoons with diverse size and morphology. The objective of this study is to determine whether the size of the lagoon is an effective factor for structuring fish diversity. In this regard, nine lagoons with distinct areas were sampled: three with an area up to 40 hectares, three with area between 40 and 80 hectares, and three with an area of over 80 hectares. Each lagoon was sampled once on the littoral and pelagic zones. At each point, fish were captured through a set of gill nets with different mesh sizes. Captured specimens were identified, quantified and evaluated for weight and length. A total of 24 fish species belonging to 10 families was obtained, with Characidae presenting the highest species richness. Cyanocharax alburnus was the only species that occurred in all lagoons. Cyphocharax voga, Astyanax eigenmmaniorum, Oligosarcus jenynsii and O. robustus were also frequent species, present in most of the sampled lagoons. Lycengraulis grossidens was captured in just two lagoons with increased conductivity. The community structure showed the highest species richness in lakes with an area over 40 ha, however the highest mean diversity values were observed in ponds up to 40 ha. Cluster Analysis yielded the formation of two groups: a group formed by just one lagoon and a second one cluster grouping all the other lagoons. This pattern may be associated with the presence of Lycengraulis grossidens as a dominant species in this lagoon clustered apart. The results indicate that lagoons with up to 40 ha present greater homogeneity on the species composition and higher average values of diversity; while intermediate ponds (between 40 and 80 ha have lower average diversity for the fish fauna due to increased heterogeneity in species abundance.

Wapan Sakahikan : the making of a lake

Energy Technology Data Exchange (ETDEWEB)

Jaremko, D.

2009-08-15

This article discussed an ecosystem project built on reclaimed oil sands lands. The oil sands mine originally required the removal of sections of the Tar and Calumet rivers, tributaries of the Athabasca River. A 76.7 hectare lake was constructed in order to salvage over 100,000 fish. The reclamation included the development of a traditional gathering area for local First Nations and Metis. The lake included a variety of fish habitats and was supported by 5 years of monitoring. The lake will be home to 8 fish species and is 23 meters in depth with shallow areas of 5 meters. Biologists helped to build the habitats, which include deep channels with varying depth and widths; shoals; overhead vegetation; and a rearing habitat area. The lake's littoral zone is approximately 30 per cent of the lake's total area. The involvement of First Nations and Metis included a traditional ceremony on the empty lake bottom. 1 fig.

Freshwater and fish

International Nuclear Information System (INIS)

Saxen, R.

1997-01-01

Severe radioactive contamination of the freshwater environment could have serious consequences for both drinking water and fish. Most of the Nordic countries have an abundance of freshwater lakes and rivers. Finland alone has about 56,000 lakes, each with a surface area of 1 hectare or more. Nearly 10% of Finland's surface is covered with lakes and rivers. In Sweden, about 9% of the surface area is freshwater, in Norway about 5%, and in Denmark only about 2%. Freshwater plays a minor role in Iceland, but even there numerous rivers discharge from the volcanic soils to the Ocean. Cs-137 and 90 Sr are likely to be the most important radionuclides with respect to long term radioactive contamination of freshwater. If radioactive deposition occurs in the absence of snow and ice radionuclides will contaminate the surface water directly and may rapidly enter the aquatic food chain. Fish which eat contaminated plankton become contaminated almost immediately. Deposition during summer increases the transfer for radionuclides to fish since fish metabolism is faster during the warm season. During the cold period, fish metabolism is slow and thus uptake and excretion of radiocaesium are also slow. (EG)

Bottom-up effects on biomass versus top-down effects on identity: a multiple-lake fish community manipulation experiment

NARCIS (Netherlands)

Lemmens, P.; Declerck, S.A.J.; Tuytens, K.; Vanderstukken, M.; De Meester, L.

2018-01-01

The extent to which ecosystems are regulated by top-down relative to bottom-up control has been a dominant paradigm in ecology for many decades. For lakes, it has been shown that predation by fish is an important determinant of variation in zooplankton and phytoplankton community characteristics.

Ciguatera fish poisoning. A southern California epidemic.

Science.gov (United States)

Barton, E D; Tanner, P; Turchen, S G; Tunget, C L; Manoguerra, A; Clark, R F

1995-01-01

Ciguatera fish poisoning results from the bioconcentration of a variety of toxins produced by marine dinoflagellates. Signs and symptoms vary widely, but it usually presents as gastrointestinal and neurologic complaints beginning shortly after the ingestion of fish containing the toxins. Symptoms may persist for months and sometimes even years. Although cases have been reported throughout the United States, epidemics are most common along tropical and subtropical coasts and usually involve the ingestion of large carnivorous fish. We review the literature and report the first epidemic of 25 cases of ciguatera fish poisoning presenting to area hospitals in Southern California that were successfully tracked by the Department of Health Services and isolated to fish caught off the coast of Baja California, Mexico. Images Figure 1. PMID:7667980

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.

Occurrence of microplastics in the gastrointestinal tract of pelagic and demersal fish from the English Channel.

Science.gov (United States)

Lusher, A L; McHugh, M; Thompson, R C

2013-02-15

Microplastics are present in marine habitats worldwide and laboratory studies show this material can be ingested, yet data on abundance in natural populations is limited. This study documents microplastics in 10 species of fish from the English Channel. 504 Fish were examined and plastics found in the gastrointestinal tracts of 36.5%. All five pelagic species and all five demersal species had ingested plastic. Of the 184 fish that had ingested plastic the average number of pieces per fish was 1.90±0.10. A total of 351 pieces of plastic were identified using FT-IR Spectroscopy; polyamide (35.6%) and the semi-synthetic cellulosic material, rayon (57.8%) were most common. There was no significant difference between the abundance of plastic ingested by pelagic and demersal fish. Hence, microplastic ingestion appears to be common, in relatively small quantities, across a range of fish species irrespective of feeding habitat. Further work is needed to establish the potential consequences. Copyright © 2012 Elsevier Ltd. All rights reserved.

Acute abdomen caused by ingested chicken wishbone: a case report

OpenAIRE

Hoxha, Faton T; Hashani, Shemsedin I; Komoni, Driton S; Gashi-Luci, Lumturije H; Kurshumliu, Fisnik I; Hashimi, Medita SH; Krasniqi, Avdyl S

2009-01-01

Introduction An ingested foreign body often passes the gastrointestinal tract without any complications. Foreign bodies, such as dentures, fish bones, chicken bones, and toothpicks, have been known to cause perforation of the GI tract. Case presentation We are presenting a case of a fifty-year-old male with acute abdomen; diffuse fibro purulent peritonitis, i.e. ileum perforation, caused by accidentally ingesting a chicken wishbone. He was treated surgically with ileum resection, and temporar...

The total body length and body weight examination among gabus Sentani fish population, Oxyeleotris heterodon, Weber 1907 (Pisces: Eleotridae) of Sentani lake, Papua, Indonesia

Science.gov (United States)

Sriyani, E. D.; Abinawanto, Bowolaksono, A.

2017-07-01

The gabus Sentani fish lived in the Sentani Lake, Papua, since million years ago. Nowadays, the population of those species is getting extinct because of the overexploitation, whereas the culture effort of this species has not been developed, yet. The purpose of the study was to examine the total body length and body weight collected from some villages surrounding Sentani Lake such as Ifar village, Sosiri village, and Putali village. The body weight average of gabus fish from Ifar village, Sosiri village, and Putali village were 373.53 g, 426.86 g, and 118.34 g respectively. While the total body length average of gabus Sentani fish from Ifar village, Sosiri village, and Putali village were 279.30 mm, 223.30 mm and 222.06 mm, respectively. The growth model was W = 0.021067L3.086 with R2 value was 35.8 %, and r value was 0.598. Gabus Sentani fish, Oxyeleotris heterodon (Weber 1907) exhibited positive allometric (b > 3).

Sherman Creek Hatchery; Washington Department of Fish and Wildlife Fish Program, 2001 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Combs, Mitch (Washington Department of Fish and Wildlife, Kettle Falls, WA)

2002-01-01

Sherman Creek Hatchery's primary objective is the restoration and enhancement of the recreational and subsistence fishery in Lake Roosevelt and Banks Lake. The Sherman Creek Hatchery (SCH) was designed to rear 1.7 million kokanee fry for acclimation and imprinting during the spring and early summer. Additionally, it was designed to trap all available returning adult kokanee during the fall for broodstock operations and evaluations. Since the start of this program, the operations on Lake Roosevelt have been modified to better achieve program goals. The Washington Department of Fish and Wildlife, Spokane Tribe of Indians and the Colville Confederated Tribe form the interagency Lake Roosevelt Hatcheries Coordination Team (LRHCT) which sets goals and objectives for both Sherman Creek and the Spokane Tribal Hatchery and serves to coordinate enhancement efforts on Lake Roosevelt and Banks Lake. The primary changes have been to replace the kokanee fingerling program with a yearling (post smolt) program of up to 1,000,000 fish. To construct and operate twenty net pens to handle the increased production. The second significant change was to rear up to 300,000 rainbow trout fingerling at SCH from July through October, for stocking into the volunteer net pens. This enables the Spokane Tribal Hatchery (STH) to rear additional kokanee to further the enhancement efforts on Lake Roosevelt. Current objectives include increased use of native/indigenous stocks where available for propagation into Upper Columbia River Basin Waters. Monitoring and evaluation is preformed by the Lake Roosevelt Fisheries Monitoring Program. From 1988 to 1998, the principle sport fishery on Lake Roosevelt has shifted from walleye to include rainbow trout and kokanee salmon (Underwood et al. 1997, Tilson and Scholz 1997). The angler use, harvest rates for rainbow and kokanee and the economic value of the fishery has increased substantially during this 10-year period. The most recent information from

Clinical and epidemiological study of 27 poisonings caused by ingesting puffer fish (Tetrodontidae in the states of Santa Catarina and Bahia, Brazil Estudo clinico-epidemiológico de 27 envenenamentos causados pela ingestão de baiacus (Tetrodontidae nos estados de Santa Catarina e Bahia, Brasil

Directory of Open Access Journals (Sweden)

Claudia Carvalho Pestana Silva

2010-02-01

Full Text Available Puffer fish can be poisonous due to the presence of the potent neurotoxins such as Tetrodotoxin (TTX and Saxitoxin (STX found in its tissues. The authors report 27 human poisonings from ingestion of puffer fish in patients treated at Toxicology Centers in the states of Santa Catarina and Bahia, Brazil, between 1984 and January 2009. Poisonings were classified as moderate (52% and severe (33%, two deaths were observed. Early diagnosis is very important to ensure respiratory support.Os baiacus ou peixes-bola podem ser venenosos devido à presença em seus tecidos corporais de Tetrodotoxina e/ou Saxitoxina, ambas potentes neurotoxinas. Os autores relatam 27 envenenamentos por ingestão da carne de baiacus. Os pacientes foram atendidos nos Centros de Toxicologia de Santa Catarina e da Bahia de 1984 a 2009. Os acidentes foram classificados em moderados (52% e graves (33%, havendo dois óbitos. O diagnóstico precoce é fundamental no sentido de garantir suporte ventilatório aos pacientes.

Defining fish community structure in Lake Winnipeg using stable isotopes (δ13C, δ15N, δ34S): Implications for monitoring ecological responses and trophodynamics of mercury and other trace elements

International Nuclear Information System (INIS)

Ofukany, Amy F.A.; Wassenaar, Leonard I.; Bond, Alexander L.; Hobson, Keith A.

2014-01-01

The ecological integrity of freshwater lakes is influenced by atmospheric and riverine deposition of contaminants, shoreline development, eutrophication, and the introduction of non-native species. Changes to the trophic structure of Lake Winnipeg, Canada, and consequently, the concentrations of contaminants and trace elements measured in tissues of native fishes, are likely attributed to agricultural runoff from the 977,800 km 2 watershed and the arrival of non-native zooplankters and fishes. We measured δ 13 C, δ 15 N, and δ 34 S along with concentrations of 15 trace elements in 17 native fishes from the north and south basins of Lake Winnipeg in 2009 and 2010. After adjusting for differences in isotopic baseline values between the two basins, fishes in the south basin had consistently higher δ 13 C and δ 34 S, and lower δ 15 N. We found little evidence of biomagnification of trace elements at the community level, but walleye (Sander vitreus) and freshwater drum (Aplodinotus grunniens) had higher mercury and selenium concentrations with increased trophic position, coincident with increased piscivory. There was evidence of growth dilution of cobalt, copper, manganese, molybdenum, thallium, and vanadium, and bioaccumulation of mercury, which could be explained by increases in algal (and consequently, lake and fish) productivity. We conclude that the north and south basins of Lake Winnipeg represent very different communities with different trophic structures and trace element concentrations. - Highlights: • Anthropogenic eutrophication and non-native species affect Lake Winnipeg’s ecosystem. • We measured stable isotopes and trace elements in 15 native fish species. • There was more evidence for growth dilution than biomagnification for most elements. • The trophic structures of the north and south basins were different. • These results will help determine the effects of recent arrival of zebra mussels

The influence of total organic carbon (TOC) on the relationship between acid neutralizing capacity (ANC) and fish status in Norwegian lakes.

Science.gov (United States)

Lydersen, Espen; Larssen, Thorjørn; Fjeld, Eirik

2004-06-29

Acid neutralizing capacity (ANC) is the parameter most commonly used as chemical indicator for fish response to acidification. Empirical relationships between fish status of surface waters and ANC have been documented earlier. ANC is commonly calculated as the difference between base cations ([BC]=[Ca2+]+[Mg2+]+[N+]+[K+]) and strong acid anions ([SAA]=[SO4(2)-]+[NO3-]+[Cl-]). This is a very robust calculation of ANC, because none of the parameters incorporated are affected by the partial pressure of CO2, in contrast to the remaining major ions in waters, pH ([H+]), aluminum ([Aln+]), alkalinity ([HCO3-/CO3(2)-]) and organic anions ([An-]). Here we propose a modified ANC calculation where the permanent anionic charge of the organic acids is assumed as a part of the strong acid anions. In many humic lakes, the weak organic acids are the predominant pH-buffering system. Because a significant amount of the weak organic acids have pK-values4.5). This means that they will be permanently present as anions, equal to the strong acid inorganic anions, SO4(2)-, NO3- and Cl-. In the literature, natural organic acids are often described as triprotic acids with a low pK1 value. Assuming a triprotic model, we suggest to add 1/3 of the organic acid charge density to the strong acid anions in the ANC calculation. The suggested organic acid adjusted ANC (ANC(OAA)), is then calculated as follows: ANC(OAA)=[BC]-([SAA]+1/3CD*TOC) where TOC is total organic carbon (mg C L(-1)), and CD=10.2 is charge density of the organic matter (microeq/mg C), based on literature data from Swedish lakes. ANC(OAA) gives significant lower values of ANC in order to achieve equal fish status compared with the traditional ANC calculation. Using ANC(OAA) the humic conditions in lakes are better taken into account. This may also help explain observations of higher ANC needed to have reproducing fish populations in lakes with higher TOC concentrations. Copryright 2003 Elsevier B.V.

Effect of boat noise and angling on lake fish behaviour

DEFF Research Database (Denmark)

Jacobsen, Lene; Baktoft, Henrik; Jepsen, Niels

2014-01-01

or (2) boating in short intervals combined with angling with artificial lures between engine runs. The response of the fish species was evaluated by high-resolution tracking using an automatic acoustic telemetry system and transmitters with sub-minute burst rates. Rutilus rutilus swimming speed......The effects of disturbances from recreational activities on the swimming speed and habitat use of roach Rutilus rutilus, perch Perca fluviatilis and pike Esox lucius were explored. Disturbances were applied for 4h as (1) boating in short intervals with a small outboard internal combustion engine...... the two types of disturbances (boating with and without angling), indicating that boating was the primary source of disturbance. This study highlights species-specific responses to recreational boating and may have implications for management of human recreational activities in lakes...

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

How many species of cichlid fishes are there in African lakes?

Science.gov (United States)

Turner, G F; Seehausen, O; Knight, M E; Allender, C J; Robinson, R L

2001-03-01

The endemic cichlid fishes of Lakes Malawi, Tanganyika and Victoria are textbook examples of explosive speciation and adaptive radiation, and their study promises to yield important insights into these processes. Accurate estimates of species richness of lineages in these lakes, and elsewhere, will be a necessary prerequisite for a thorough comparative analysis of the intrinsic and extrinsic factors influencing rates of diversification. This review presents recent findings on the discoveries of new species and species flocks and critically appraises the relevant evidence on species richness from recent studies of polymorphism and assortative mating, generally using behavioural and molecular methods. Within the haplochromines, the most species-rich lineage, there are few reported cases of postzygotic isolation, and these are generally among allopatric taxa that are likely to have diverged a relatively long time in the past. However, many taxa, including many which occur sympatrically and do not interbreed in nature, produce viable, fertile hybrids. Prezygotic barriers are more important, and persist in laboratory conditions in which environmental factors have been controlled, indicating the primary importance of direct mate preferences. Studies to date indicate that estimates of alpha (within-site) diversity appear to be robust. Although within-species colour polymorphisms are common, these have been taken into account in previous estimates of species richness. However, overall estimates of species richness in Lakes Malawi and Victoria are heavily dependent on the assignation of species status to allopatric populations differing in male colour. Appropriate methods for testing the specific status of allopatric cichlid taxa are reviewed and preliminary results presented.

Fish-allergic patients may be able to eat fish.

Science.gov (United States)

Mourad, Ahmad A; Bahna, Sami L

2015-03-01

Reported fish allergy prevalence varies widely, with an estimated prevalence of 0.2% in the general population. Sensitization to fish can occur by ingestion, skin contact or inhalation. The manifestations can be IgE or non-IgE mediated. Several fish allergens have been identified, with parvalbumins being the major allergen in various species. Allergenicity varies among fish species and is affected by processing or preparation methods. Adverse reactions after eating fish are often claimed to be 'allergy' but could be a reaction to hidden food allergen, fish parasite, fish toxins or histamine in spoiled fish. Identifying such causes would allow free consumption of fish. Correct diagnosis of fish allergy, including the specific species, might provide the patient with safe alternatives. Patients have been generally advised for strict universal avoidance of fish. However, testing with various fish species or preparations might identify one or more forms that can be tolerated.

Human exposure to metals due to consumption of fish from an artificial lake basin close to an active mining area in Katanga (D.R. Congo)

International Nuclear Information System (INIS)

Squadrone, S.; Burioli, E.; Monaco, G.; Koya, M.K.; Prearo, M.; Gennero, S.; Dominici, A.; Abete, M.C.

2016-01-01

The concentrations of 14 essential and nonessential trace elements were determined in fish from Lake Tshangalele, Katanga province, Democratic Republic of Congo. This province has been a place of intensive mining activities for centuries, which have increased in recent years, due to the use of metals such as copper and cobalt for the industries of fast-growing countries. Lake Tshangalele, which receives effluents from metallurgical and mining plants in Likasi, is home to several fish species that are an important part of the diet of the local population, and, therefore, it constitutes a relevant site for documenting the human exposure to metals as a result of a fish diet. The highest concentrations (median levels, dry weight) of cobalt (7.25 mg kg"− "1), copper (88.1 mg kg"− "1), iron (197.5 mg kg"− "1), manganese (65.35 mg kg"− "1), zinc (122.9 mg kg"− "1) and aluminum (135.4 mg kg"− "1) were found in fish collected closest to the copper mining plant, with decreasing concentrations along the lake, up to the dam. In the most contaminated fish samples, values of up to 270.1 mg kg"− "1 for Al, 173.1 mg kg"− "1 for Cu, 220.9 mg kg"− "1 for Zn, 211.0 mg kg"− "1 for Mn, 324.2 mg kg"− "1 for Fe, 15.1 mg kg"− "1 for Co, 4.2 mg kg"− "1 for Cr, 1.6 mg kg"− "1 for Cd, 1.9 mg kg"− "1 for Pb, and 1.8 mg kg"− "1 for Ni were found. Metal contamination from mining activity resulted in being of great concern because of potential health risks to the local inhabitants due to the consumption of heavily contaminated fish. Capsule: High levels of metals, especially cobalt, aluminum, iron, manganese, zinc and cadmium were found in fish from Tshangalele water system. - Highlights: • Metal contamination from mining activity is of great concern for human exposure. • We analyzed metal content in fish from Lake Tshangalele (Katanga Copperbelt). • Fish consumption largely contributes to intake of Co and other metals. • In some samples, Co, Cu, Mn, Al

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

Emergency Fish Restoration Project; Final Report 2002.

Energy Technology Data Exchange (ETDEWEB)

LeCaire, Richard

2003-03-01

Lake Roosevelt is a 151-mile impoundment created by the construction of Grand Coulee Dam during the early 1940's. The construction of the dam permanently and forever blocked the once abundant anadromous fish runs to the upper Columbia Basin. Since the construction of Grand Coulee Dam in 1943 and Chief Joseph Dam in 1956 this area is known as the blocked area. The blocked area is totally dependant upon resident fish species to provide a subsistence, recreational and sport fishery. The sport fishery of lake Roosevelt is varied but consists mostly of Rainbow trout (Oncorhynchus mykiss), Kokanee salmon (Oncorhynchus nerka), Walleye (Stizostedion vitreum) Small mouth bass (Micropterus dolomieui) and white sturgeon (Acipenser transmontanus). Currently, Bonneville Power Administration funds and administers two trout/kokanee hatcheries on Lake Roosevelt. The Spokane Tribe of Indians operates one hatchery, the Washington Department of Fish and Wildlife the other. In addition to planting fish directly into Lake Roosevelt, these two hatcheries also supply fish to a net pen operation that also plants the lake. The net pen project is administered by Bonneville Power funded personnel but is dependant upon volunteer labor for daily feeding and monitoring operations. This project has demonstrated great success and is endorsed by the Colville Confederated Tribes, the Spokane Tribe of Indians, the Washington Department of Fish and Wildlife, local sportsmen associations, and the Lake Roosevelt Forum. The Lake Roosevelt/Grand Coulee Dam area is widely known and its diverse fishery is targeted by large numbers of anglers annually to catch rainbow trout, kokanee salmon, small mouth bass and walleye. These anglers contribute a great deal to the local economy by fuel, grocery, license, tackle and motel purchases. Because such a large portion of the local economy is dependant upon the Lake Roosevelt fishery and tourism, any unusual operation of the Lake Roosevelt system may have a

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

Characterization of the quality of water, bed sediment, and fish in Mittry Lake, Arizona, 2014–15

Science.gov (United States)

Hermosillo, Edyth; Coes, Alissa L.

2017-03-01

Water, bed-sediment, and fish sampling was conducted in Mittry Lake, Arizona, in 2014–15 to establish current water-quality conditions of the lake. The parameters of temperature, dissolved-oxygen concentration, specific conductance, and alkalinity were measured in the field. Water samples were collected and analyzed for dissolved major ions, dissolved trace elements, dissolved nutrients, dissolved organic carbon, dissolved pesticides, bacteria, and suspended-sediment concentrations. Bed-sediment and fish samples were analyzed for trace elements, halogenated compounds, total mercury, and methylmercury.U.S. Environmental Protection Agency secondary maximum contaminant levels in drinking water were exceeded for sulfate, chloride, and manganese in the water samples. Trace-element concentrations were relatively similar between the inlet, middle, and outlet locations. Concentrations for nutrients in all water samples were below the Arizona Department of Environmental Quality’s water-quality standards for aquatic and wildlife uses, and all bacteria levels were below the Arizona Department of Environmental Quality’s recommended recreational water-quality criteria. Three out of 81 pesticides were detected in the water samples.Trace-element concentrations in bed sediment were relatively consistent between the inlet, middle, and outlet locations. Lead, manganese, nickel, and zinc concentrations, however, decreased from the inlet to outlet locations. Concentrations for lead, nickel, and zinc in some bed-sediment samples exceeded consensus-based sediment-quality guidelines probable effect concentrations. Eleven out of 61 halogenated compounds were detected in bed sediment at the inlet location, whereas three were detected at the middle location, and five were detected at the outlet location. No methylmercury was detected in bed sediment. Total mercury was detected in bed sediment at concentrations below the consensus-based sediment-quality guidelines probable effect

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.

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

Pacific salmonines in the Great Lakes Basin

Science.gov (United States)

Claramunt, Randall M.; Madenjian, Charles P.; Clapp, David; Taylor, William W.; Lynch, Abigail J.; Léonard, Nancy J.

2012-01-01

Pacific salmon (genus Oncorhynchus) are a valuable resource, both within their native range in the North Pacific rim and in the Great Lakes basin. Understanding their value from a biological and economic perspective in the Great Lakes, however, requires an understanding of changes in the ecosystem and of management actions that have been taken to promote system stability, integrity, and sustainable fisheries. Pacific salmonine introductions to the Great Lakes are comprised mainly of Chinook salmon, coho salmon, and steelhead and have accounted for 421, 177, and 247 million fish, respectively, stocked during 1966-2007. Stocking of Pacific salmonines has been effective in substantially reducing exotic prey fish abundances in several of the Great Lakes (e.g., lakes Michigan, Huron, and Ontario). The goal of our evaluation was to highlight differences in management strategies and perspectives across the basin, and to evaluate policies for Pacific salmonine management in the Great Lakes. Currently, a potential conflict exists between Pacific salmonine management and native fish rehabilitation goals because of the desire to sustain recreational fisheries and to develop self-sustaining populations of stocked Pacific salmonines in the Great Lakes. We provide evidence that suggests Pacific salmonines have not only become naturalized to the food webs of the Great Lakes, but that their populations (specifically Chinook salmon) may be fluctuating in concert with specific prey (i.e., alewives) whose populations are changing relative to environmental conditions and ecosystem disturbances. Remaining questions, however, are whether or not “natural” fluctuations in predator and prey provide enough “stability” in the Great Lakes food webs, and even more importantly, would a choice by managers to attempt to reduce the severity of predator-prey oscillations be antagonistic to native fish restoration efforts. We argue that, on each of the Great Lakes, managers are pursuing

Restoration of Eutrophic Lakes with Fluctuating Water Levels: A 20-Year Monitoring Study of Two Inter-Connected Lakes

Directory of Open Access Journals (Sweden)

Meryem Beklioğlu

2017-02-01

Full Text Available Eutrophication continues to be the most important problem preventing a favorable environmental state and detrimentally impacting the ecosystem services of lakes. The current study describes the results of analyses of 20 year monitoring data from two interconnected Anatolian lakes, Lakes Mogan and Eymir, receiving sewage effluents and undergoing restoration. The first step of restoration in both lakes was sewage effluent diversion. Additionally, in hypertrophic Lake Eymir, biomanipulation was conducted, involving removal of benthi-planktivorous fish and prohibition of pike fishing. The monitoring period included high (H and low (L water levels (WL enabling elucidation of the effects of hydrological changes on lake restoration. In shallower Lake Mogan, macrophyte abundance increased after the sewage effluent diversion in periods with low water levels even at turbid water. In comparatively deeper Lake Eymir, the first biomanipulation led to a clear water state with abundant macrophyte coverage. However, shortly after biomanipulation, the water clarity declined, coinciding with low water level (LWL periods during which nutrient concentrations increased. A second biomanipulation was conducted, mostly during high water level (HWL period, resulting in a major decrease in nutrient concentrations and clearer water, but without an expansion of macrophytes. We conclude that repetitive fish removal may induce recovery but its success may be confounded by high availability of nutrients and adverse hydrological conditions.

Persistent organic pollutants (POPs) in fish with different feeding habits inhabiting a shallow lake ecosystem.

Science.gov (United States)

Barni, María F Silva; Ondarza, Paola M; Gonzalez, Mariana; Da Cuña, Rodrigo; Meijide, Fernando; Grosman, Fabián; Sanzano, Pablo; Lo Nostro, Fabiana L; Miglioranza, Karina S B

2016-04-15

The occurrence of persistent organic pollutants (POPs) in the environment can affect organisms inhabiting aquatic systems, in particular shallow lakes that are vulnerable to environmental stressors. This study aimed to assess POPs accumulation and changes at histological and physiological levels in tissues of three fish species with different trophic habits. Gills, brain, muscle, liver and gonads of Odontesthes bonariensis, Oligosarcus jenynsii and Cyphocharax voga were collected from the shallow lake La Peregrina, located in an agricultural area from Argentina. In addition, contaminant levels in surface water (SW), suspended particulate matter (SPM) and bottom sediments (BS) were assessed. Histological lesions were evaluated in fish tissues and levels of vitellogenin (VTG) were assessed in plasma of male fish in order to correlate these alterations with the presence of POPs in the environment. Organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined by GC-ECD. Biotic and abiotic samples showed the same POPs distribution pattern: OCPs>PCBs>PBDEs. Although tissue distribution of OCPs was species-specific, muscle showed the lowest levels in all species. The most abundant contaminants were endosulfans, suggesting their widespread use in the area. O. bonariensis showed the highest endosulfans levels in liver (184.2-219ngg(-1)wet w), which was associated with the high SPM levels considering this species is a filter feeder. The occurrence of PCBs and PBDEs shows the ubiquity of these pollutants in the area. Histological lesions in gills and liver of O. bonariensis and O. jenynsii, might be related with the high levels of endosulfans in these organs. The detection of VTG in males warns about a possible exposure to estrogenic compounds in the environment. In conclusion, the simultaneous exposure of fish to multiple environmental pollutants leads to different alterations, so measures should be taken in

Low-level maternal methylmercury exposure through rice ingestion and potential implications for offspring health

International Nuclear Information System (INIS)

Rothenberg, Sarah E.; Feng Xinbin; Li Ping

2011-01-01

Fish consumption is considered the primary pathway for MeHg (MeHg) exposure; however, MeHg exposure also occurs through rice ingestion. Rice is grown in an aquatic environment and although documented MeHg concentrations in rice are lower compared to fish tissue, human exposures exceed international guidelines in some regions where rice is a staple food and rice MeHg levels are elevated. Studies concerning human health exposure to MeHg should also include populations where maternal MeHg exposure occurs through ingestion of rice. Rice does not contain long-chain polyunsaturated fatty acids, which are associated with confounding developmental outcomes in offspring. Rice is also a staple food for more than half the world's population; therefore, it is critical to investigate the potential health risks of maternal ingestion of rice to the developing fetus, the most susceptible population to the deleterious effects of MeHg. Data concerning MeHg in rice are reviewed and micronutrients in rice are discussed. - Research highlights: → Maternal methylmercury exposure through rice may be important. → Rice does not contain the same micronutrients as fish, but may contain methylmercury. → Effects to offspring from methylmercury without beneficial micronutrients are unknown. - Studies concerning maternal methylmercury exposure and cognitive outcomes for offspring should include populations where rice ingestion is the primary methylmercury exposure pathway.

Low-level maternal methylmercury exposure through rice ingestion and potential implications for offspring health

Energy Technology Data Exchange (ETDEWEB)

Rothenberg, Sarah E., E-mail: rothenberg.sarah@gmail.com [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 46 Guanshui Lu, Guiyang 550002 (China); Feng Xinbin, E-mail: fengxinbin@vip.skleg.cn [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 46 Guanshui Lu, Guiyang 550002 (China); Li Ping [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 46 Guanshui Lu, Guiyang 550002 (China)

2011-04-15

Fish consumption is considered the primary pathway for MeHg (MeHg) exposure; however, MeHg exposure also occurs through rice ingestion. Rice is grown in an aquatic environment and although documented MeHg concentrations in rice are lower compared to fish tissue, human exposures exceed international guidelines in some regions where rice is a staple food and rice MeHg levels are elevated. Studies concerning human health exposure to MeHg should also include populations where maternal MeHg exposure occurs through ingestion of rice. Rice does not contain long-chain polyunsaturated fatty acids, which are associated with confounding developmental outcomes in offspring. Rice is also a staple food for more than half the world's population; therefore, it is critical to investigate the potential health risks of maternal ingestion of rice to the developing fetus, the most susceptible population to the deleterious effects of MeHg. Data concerning MeHg in rice are reviewed and micronutrients in rice are discussed. - Research highlights: > Maternal methylmercury exposure through rice may be important. > Rice does not contain the same micronutrients as fish, but may contain methylmercury. > Effects to offspring from methylmercury without beneficial micronutrients are unknown. - Studies concerning maternal methylmercury exposure and cognitive outcomes for offspring should include populations where rice ingestion is the primary methylmercury exposure pathway.

Presentation of a model simulating the response of lakes to fertilizations to reduce radiocesium levels in fish

International Nuclear Information System (INIS)

Hakanson, L.; Ottosson, F.; Abrahamsson, O.; Johansson, T.

1998-01-01

Lake fertilization is a potential remedy for toxic contamination in lakes with low productivity, which are known to be sensitive to, e.g. radionuclides, metals and organic toxins. This study presents a model to plan the duration and predict the outcome of fertilization in lakes. Several methods of lake fertilization have been used in field experiments: (1) Lake and wetland liming using 'mixed' lime with added phosphorus; (2) treatment with commercial fertilizers; and (3) using effluents (containing phosphorus) from fish farms. This model is basically a dynamic model using differential equations to handle fluxes, amounts and concentrations. It also includes several empirical relationships, because the model is meant to be used in practice and the driving variables should be few and readily available, like catchment and lake morphometric data. The model is primarily intended to be used as a sub-model predicting realistic changes in phosphorus and potassium concentrations and in lake pH caused by these remedial measures within the framework of a more extensive lake model for radiocesium. It is, however, meant to be based on the fundamental processes regulating phosphorus fluxes in lakes, and could be of interest also in contexts other than radioecology. It is driven by the amount of fertilizer added to the lake and the month of treatment. The consequences for the spread, biological uptake and concentrations of radiocesium are also discussed and simulated. The phosphorus model is, and must be, easy to handle since all the input data should be derived either from maps or from regular monitoring programs. In this paper, the model is presented and calibrations are examined. The results of the calibrations indicate that the model should be useful for managers to optimise lake fertilization, e.g. in contexts of lake radioecology where the benefits and drawbacks of different remedial strategies are evaluated (multi-attribute analysis). (Copyright (c) 1998 Elsevier Science B

Data on Occurrence of Selected Trace Metals, Organochlorines, and Semivolatile Organic Compounds in Edible Fish Tissues From Lake Worth, Fort Worth, Texas 1999

National Research Council Canada - National Science Library

Moring, J. B

2002-01-01

.... Air Force and in collaboration with the Texas Department of Health, collected samples of edible fish tissues from Lake Worth for analysis of selected trace metals, organochlorines, and semivolatile...

[Further information on fish parasites from Lake Trasimeno. II. Observations on the population of Scardinius erythrophthalmus L].

Science.gov (United States)

Aisa, E; Desideri, L; Guerrieri, P; Bonelli, P

1983-09-30

An investigation was carried out to identify the actual state of parasitism in the Scardinius erythrophthalmus L. population of Trasimeno lake (Umbria, Italy). Seasonal samples of fishes were taken in different points of the litoral and pelagic zones. The parasites found, together with the somatometric values and the characteristics of their localizations are reported. It has been found: a high number of infested specimens; eleven species of parasites, of which five were not yet known to be in the lake; frequency variations of certain species. The species of parasites observed are distributed in the Paleartic region. The five species, whose presence was not known in the lake, are considered to be allochtonous. The organs most frequently involved were, in descending order, the gills, the ureters, the gonads, the intestinal and mesenteric serous membranes, the liver. The most marked histologic alterations and reactions were observed as a consequence of Ergasilus sieboldi Nord. action and, in several cases, with the presence of Ligula intestinalis L. larvae.

Food Ingestion Factors of the Korean Exposure Factors Handbook

Directory of Open Access Journals (Sweden)

Jae-Yeon Jang

2014-01-01

Full Text Available The purpose of this study was to establish food ingestion factors needed to assess exposure to contaminants through food ingestion. The study reclassified the raw data of the Korean National Health and Nutrition Examination Survey in 2001 into 12 subcategories including grain products, meat products, fish and shellfish, and vegetables for international comparability of exposure evaluation. The criteria for food intake calculation were unified according to the characteristics of food groups, and recommended values for food ingestion factors were calculated through moisture correction and recategorization of cooked, processed, and mixed foods for each group. The average intake rate for grain and grain products was 6.25 g/kg-d per capita and the men's intake rate was approximately 8% higher than that of the women. The average intake rate of meat and meat products was 1.62 g/kg-d per capita and the men's intake rate was 30% higher than that of the women, on average. The average intake rate of fish and shellfish was 1.53 g/kg-d per capita, and the age groups of 1 to 2 and 3 to 6 recorded higher capita intake rates than other age groups, 2.62 g/kg-d and 2.25 g/kg-d, respectively. The average intake rate of vegetables was 6.47 g/kg-d per capita, with the age group of 1 to 2 recording the highest per capita intake rate of 9.79 g/kg-d and that of 13 to 19 recording the lowest mean. The study also offers recommended values for food ingestion factors of other food groups by gender, age, and region. The food ingestion exposure factors will need future updates in consideration of ongoing changes in food consumption behavior.

Food ingestion factors of the Korean exposure factors handbook.

Science.gov (United States)

Jang, Jae-Yeon; Jo, Soo-Nam; Kim, Sun-Ja; Myung, Hyung-Nam; Kim, Cho-Il

2014-01-01

The purpose of this study was to establish food ingestion factors needed to assess exposure to contaminants through food ingestion. The study reclassified the raw data of the Korean National Health and Nutrition Examination Survey in 2001 into 12 subcategories including grain products, meat products, fish and shellfish, and vegetables for international comparability of exposure evaluation. The criteria for food intake calculation were unified according to the characteristics of food groups, and recommended values for food ingestion factors were calculated through moisture correction and recategorization of cooked, processed, and mixed foods for each group. The average intake rate for grain and grain products was 6.25 g/kg-d per capita and the men's intake rate was approximately 8% higher than that of the women. The average intake rate of meat and meat products was 1.62 g/kg-d per capita and the men's intake rate was 30% higher than that of the women, on average. The average intake rate of fish and shellfish was 1.53 g/kg-d per capita, and the age groups of 1 to 2 and 3 to 6 recorded higher capita intake rates than other age groups, 2.62 g/kg-d and 2.25 g/kg-d, respectively. The average intake rate of vegetables was 6.47 g/kg-d per capita, with the age group of 1 to 2 recording the highest per capita intake rate of 9.79 g/kg-d and that of 13 to 19 recording the lowest mean. The study also offers recommended values for food ingestion factors of other food groups by gender, age, and region. The food ingestion exposure factors will need future updates in consideration of ongoing changes in food consumption behavior.

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.

Mercury biomagnification in the food web of Lake Tanganyika (Tanzania, East Africa)

Energy Technology Data Exchange (ETDEWEB)

Campbell, L. [School of Environmental Studies and Department of Biology, Queen' s University, Kingston, Ontario, K7L-3N6 (Canada)], E-mail: linda.campbell@queensu.ca; Verburg, Piet [National Institute of Water and Atmospheric Research, PO Box 11-115, Hamilton 3251 (New Zealand); Dixon, D.G. [Department of Biology, University of Waterloo, 200 University Avenue, Waterloo (Canada); Hecky, R.E. [Large Lakes Observatory, University of Minnesota, Duluth, 10 University Drive 204 RLBDuluth, MN 55812-2496 (United States)

2008-09-01

Lake Tanganyika is a globally important lake with high endemic biodiversity. Millions of people in the lake basin depend on several fish species for consumption. Due to the importance of fish consumption as an exposure route of mercury to humans, we sampled Lake Tanganyika in 2000 to assess total mercury concentrations and biomagnification of total mercury through the food web. Stable nitrogen and carbon isotope analyses of food web structure indicate a complex food web with overlapping omnivory with some specialist fish species. Stable nitrogen isotope analyses further confirm that mercury is biomagnifying through the Tanganyika food web at rates similar to those seen in Lakes Malawi and Victoria, the other two African Great Lakes. Most collected fish species and all invertebrate species had mercury concentrations below 0.2 {mu}g Hg/g wet weight. However, several fish species, Ctenochromis horei (average 0.15 {mu}g/g ww), Neolamprologus boulengeri (0.2 {mu}g/g ww) , Bathybates spp.spp. (0.21 {mu}g/g ww), Mastacembelus cunningtoni (0.22 {mu}g/g ww) and Clarias theodorae (0.22 {mu}g/g ww) approached or slightly exceeded the World Health Organization (WHO)'s recommended guideline of 0.2 {mu}g Hg/g for vulnerable populations with high rates of fish consumption. Two individuals of the piscivorous fish species Lates microlepis (0.54, 0.78 {mu}g/g ww) and a Polypterus congicus (1.3 {mu}g/g ww) exceeded the international marketing limit value of 0.5 {mu}g/g ww. Because C. theodorae and L. microlepis are also important market fish species, there is a need to monitor mercury concentrations in internationally marketed fish from Lake Tanganikya to ensure that those fish do not present a risk to human consumers.

Mercury biomagnification in the food web of Lake Tanganyika (Tanzania, East Africa)

International Nuclear Information System (INIS)

Campbell, L.; Verburg, Piet; Dixon, D.G.; Hecky, R.E.

2008-01-01

Lake Tanganyika is a globally important lake with high endemic biodiversity. Millions of people in the lake basin depend on several fish species for consumption. Due to the importance of fish consumption as an exposure route of mercury to humans, we sampled Lake Tanganyika in 2000 to assess total mercury concentrations and biomagnification of total mercury through the food web. Stable nitrogen and carbon isotope analyses of food web structure indicate a complex food web with overlapping omnivory with some specialist fish species. Stable nitrogen isotope analyses further confirm that mercury is biomagnifying through the Tanganyika food web at rates similar to those seen in Lakes Malawi and Victoria, the other two African Great Lakes. Most collected fish species and all invertebrate species had mercury concentrations below 0.2 μg Hg/g wet weight. However, several fish species, Ctenochromis horei (average 0.15 μg/g ww), Neolamprologus boulengeri (0.2 μg/g ww) , Bathybates spp.spp. (0.21 μg/g ww), Mastacembelus cunningtoni (0.22 μg/g ww) and Clarias theodorae (0.22 μg/g ww) approached or slightly exceeded the World Health Organization (WHO)'s recommended guideline of 0.2 μg Hg/g for vulnerable populations with high rates of fish consumption. Two individuals of the piscivorous fish species Lates microlepis (0.54, 0.78 μg/g ww) and a Polypterus congicus (1.3 μg/g ww) exceeded the international marketing limit value of 0.5 μg/g ww. Because C. theodorae and L. microlepis are also important market fish species, there is a need to monitor mercury concentrations in internationally marketed fish from Lake Tanganikya to ensure that those fish do not present a risk to human consumers

Fish community responses to submerged aquatic vegetation in Maumee Bay, Western Lake Erie

Science.gov (United States)

Miller, Jacob; Kocovsky, Patrick; Wiegmann, Daniel; Miner, Jeffery G.

2018-01-01

Submerged aquatic vegetation (SAV) in clearwater systems simultaneously provides habitat for invertebrate prey and acts as refugia for small fishes. Many fishes in Lake Erie rely on shallow, heavily vegetated bays as spawning grounds and the loss or absence of which is known to reduce recruitment in other systems. The Maumee River and Maumee Bay, which once had abundant macrophyte beds, have experienced a decline of SAV and an increase in suspended solids (turbidity) over the last century due to numerous causes. To compare fish communities in open‐water (turbid) and in SAV (clearer water) habitats in this region, which is designated by the U.S. Environmental Protection Agency as an Area of Concern, and to indicate community changes that could occur with expansion of SAV habitat, we sampled a 300‐ha sector of northern Maumee Bay that contained both habitats. Using towed neuston nets through patches of each habitat, we determined that areas of SAV contained more species and a different species complex (based on the Jaccard index and the wetland fish index), than did the open‐water habitat (averaging 8.6 versus 5 species per net trawl). The SAV habitat was dominated by centrarchids, namely Largemouth Bass Micropterus salmoides, Bluegill Lepomis macrochirus, and Black Crappie Pomoxis nigromaculatus. Open‐water habitat was dominated by Spottail Shiner Notropis hudsonius, Gizzard Shad Dorosoma cepedianum, and White Perch Morone americana, an invasive species. These results indicate that restoration efforts aimed at decreasing turbidity and increasing the distribution of SAV could cause substantive shifts in the fish community and address important metrics for assessing the beneficial use impairments in this Area of Concern.

POPs and other persistent organic compounds in fish from remote alpine lakes in the Grisons, Switzerland

Energy Technology Data Exchange (ETDEWEB)

Schmid, P.; Gujer, E.; Zennegg, M. [Swiss Federal Laboratories for Materials Testing and Research (EMPA), Duebendorf (Switzerland); Lanfranchi, M. [Agency for Nature and Environment of the Canton Grisons, Chur (Switzerland)

2004-09-15

Global transfer of persistent semivolatile organic compounds, such as persistent organic pollutants (POPs), is effected by long-range atmospheric transport in combination with condensation and volatilization processes. Within the global atmosphere, evaporation in warm latitudes and deposition in cold latitudes leads to a transfer of contaminants towards the poles. The phenomenon of atmospheric migration of semivolatile chemicals, such as PCB and DDT, has been predicted and associated with the term ''global distillation'' by Goldberg, and the model has been extensively reviewed by Mackay and Wania. For comparatively less volatile components such as PCDD/F and PBDE, particle-bound deposition is the dominating transfer mechanism. Therefore, the input of these compounds in remote alpine regions without point sources is controlled by atmospheric deposition (dry and wet) and condensation. For organochlorine compounds, such as pesticides and polychlorinated biphenyls (PCB), it has been shown that accumulation is enhanced by temperaturecontrolled condensation also in alpine regions with low average temperatures. The hydrology of remote alpine lakes is determined by direct atmospheric deposition feeding and feeding with water from the surrounding catchment area, without significant inputs from tributaries or from nearby anthropogenic activities. Fish dwelling in these ecosystems represents an excellent indicator for the long-term input of bioaccumulating contaminants, such as POPs and other persistent organic compounds. In the present study, fish from 7 alpine lakes from the Grisons (Switzerland) situated between 2062 and 2637 m above sea level were investigated. With the exception of Laghetto Moesola which is situated adjacent to a mountain pass road, input from local anthropogenic emissions can be excluded for these lakes.

Human exposure to metals due to consumption of fish from an artificial lake basin close to an active mining area in Katanga (D.R. Congo)

Energy Technology Data Exchange (ETDEWEB)

Squadrone, S., E-mail: stefania.squadrone@izsto.it [Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d' Aosta, via Bologna 148, 10154 Torino (Italy); Burioli, E.; Monaco, G. [Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d' Aosta, via Bologna 148, 10154 Torino (Italy); Koya, M.K. [Institut Supérieur d' Etudes Agronomiques (ISEA) de Kaseya/Kongolo (Congo, The Democratic Republic of the); Prearo, M.; Gennero, S. [Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d' Aosta, via Bologna 148, 10154 Torino (Italy); Dominici, A. [Independent Veterinarian Researcher, Turin (Italy); Abete, M.C. [Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d' Aosta, via Bologna 148, 10154 Torino (Italy)

2016-10-15

The concentrations of 14 essential and nonessential trace elements were determined in fish from Lake Tshangalele, Katanga province, Democratic Republic of Congo. This province has been a place of intensive mining activities for centuries, which have increased in recent years, due to the use of metals such as copper and cobalt for the industries of fast-growing countries. Lake Tshangalele, which receives effluents from metallurgical and mining plants in Likasi, is home to several fish species that are an important part of the diet of the local population, and, therefore, it constitutes a relevant site for documenting the human exposure to metals as a result of a fish diet. The highest concentrations (median levels, dry weight) of cobalt (7.25 mg kg{sup −} {sup 1}), copper (88.1 mg kg{sup −} {sup 1}), iron (197.5 mg kg{sup −} {sup 1}), manganese (65.35 mg kg{sup −} {sup 1}), zinc (122.9 mg kg{sup −} {sup 1}) and aluminum (135.4 mg kg{sup −} {sup 1}) were found in fish collected closest to the copper mining plant, with decreasing concentrations along the lake, up to the dam. In the most contaminated fish samples, values of up to 270.1 mg kg{sup −} {sup 1} for Al, 173.1 mg kg{sup −} {sup 1} for Cu, 220.9 mg kg{sup −} {sup 1} for Zn, 211.0 mg kg{sup −} {sup 1} for Mn, 324.2 mg kg{sup −} {sup 1} for Fe, 15.1 mg kg{sup −} {sup 1} for Co, 4.2 mg kg{sup −} {sup 1} for Cr, 1.6 mg kg{sup −} {sup 1} for Cd, 1.9 mg kg{sup −} {sup 1} for Pb, and 1.8 mg kg{sup −} {sup 1} for Ni were found. Metal contamination from mining activity resulted in being of great concern because of potential health risks to the local inhabitants due to the consumption of heavily contaminated fish. Capsule: High levels of metals, especially cobalt, aluminum, iron, manganese, zinc and cadmium were found in fish from Tshangalele water system. - Highlights: • Metal contamination from mining activity is of great concern for human exposure. • We analyzed metal content in

Some results of recent surveys of fish and shellfish consumption by age and region of U.S. residents

International Nuclear Information System (INIS)

Rupp, E.M.; Baes, C.F. III; Miller, F.L.

1980-01-01

Since ingestion of foods is considered a major source of pollutant intake by man, the knowledge of detailed food consumption patterns is necessary to determine health risks and compliance with regulatory standards. As currently available literature lacks data necessary for complete evaluation of aquatic foods via human consumption of fish and shellfish, a review of recent surveys of fish consumption in the U.S. was performed. The data in these surveys were subjected to statistical analysis to determine percentage distributions of individuals eating different quantities of marine and freshwater fish and shellfish. Included are surveys on consumption of sportfish from the Columbia River and Lake Michigan areas and a comprehensive study of fish consumption in the nine census regions of the U.S. The results of these studies indicate that the quantity, as reported, of each type of fish eaten increases as a function of the age of consumers. Regional differences are most apparent in the use of shellfish and freshwater fish. About 94% of children and 96-100% of adults eat some kind of fish with a per capita average of 4.97 kg/yr. Since this quantity is on an actual consumption basis, as as opposed to 'as purchased', the per capita consumption rate is lower than usually reported in the literature. (author)

Chernobyl radiocesium in freshwater fish: Long-term dynamics and sources of variation

Energy Technology Data Exchange (ETDEWEB)

Sundbom, M [Uppsala Univ., Dept. of Limnology, Uppsala (Sweden)

2002-04-01

The aim of this thesis was to investigate both the long-term temporal pattern and sources of individual variation for radiocesium in freshwater fish. The basis for the study is time series of {sup 137}Cs activity concentrations in fish from three lakes in the area North-west of Uppsala, Sweden that received considerable amounts of {sup 137}Cs from Chernobyl in may 1986. The lakes were Lake Ekholmssjoen, Lake Flatsjoen and Lake Siggeforasjoen, all small forest lakes, but with different morphometrical and chemical characteristics. The data were collected regularly, usually several times per year, during 1986-2000, using consistent methods. More than 7600 fish individuals from 7 species covering wide size ranges and feeding habits were analysed for {sup 137}Cs. For each fish was the length, weight, sex, and often the stomach contend recorded. The evaluation on long-term trends were based on data from all three lakes, while the study on sources of variation evaluated data from Lake Flatsjoen only. (au)