WorldWideScience

Sample records for harvested fish populations

  1. Ecological dynamics of age selective harvesting of fish population: Maximum sustainable yield and its control strategy

    International Nuclear Information System (INIS)

    Jana, Debaldev; Agrawal, Rashmi; Upadhyay, Ranjit Kumar; Samanta, G.P.

    2016-01-01

    Highlights: • Age-selective harvesting of prey and predator are considered by multi-delayed prey-predator system. • System experiences stable coexistence to oscillatory mode and vice versa via Hopf-bifurcation depending upon the parametric restrictions. • MSY, bionomic equilibrium and optimal harvesting policy are also depending upon the age-selection of prey and predator. • All the analytic results are delay dependent. • Numerical examples support the analytical findings. - Abstract: Life history of ecological resource management and empirical studies are increasingly documenting the impact of selective harvesting process on the evolutionary stable strategy of both aquatic and terrestrial ecosystems. In the present study, the interaction between population and their independent and combined selective harvesting are framed by a multi-delayed prey-predator system. Depending upon the age selection strategy, system experiences stable coexistence to oscillatory mode and vice versa via Hopf-bifurcation. Economic evolution of the system which is mainly featured by maximum sustainable yield (MSY), bionomic equilibrium and optimal harvesting vary largely with the commensurate age selections of both population because equilibrium population abundance becomes age-selection dependent. Our study indicates that balance between harvesting delays and harvesting intensities should be maintained for better ecosystem management. Numerical examples support the analytical findings.

  2. Cooperative Game for Fish Harvesting and Pollution Control

    KAUST Repository

    Dia, Ben Mansour

    2015-01-07

    We study fishery strategies in a shallow river subject to agricultural and industrial pollution. The flowing pollutants in the river are modeled by a nonlinear stochastic differential equation in a general manner. The logistic growth model for the fish population is modified to cover the pollution impact on the fish growth rate. A stochastic cooperative game is formulated to design strategies for preserving the fish population by controlling the pollution as well as the harvesting fish.

  3. The effects of harvest on waterfowl populations

    Science.gov (United States)

    Cooch, Evan G.; Guillemain, Matthieu; Boomer, G Scott; Lebreton, Jean-Dominique; Nichols, James D.

    2014-01-01

    Change in the size of populations over space and time is, arguably, the motivation for much of pure and applied ecological research. The fundamental model for the dynamics of any population is straightforward: the net change in the abundance is the simple difference between the number of individuals entering the population and the number leaving the population, either or both of which may change in response to factors intrinsic and extrinsic to the population. While harvest of individuals from a population constitutes a clear extrinsic source of removal of individuals, the response of populations to harvest is frequently complex, reflecting an interaction of harvest with one or more population processes. Here we consider the role of these interactions, and factors influencing them, on the effective harvest management of waterfowl populations. We review historical ideas concerning harvest and discuss the relationship(s) between waterfowl life histories and the development and application of population models to inform harvest management. The influence of population structure (age, spatial) on derivation of optimal harvest strategies (with and without explicit consideration of various sources of uncertainty) is considered. In addition to population structure, we discuss how the optimal harvest strategy may be influenced by: 1) patterns of density-dependence in one or more vital rates, and 2) heterogeneity in vital rates among individuals within an age-sex-size class. Although derivation of the optimal harvest strategy for simple population models (with or without structure) is generally straightforward, there are several potential difficulties in application. In particular, uncertainty concerning the population structure at the time of harvest, and the ability to regulate the structure of the harvest itself, are significant complications. We therefore review the evidence of effects of harvest on waterfowl populations. Some of this evidence has

  4. Fish population dynamics

    National Research Council Canada - National Science Library

    Gulland, J. A

    1977-01-01

    This book describes how the dynamics of fish populations can be analysed in terms of the factors affecting their rates of growth, mortality and reproduction, with particular emphasis on the effects of fishing...

  5. The consequences of balanced harvesting of fish communities

    DEFF Research Database (Denmark)

    Jacobsen, Nis Sand; Gislason, Henrik; Andersen, Ken Haste

    2014-01-01

    community structure and yield. We use a size- and trait-based model that resolves individual interactions through competition and predation to compare balanced harvesting with traditional selective harvesting, which protects juvenile fish from fishing. Four different exploitation patterns, generated......Balanced harvesting, where species or individuals are exploited in accordance with their productivity, has been proposed as a way to minimize the effects of fishing on marine fish communities and ecosystems. This calls for a thorough examination of the consequences balanced harvesting has on fish...... by combining selective or unselective harvesting with balanced or unbalanced fishing, are compared. We find that unselective balanced fishing, where individuals are exploited in proportion to their productivity, produces a slightly larger total maximum sustainable yield than the other exploitation patterns and...

  6. Combining Post-Harvest Fish Value Chain and Social Change ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    , they are not achieving their full potential in Africa. This project will examine interventions to reduce poverty and to improve food and nutrition security using post-harvest innovations in the fish value chain. Post-harvest handling in Zambia and ...

  7. Prediction of fish biomass, harvest and prey--predator relations in reservoirs

    International Nuclear Information System (INIS)

    Jenkins, R.M.

    1977-01-01

    Regression analyses of the effect of total dissolved solids on fish standing crops in 166 reservoirs produced formulas with coefficients of determination of 0.63 to 0.81. These formulas provide indexes to average biotic conditions and help to identify stressed aquatic environments. Simple predictive formulas are also presented for clupeid crops in various reservoir types, as clupeids are the fishes most frequently impinged or entrained at southern power plants. A method of calculating the adequacy of the available prey crop in relation to the predator crop is advanced to further aid in identification of perturbed prey populations. Assessment of stress as reflected by changes in sport fishing success can also be approached by comparison of the predicted harvest potential with actual fish harvest data. Use of these predictive indexes is recommended until more elaborate models are developed to identify power plant effects

  8. The Extent of Immature Fish Harvesting by the Commercial Fishery ...

    African Journals Online (AJOL)

    The sustainability of a given fishery is a function of the number of sexually matured fish present in water. If there is intensive immature fishing, the population of fish reaching the stage of recruitment will decrease, which in turn results in lower yield and biomass. The present study was conducted to estimate the extent of ...

  9. Public health implications of post-harvest fish handling practices in ...

    African Journals Online (AJOL)

    A wide range of handling practices for harvested fish exists and they have economic as well as public health implications. This paper is a review of the existing problems in fish handling technologies at post-harvest in Nigeria. The public health aspects with the associated implications are highlighted. Status of policy on fish ...

  10. Quantifying the annual fish harvest from South Africa's largest ...

    African Journals Online (AJOL)

    2009-08-19

    Aug 19, 2009 ... The resultant total catch divided by the lakeshore population equated to a per capita fish supply of 11.1 ... ment, tourism development, optimal economic benefit from water, and ... To estimate seasonal catch rates, randomly stratified rov- ing creel ... Ēi is the mean effort on any day during sampling period i.

  11. Survival models for harvest management of mourning dove populations

    Science.gov (United States)

    Otis, D.L.

    2002-01-01

    Quantitative models of the relationship between annual survival and harvest rate of migratory game-bird populations are essential to science-based harvest management strategies. I used the best available band-recovery and harvest data for mourning doves (Zenaida macroura) to build a set of models based on different assumptions about compensatory harvest mortality. Although these models suffer from lack of contemporary data, they can be used in development of an initial set of population models that synthesize existing demographic data on a management-unit scale, and serve as a tool for prioritization of population demographic information needs. Credible harvest management plans for mourning dove populations will require a long-term commitment to population monitoring and iterative population analysis.

  12. Fish populations in Plynlimon streams

    Directory of Open Access Journals (Sweden)

    D. T. Crisp

    1997-01-01

    Full Text Available In Plynlimon streams, brown trout (Salmo trutta L. are widespread in the upper Wye at population densities of 0.03 to 0.32 fish m-2 and show evidence of successful recruitment in most years. In the upper Severn, brown trout are found only in an area of c. 1670 -2 downstream of Blaenhafren Falls at densities of 0.03 to 0.24 fish -2 and the evidence suggests very variable year to year success in recruitment (Crisp & Beaumont, 1996. Analyses of the data show that temperature differences between afforested and unafforested streams may affect the rates of trout incubation and growth but are not likely to influence species survival. Simple analyses of stream discharge data suggest, but do not prove, that good years for recruitment in the Hafren population were years of low stream discharge. This may be linked to groundwater inputs detected in other studies in this stream. More research is needed to explain the survival of the apparently isolated trout population in the Hafren.

  13. Estimation of sport fish harvest for risk and hazard assessment of environmental contaminants

    International Nuclear Information System (INIS)

    Poston, T.M.; Strenge, D.L.

    1989-01-01

    Consumption of contaminated fish flesh can be a significant route of human exposure to hazardous chemicals. Estimation of exposure resulting from the consumption of fish requires knowledge of fish consumption and contaminant levels in the edible portion of fish. Realistic figures of sport fish harvest are needed to estimate consumption. Estimates of freshwater sport fish harvest were developed from a review of 72 articles and reports. Descriptive statistics based on fishing pressure were derived from harvest data for four distinct groups of freshwater sport fish in three water types: streams, lakes, and reservoirs. Regression equations were developed to relate harvest to surface area fished where data bases were sufficiently large. Other aspects of estimating human exposure to contaminants in fish flesh that are discussed include use of bioaccumulation factors for trace metals and organic compounds. Using the bioaccumulation factor and the concentration of contaminants in water as variables in the exposure equation may also lead to less precise estimates of tissue concentration. For instance, muscle levels of contaminants may not increase proportionately with increases in water concentrations, leading to overestimation of risk. In addition, estimates of water concentration may be variable or expressed in a manner that does not truly represent biological availability of the contaminant. These factors are discussed. 45 refs., 1 fig., 7 tabs

  14. Development of harvesting and up concentration technologies for microalgae as an ingredient in fish feed

    DEFF Research Database (Denmark)

    Safafar, Hamed; Jacobsen, Charlotte; Møller, Per

    2014-01-01

    andfish oil. In applications of algae in fish feed, it is essential to produce a product comparable to fish proteinand fish oil both in terms of quality and costs.Downstream processing of microalgae includes harvest, dewatering, cell rupture, fractionation and drying.The dewatering and drying which...... ingredients forfish feed. Further we evaluate the chemical composition of six different microalgae species including;Nanochloropsis limnethica, Chlorella sorokiniana, Phaeodactylum tinctorium, Dunaliella salina,Nannochloropsis salina and Nannochloropsis occulata ....

  15. Population structure and adaptation in fishes

    DEFF Research Database (Denmark)

    Limborg, Morten

    Marine fishes represent a valuable resource for the global economy and food consumption. Accordingly, many species experience high levels of exploitation necessitating effective management plans. However, long term sustainability may be jeopardized from insufficient knowledge about intra-specific......Marine fishes represent a valuable resource for the global economy and food consumption. Accordingly, many species experience high levels of exploitation necessitating effective management plans. However, long term sustainability may be jeopardized from insufficient knowledge about intra......-specific population structure and adaptive divergence. The large population sizes and high migration rates common to most marine fishes impede the differentiating effect of genetic drift, having led to expectations of no population structure and that the occurrence of local adaptation should be rare in these species....... Comprehensive genetic analyses on the small pelagic fish European sprat (Sprattus sprattus) revealed significant population structure throughout its distribution with an overall pattern of reduced connectivity across environmental transition zones. Population structure reflected both historical separations over...

  16. The effect of seasonal harvesting on a single-species discrete population model with stage structure and birth pulses

    International Nuclear Information System (INIS)

    Gao Shujing; Chen Lansun

    2005-01-01

    In this paper, we propose an exploited single-species discrete model with stage structure for the dynamics in a fish population for which births occur in a single pulse once per time period. Using the stroboscopic map, we obtain an exact cycle of the system, and obtain the threshold conditions for its stability. Bifurcation diagrams are constructed with the birth rate as the bifurcation parameter, and these are observed to display complex dynamic behaviors, including chaotic bands with period windows, pitch-fork and tangent bifurcation. This suggests that birth pulse provides a natural period or cyclicity that makes the dynamical behavior more complex. Moreover, we show that the timing of harvesting has a strong impact on the persistence of the fish population, on the volume of mature fish stock and on the maximum annual-sustainable yield. An interesting result is obtained that, after the birth pulse, the earlier culling the mature fish, the larger harvest can tolerate

  17. As multiple fish species in large marine ecosystems are harvested ...

    African Journals Online (AJOL)

    CMPTMAC10

    and of other top predators such as marine mammals. This concern ... whereas single-species fishing theory implies that fishing leads to surplus by removing larger, older, less-productive ...... pools (the “cod is not a tuna” problem, Longhurst.

  18. Harvesting Renewable Resources of Population with Size Structure and Diffusion

    Directory of Open Access Journals (Sweden)

    Qiang-Jun Xie

    2014-01-01

    Full Text Available The aim of this work is to explore the optimal exploitation way for a biological resources model incorporating individual’s size difference and spatial effects. The existence of a unique nonnegative solution to the state system is shown by means of Banach’s fixed point theorem, and the continuous dependence of the population density with the harvesting effort is given. The optimal harvesting strategy is established via normal cone and adjoint system technique. Some conditions are found to assure that there is only one optimal policy.

  19. Design of Hybrid Solar and Wind Energy Harvester for Fishing Boat

    Science.gov (United States)

    Banjarnahor, D. A.; Hanifan, M.; Budi, E. M.

    2017-07-01

    In southern beach of West Java, Indonesia, there are many villagers live as fishermen. They use small boats for fishing, in one to three days. Therefore, they need a fish preservation system. Fortunately, the area has high potential of solar and wind energy. This paper presents the design of a hybrid solar and wind energy harvester to power a refrigerator in the fishing boat. The refrigerator should keep the fish in 2 - 4 °C. The energy needed is 720 Wh daily. In the area, the daily average wind velocity is 4.27 m/s and the sun irradiation is 672 W/m2. The design combined two 100W solar panels and a 300W wind turbine. The testing showed that the solar panels can harvest 815 - 817 Wh of energy, while the wind turbine can harvest 43 - 62 Wh of energy daily. Therefore, the system can fulfil the energy requirement in fishing boat, although the solar panels were more dominant. To install the wind turbine on the fishing-boat, a computational design had been conducted. The boat hydrostatic dimension was measured to determine its stability condition. To reach a stable equilibrium condition, the wind turbine should be installed no more than 1.7 m of height.

  20. Combination of genetics and spatial modelling highlights the sensitivity of cod (Gadus morhua) population diversity in the North Sea to distributions of fishing

    DEFF Research Database (Denmark)

    Heath, Michael R.; Culling, Mark A.; Crozier, Walter W.

    2014-01-01

    Conserving genetic diversity in animal populations is important for sustaining their ability to respond to environmental change. However, the “between-population” component of genetic diversity (biocomplexity) is threatened in many exploited populations, particularly marine fish, where harvest ma...

  1. Improving fish post-harvest management and marketing in Malawi ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Gender training and behavior change communication activities will address the gender and social relations in the fisheries value chain. The team will work with policymakers to increase recognition of the importance of fish production and gender equality in national and regional policies. Men and women from the Malawian ...

  2. The Extent of Immature Fish Harvesting by the Commercial Fishery ...

    African Journals Online (AJOL)

    Bheema

    visual examination of developmental stages of gonads based on their size, structure and the space .... the gonads using a five point maturity scale. .... determined based on empirical data collected from fishermen (Fig 3). .... changing their life history pattern in order to compensate for the losses imposed by fishing.

  3. Relations between fish abundances, summer temperatures, and forest harvest in a northern Minnesota stream system from 1997 to 2007

    Science.gov (United States)

    Eric Merten; Nathaniel Hemstad; Susan Eggert; Lucinda Johnson; Randall Kolka; Bruce Vondracek; Raymond. Newman

    2010-01-01

    Short-term effects of forest harvest on fish habitat have been well documented, including sediment inputs, leaf litter reductions, and stream warming. However, few studies have considered changes in local climate when examining postlogging changes in fish communities. To address this need, we examined fish abundances between 1997 and 2007 in a basin in a northern...

  4. The impact of fish and the commercial marine harvest on the ocean iron cycle.

    Directory of Open Access Journals (Sweden)

    Allison R Moreno

    Full Text Available Although iron is the fourth most abundant element in the Earth's crust, bioavailable iron limits marine primary production in about one third of the ocean. This lack of iron availability has implications in climate change because the removal of carbon dioxide from the atmosphere by phytoplankton requires iron. Using literature values for global fish biomass estimates, and elemental composition data we estimate that fish biota store between 0.7-7 × 10(11 g of iron. Additionally, the global fish population recycles through excretion between 0.4-1.5 × 10(12 g of iron per year, which is of a similar magnitude as major recognized sources of iron (e.g. dust, sediments, ice sheet melting. In terms of biological impact this iron could be superior to dust inputs due to the distributed deposition and to the greater solubility of fecal pellets compared to inorganic minerals. To estimate a loss term due to anthropogenic activity the total commercial catch for 1950 to 2010 was obtained from the Food and Agriculture Organization of the United Nations. Marine catch data were separated by taxa. High and low end values for elemental composition were obtained for each taxonomic category from the literature and used to calculate iron per mass of total harvest over time. The marine commercial catch is estimated to have removed 1-6 × 10(9 g of iron in 1950, the lowest values on record. There is an annual increase to 0.7-3 × 10(10 g in 1996, which declines to 0.6-2 × 10(10 g in 2010. While small compared to the total iron terms in the cycle, these could have compounding effects on distribution and concentration patterns globally over time. These storage, recycling, and export terms of biotic iron are not currently included in ocean iron mass balance calculations. These data suggest that fish and anthropogenic activity should be included in global oceanic iron cycles.

  5. A method for mass harvesting islets (Brockmann bodies) from teleost fish.

    Science.gov (United States)

    Yang, H; Wright, J R

    1995-01-01

    In certain species of fish, the insulin-producing tissue is uniquely located in separate structures called Brockmann bodies (BBs). Tilapia BBs have been shown to be a simple and inexpensive source of islet cells for xenotransplantation research. Each donor tilapia contains roughly 12-15 BBs, measuring from 0.3 to 5.0 mm in maximum dimension, in a triangular region of adipose tissue bounded by the liver, stomach, and spleen/gallbladder. At present, the larger BBs (usually 2-4) are harvested by microdissecting these "BB regions" using jeweler's forceps and microvascular scissors while being visualized with the aid of a dissecting microscope. It is a simple but time-consuming task that would not be applicable for harvesting massive amounts of BB tissue for large animal studies. Therefore, we have developed an easier and more efficient method of harvesting BBs based on a standard enzymatic method for isolating human adipocytes. BB regions are harvested from donor fish and pooled into a 50 mL plastic tube containing collagenase Type II (3 mg/mL) in Hank's balanced salt solution (HBSS); the tube is then placed in a 37 degrees C waterbath/shaker for roughly 15 min. The exact length of the digestion interval is determined by visual inspection of the tube to determine whether the BBs have been liberated. The digestion is then stopped by adding excess cold HBSS. The adipocytes float while the BBs and residual connective tissue (i.e., a few blood vessels, nerves, and bile ducts) form a pellet. The pellet is washed several times in HBSS and then placed in a culture dish. The BBs are easily handpicked with a siliconized pipette. Based on functional data and DNA content, this new method roughly doubles or triples our yield of BB tissue per donor fish. To determine whether BBs harvested in this manner functioned in a manner similar to those harvested by microdissection, we performed a series of transplants using mass-harvested BBs. Long-term normoglycemia was achieved in

  6. Using interview-based recall surveys to estimate cod Gadus morhua and eel Anguilla anguilla harvest in Danish recreational fishing

    DEFF Research Database (Denmark)

    Sparrevohn, Claus Reedtz; Storr-Paulsen, Marie

    2012-01-01

    Using interview-based recall surveys to estimate cod Gadus morhua and eel Anguilla anguilla harvest in Danish recreational fishing. – ICES Journal of Marine Science, 69: 323–330.Marine recreational fishing is a popular outdoor activity in Denmark, practised by both anglers and passive gear fishers....... However, the impact on the targeted stocks is unknown, so to estimate the 2009 harvest of cod Gadus morhua and eel Anguilla anguilla, two separate interview-based surveys were initiated and carried out in 2009/2010. The first recall survey exclusively targeted fishers who had been issued......, in certain areas, the recreational harvest of cod accounted for more than 30% of the total yield. The majority (81%) of the recreational cod harvest was taken by anglers. Eels, however, are almost exclusively caught with passive gear (fykenets) and a total of 104 t year−1 was harvested, which corresponds...

  7. Harvesting a knowledge commons: collective action, transparency, and innovation at the Portland Fish Exchange

    Directory of Open Access Journals (Sweden)

    Jennifer F. Brewer

    2014-03-01

    Full Text Available While localist visions of alternative food systems advocate for the expansion of local ecological knowledge through more proximate producer-consumer relationships, globalized seafood supply-demand chains persist. Moving beyond this dichotomy, commons scholars recognize that collective action among resource users at the local level can shape cross-scalar producer relations with government and more capitalized firms operating in regional and global markets. In the case of the New England groundfishery, a quasi-public fish auction not only transformed the scalar, logistical, and financial parameters of harvester-buyer relationships, it altered the production and use of local knowledge among some harvesters, and their technological choices. Resulting markets offer potential benefits that extend to broader publics, by increasing the monetary value and experimental development of a knowledge commons. Qualitative analysis of field data shows that with new market transparency, fish are no longer valued as an undifferentiated commodity, but as a variety of products with individually nuanced price structures. Displacement of local seafood buyers incurred some shoreside job losses, but fishers on smaller, owner-operated boats in multi-generational fishing harbours benefit particularly from new opportunities compared to larger, fleet boats due to different labour relations, allocations of decision-making responsibilities, observational contexts, and associated information flows. Implications for the mobilization of knowledge-action linkages to influence formal resource management arenas merit further research.

  8. COMMERCIAL FISH HARVEST IN INLAND WATER BODIES OF GERMANY (A REVIEW

    Directory of Open Access Journals (Sweden)

    А. Didenko

    2016-10-01

    Full Text Available Purpose. To analyze scientific and statistical sources on commercial fishery in inland water bodies of Germany. To summarize German experience and identify specific features of this sector. Findings. Commercial fishery in Germany is carried out on 30% (≈250 000 hectares of inland water bodies of Germany. The main fishing regions are prealpine lakes in Bavaria, Lake Constance, lakes in Schleswig-Holstein, Mecklenburg-Western Pomerania federal states as well as lakes and rivers of Brandenburg and Berlin. Commercial fishing on rivers usually has a local importance and is practiced in regions with poorly developed industry. There were 670 commercial fishing organizations in 2014, where 932 people were employed. Each fishing license owner is allowed deploying simultaneously a clearly defined number of fishing gears depending on season. In addition, fishing nets are regulated not only based on their mesh size and length, but also height and the minimum thread diameter. The cardinal difference of German inland fishing is the absence of the periods of total ban on commercial fishing. There are only ban periods for fishing on certain fish species during their spawning seasons. These periods differ for federal states and are listed in the relevant regional fishing rules. The total fish catch in inland waters of Germany by commercial fishermen in 2014 was 3132 tons, much lower than the catches of anglers who caught 18 450 tons at the same year. Most of fish were caught by fishing organizations in the Brandenburg Federal State. Average fish productivity in 2014 was approx. 13 kg/ha (ranging from 10 to 20 kg/ha. Whitefish was the dominant species in catches in the Lake Constance and prealpine lakes of Bavaria, while cyprinids (roach, bream, silver bream, blue bream, etc. dominated in Northern Germany. The profit of commercial fish catch in 2014 was about 12.5 million euros. Among numerous activities aimed at preserving commercial fish populations, Germans

  9. Bifurcation and Control in a Singular Phytoplankton-Zooplankton-Fish Model with Nonlinear Fish Harvesting and Taxation

    Science.gov (United States)

    Meng, Xin-You; Wu, Yu-Qian

    In this paper, a delayed differential algebraic phytoplankton-zooplankton-fish model with taxation and nonlinear fish harvesting is proposed. In the absence of time delay, the existence of singularity induced bifurcation is discussed by regarding economic interest as bifurcation parameter. A state feedback controller is designed to eliminate singularity induced bifurcation. Based on Liu’s criterion, Hopf bifurcation occurs at the interior equilibrium when taxation is taken as bifurcation parameter and is more than its corresponding critical value. In the presence of time delay, by analyzing the associated characteristic transcendental equation, the interior equilibrium loses local stability when time delay crosses its critical value. What’s more, the direction of Hopf bifurcation and stability of the bifurcating periodic solutions are investigated based on normal form theory and center manifold theorem, and nonlinear state feedback controller is designed to eliminate Hopf bifurcation. Furthermore, Pontryagin’s maximum principle has been used to obtain optimal tax policy to maximize the benefit as well as the conservation of the ecosystem. Finally, some numerical simulations are given to demonstrate our theoretical analysis.

  10. Optimal harvesting of fish stocks under a time-varying discount rate.

    Science.gov (United States)

    Duncan, Stephen; Hepburn, Cameron; Papachristodoulou, Antonis

    2011-01-21

    Optimal control theory has been extensively used to determine the optimal harvesting policy for renewable resources such as fish stocks. In such optimisations, it is common to maximise the discounted utility of harvesting over time, employing a constant time discount rate. However, evidence from human and animal behaviour suggests that we have evolved to employ discount rates which fall over time, often referred to as "hyperbolic discounting". This increases the weight on benefits in the distant future, which may appear to provide greater protection of resources for future generations, but also creates challenges of time-inconsistent plans. This paper examines harvesting plans when the discount rate declines over time. With a declining discount rate, the planner reduces stock levels in the early stages (when the discount rate is high) and intends to compensate by allowing the stock level to recover later (when the discount rate will be lower). Such a plan may be feasible and optimal, provided that the planner remains committed throughout. However, in practice there is a danger that such plans will be re-optimized and adjusted in the future. It is shown that repeatedly restarting the optimization can drive the stock level down to the point where the optimal policy is to harvest the stock to extinction. In short, a key contribution of this paper is to identify the surprising severity of the consequences flowing from incorporating a rather trivial, and widely prevalent, "non-rational" aspect of human behaviour into renewable resource management models. These ideas are related to the collapse of the Peruvian anchovy fishery in the 1970's. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Adaptive harvest management for the Svalbard population of Pink-Footed Geese: 2014 progress summary

    Science.gov (United States)

    Johnson, Fred A.; Madsen, J.

    2015-01-01

    This document describes progress to date on the development of an adaptive harvest-management strategy for maintaining the Svalbard population of pink-footed geese (Anser brachyrhynchus) near their agreed target level (60 thousand) by providing for sustainable harvests in Norway and Denmark.  Specifically, this report provides an assessment of the most recent monitoring information and its implications for the harvest management strategy.

  12. On the dynamics of exploited fish populations

    National Research Council Canada - National Science Library

    Beverton, R. J. H; Holt, Sidney J

    1993-01-01

    ...-brooding cichlids, and viviparity in many sharks and toothcarps. Moreover, fish are of considerable importance to the survival of the human species in the form of nutritious, delicious and diverse food. Rational exploitation and management of our global stocks of fishes must rely upon a detailed and precise insight of their biology. The...

  13. Population Modeling Approach to Optimize Crop Harvest Strategy. The Case of Field Tomato.

    Science.gov (United States)

    Tran, Dinh T; Hertog, Maarten L A T M; Tran, Thi L H; Quyen, Nguyen T; Van de Poel, Bram; Mata, Clara I; Nicolaï, Bart M

    2017-01-01

    In this study, the aim is to develop a population model based approach to optimize fruit harvesting strategies with regard to fruit quality and its derived economic value. This approach was applied to the case of tomato fruit harvesting under Vietnamese conditions. Fruit growth and development of tomato (cv. "Savior") was monitored in terms of fruit size and color during both the Vietnamese winter and summer growing seasons. A kinetic tomato fruit growth model was applied to quantify biological fruit-to-fruit variation in terms of their physiological maturation. This model was successfully calibrated. Finally, the model was extended to translate the fruit-to-fruit variation at harvest into the economic value of the harvested crop. It can be concluded that a model based approach to the optimization of harvest date and harvest frequency with regard to economic value of the crop as such is feasible. This approach allows growers to optimize their harvesting strategy by harvesting the crop at more uniform maturity stages meeting the stringent retail demands for homogeneous high quality product. The total farm profit would still depend on the impact a change in harvesting strategy might have on related expenditures. This model based harvest optimisation approach can be easily transferred to other fruit and vegetable crops improving homogeneity of the postharvest product streams.

  14. Wild reindeer in Norway – population ecology, management and harvest

    Directory of Open Access Journals (Sweden)

    Eigil Reimers

    2007-04-01

    Full Text Available Wild reindeer in Norway, presently (winter 2005-06 numbering some 25 000 animals, are found in 23 more or less separated areas in the mountainous southern part of the country (see map in appendix. All herds are hunted and management is organized in close cooperation between owner organizations and state agencies. I will provide a historical review of the wild reindeer management and research in Norway and conclude with the present situation. We identify 3 types of wild reindeer on basis of their origin: (1 the original wild reindeer with minor influence from previous domestic reindeer herding activities (Snøhetta, Rondane and Sølenkletten, (2 wild reindeer with some influx of animals from past domestic reindeer herding in the area (Nordfjella, Hardangervidda, Setesdal-Ryfylke and (3 feral reindeer with a domesticated origin (reindeer released or escaped from past reindeer husbandry units; Forolhogna, Ottadalen North and Ottadalen South, Norefjell-Reinsjøfjell and several smaller areas. In Norway, genetic origin (wild or domesticated, body size and reproductive performance of reindeer differ among areas. Feral reindeer have higher body weights and enjoy higher reproductive rates than their originally wild counterparts. These differences may partially be explained by differences in food quality and availability among the populations. However, there is a growing suspicion that other explanatory factors are also involved. Wild reindeer are more vigilant and show longer fright and flight distances than feral reindeer. Number of animals harvested was 4817, or ca. 20% of the total population in 2005, but varies between 40% in feral reindeer areas to below 20% in some of the "wild" reindeer areas. Causal factors behind this variation include differences in age at maturation, postnatal calf mortality and herd structure. The Norwegian Institute for nature research (NINA in cooperation with the Directorate for nature management (DN allocate considerable

  15. The Impact of Marine Protected Areas on Reef-Wide Population Structure and Fishing-Induced Phenotypes in Coral-Reef Fishes

    Science.gov (United States)

    Fidler, Robert Young, III

    Overfishing and destructive fishing practices threaten the sustainability of fisheries worldwide. In addition to reducing population sizes, anthropogenic fishing effort is highly size-selective, preferentially removing the largest individuals from harvested stocks. Intensive, size-selective mortality induces widespread phenotypic shifts toward the predominance of smaller and earlier-maturing individuals. Fish that reach sexual maturity at smaller size and younger age produce fewer, smaller, and less viable larvae, severely reducing the reproductive capacity of exploited populations. These directional phenotypic alterations, collectively known as "fisheries-induced evolution" (FIE) are among the primary causes of the loss of harvestable fish biomass. Marine protected areas (MPAs) are one of the most widely utilized components of fisheries management programs around the world, and have been proposed as a potential mechanism by which the impacts of FIE may be mitigated. The ability of MPAs to buffer exploited populations against fishing pressure, however, remains debated due to inconsistent results across studies. Additionally, empirical evidence of phenotypic shifts in fishes within MPAs is lacking. This investigation addresses both of these issues by: (1) using a categorical meta-analysis of MPAs to standardize and quantify the magnitude of MPA impacts across studies; and (2) conducting a direct comparison of life-history phenotypes known to be influenced by FIE in six reef-fish species inside and outside of MPAs. The Philippines was used as a model system for analyses due to the country's significance in global marine biodiversity and reliance on MPAs as a fishery management tool. The quantitative impact of Philippine MPAs was assessed using a "reef-wide" meta-analysis. This analysis used pooled visual census data from 39 matched pairs of MPAs and fished reefs surveyed twice over a mean period of 3 years. In 17 of these MPAs, two additional surveys were conducted

  16. Will Tidal Wetland Restoration Enhance Populations of Native Fishes?

    Directory of Open Access Journals (Sweden)

    Larry R. Brown

    2003-10-01

    Full Text Available Restoration of tidal wetlands might enhance populations of native fishes in the San Francisco Estuary of California. The purpose of this paper is to: (1 review the currently available information regarding the importance of tidal wetlands to native fishes in the San Francisco Estuary, (2 construct conceptual models on the basis of available information, (3 identify key areas of scientific uncertainty, and (4 identify methods to improve conceptual models and reduce uncertainty. There are few quantitative data to suggest that restoration of tidal wetlands will substantially increase populations of native fishes. On a qualitative basis, there is some support for the idea that tidal wetland restoration will increase populations of some native fishes; however, the species deriving the most benefit from restoration might not be of great management concern at present. Invasion of the San Francisco Estuary by alien plants and animals appears to be a major factor in obscuring the expected link between tidal wetlands and native fishes. Large-scale adaptive management experiments (>100 hectares appear to be the best available option for determining whether tidal wetlands will provide significant benefit to native fishes. Even if these experiments are unsuccessful at increasing native fish populations, the restored wetlands should benefit native birds, plants, and other organisms.

  17. Impacts of invasive fish removal through angling on population characteristics and juvenile growth rate.

    Science.gov (United States)

    Evangelista, Charlotte; Britton, Robert J; Cucherousset, Julien

    2015-06-01

    Exploitation can modify the characteristics of fish populations through the selective harvesting of individuals, with this potentially leading to rapid ecological and evolutionary changes. Despite the well-known effects of invasive fishes on aquatic ecosystems generally, the potential effects of their selective removal through angling, a strategy commonly used to manage invasive fish, are poorly understood. The aim of this field-based study was to use the North American pumpkinseed Lepomis gibbosus as the model species to investigate the consequences of selective removal on their population characteristics and juvenile growth rates across 10 populations in artificial lakes in southern France. We found that the maximal individual mass in populations decreased as removal pressure through angling increased, whereas we did not observed any changes in the maximal individual length in populations as removal pressure increased. Total population abundance did not decrease as removal pressure increased; instead, here was a U-shaped relationship between removal pressure and the abundance of medium-bodied individuals. In addition, population biomass had a U-shaped curve response to removal pressure, implying that invasive fish populations can modulate their characteristics to compensate for the negative effects of selective removals. In addition, individual lengths at age 2 and juvenile growth rates decreased as removal pressure through angling increased, suggesting a shift toward an earlier size at maturity and an overall slower growing phenotype. Therefore, these outputs challenge the efficiency of selective management methods, suggesting the use of more proactive strategies to control invasive populations, and the need to investigate the potential ecological and evolutionary repercussions of nonrandom removal.

  18. Fishes in a changing world: learning from the past to promote sustainability of fish populations.

    Science.gov (United States)

    Gordon, T A C; Harding, H R; Clever, F K; Davidson, I K; Davison, W; Montgomery, D W; Weatherhead, R C; Windsor, F M; Armstrong, J D; Bardonnet, A; Bergman, E; Britton, J R; Côté, I M; D'agostino, D; Greenberg, L A; Harborne, A R; Kahilainen, K K; Metcalfe, N B; Mills, S C; Milner, N J; Mittermayer, F H; Montorio, L; Nedelec, S L; Prokkola, J M; Rutterford, L A; Salvanes, A G V; Simpson, S D; Vainikka, A; Pinnegar, J K; Santos, E M

    2018-03-01

    Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation and declines in water quality. The important challenges raised by these issues have been recognized and have led to considerable advances over past decades in managing and mitigating threats to fishes worldwide. In this review, we identify the major threats faced by fish populations alongside recent advances that are helping to address these issues. There are very significant efforts worldwide directed towards ensuring a sustainable future for the world's fishes and fisheries and those who rely on them. Although considerable challenges remain, by drawing attention to successful mitigation of threats to fish and fisheries we hope to provide the encouragement and direction that will allow these challenges to be overcome in the future. © 2018 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the British Isles.

  19. Potential impact of harvesting on the population dynamics of two epiphytic bromeliads

    Science.gov (United States)

    Toledo-Aceves, Tarin; Hernández-Apolinar, Mariana; Valverde, Teresa

    2014-08-01

    Large numbers of epiphytes are extracted from cloud forests for ornamental use and illegal trade in Latin America. We examined the potential effects of different harvesting regimes on the population dynamics of the epiphytic bromeliads Tillandsia multicaulis and Tillandsia punctulata. The population dynamics of these species were studied over a 2-year period in a tropical montane cloud forest in Veracruz, Mexico. Prospective and retrospective analyses were used to identify which demographic processes and life-cycle stages make the largest relative contribution to variation in population growth rate (λ). The effect of simulated harvesting levels on population growth rates was analysed for both species. λ of both populations was highly influenced by survival (stasis), to a lesser extent by growth, and only slightly by fecundity. Vegetative growth played a central role in the population dynamics of these organisms. The λ value of the studied populations did not differ significantly from unity: T. multicaulis λ (95% confidence interval) = 0.982 (0.897-1.060) and T. punctulata λ = 0.967 (0.815-1.051), suggesting population stability. However, numerical simulation of different levels of extraction showed that λ would drop substantially even under very low (2%) harvesting levels. Matrix analysis revealed that T. multicaulis and T. punctulata populations are likely to decline and therefore commercial harvesting would be unsustainable. Based on these findings, management recommendations are outlined.

  20. Bioaccessibility of metals in fish, shellfish, wild game, and seaweed harvested in British Columbia, Canada.

    Science.gov (United States)

    Laird, Brian D; Chan, Hing Man

    2013-08-01

    Fish, shellfish, wild game, and seaweed are important traditional foods that are essential to the physical and cultural well-being of Indigenous peoples in Canada. The goal of this study was to measure the concentration and bioaccessibility of As, Cd, Hg, Se, Cu and Mn in 45 commonly consumed traditional foods collected by harvested by the First Nations Food, Nutrition, and Environment Study (FNFNES) from 21 First Nations communities in British Columbia, Canada, in 2008-2009. A significant and negative correlation was observed between Hg concentration and Hg bioaccessibility. Metal bioaccessibility tended to be high; median values ranging between 52% (Mn) and 83% (Cu). The notable exceptions were observed for As in wild game organs (7-19%) and rabbit meat (4%) as well as Hg in salmon eggs (10%). Results of Principal Components Analysis confirmed the unique pattern of bioaccessibility of As and Hg in traditional foods, suggesting that, unlike other metals, As and Hg bioaccessibility are not simply controlled by food digestibility under the operating conditions of the in vitro model. These data provide useful information for dietary contaminant risk assessment and intake assessments of essential trace elements. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Disentangling the effects of climate, density dependence, and harvest on an iconic large herbivore's population dynamics

    DEFF Research Database (Denmark)

    Koons, David; Colchero, Fernando; Hersey, Kent

    2015-01-01

    Understanding the relative effects of climate, harvest, and density dependence on population dynamics is critical for guiding sound population management, especially for ungulates in arid and semi-arid environments experiencing climate change. To address these issues for bison in southern Utah, we...... than precipitation and other temperature-related variables (model weight > 3 times more than that for other climate variables). Although we hypothesized that harvest is the primary driving force of bison population dynamics in southern Utah, our elasticity analysis indicated that changes in early...... spring temperature could have a greater ‘relative effect’ on equilibrium abundance than either harvest or the strength of density dependence. Our findings highlight the utility of incorporating elasticity analyses into state-space population models, and the need to include climatic processes in wildlife...

  2. Quantifying relative fishing impact on fish populations based on spatio-temporal overlap of fishing effort and stock density

    DEFF Research Database (Denmark)

    Vinther, Morten; Eero, Margit

    2013-01-01

    Evaluations of the effects of management measures on fish populations are usually based on the analyses of population dynamics and estimates of fishing mortality from stock assessments. However, this approach may not be applicable in all cases, in particular for data-limited stocks, which may...... GAM analyses to predict local cod densities and combine this with spatio-temporal data of fishing effort based on VMS (Vessel Monitoring System). To quantify local fishing impact on the stock, retention probability of the gears is taken into account. The results indicate a substantial decline...... in the impact of the Danish demersal trawl fleet on cod in the Kattegat in recent years, due to a combination of closed areas, introduction of selective gears and changes in overall effort....

  3. Population connectivity of an overexploited coastal fish ...

    African Journals Online (AJOL)

    Sciaenidae), in an ocean-warming hotspot. ... in this global hotspot of seawater temperature changes. Keywords: Angola–Benguela Frontal Zone, climate change, demographic history, marine fisheries, molecular ecology, population structure ...

  4. The impacts of mobile fishing gear on seafloor habitats in the Gulf of Maine (Northwest Atlantic): implications for conservation of fish populations

    Science.gov (United States)

    Auster, Peter J.; Malatesta, Richard J.; Langton, Richard W.; Watting, Les; Valentine, Page C.; Donaldson, Carol Lee S.; Langton, Elizabeth W.; Shepard, Andrew N.; Babb, War G.

    1997-01-01

    Fishing gear alters seafloor habitats, but the extent of these alterations, and their effects, have not been quantified extensively in the northwest Atlantic. Understanding the extent of these impacts, and their effects on populations of living marine resources, is needed to properly manage current and future levels of fishing effort and fishing power. For example, the entire U.S. side of the Gulf of Maine was impacted annually by mobile fishing gear between 1984 and 1990, based on calculations of area swept by trawl and dredge gear. Georges Bank was imparted three to nearly four times annually during the same period. Studies at three sites in the Gulf of Maine (off Swans Island, Jeffreys Bank, and Stellwagen Bank) showed that mobile fishing gear altered the physical structure (=complexity) of benthic habitats. Complexity was reduced by direct removal of biogenic (e.g., sponges, hydrozoans, bryozoans, amphipod tubes, holothurians, shell aggregates) and‐ sedimentary (e.g., sand waves, depressions) structures. Also, removal of organisms that create.structures (e.g., crabs, scallops) indirectly reduced complexity. Reductions in habitat complexity may lead to increased predation on juveniles of harvested species and ultimately recruitment to the harvestable stock. Because of a lack of reference sites, where use of mobile fishing is prohibited, no empirical studies have yet been conducted on a scale that could demonstrate population level effects of habitat‐management options. If marine fisheries management is to evolve toward an ecosystem or habitat management approach, experiments are required on the effects of habitat change, both anthropogenic and natural.

  5. Effects of fire on fish populations: Landscape perspectives on persistance of native fishes and nonnative fish invasions

    Science.gov (United States)

    Dunham, J.B.; Young, M.; Gresswell, Robert E.; Rieman, B.

    2003-01-01

    Our limited understanding of the short and long-term effects of fire on fish contributes to considerable uncertainty in assessments of the risks and benefits of fire management alternatives. A primary concern among the many potential effects of fire is the effects of fire and fire management on persistence of native fish populations. Limited evidence suggests vulnerability of fish to fire is contingent upon the quality of affected habitats, the amount and distribution of habitat (habitat fragmentation), and habitat specificity of the species in question. Species with narrow habitat requirements in highly degraded and fragmented systems are likely to be most vulnerable to fire and fire-related disturbance. In addition to effects of fire on native fish, there are growing concerns about the effects of fire on nonnative fish invasions. The role of fire in facilitating invasions by nonnative fishes is unknown, but experience with other species suggests some forms of disturbance associated with fire may facilitate invasion. Management efforts to promote persistence of fishes in fire-prone landscapes can take the form of four basic alternatives: (1) pre-fire management; (2) post-fire management; (3) managing fire itself (e.g. fire fighting); and (4) monitoring and adaptive management. Among these alternatives, pre-fire management is likely to be most effective. Effective pre-fire management activities will address factors that may render fish populations more vulnerable to the effects of fire (e.g. habitat degradation, fragmentation, and nonnative species). Post-fire management is also potentially important, but suffers from being a reactive approach that may not address threats in time to avert them. Managing fire itself can be important in some contexts, but negative consequences for fish populations are possible (e.g. toxicity of fire fighting chemicals to fish). Monitoring and adaptive management can provide important new information for evaluating alternatives, but

  6. Effects of human population density and proximity to markets on coral reef fishes vulnerable to extinction by fishing.

    Science.gov (United States)

    Brewer, T D; Cinner, J E; Green, A; Pressey, R L

    2013-06-01

    Coral reef fisheries are crucial to the livelihoods of tens of millions of people; yet, widespread habitat degradation and unsustainable fishing are causing severe depletion of stocks of reef fish. Understanding how social and economic factors, such as human population density, access to external markets, and modernization interact with fishing and habitat degradation to affect fish stocks is vital to sustainable management of coral reef fisheries. We used fish survey data, national social and economic data, and path analyses to assess whether these factors explain variation in biomass of coral reef fishes among 25 sites in Solomon Islands. We categorized fishes into 3 groups on the basis of life-history characteristics associated with vulnerability to extinction by fishing (high, medium, and low vulnerability). The biomass of fish with low vulnerability was positively related to habitat condition. The biomass of fishes with high vulnerability was negatively related to fishing conducted with efficient gear. Use of efficient gear, in turn, was strongly and positively related to both population density and market proximity. This result suggests local population pressure and external markets have additive negative effects on vulnerable reef fish. Biomass of the fish of medium vulnerability was not explained by fishing intensity or habitat condition, which suggests these species may be relatively resilient to both habitat degradation and fishing. © 2012 Society for Conservation Biology.

  7. Fish Commoditization: Sustainability Strategies to Protect Living Fish

    Science.gov (United States)

    Lam, Mimi E.; Pitcher, Tony J.

    2012-01-01

    The impacts of early fishing on aquatic ecosystems were minimal, as primitive technologies were used to harvest fish primarily for food. As fishing technology grew more sophisticated and human populations dispersed and expanded, local economies transitioned from subsistence to barter and trade. Expanded trade networks and mercantilization led to…

  8. DISPLACE: a dynamic, individual-based model for spatial fishing planning and effort displacement: Integrating underlying fish population models

    DEFF Research Database (Denmark)

    Bastardie, Francois; Nielsen, J. Rasmus; Miethe, Tanja

    or to the alteration of individual fishing patterns. We demonstrate that integrating the spatial activity of vessels and local fish stock abundance dynamics allow for interactions and more realistic predictions of fishermen behaviour, revenues and stock abundance......We previously developed a spatially explicit, individual-based model (IBM) evaluating the bio-economic efficiency of fishing vessel movements between regions according to the catching and targeting of different species based on the most recent high resolution spatial fishery data. The main purpose...... was to test the effects of alternative fishing effort allocation scenarios related to fuel consumption, energy efficiency (value per litre of fuel), sustainable fish stock harvesting, and profitability of the fisheries. The assumption here was constant underlying resource availability. Now, an advanced...

  9. A tale of two polar bear populations: Ice habitat, harvest, and body condition

    Science.gov (United States)

    Rode, Karyn D.; Peacock, Elizabeth; Taylor, Mitchell K.; Stirling, Ian; Born, Erik W.; Laidre, Kristin L.; Wiig, Øystein

    2012-01-01

    One of the primary mechanisms by which sea ice loss is expected to affect polar bears is via reduced body condition and growth resulting from reduced access to prey. To date, negative effects of sea ice loss have been documented for two of 19 recognized populations. Effects of sea ice loss on other polar bear populations that differ in harvest rate, population density, and/or feeding ecology have been assumed, but empirical support, especially quantitative data on population size, demography, and/or body condition spanning two or more decades, have been lacking. We examined trends in body condition metrics of captured bears and relationships with summertime ice concentration between 1977 and 2010 for the Baffin Bay (BB) and Davis Strait (DS) polar bear populations. Polar bears in these regions occupy areas with annual sea ice that has decreased markedly starting in the 1990s. Despite differences in harvest rate, population density, sea ice concentration, and prey base, polar bears in both populations exhibited positive relationships between body condition and summertime sea ice cover during the recent period of sea ice decline. Furthermore, females and cubs exhibited relationships with sea ice that were not apparent during the earlier period (1977–1990s) when sea ice loss did not occur. We suggest that declining body condition in BB may be a result of recent declines in sea ice habitat. In DS, high population density and/or sea ice loss, may be responsible for the declines in body condition.

  10. Population genomics of marine fishes: next generation prospects and challenges

    DEFF Research Database (Denmark)

    Hansen, Jakob Hemmer; Therkildsen, Nina Overgaard; Pujolar, J.M.

    2014-01-01

    Over the past few years, technological advances have facilitated giant leaps forward in our ability to generate genome-wide molecular data, offering exciting opportunities for gaining new insights into the ecology and evolution of species where genomic information is still limited. Marine fishes...... time scales, identifying genomic signatures associated with population divergence under gene flow, and determining the genetic basis of phenotypic traits. We also consider future challenges pertaining to the implementation of genome-wide coverage through next-generation sequencing and genotyping...... methods in marine fishes. Complications associated with fast decay of linkage disequilibrium, as expected for species with large effective population sizes, and the possibility that adaptation is associated with both soft selective sweeps and polygenic selection, leaving complex genomic signatures...

  11. Coral reef fish populations can persist without immigration

    KAUST Repository

    Salles, Océane C.

    2015-11-18

    Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula, at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase.

  12. Eel, cod and seatrout harvest in Danish recreational fishing during 2011

    DEFF Research Database (Denmark)

    Sparrevohn, Claus Reedtz; Storr-Paulsen, Marie

    , it was estimated that 80 t [Relative standard error (RSE)=6%] eel, close to 1,300 t (RSE=5 %) cod and 400 t (RSE=5 %) seatrout (including freshwater catches) was harvested in the recreational fishery. Eel is almost exclusively taken in the passive gear fykenet fishery and seatrout was mainly caught by anglers...

  13. Intervention analysis of power plant impact on fish populations

    International Nuclear Information System (INIS)

    Madenjian, C.P.

    1984-01-01

    Intervention analysis was applied to 10 yr (years 1973-1982) of field fish abundance data at the D. C. Cook Nuclear Power Plant, southeastern Lake Michigan. Three log-transformed catch series, comprising monthly observations, were examined for each combination of two species (alewife, Alosa pseudoharenga, or yellow perch, Perca flavescens) and gear (trawl or gill net): catch at the plant discharged transect, catch at the reference transect, and the ratio of plant catch to reference catch. Time series separated by age groups were examined. Based on intervention analysis, no change in the abundance of fish populations could be attributed to plant operation. Additionally, a modification of the intervention analysis technique was applied to investigate trends in abundance at both the plant discharge and reference transects. Significant declines were detected for abundance of alewife adults at both of the transects. Results of the trend analysis support the contention that the alewives have undergone a lakewide decrease in abundance during the 1970s

  14. Effect of leaf harvesting on reproduction and natural populations of Indian Wild Banana Ensete superbum (Roxb. Cheesman (Zingiberales: Musaceae

    Directory of Open Access Journals (Sweden)

    Mahendra R. Bhise

    2015-04-01

    Full Text Available Ensete superbum (Roxb. Cheesman an important taxon in India is threatened in Maharashtra. It is sporadically distributed on high altitude slopes and rocky cliffs in the Western Ghats. It is an important medicinal and economic plant utilized by people living in rural areas, while the leaves are also utilized in urban areas. The leaves are harvested for commercial purposes. The effect of leaf harvest on natural population with respect to regeneration of new plantlets was evaluated. The results revealed that, non-scientific leaf harvesting resulted in significantly reduced flowering and fruiting, less number of new plantlets in the population, and population degradation. Therefore, leaf harvesting should be practiced in a controlled manner to maintain the population health of this highly potential species. 

  15. Energetic and ecological constraints on population density of reef fishes.

    Science.gov (United States)

    Barneche, D R; Kulbicki, M; Floeter, S R; Friedlander, A M; Allen, A P

    2016-01-27

    Population ecology has classically focused on pairwise species interactions, hindering the description of general patterns and processes of population abundance at large spatial scales. Here we use the metabolic theory of ecology as a framework to formulate and test a model that yields predictions linking population density to the physiological constraints of body size and temperature on individual metabolism, and the ecological constraints of trophic structure and species richness on energy partitioning among species. Our model was tested by applying Bayesian quantile regression to a comprehensive reef-fish community database, from which we extracted density data for 5609 populations spread across 49 sites around the world. Our results indicate that population density declines markedly with increases in community species richness and that, after accounting for richness, energetic constraints are manifested most strongly for the most abundant species, which generally are of small body size and occupy lower trophic groups. Overall, our findings suggest that, at the global scale, factors associated with community species richness are the major drivers of variation in population density. Given that populations of species-rich tropical systems exhibit markedly lower maximum densities, they may be particularly susceptible to stochastic extinction. © 2016 The Author(s).

  16. Ocean acidification alters fish populations indirectly through habitat modification

    Science.gov (United States)

    Nagelkerken, Ivan; Russell, Bayden D.; Gillanders, Bronwyn M.; Connell, Sean D.

    2016-01-01

    Ocean ecosystems are predicted to lose biodiversity and productivity from increasing ocean acidification. Although laboratory experiments reveal negative effects of acidification on the behaviour and performance of species, more comprehensive predictions have been hampered by a lack of in situ studies that incorporate the complexity of interactions between species and their environment. We studied CO2 vents from both Northern and Southern hemispheres, using such natural laboratories to investigate the effect of ocean acidification on plant-animal associations embedded within all their natural complexity. Although we substantiate simple direct effects of reduced predator-avoidance behaviour by fishes, as observed in laboratory experiments, we here show that this negative effect is naturally dampened when fish reside in shelter-rich habitats. Importantly, elevated CO2 drove strong increases in the abundance of some fish species through major habitat shifts, associated increases in resources such as habitat and prey availability, and reduced predator abundances. The indirect effects of acidification via resource and predator alterations may have far-reaching consequences for population abundances, and its study provides a framework for a more comprehensive understanding of increasing CO2 emissions as a driver of ecological change.

  17. Analysis of impingement impacts on Hudson River fish populations

    International Nuclear Information System (INIS)

    Barnthouse, L.W.; van Winkle, W.

    1988-01-01

    Impacts of impingement, expressed as reductions in year-class abundance, were calculated for six Hudson River fish populations. Estimates were made for the 1974 and 1975 year classes of white perch, striped bass, Atlantic tomcod, and American shad, and the 1974 year classes of alewife and blueback herring. The maximum estimated reductions in year-class abundance were less than 5% for all year classes except the 1974 and 1975 white perch year classes and the 1974 striped bass year class. Only for white perch were the estimates greater than 10% per year. For striped bass, the 146,000 fish from the 1974 year class that were killed by impingement could have produced 12,000-16,000 5-year-old fish or 270-300 10-year-olds. Also estimated were the reductions in mortality that could have been achieved had closed-cycle cooling systems been installed at one or more of three power plants (Bowline point, Indian Point, and Roseton) and had the screen-wash systems at Bowline Point and Indian Point been modified to improve the survival of impinged fish. Closed-cycle cooling at all three plants would have reduced impingement impacts on white perch, striped bass, and Atlantic tomcod by 75% or more; installation of closed-cycle cooling at Indian Point alone would have reduced impingement impacts on white perch and Atlantic tomcod by 50%-80%. Modified traveling screens would have been less effective than closed-cycle cooling, but still would have reduced impingement impacts on white perch by roughly 20%. 23 refs., 1 fig., 3 tabs

  18. The effects of river flooding on the fish populations of two eastern ...

    African Journals Online (AJOL)

    fish populations in two eastern Cape estuaries is compared. .... Methods. Catch per unit effort (CPUE) of fish in the Swartkops and Sundays estuaries was obtained by means of gill-nets. ..... Abundance of other species was little affected ex-.

  19. Population and coherence dynamics in light harvesting complex II (LH2).

    Science.gov (United States)

    Yeh, Shu-Hao; Zhu, Jing; Kais, Sabre

    2012-08-28

    The electronic excitation population and coherence dynamics in the chromophores of the photosynthetic light harvesting complex 2 (LH2) B850 ring from purple bacteria (Rhodopseudomonas acidophila) have been studied theoretically at both physiological and cryogenic temperatures. Similar to the well-studied Fenna-Matthews-Olson (FMO) protein, oscillations of the excitation population and coherence in the site basis are observed in LH2 by using a scaled hierarchical equation of motion approach. However, this oscillation time (300 fs) is much shorter compared to the FMO protein (650 fs) at cryogenic temperature. Both environment and high temperature are found to enhance the propagation speed of the exciton wave packet yet they shorten the coherence time and suppress the oscillation amplitude of coherence and the population. Our calculations show that a long-lived coherence between chromophore electronic excited states can exist in such a noisy biological environment.

  20. Ecotourism and sea turtle harvesting in a fishing village of Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Pegas Fernanda

    2010-01-01

    Full Text Available Many environmentalists believe ecotourism has the potential to generate net benefits for people and nature. For more than two decades, the Brazilian Sea Turtle Conservation Program (TAMAR has provided jobs and income through ecotourism in Praia do Forte, Brazil, in exchange for reduced harvesting of sea turtles. In this article we evaluate the relationships between ecotourism at TAMAR and local support for sea turtle conservation. Nine months of ethnographic research (2006-2008 suggest that ecotourism-related employment and income have been somewhat stable and reliable. The average income of respondents who worked with TAMAR was lower than that reported by people not working with TAMAR. Workers noted other non-economic benefits. Though the majority supported sea turtle conservation, it is unclear how feelings will waver with new mass tourism developments in the region. As the cost of living increases, residents may increasingly be inclined to look for work outside TAMAR. Development also attracts new immigrants, making it difficult for locals to control sea turtle harvesting. These trends challenge the notion that economic incentives for locals alone will ensure conservation. Further research is needed to understand the conditions under which ecotourism may foster long-term conservation in the face of larger developments surrounding community ecotourism projects.

  1. Implicit assumptions underlying simple harvest models of marine bird populations can mislead environmental management decisions.

    Science.gov (United States)

    O'Brien, Susan H; Cook, Aonghais S C P; Robinson, Robert A

    2017-10-01

    Assessing the potential impact of additional mortality from anthropogenic causes on animal populations requires detailed demographic information. However, these data are frequently lacking, making simple algorithms, which require little data, appealing. Because of their simplicity, these algorithms often rely on implicit assumptions, some of which may be quite restrictive. Potential Biological Removal (PBR) is a simple harvest model that estimates the number of additional mortalities that a population can theoretically sustain without causing population extinction. However, PBR relies on a number of implicit assumptions, particularly around density dependence and population trajectory that limit its applicability in many situations. Among several uses, it has been widely employed in Europe in Environmental Impact Assessments (EIA), to examine the acceptability of potential effects of offshore wind farms on marine bird populations. As a case study, we use PBR to estimate the number of additional mortalities that a population with characteristics typical of a seabird population can theoretically sustain. We incorporated this level of additional mortality within Leslie matrix models to test assumptions within the PBR algorithm about density dependence and current population trajectory. Our analyses suggest that the PBR algorithm identifies levels of mortality which cause population declines for most population trajectories and forms of population regulation. Consequently, we recommend that practitioners do not use PBR in an EIA context for offshore wind energy developments. Rather than using simple algorithms that rely on potentially invalid implicit assumptions, we recommend use of Leslie matrix models for assessing the impact of additional mortality on a population, enabling the user to explicitly define assumptions and test their importance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Broad shifts in the resource use of a commercially harvested fish following the invasion of dreissenid mussels.

    Science.gov (United States)

    Fera, Shannon A; Rennie, Michael D; Dunlop, Erin S

    2017-06-01

    Dreissenid mussels, including the zebra (Dreissena polymorpha) and quagga (Dreissena rostiformus bugensis) mussel, are invasive species known for their capacity to act as ecosystem engineers. They have caused significant changes in the many freshwater systems they have invaded by increasing water clarity, reducing primary productivity, and altering zooplankton and benthic invertebrate assemblages. What is less clear is how their ecosystem engineering effects manifest up the food web to impact higher trophic levels, including fish. Here, we use a biological tracer (stable isotopes of carbon and nitrogen) to analyze long-term and broad-scale trends in the resource use of benthivorous lake whitefish (Coregonus clupeaformis) in the Laurentian Great Lakes, where dreissenid mussels have become established in each lake except Lake Superior. We measured stable isotope ratios from archived material (fish scale samples) collected over several decades by multiple agencies and from 14 locations around the Great Lakes. In the majority of locations, the δ 13 C of lake whitefish increased following the establishment of dreissenid mussels. Trends in δ 15 N were less clear, but significant breakpoints in the time series occurred within 5 yr of dreissenid establishment in several locations, followed by declines in δ 15 N. In contrast, isotopic signatures in Lake Superior locations did not show these trends. Our results provide evidence that lake whitefish shifted toward greater reliance on nearshore benthic production, supporting the theory that fundamental energy pathways are changed when dreissenid mussels become established. Importantly, these effects were noted across multiple, large, and complex ecosystems spanning a broad geographic area. Our study underscores the potential for aquatic invasive species to alter key ecosystem services as demonstrated here through their impacts on energy pathways supporting a commercially harvested fish species. © 2017 by the Ecological

  3. Identification of fish populations with particular reference to the pelagic fish stocks of the Indian Ocean region

    Digital Repository Service at National Institute of Oceanography (India)

    Dwivedi, S.N.

    The most essential step in any fishery management is the identification of discrete fish populations. This is particularly important for the development of Indian Ocean pelagic fisheries. The simple signal character analysis of meristic or metric...

  4. Study of Vertical Axis Wind Turbine for Energy Harvester in A Fishing Boat

    Science.gov (United States)

    Budi, E. M.; Banjarnahor, D. A.; Hanifan, M.

    2017-07-01

    The wind speed in the southern beach of West Java Indonesia is quite promising for wind energy harvesting. A field survey reported that the wind speed reached 10 m/s, while the average recorded in a year is about 4.7 m/s. In this study, two vertical axis wind turbines (VAWT) were compared to be used in that area through calculation as well as experiments. The experiments measured that the turbines can produce about 7.82W and 2.33W of electricity respectively. These experiments are compared with theoretical calculation to obtain the performance of both turbines used. The coefficient of performance (cp) experimentally is 0.09 for Turbine 1 (hybrid Savonius-Darrieus rotor) and 0.14 for Turbine 2 (Savonius rotor). While, rotor’s mechanical performance Cpr, obtained theoritically through calculation, is 0.36 for Turbine 1 and 0.12 for Turbine 2. These results are analysed from mechanical and electrical view.

  5. Browsing Patterns of White-Tailed Deer Following Increased Timber Harvest and a Decline in Population Density

    Directory of Open Access Journals (Sweden)

    Shawn M. Crimmins

    2010-01-01

    Full Text Available We examined browsing patterns of white-tailed deer (Odocoileus virginianus on a site in the central Appalachians that experienced a substantial (>50% reduction in deer population density and an increase in the amount of timber harvest since 2001. We sampled woody browse in and immediately adjacent to 12 clearcuts ranging in age from 0–5 years postharvest in summer 2007. Clearcut-interior areas had higher woody browse abundance and browsing rates than clearcut-edge or mature forest areas. Woody browse abundance was slightly higher within individual clearcuts than in 2001 at higher population densities and lower timber harvest rates. Overall browsing rates declined from approximately 17% in 2001 to less than 5% during our study, suggesting that the combination of deer population control, and increasing the amount of timber harvest across the landscape can reduce herbivory to levels that may not impede growth and survival of forest vegetation.

  6. Assessment of the pelagic fish populations using CEN multi-mesh gillnets: consequences for the characterization of the fish communities

    Directory of Open Access Journals (Sweden)

    C. Deceliere-Vergès

    2008-01-01

    Full Text Available The contribution of CEN standard pelagic nets to the assessment of fish communities is tested by comparing three metrics (species composition, species abundance, and size structures measured in accordance with the standard (i.e. using benthic nets only to those calculated from the total effort (i.e. including pelagic nets. Hydroacoustic surveys were used simultaneously to assess fish densities in the pelagic habitat. The results show that in most cases the pelagic nets did not provide any extra information about these three metrics. However, their inclusion in the calculation of CPUE and size structures may affect the picture of the fish communities, especially in lakes containing salmonid populations. This study highlights the need to sample pelagic fish when assessing fish communities in order to determine lake quality.

  7. The Bifurcation and Control of a Single-Species Fish Population Logistic Model with the Invasion of Alien Species

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2014-01-01

    Full Text Available The objective of this paper is to study systematically the bifurcation and control of a single-species fish population logistic model with the invasion of alien species based on the theory of singular system and bifurcation. It regards Spartina anglica as an invasive species, which invades the fisheries and aquaculture. Firstly, the stabilities of equilibria in this model are discussed. Moreover, the sufficient conditions for existence of the trans-critical bifurcation and the singularity induced bifurcation are obtained. Secondly, the state feedback controller is designed to eliminate the unexpected singularity induced bifurcation by combining harvested effort with the purification capacity. It obviously inhibits the switch of population and makes the system stable. Finally, the numerical simulation is proposed to show the practical significance of the bifurcation and control from the biological point of view.

  8. Effects of harvest on the sustainability and leaf productivity of populations of two palm species in Maya homegardens.

    Science.gov (United States)

    Martínez-Ballesté, Andrea; Martorell, Carlos

    2015-01-01

    Traditional management practices are usually thought to be sustainable. The Maya manage Sabal (Arecaceae) palms in homegardens, using their leaves for thatching. The sustainability of such production systems depends on the long-term persistence of palm populations, whereas resource availability also depends on the number of leaves on individual palms. We examined how leaf harvest affects Sabal yapa and S. mexicana population growth rates (λ) and leaf production, comparing traditional and alternative harvest regimes in terms of sustainability and productivity. Demographic, harvest and leaf production data were recorded for three years in two homegardens. We used general integral projection models linked to leaf-production models to describe population dynamics and productivity. Harvest had no effect on S. yapa's vital rates or on λ, but it changed the growth rate of individuals of S. mexicana, with a negligible impact on λ. Homegardens affected λ values, reflecting the species' ecological affinities. S. mexicana, introduced from mesic forests, required watering and shade; therefore, its population declined rapidly in the homegarden that lacked both water and shade. The λ of the xerophilic S. yapa was slightly larger without watering than with watering. Palms usually compensated for leaf extraction, causing the number of leaves harvested per individual to increase with harvest intensity. Nevertheless, traditional management is relatively mild, allowing standing leaves to accumulate but reducing the homegarden's yield. Apparently, the Maya do not seek to maximize annual production but to ensure the availability of large numbers of leaves in homegardens. These leaves may then be used when the entire roof of a hut needs to be replaced every few years.

  9. Proximate analysis of female population of wild feather back fish ...

    African Journals Online (AJOL)

    User

    2011-05-09

    May 9, 2011 ... Key words: Body composition, Notopterus notopterus, condition factor, wild fish. INTRODUCTION. Proximate body composition is the analysis of water, fat, protein and ash contents of the fish (Love, 1980). Proximate composition is a good indicator of physiology which is needed for routine analysis of ...

  10. Fish collagen is an important panallergen in the Japanese population.

    Science.gov (United States)

    Kobayashi, Y; Akiyama, H; Huge, J; Kubota, H; Chikazawa, S; Satoh, T; Miyake, T; Uhara, H; Okuyama, R; Nakagawara, R; Aihara, M; Hamada-Sato, N

    2016-05-01

    Collagen was identified as a fish allergen in early 2000s. Although its allergenic potential has been suggested to be low, risks associated with collagen as a fish allergen have not been evaluated to a greater extent. In this study, we aimed to clarify the importance of collagen as a fish allergen. Our results showed that 50% of Japanese patients with fish allergy had immunoglobulin E (IgE) against mackerel collagen, whereas 44% had IgE against mackerel parvalbumin. IgE inhibition assay revealed high cross-reactivity of mackerel collagen to 22 fish species (inhibition rates: 87-98%). Furthermore, a recently developed allergy test demonstrated that collagen triggered IgE cross-linking on mast cells. These data indicate that fish collagen is an important and very common panallergen in fish consumed in Japan. The high rate of individuals' collagen allergy may be attributable to the traditional Japanese custom of raw fish consumption. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Preferences for government enforcement of a common pool harvest quota: Theory and experimental evidence from fishing communities in Colombia

    OpenAIRE

    Maria Alejandra Velez; John K. Stranlund; James J. Murphy

    2012-01-01

    We examine individual harvesters’ preferences for government enforcement of a quota imposed on the exploitation of a common pool resource. We develop a model of Nash behavior by identical risk neutral harvesters to explain individual equilibrium preferences for enforcement of an efficient harvest quota. If the quota is not enforced well, we demonstrate that individual harvesters will always prefer increased enforcement—either increased monitoring or increased penalties—of the quota. We conduc...

  12. STRUCTURE, GROWTH AND MORPHOLOGY OF FISH POPULATIONS FROM GRAVEL-PIT VUKOVINA

    Directory of Open Access Journals (Sweden)

    Ivan Jakovlić

    2001-12-01

    Full Text Available After the structure of fish populations from gravel-pit Vukovina was determined, those populations were checked for 10 morphometric and 4 meristic parameters, as well as for length-mass relationship. For chub (Leuciscus cephalus and pumpkinseed (Lepomis gibbosus some meristic characters expressed the values beyond those mentioned in the standard key for the freshwater fish species determination. When compared to other locations, length-mass relationship and condition factor (CF were significantly lower for all checked populations. This indicates that gravel-pit Vukovina is extremely oligotrophic and has very poor fish production.

  13. Monitoring of fish species in the Lamone river: distribution and morphometric measures of the populations

    Directory of Open Access Journals (Sweden)

    Riccardo Bozzi

    2010-01-01

    Full Text Available Fish samplings were carried out monthly from spring to autumn during 2008, on the Lamone river and the Campigno stream by an electrofishing, in order to verify the presence of fish populations and the most common species represented. Barb, Barbus plebejus, Blageon, Leuciscus muticellus, Chub, Leuciscus cephalus, South European Nase, Chondrostoma genei were identified. A small population of Brown trout, Salmo trutta fario was also recognized. Barb is the most represented species in all the sites. The samplings highlight that Lamone river presented conditions suitable to fully guarantee the life of the fish populations.

  14. Bottom-up effects of climate on fish populations: data from the Continuous Plankton Recorder

    DEFF Research Database (Denmark)

    Pitois, S.G.; Lynam, C.P.; Jansen, Teunis

    2012-01-01

    The Continuous Plankton Recorder (CPR) dataset on fish larvae has an extensive spatio-temporal coverage that allows the responses of fish populations to past changes in climate variability, including abrupt changes such as regime shifts, to be investigated. The newly available dataset offers...... in the plankton ecosystem, while the larvae of migratory species such as Atlantic mackerel responded more to hydrographic changes. Climate variability seems more likely to influence fish populations through bottom-up control via a cascading effect from changes in the North Atlantic Oscillation (NAO) impacting...... with fishing effects interacting with climate effects and this study supports furthering our under - standing of such interactions before attempting to predict how fish populations respond to climate variability...

  15. Climate change effects on North American inland fish populations and assemblages

    Science.gov (United States)

    Lynch, Abigail J.; Myers, Bonnie; Chu, Cindy; Eby, Lisa A.; Falke, Jeffrey A.; Kovach, Ryan P.; Krabbenhoft, Trevor J.; Kwak, Thomas J.; Lyons, John; Paukert, Craig P.; Whitney, James E.

    2016-01-01

    Climate is a critical driver of many fish populations, assemblages, and aquatic communities. However, direct observational studies of climate change impacts on North American inland fishes are rare. In this synthesis, we (1) summarize climate trends that may influence North American inland fish populations and assemblages, (2) compile 31 peer-reviewed studies of documented climate change effects on North American inland fish populations and assemblages, and (3) highlight four case studies representing a variety of observed responses ranging from warmwater systems in the southwestern and southeastern United States to coldwater systems along the Pacific Coast and Canadian Shield. We conclude by identifying key data gaps and research needs to inform adaptive, ecosystem-based approaches to managing North American inland fishes and fisheries in a changing climate.

  16. Forest bat population dynamics over 14 years at a climate refuge: Effects of timber harvesting and weather extremes.

    Science.gov (United States)

    Law, Bradley S; Chidel, Mark; Law, Peter R

    2018-01-01

    Long-term data are needed to explore the interaction of weather extremes with habitat alteration; in particular, can 'refugia' buffer population dynamics against climate change and are they robust to disturbances such as timber harvesting. Because forest bats are good indicators of ecosystem health, we used 14 years (1999-2012) of mark-recapture data from a suite of small tree-hollow roosting bats to estimate survival, abundance and body condition in harvested and unharvested forest and over extreme El Niño and La Niña weather events in southeastern Australia. Trapping was replicated within an experimental forest, located in a climate refuge, with different timber harvesting treatments. We trapped foraging bats and banded 3043 with a 32% retrap rate. Mark-recapture analyses allowed for dependence of survival on time, species, sex, logging treatment and for transients. A large portion of the population remained resident, with a maximum time to recapture of nine years. The effect of logging history (unlogged vs 16-30 years post-logging regrowth) on apparent survival was minor and species specific, with no detectable effect for two species, a positive effect for one and negative for the other. There was no effect of logging history on abundance or body condition for any of these species. Apparent survival of residents was not strongly influenced by weather variation (except for the smallest species), unlike previous studies outside of refugia. Despite annual variation in abundance and body condition across the 14 years of the study, no relationship with extreme weather was evident. The location of our study area in a climate refuge potentially buffered bat population dynamics from extreme weather. These results support the value of climate refugia in mitigating climate change impacts, though the lack of an external control highlights the need for further studies on the functioning of climate refugia. Relatively stable population dynamics were not compromised by

  17. Evaluating harvest-based control of invasive fish with telemetry: Performance of sea lamprey traps in the Great Lakes

    Science.gov (United States)

    Holbrook, Christopher; Bergstedt, Roger A.; Barber, Jessica M.; Bravener, Gale A; Jones, Michael L.; Krueger, Charles C.

    2016-01-01

    Physical removal (e.g., harvest via traps or nets) of mature individuals may be a cost-effective or socially acceptable alternative to chemical control strategies for invasive species, but requires knowledge of the spatial distribution of a population over time. We used acoustic telemetry to determine the current and possible future role of traps to control and assess invasive sea lampreys, Petromyzon marinus, in the St. Marys River, the connecting channel between Lake Superior and Lake Huron. Exploitation rates (i.e., fractions of an adult sea lamprey population removed by traps) at two upstream locations were compared among three years and two points of entry to the system. Telemetry receivers throughout the drainage allowed trap performance (exploitation rate) to be partitioned into two components: proportion of migrating sea lampreys that visited trap sites (availability) and proportion of available sea lampreys that were caught by traps (local trap efficiency). Estimated exploitation rates were well below those needed to provide population control in the absence of lampricides and were limited by availability and local trap efficiency. Local trap efficiency estimates for acoustic-tagged sea lampreys were lower than analogous estimates regularly obtained using traditional mark–recapture methods, suggesting that abundance had been previously underestimated. Results suggested major changes would be required to substantially increase catch, including improvements to existing traps, installation of new traps, or other modifications to attract and retain more sea lampreys. This case study also shows how bias associated with telemetry tags can be estimated and incorporated in models to improve inferences about parameters that are directly relevant to fishery management.

  18. Marine foraging and annual fish consumption of a south polar Skua population in the maritime Antarctic

    NARCIS (Netherlands)

    Hahn, S.M.; Ritz, M.S.; Reinhardt, K.

    2008-01-01

    Pelagic fish are an important component of Antarctic food webs but few quantitative data exist on energy transfer from fish to seabirds for the Seasonal Pack-ice Zone. We studied a local population of south polar, skuas Catharacta maccormicki during a whole breeding cycle and estimated its entire

  19. Report of the Workshop on Population Characteristics and Change in Coastal Fishing Communities: Madras, India, 10-14 March 1997

    National Research Council Canada - National Science Library

    1997-01-01

    This workshop brought together 23 fisheries scientists/socio-economists and population experts with experience in demographic and population research on fishing communities and in fisheries management...

  20. First genealogy for a wild marine fish population reveals multigenerational philopatry

    KAUST Repository

    Salles, Océ ane C.; Pujol, Benoit; Maynard, Jeffrey A.; Almany, Glenn R.; Berumen, Michael L.; Jones, Geoffrey P.; Saenz-Agudelo, Pablo; Srinivasan, Maya; Thorrold, Simon R.; Planes, Serge

    2016-01-01

    Natal philopatry, the return of individuals to their natal area for reproduction, has advantages and disadvantages for animal populations. Natal philopatry may generate local genetic adaptation, but it may also increase the probability of inbreeding that can compromise persistence. Although natal philopatry is well documented in anadromous fishes, marine fish may also return to their birth site to spawn. How philopatry shapes wild fish populations is, however, unclear because it requires constructing multigenerational pedigrees that are currently lacking for marine fishes. Here we present the first multigenerational pedigree for a marine fish population by repeatedly genotyping all individuals in a population of the orange clownfish (Amphiprion percula) at Kimbe Island (Papua New Guinea) during a 10-y period. Based on 2927 individuals, our pedigree analysis revealed that longitudinal philopatry was recurrent over five generations. Progeny tended to settle close to their parents, with related individuals often sharing the same colony. However, successful inbreeding was rare, and genetic diversity remained high, suggesting occasional inbreeding does not impair local population persistence. Local reproductive success was dependent on the habitat larvae settled into, rather than the habitat they came from. Our study suggests that longitudinal philopatry can influence both population replenishment and local adaptation of marine fishes. Resolving multigenerational pedigrees during a relatively short period, as we present here, provides a framework for assessing the ability of marine populations to persist and adapt to accelerating climate change.

  1. First genealogy for a wild marine fish population reveals multigenerational philopatry

    KAUST Repository

    Salles, Océane C.

    2016-11-01

    Natal philopatry, the return of individuals to their natal area for reproduction, has advantages and disadvantages for animal populations. Natal philopatry may generate local genetic adaptation, but it may also increase the probability of inbreeding that can compromise persistence. Although natal philopatry is well documented in anadromous fishes, marine fish may also return to their birth site to spawn. How philopatry shapes wild fish populations is, however, unclear because it requires constructing multigenerational pedigrees that are currently lacking for marine fishes. Here we present the first multigenerational pedigree for a marine fish population by repeatedly genotyping all individuals in a population of the orange clownfish (Amphiprion percula) at Kimbe Island (Papua New Guinea) during a 10-y period. Based on 2927 individuals, our pedigree analysis revealed that longitudinal philopatry was recurrent over five generations. Progeny tended to settle close to their parents, with related individuals often sharing the same colony. However, successful inbreeding was rare, and genetic diversity remained high, suggesting occasional inbreeding does not impair local population persistence. Local reproductive success was dependent on the habitat larvae settled into, rather than the habitat they came from. Our study suggests that longitudinal philopatry can influence both population replenishment and local adaptation of marine fishes. Resolving multigenerational pedigrees during a relatively short period, as we present here, provides a framework for assessing the ability of marine populations to persist and adapt to accelerating climate change.

  2. Distribution of 137Cs among individuals in fish and mammal populations in Chornobyl

    International Nuclear Information System (INIS)

    Smith, M.; Glenn, T.; Oleksyk, T.; Gashchak, S.; Zalissky, A.

    2001-01-01

    The frequency distribution of 137 Cs in populations of fish and mammals is not normal, because there is a strong relationship between the standard deviation and the mean of the distributions for both fish and mammals. The distribution for mammals is more skewed than for fish. These two types of vertebrates probably use their environment in fundamentally different ways and/or 137 Cs is distributed more heterogeneously in terrestrial than in aquatic environments. The greatest risk from the contaminant is confined to a few individuals in each population

  3. Coral reef fish populations can persist without immigration

    KAUST Repository

    Salles, Océ ane C.; Maynard, Jeffrey A.; Joannides, Marc; Barbu, Corentin M.; Saenz-Agudelo, Pablo; Almany, Glenn R.; Berumen, Michael L.; Thorrold, Simon R.; Jones, Geoffrey P.; Planes, Serge

    2015-01-01

    and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual

  4. Spatially resolved fish population analysis for designing MPAs

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Mosegaard, Henrik; Jensen, Henrik

    2009-01-01

    demonstrated that ecosystem self-regulation must be included when modelling the efficiency of MPAs, and for lesser sandeel, that self-regulation partially counteracts the benefits of a fishing sanctuary. The use of realistic habitat connectivity is critical for both qualitative and quantitative MPA assessment...

  5. Portfolio theory as a management tool to guide conservation and restoration of multi-stock fish populations

    Science.gov (United States)

    DuFour, Mark R.; May, Cassandra J.; Roseman, Edward F.; Ludsin, Stuart A.; Vandergoot, Christopher S.; Pritt, Jeremy J.; Fraker, Michael E.; Davis, Jeremiah J.; Tyson, Jeffery T.; Miner, Jeffery G.; Marschall, Elizabeth A.; Mayer, Christine M.

    2015-01-01

    Habitat degradation and harvest have upset the natural buffering mechanism (i.e., portfolio effects) of many large-scale multi-stock fisheries by reducing spawning stock diversity that is vital for generating population stability and resilience. The application of portfolio theory offers a means to guide management activities by quantifying the importance of multi-stock dynamics and suggesting conservation and restoration strategies to improve naturally occurring portfolio effects. Our application of portfolio theory to Lake Erie Sander vitreus (walleye), a large population that is supported by riverine and open-lake reef spawning stocks, has shown that portfolio effects generated by annual inter-stock larval fish production are currently suboptimal when compared to potential buffering capacity. Reduced production from riverine stocks has resulted in a single open-lake reef stock dominating larval production, and in turn, high inter-annual recruitment variability during recent years. Our analyses have shown (1) a weak average correlation between annual river and reef larval production (ρ̄ = 0.24), suggesting that a natural buffering capacity exists in the population, and (2) expanded annual production of larvae (potential recruits) from riverine stocks could stabilize the fishery by dampening inter-annual recruitment variation. Ultimately, our results demonstrate how portfolio theory can be used to quantify the importance of spawning stock diversity and guide management on ecologically relevant scales (i.e., spawning stocks) leading to greater stability and resilience of multi-stock populations and fisheries.

  6. Spatial distribution and optimal harvesting of an age-structured population in a fluctuating environment.

    Science.gov (United States)

    Engen, Steinar; Lee, Aline Magdalena; Sæther, Bernt-Erik

    2018-02-01

    We analyze a spatial age-structured model with density regulation, age specific dispersal, stochasticity in vital rates and proportional harvesting. We include two age classes, juveniles and adults, where juveniles are subject to logistic density dependence. There are environmental stochastic effects with arbitrary spatial scales on all birth and death rates, and individuals of both age classes are subject to density independent dispersal with given rates and specified distributions of dispersal distances. We show how to simulate the joint density fields of the age classes and derive results for the spatial scales of all spatial autocovariance functions for densities. A general result is that the squared scale has an additive term equal to the squared scale of the environmental noise, corresponding to the Moran effect, as well as additive terms proportional to the dispersal rate and variance of dispersal distance for the age classes and approximately inversely proportional to the strength of density regulation. We show that the optimal harvesting strategy in the deterministic case is to harvest only juveniles when their relative value (e.g. financial) is large, and otherwise only adults. With increasing environmental stochasticity there is an interval of increasing length of values of juveniles relative to adults where both age classes should be harvested. Harvesting generally tends to increase all spatial scales of the autocovariances of densities. Copyright © 2017. Published by Elsevier Inc.

  7. 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.

  8. Fish Habitat and Fish Populations in a Southern Appalachian Watershed before and after Hurricane Hugo

    Science.gov (United States)

    C. Andrew Dolloff; Patricia A. Flebbe; Michael D. Owen

    1994-01-01

    Habitat features and relative abundance of all fish species were estimated in 8.4 km of a small mountain stream system before and 11 months after Hurricane Hugo crossed the southern Appalachians in September 1989. There was no change in the total amount (area) of each habitat type but the total number of habitat units decreased and average size and depth of habitat...

  9. Genetic evidence of population structuring in the neotropical freshwater fish Brycon hilarii (Valenciennes, 1850

    Directory of Open Access Journals (Sweden)

    A Sanches

    Full Text Available Brycon hilarii is a migratory fish widely distributed throughout the Paraguay River Basin. It is appreciated in sport fishing and for its superior meat quality. It is also the main species for tourist attraction in the Bonito region (State of Mato Grosso do Sul, Brazil. Considering the lack of information on the genetic structure of the fish of this species, the aim of the present study was to detect the genetic variability of Brycon hilarii through RAPD markers. A total of eighty specimens collected in different seasons at four sites of the Miranda River sub-basin (Paraguay River Basin, Brazil were used for analysis. The results of genetic similarity, Shannon diversity, and AMOVA revealed differences between the sampling sites. Through AMOVA, differences between populations were more evident among the animals collected during the non-reproductive season, corresponding to a time of less movement of these fish. A population structuring model in which B. hilarii appears organized into genetically differentiated reproductive units that coexist and co-migrate through the studied system was suggested, contrasting the currently accepted idea that freshwater migratory fish form large panmictic populations in a determined hydrographic system. Despite the lack of a complete picture regarding the distribution of B. hilarii in the studied region, this initial idea on its population genetic structure could be an important contribution to providing aid for management and conservation programs of these fish.

  10. Ocean Acidification Effects on Atlantic Cod Larval Survival and Recruitment to the Fished Population.

    Science.gov (United States)

    Stiasny, Martina H; Mittermayer, Felix H; Sswat, Michael; Voss, Rüdiger; Jutfelt, Fredrik; Chierici, Melissa; Puvanendran, Velmurugu; Mortensen, Atle; Reusch, Thorsten B H; Clemmesen, Catriona

    2016-01-01

    How fisheries will be impacted by climate change is far from understood. While some fish populations may be able to escape global warming via range shifts, they cannot escape ocean acidification (OA), an inevitable consequence of the dissolution of anthropogenic carbon dioxide (CO2) emissions in marine waters. How ocean acidification affects population dynamics of commercially important fish species is critical for adapting management practices of exploited fish populations. Ocean acidification has been shown to impair fish larvae's sensory abilities, affect the morphology of otoliths, cause tissue damage and cause behavioural changes. Here, we obtain first experimental mortality estimates for Atlantic cod larvae under OA and incorporate these effects into recruitment models. End-of-century levels of ocean acidification (~1100 μatm according to the IPCC RCP 8.5) resulted in a doubling of daily mortality rates compared to present-day CO2 concentrations during the first 25 days post hatching (dph), a critical phase for population recruitment. These results were consistent under different feeding regimes, stocking densities and in two cod populations (Western Baltic and Barents Sea stock). When mortality data were included into Ricker-type stock-recruitment models, recruitment was reduced to an average of 8 and 24% of current recruitment for the two populations, respectively. Our results highlight the importance of including vulnerable early life stages when addressing effects of climate change on fish stocks.

  11. Elucidating dynamic responses of North Pacific fish populations to climatic forcing: Influence of life-history strategy

    Science.gov (United States)

    Yatsu, A.; Aydin, K. Y.; King, J. R.; McFarlane, G. A.; Chiba, S.; Tadokoro, K.; Kaeriyama, M.; Watanabe, Y.

    2008-05-01

    In order to explore mechanistic linkages between low-frequency ocean/climate variability, and fish population responses, we undertook comparative studies of time-series of recruitment-related productivity and the biomass levels of fish stocks representing five life-history strategies in the northern North Pacific between the 1950s and the present. We selected seven species: Japanese sardine ( Sardinopus melanostictus) and California sardine ( Sardinopus sagax) (opportunistic strategists), walleye pollock ( Theragra chalcogramma, intermediate strategist), pink salmon ( Oncorhynchus gorbuscha, salmonic strategist), sablefish ( Anoplopoma fimbria) and Pacific halibut ( Hippoglossus stenolepis) (periodic strategists) and spiny dogfish ( Squalus acanthias, equilibrium strategist). The responses in terms of productivity of sardine, pink salmon, sablefish and halibut to climatic regime shifts were generally immediate, delayed, or no substantial responses depending on the particular regime shift year and fish stock (population). In walleye pollock, there were some periods of high productivity and low productivity, but not coincidental to climatic regime shifts, likely due to indirect climate forcing impacts on both bottom-up and top-down processes. Biomass of zooplankton and all fish stocks examined, except for spiny dogfish whose data were limited, indicated a decadal pattern with the most gradual changes in periodic strategists and most intensive and rapid changes in opportunistic strategists. Responses of sardine productivity to regime shifts were the most intense, probably due to the absence of density-dependent effects and the availability of refuges from predators when sardine biomass was extremely low. Spiny dogfish were least affected by environmental variability. Conversely, spiny dogfish are likely to withstand only modest harvest rates due to their very low intrinsic rate of increase. Thus, each life-history strategy type had a unique response to climatic

  12. Sustainably Harvesting a Large Carnivore? Development of Eurasian Lynx Populations in Norway During 160 Years of Shifting Policy

    Science.gov (United States)

    Linnell, John D. C.; Broseth, Henrik; Odden, John; Nilsen, Erlend Birkeland

    2010-05-01

    The management of large carnivores in multiuse landscapes is always controversial, and managers need to balance a wide range of competing interests. Hunter harvest is often used to limit population size and distribution but is proving to be both controversialand technically challenging. Eurasian lynx ( Lynx lynx) are currently managed as a game species in Norway. We describe an adaptive management approach where quota setting is based on an annual census and chart the population development through the period 1996-2008, as management has become significantly more sophisticated and better informed by the increased availability of scientific data. During this period the population has been through a period of high quotas and population decline caused by fragmented management authority and overoptimistic estimates of lynx reproduction, followed by a period of recovery due to quota reductions. The modern management regime is placed in the context of shifting policy during the last 160 years, during which management goals have moved from extermination stimulated by bounties, through a short phase of protection, and now to quota-regulated harvest. Much management authority has also been delegated from central to local levels. We conclude that adaptive management has the potential to keep the population within some bounded limits, although there will inevitably be fluctuation.

  13. Population models for Greater Snow Geese: a comparison of different approaches to assess potential impacts of harvest

    Directory of Open Access Journals (Sweden)

    Gauthier, G.

    2004-06-01

    Full Text Available Demographic models, which are a natural extension of capture-recapture (CR methodology, are a powerful tool to guide decisions when managing wildlife populations. We compare three different modelling approaches to evaluate the effect of increased harvest on the population growth of Greater Snow Geese (Chen caerulescens atlantica. Our first approach is a traditional matrix model where survival was reduced to simulate increased harvest. We included environmental stochasticity in the matrix projection model by simulating good, average, and bad years to account for the large inter-annual variation in fecundity and first-year survival, a common feature of birds nesting in the Arctic. Our second approach is based on the elasticity (or relative sensitivity of population growth rate (lambda to changes in survival as simple functions of generation time. Generation time was obtained from the mean transition matrix based on the observed proportion of good, average and bad years between 1985 and 1998. If we assume that hunting mortality is additive to natural mortality, then a simple formula predicts changes in lambda as a function of changes in harvest rate. This second approach can be viewed as a simplification of the matrix model because it uses formal sensitivity results derived from population projection. Our third, and potentially more powerful approach, uses the Kalman Filter to combine information on demographic parameters, i.e. the population mechanisms summarized in a transition matrix model, and the census information (i.e. annual survey within an overall Gaussian likelihood. The advantage of this approach is that it minimizes process and measured uncertainties associated with both the census and demographic parameters based on the variance of each estimate. This third approach, in contrast to the second, can be viewed as an extension of the matrix model, by combining its results with the independent census information.

  14. Knowledge about fish consumption advisories: a risk communication failure within a university population.

    Science.gov (United States)

    Burger, Joanna; Gochfeld, Michael

    2008-02-15

    Considerable attention has focused on whether people are aware of fish consumption advisories, particularly among fishermen and as a function of demographic variables. Yet little attention has been directed at the messages people are receiving from fish consumption advisories. This study examines knowledge about the benefits and risks of fish in relation to ethnicity and the degree of knowledge in a general university population in New Jersey. Subjects were asked open-ended questions about risks and benefits and responses were grouped into categories. A far greater percent of people had heard something about the risks and benefits of eating fish than could report specific information about the risks or benefits. While only 16% of subjects did not know what the benefits of eating fish were, 62% did not have any specific information about why there were warnings. However, for people who had some specific information, a higher proportion (57%) could identify the chemicals (PCBs, mercury) causing the risks, than could identify omega-3 fatty acids as contributing to benefits (40%). Much of the knowledge was very general, such as eating fish is "good for the heart", "good for you", or "brain food". Less than half of the subjects could name species of fish that were either high or low in contaminants. There were ethnic disparities in knowledge about both the benefits and the risks from fish consumption. A higher percentage of whites knew about both the benefits and risks of fish consumption than others; Asians knew the least about the risks, and blacks and hispanics knew the least about the benefits. There were also ethnic differences in ability to name fish that are low in contaminants, or high in contaminants. Minorities, particularly hispanics, were unable to list species that are high in contaminants. We identified three levels of knowledge about fish consumption: 1) whether people are aware of the risks or benefits of fish consumption, 2) whether they have any

  15. Forest bat population dynamics over 14 years at a climate refuge: Effects of timber harvesting and weather extremes.

    Directory of Open Access Journals (Sweden)

    Bradley S Law

    Full Text Available Long-term data are needed to explore the interaction of weather extremes with habitat alteration; in particular, can 'refugia' buffer population dynamics against climate change and are they robust to disturbances such as timber harvesting. Because forest bats are good indicators of ecosystem health, we used 14 years (1999-2012 of mark-recapture data from a suite of small tree-hollow roosting bats to estimate survival, abundance and body condition in harvested and unharvested forest and over extreme El Niño and La Niña weather events in southeastern Australia. Trapping was replicated within an experimental forest, located in a climate refuge, with different timber harvesting treatments. We trapped foraging bats and banded 3043 with a 32% retrap rate. Mark-recapture analyses allowed for dependence of survival on time, species, sex, logging treatment and for transients. A large portion of the population remained resident, with a maximum time to recapture of nine years. The effect of logging history (unlogged vs 16-30 years post-logging regrowth on apparent survival was minor and species specific, with no detectable effect for two species, a positive effect for one and negative for the other. There was no effect of logging history on abundance or body condition for any of these species. Apparent survival of residents was not strongly influenced by weather variation (except for the smallest species, unlike previous studies outside of refugia. Despite annual variation in abundance and body condition across the 14 years of the study, no relationship with extreme weather was evident. The location of our study area in a climate refuge potentially buffered bat population dynamics from extreme weather. These results support the value of climate refugia in mitigating climate change impacts, though the lack of an external control highlights the need for further studies on the functioning of climate refugia. Relatively stable population dynamics were not

  16. Assessing risks to fish populations near a proposed disposal facility for used nuclear fuel

    International Nuclear Information System (INIS)

    Hart, D.; Miesenheimer, P.; Hull, R.

    1995-01-01

    The concept of used nuclear fuel disposal in the Canadian Shield is currently undergoing a federal environmental assessment review process. As part of this review, potential risks to brook trout populations in the vicinity of such an underground repository were considered. Chemical fate, transport and exposure models have been utilized to estimate the dose rates from released radionuclides and other fuel constituents, and these likely will not be sufficient to harm fish in nearby streams. However, other stressors such as habitat alteration (e.g., loss of upwelling) and/or fishing pressure associated with increased public access could have significant population impacts if the site is located in a pristine northern region. Population models are utilized to explore the risks of local population reduction for different combinations of fishing pressure and habitat degradation

  17. Clinical epidemiology of reduced kidney function among elderly male fishing and agricultural population in Taipei, Taiwan.

    Science.gov (United States)

    Kuo, Chi-Mei; Chien, Wu-Hsiung; Shen, Hsi-Che; Hu, Yi-Chun; Chen, Yu-Fen; Tung, Tao-Hsin

    2013-01-01

    To quantify the prevalence of and associated factors for chronic kidney disease (CKD) among male elderly fishing and agricultural population in Taipei, Taiwan. Subjects (n = 2,766) aged 65 years and over voluntarily admitted to a teaching hospital for a physical checkup were collected in 2010. CKD was defined as an estimated glomerular filtration rate agricultural population.

  18. High-throughput telomere length quantification by FISH and its application to human population studies.

    Science.gov (United States)

    Canela, Andrés; Vera, Elsa; Klatt, Peter; Blasco, María A

    2007-03-27

    A major limitation of studies of the relevance of telomere length to cancer and age-related diseases in human populations and to the development of telomere-based therapies has been the lack of suitable high-throughput (HT) assays to measure telomere length. We have developed an automated HT quantitative telomere FISH platform, HT quantitative FISH (Q-FISH), which allows the quantification of telomere length as well as percentage of short telomeres in large human sample sets. We show here that this technique provides the accuracy and sensitivity to uncover associations between telomere length and human disease.

  19. Avian response to timber harvesting applied experimentally to manage Cerulean Warbler breeding populations

    Science.gov (United States)

    Sheehan, James; Wood, Petra Bohall; Buehler, David A.; Keyser, Patrick D.; Larkin, Jeffrey L.; Rodewald, Amanda D.; Wigley, T. Bently; Boves, Than J.; George, Gregory A.; Bakermans, Marja H.; Beachy, Tiffany A.; Evans, Andrea; McDermott, Molly E.; Newell, Felicity L.; Perkins, Kelly A.; White, Matthew

    2014-01-01

    Timber harvesting has been proposed as a management tool to enhance breeding habitat for the Cerulean Warbler (Setophaga cerulea), a declining Neotropical–Nearctic migratory songbird that nests in the canopy of mature eastern deciduous forests. To evaluate how this single-species management focus might fit within an ecologically based management approach for multiple forest birds, we performed a manipulative experiment using four treatments (three intensities of timber harvests and an unharvested control) at each of seven study areas within the core Cerulean Warbler breeding range. We collected pre-harvest (one year) and post-harvest (four years) data on the territory density of Cerulean Warblers and six additional focal species, avian community relative abundance, and several key habitat variables. We evaluated the avian and habitat responses across the 3–32 m2 ha−1 residual basal area (RBA) range of the treatments. Cerulean Warbler territory density peaked with medium RBA (∼16 m2 ha−1). In contrast, territory densities of the other focal species were negatively related to RBA (e.g., Hooded Warbler [Setophaga citrina]), were positively related to RBA (e.g., Ovenbird [Seiurus aurocapilla]), or were not sensitive to this measure (Scarlet Tanager [Piranga olivacea]). Some species (e.g., Hooded Warbler) increased with time post-treatment and were likely tied to a developing understory, whereas declines (e.g., Ovenbird) were immediate. Relative abundance responses of additional species were consistent with the territory density responses of the focal species. Across the RBA gradient, greatest separation in the avian community was between early successional forest species (e.g., Yellow-breasted Chat [Icteria virens]) and closed-canopy mature forest species (e.g., Ovenbird), with the Cerulean Warbler and other species located intermediate to these two extremes. Overall, our results suggest that harvests within 10–20 m2 ha−1 RBA yield the largest

  20. It is the economy, stupid! Projecting the fate of fish populations using ecological-economic modeling.

    Science.gov (United States)

    Quaas, Martin F; Reusch, Thorsten B H; Schmidt, Jörn O; Tahvonen, Olli; Voss, Rudi

    2016-01-01

    Four marine fish species are among the most important on the world market: cod, salmon, tuna, and sea bass. While the supply of North American and European markets for two of these species - Atlantic salmon and European sea bass - mainly comes from fish farming, Atlantic cod and tunas are mainly caught from wild stocks. We address the question what will be the status of these wild stocks in the midterm future, in the year 2048, to be specific. Whereas the effects of climate change and ecological driving forces on fish stocks have already gained much attention, our prime interest is in studying the effects of changing economic drivers, as well as the impact of variable management effectiveness. Using a process-based ecological-economic multispecies optimization model, we assess the future stock status under different scenarios of change. We simulate (i) technological progress in fishing, (ii) increasing demand for fish, and (iii) increasing supply of farmed fish, as well as the interplay of these driving forces under different scenarios of (limited) fishery management effectiveness. We find that economic change has a substantial effect on fish populations. Increasing aquaculture production can dampen the fishing pressure on wild stocks, but this effect is likely to be overwhelmed by increasing demand and technological progress, both increasing fishing pressure. The only solution to avoid collapse of the majority of stocks is institutional change to improve management effectiveness significantly above the current state. We conclude that full recognition of economic drivers of change will be needed to successfully develop an integrated ecosystem management and to sustain the wild fish stocks until 2048 and beyond. © 2015 John Wiley & Sons Ltd.

  1. Mercury in fish from the Madeira River and health risk to Amazonian and riverine populations.

    Science.gov (United States)

    Soares, José Maria; Gomes, José M; Anjos, Marcelo R; Silveira, Josianne N; Custódio, Flavia B; Gloria, M Beatriz A

    2018-07-01

    The objective of this study was to quantify total mercury in highly popular Amazonian fish pacu, curimatã, jaraqui, and sardinha from the Madeira River and to estimate the exposure to methylmercury from fish consumption. The samples were obtained from two locations - Puruzinho Igarapé and Santa Rosa - near Humaitá, Amazonia, Brazil in two seasons of 2015 (high and low waters). The fish were identified, weighed and measured, and lipids were quantified. Total mercury was determined by gold amalgamation-atomic absorption spectrometry. Mean levels were used to calculate exposure of Amazonian and riverine populations. There was significant correlation (p < 0.05) between length × weight for all fish; length × lipid and weight × lipid were significant only for pacu. Total mercury levels varied along muscle tissue for the fish, except for sardinha; therefore muscle from the dorsal area along the fish were sampled, homogenized and used for analysis. The levels of total mercury varied from 0.01 to 0.46 mg/kg, with higher median levels in sardinha (0.24 mg/kg), followed by curimatã (0.16 mg/kg), jaraqui (0.13 mg/kg) and pacu (0.04 mg/kg), corresponding with the respective feeding habits along the trophic chain. Total mercury levels were not affected by the location of fish capture and by high and low waters seasons. Total mercury correlated significantly with length and weight for jaraqui and with length for sardinha (negative correlation). Total mercury levels in fish complied with legislation; however, exposures to methylmercury from fish consumption overpassed the safe intake reference dose for sardinha for Amazonians; however, for the riverine communities, all of the fish would cause potential health risk, mainly for children and women of childbearing age. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Increased Levels of Harvest and Habitat Law Enforcement and Public Awareness for Anadromous Salmonids and Resident Fish in the Columbia River Basin -- Demonstration Period, 1992--1994, Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    NeSmith, Frank (Idaho Department of Fish and Game, Boise, ID); Long, Mack (Montana Department of Fish, Wildlife and Paks, Kalispell, MT); Matthews, Dayne (Washington Department of Fish and Wildlife, Olympia, WA)

    1995-06-01

    This report was funded by the Bonneville Power Administration (BPA), US Department of Energy, as part of BPA`s program to protect, mitigate, and enhance fish and wildlife affected by the development and operation of hydroelectric facilities on the Columbia River and its tributaries. Illegal harvest and violation of habitat protection regulations are factors affecting the survival of many native species of anadromous and resident fish in the Columbia Basin.

  3. Increased levels of harvest and habitat law enforcement and public awareness for anadromous salmonids and resident fish in the Columbia River Basin - Demonstration period, 1992-1994. Final report

    International Nuclear Information System (INIS)

    1995-06-01

    This report was funded by the Bonneville Power Administration (BPA), US Department of Energy, as part of BPA's program to protect, mitigate, and enhance fish and wildlife affected by the development and operation of hydroelectric facilities on the Columbia River and its tributaries. Illegal harvest and violation of habitat protection regulations are factors affecting the survival of many native species of anadromous and resident fish in the Columbia Basin

  4. Factors affecting the recovery of fish populations in an industrial river. [Brown trout

    Energy Technology Data Exchange (ETDEWEB)

    Turnpenny, A W.M.; Williams, R

    1981-01-01

    The river Ebbw Fawr, an industrial river of South-East Wales, was investigated over a three-year period to follow the re-establishment of fish populations as a result of pollution control measures at coal washeries and a steelworks on the river. These measures were effective in reducing levels of toxic materials and restoring dissolved oxygen levels and pH values acceptable for fish. Five freshwater fish species became established in parts of the river during the study period (1974-77). The brown trout Salmo trutta l. was the first to enter, followed by eel Anguilla anguilla l., stoneloach Noemacheilus barbatulus l., stickleback Gasterosteus aculeatus l. and bullhead Cottus gobio l., respectively. The flounder Platicthys flesus l., a euryhaline species, penetrated the river beyond the upper tidal limit. The minnow Phoxinus phoxinus l., a resident of other parts of the Ebbw system, did not recolonise during the study. Calculated toxicities and the results of fish caging tests indicated that water quality was satisfactory for fish populations throughout the river with the possible exception of a short reach immediately below the steelworks. The absence of fish from some upstream reaches with good water quality was due to the limited numbers of fish available for recolonisation and their restricted movements. Good growth and condition factors among the recolonising brown trout stock suggest that a sport fishery could be developed on the river, though constraints on spawning due to residual silt pollution indicate that stocking with hatchery reared fish will be necessary to maintain trout numbers.

  5. Fish population responses to hydrological variation in a seasonal wetland in southeast México

    Directory of Open Access Journals (Sweden)

    Luis H. Escalera-Vázquez

    2017-06-01

    Full Text Available ABSTRACT Hydrological variation differently affects fish species. In the present study, the response of local populations of 13 fish local species to hydrological variation in a tropical wetland was evaluated. The objectives were to analyze the abundance response of fish species with distinct life history strategies and to assess the role of hydrological variation on fish population patterns. We found that opportunistic strategists were favored by high hydrological variation in drought periods, the equilibrium strategists were related to stable habitats, and periodic strategists were regulated by floods and temperature. However, the life history strategies identified for some species in this study do not correspond to the classification reported in other studies. Our results highlight the importance to study the abundance responses of species at local and regional scales to identify variations in life-history strategies, which can reflect local adaptations of species to hydrological changes, this is useful in order to understand and predict the responses of fish populations to the local environment.

  6. Population dynamics of the invasive fish, Gambusia affinis , in ...

    African Journals Online (AJOL)

    Repeated-measures ANOVA analyses on the catch per unit effort (CPUE) of G. affinis between sampling events and dams revealed significant differences in population dynamics among dams, although an overall trend of rapid increase followed by plateau in summer, with a rapid decline in winter was seen in most dams.

  7. Using recall surveys to estimate harvest of cod, eel and sea migrating brown trout in Danish angling and recreational passive gear fishing

    DEFF Research Database (Denmark)

    Sparrevohn, Claus Reedtz; Nielsen, Jan; Storr-Paulsen, Marie

    , as all recreational fishermen have to purchase a personal non-transferable and time limited national license before fishing. However, this list will not include those fishing illegally without a license. Therefore, two types of recall surveys with their own questionnaires and group of respondents were...... carried out. The first survey - the license list survey – was carried out once in 2009 and twice in 2010. This survey had a sampling frame corresponding to the list of persons that had purchased a license within the last 12 months. Respondents were asked to provide detailed information on catch and effort...... per ICES area and quarter. In order to also estimate the fraction of fishermen that fished without a valid license, a second survey, called – the Omnibus survey-, was carried out four times. This survey targeted the entire Danish population between 16 and 74 of age...

  8. Assessing three fish species ecological status in Colorado River, Grand Canyon based on physical habitat and population models.

    Science.gov (United States)

    Yao, Weiwei; Chen, Yuansheng

    2018-04-01

    Colorado River is a unique ecosystem and provides important ecological services such as habitat for fish species as well as water power energy supplies. River management for this ecosystem requires assessment and decision support tools for fish which involves protecting, restoring as well as forecasting of future conditions. In this paper, a habitat and population model was developed and used to determine the levels of fish habitat suitability and population density in Colorado River between Lees Ferry and Lake Mead. The short term target fish populations are also predicted based on native fish recovery strategy. This model has been developed by combining hydrodynamics, heat transfer and sediment transport models with a habitat suitability index model and then coupling with habitat model into life stage population model. The fish were divided into four life stages according to the fish length. Three most abundant and typical native and non-native fish were selected as target species, which are rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and flannelmouth sucker (Catostomus latipinnis). Flow velocity, water depth, water temperature and substrates were used as the suitability indicators in habitat model and overall suitability index (OSI) as well as weight usable area (WUA) was used as an indicator in population model. A comparison was made between simulated fish population alteration and surveyed fish number fluctuation during 2000 to 2009. The application of this habitat and population model indicates that this model can be accurate present habitat situation and targets fish population dynamics of in the study areas. The analysis also indicates the flannelmouth sucker population will steadily increase while the rainbow trout will decrease based on the native fish recovery scheme. Copyright © 2018. Published by Elsevier Inc.

  9. Environmental coupling and population dynamics in the PE545 light-harvesting complex

    Energy Technology Data Exchange (ETDEWEB)

    Aghtar, Mortaza; Kleinekathöfer, Ulrich, E-mail: u.kleinekathoefer@jacobs-university.de

    2016-01-15

    Long-lived quantum coherences have been shown experimentally in the Fenna–Matthews–Olson (FMO) complex of green sulfur bacteria as well as in the phycoerythrin 545 (PE545) photosynthetic antenna system of marine algae. A combination of classical molecular dynamics simulations, quantum chemistry and quantum dynamical calculations is employed to determine the excitation transfer dynamics in PE545. One key property of the light-harvesting system concerning the excitation transfer and dephasing phenomena is the spectral density. This quantity is determined from time series of the vertical excitation energies of the aggregate. In the present study we focus on the quantum dynamical simulations using the earlier QM/MM calculations as input. Employing an ensemble-averaged classical path-based wave packet dynamics, the excitation transfer dynamics between the different bilins in the PE545 complex is determined and analyzed. Furthermore, the nature of the environmental fluctuations determining the transfer dynamics is discussed. - Highlights: • Modeling of excitation energy transfer in the light-harvesting system PE545. • Combination of molecular dynamics simulations, quantum chemistry and quantum dynamics. • Spectral densities for bilins in the PE545 complex.

  10. Proxy measures of fitness suggest coastal fish farms can act as population sources and not ecological traps for wild gadoid fish.

    Directory of Open Access Journals (Sweden)

    Tim Dempster

    Full Text Available BACKGROUND: Ecological traps form when artificial structures are added to natural habitats and induce mismatches between habitat preferences and fitness consequences. Their existence in terrestrial systems has been documented, yet little evidence suggests they occur in marine environments. Coastal fish farms are widespread artificial structures in coastal ecosystems and are highly attractive to wild fish. METHODOLOGY/PRINCIPAL FINDINGS: To investigate if coastal salmon farms act as ecological traps for wild Atlantic cod (Gadus morhua and saithe (Pollachius virens, we compared proxy measures of fitness between farm-associated fish and control fish caught distant from farms in nine locations throughout coastal Norway, the largest coastal fish farming industry in the world. Farms modified wild fish diets in both quality and quantity, thereby providing farm-associated wild fish with a strong trophic subsidy. This translated to greater somatic (saithe: 1.06-1.12 times; cod: 1.06-1.11 times and liver condition indices (saithe: 1.4-1.8 times; cod: 2.0-2.8 times than control fish caught distant from farms. Parasite loads of farm-associated wild fish were modified from control fish, with increased external and decreased internal parasites, however the strong effect of the trophic subsidy overrode any effects of altered loads upon condition. CONCLUSIONS AND SIGNIFICANCE: Proxy measures of fitness provided no evidence that salmon farms function as ecological traps for wild fish. We suggest fish farms may act as population sources for wild fish, provided they are protected from fishing while resident at farms to allow their increased condition to manifest as greater reproductive output.

  11. An examination of the population dynamics of syngnathid fishes within Tampa Bay, Florida, USA

    Directory of Open Access Journals (Sweden)

    Heather D. MASONJONES, Emily ROSE, Lori Benson McRAE,Danielle L. DIXSON

    2010-02-01

    Full Text Available Seagrass ecosystems worldwide have been declining, leading to a decrease in associated fish populations, especially those with low mobility such as syngnathids (pipefish and seahorses. This two-year pilot study investigated seasonal patterns in density, growth, site fidelity, and population dynamics of Tampa Bay (FL syngnathid fishes at a site adjacent to two marinas under construction. Using a modified mark-recapture technique, fish were collected periodically from three closely located sites that varied in seagrass species (Thalassia spp., Syringodium spp., and mixed-grass sites and their distance from open water, but had consistent physical/chemical environmental characteristics. Fish were marked, photographed for body size and gender measurements, and released the same day at the capture site. Of the 5695 individuals surveyed, 49 individuals were recaptured, indicating a large, flexible population. Population density peaks were observed in July of both years, with low densities in late winter and late summer. Spatially, syngnathid densities were highest closest to the mouth of the bay and lowest near the shoreline. Seven species of syngnathid fishes were observed, and species-specific patterns of seagrass use emerged during the study. However, only two species, Syngnathus scovelli and Hippocampus zosterae, were observed at high frequencies. For these two species, body size decreased across the study period, but while S. scovelli’s population density decreased, H. zosterae’s increased. Across six of the seven species, population size declined over the course of this preliminary study; however, seasonal shifts were impossible to distinguish from potential anthropogenic effects of construction [Current Zoology 56 (1: 118–133, 2010].

  12. Population structure of fishes from an urban stream

    Directory of Open Access Journals (Sweden)

    Naiara Zanatta

    2017-05-01

    Full Text Available The aim of this study was to identify the population structure of the ichthyofauna in an urban stream within an environmental protection area in southern Brazil. Quarterly samplings were conducted between October 2009 and August 2010. Poecilia reticulata was the most abundant species, followed by Hypostomus ancistroides and Rhamdia quelen. It was found a higher proportion of adults instead of juveniles from P. reticulata and R. quelen populations, while the opposite was recorded for H. ancistroides. Sex ratio of 1:1 was found for H. ancistroides, but differed significantly for P. reticulata and R. quelen. Females of P. reticulata and R. quelen reached higher length than males in the smaller and higher length-classes, while H. ancistroides females were only longer in initial length-classes. It was recorded higher occurrence of mature and maturing individuals. Mature individuals of H. ancistroides were sampled in October, and P. reticulata and R. quelen throughout the sampling period. Despite adverse environmental conditions, the occurrence of juveniles indicates reproductive activity for these species. Population structure studies in degraded systems are urgent, since life-history features of species may suffer changes due to anthropic impacts. Providing such information contributes to decision making and management of degraded systems.

  13. Fish consumption, not fatty acid status, is related to quality of life in a healthy population

    NARCIS (Netherlands)

    Schiepers, Olga; De Groot, Renate; Jolles, Jelle; Van Boxtel, Martin

    2010-01-01

    Schiepers, O. J., De Groot, R. H. M., Jolles, J., & Van Boxtel, M. P. J. (2010). Fish consumption, not fatty acid status, is related to quality of life in a healthy population. Prostaglandins Leukot Essent Fatty Acids, 83(1), 31-35.

  14. Estuarine fish biodiversity of Socotra Island (N.W. Indian Ocean): from the fish community to the functioning of Terapon jarbua populations

    OpenAIRE

    Lavergne, Edouard

    2012-01-01

    Understanding connectivity between estuarine nurseries and marine habitats is fundamental to explore fish population dynamics and to the design of effective conservation and fisheries management strategies. The aim of this work was to provide the first faunistic and ecological baseline of Socotra Island (North-Western Indian Ocean) estuaries and lagoon fishes for governmental coastal managers and decision makers, with a particular focus on the population functioning of a sentinel species: Ter...

  15. Behavior Data - The effect of dietary taurine on feed attraction and physiology of carnivorous marine fish

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — As the global population continues to rise, so does the demand for sustainable sources of protein. The worldwide harvest of wild fish has remained flat for three...

  16. Overestimating fish counts by non-instantaneous visual censuses: consequences for population and community descriptions.

    Directory of Open Access Journals (Sweden)

    Christine Ward-Paige

    Full Text Available BACKGROUND: Increasingly, underwater visual censuses (UVC are used to assess fish populations. Several studies have demonstrated the effectiveness of protected areas for increasing fish abundance or provided insight into the natural abundance and structure of reef fish communities in remote areas. Recently, high apex predator densities (>100,000 individuals x km(-2 and biomasses (>4 tonnes x ha(-1 have been reported for some remote islands suggesting the occurrence of inverted trophic biomass pyramids. However, few studies have critically evaluated the methods used for sampling conspicuous and highly mobile fish such as sharks. Ideally, UVC are done instantaneously, however, researchers often count animals that enter the survey area after the survey has started, thus performing non-instantaneous UVC. METHODOLOGY/PRINCIPAL FINDINGS: We developed a simulation model to evaluate counts obtained by divers deploying non-instantaneous belt-transect and stationary-point-count techniques. We assessed how fish speed and survey procedure (visibility, diver speed, survey time and dimensions affect observed fish counts. Results indicate that the bias caused by fish speed alone is huge, while survey procedures had varying effects. Because the fastest fishes tend to be the largest, the bias would have significant implications on their biomass contribution. Therefore, caution is needed when describing abundance, biomass, and community structure based on non-instantaneous UVC, especially for highly mobile species such as sharks. CONCLUSIONS/SIGNIFICANCE: Based on our results, we urge that published literature state explicitly whether instantaneous counts were made and that survey procedures be accounted for when non-instantaneous counts are used. Using published density and biomass values of communities that include sharks we explore the effect of this bias and suggest that further investigation may be needed to determine pristine shark abundances and the

  17. Importance of the habitat choice behavior assumed when modeling the effects of food and temperature on fish populations

    Science.gov (United States)

    Wildhaber, Mark L.; Lamberson, Peter J.

    2004-01-01

    Various mechanisms of habitat choice in fishes based on food and/or temperature have been proposed: optimal foraging for food alone; behavioral thermoregulation for temperature alone; and behavioral energetics and discounted matching for food and temperature combined. Along with development of habitat choice mechanisms, there has been a major push to develop and apply to fish populations individual-based models that incorporate various forms of these mechanisms. However, it is not known how the wide variation in observed and hypothesized mechanisms of fish habitat choice could alter fish population predictions (e.g. growth, size distributions, etc.). We used spatially explicit, individual-based modeling to compare predicted fish populations using different submodels of patch choice behavior under various food and temperature distributions. We compared predicted growth, temperature experience, food consumption, and final spatial distribution using the different models. Our results demonstrated that the habitat choice mechanism assumed in fish population modeling simulations was critical to predictions of fish distribution and growth rates. Hence, resource managers who use modeling results to predict fish population trends should be very aware of and understand the underlying patch choice mechanisms used in their models to assure that those mechanisms correctly represent the fish populations being modeled.

  18. Biological reference points for fish stocks in a multispecies context

    DEFF Research Database (Denmark)

    Collie, J.S.; Gislason, Henrik

    2001-01-01

    Biological reference points (BRPs) are widely used to define safe levels of harvesting for marine fish populations. Most BRPs are either minimum acceptable biomass levels or maximum fishing mortality rates. The values of BRPs are determined from historical abundance data and the life...

  19. Fish population studies using parasites from the Southeastern Pacific Ocean: considering host population changes and species body size as sources of variability of parasite communities.

    Science.gov (United States)

    George-Nascimento, Mario; Oliva, Marcelo

    2015-01-01

    Research using parasites in fish population studies in the South Eastern Pacific (SEP) is summarized. There are 27 such studies (snapshots mainly) in single host species sampled at different geographic localities and at somewhat similar times. They have been devoted mainly to economically important species, though others on coastal and intertidal fish or on less- or non-commercial species provide insights on scales of temporal and spatial variation of parasite infracommunities. Later, we assess whether the probability of harbouring parasites depends on the host species body size. Our results indicate that a stronger tool for fish population studies may be developed under regular (long term) scrutiny of parasite communities, especially of small fish host species, due to their larger variability in richness, abundance and total biomass, than in large fish species. Finally, it might also be necessary to consider the effects of fishing on parasite communities as well as the natural oscillations (coupled or not) of host and parasite populations.

  20. Population persistence of stream fish in response to environmental change: integrating data and models across space

    Science.gov (United States)

    Letcher, B. H.; Schueller, P.; Bassar, R.; Coombs, J.; Rosner, A.; Sakrejda, K.; Kanno, Y.; Whiteley, A.; Nislow, K. H.

    2013-12-01

    For stream fishes, environmental variation is a key driver of individual body growth/movement/survival and, by extension, population dynamics. Identifying how stream fish respond to environmental variation can help clarify mechanisms responsible for population dynamics and can help provide tools to forecast relative resilience of populations across space. Forecasting dynamics across space is challenging, however, because it can be difficult to conduct enough studies with enough intensity to fully characterize broad-scale population response to environmental change. We have adopted a multi-scale approach, using detailed individual-based studies and analyses (integral projection matrix) to determine sensitivities of population growth to environmental variation combined with broad spatial data and analyses (occupancy and abundance models) to estimate patterns of population response across space. Population growth of brook trout was most sensitive to stream flow in the spring and winter, most sensitive to stream temperature in the fall and sensitive to both flow and temperature in the summer. High flow in the spring and winter had negative effects on population growth while high temperature had a negative effect in the fall. Flow had no effect when it was cold, but a positive effect when it was warm in the summer. Combined with occupancy and abundance models, these data give insight into the spatial structure of resilient populations and can help guide prioritization of management actions.

  1. Genetic analysis of a red tilapia (Oreochromis spp.) population undergoing three generations of selection for increased body weight at harvest.

    Science.gov (United States)

    Hamzah, Azhar; Thoa, Ngo Phu; Nguyen, Nguyen Hong

    2017-11-01

    Quantitative genetic analysis was performed on 10,919 data records collected over three generations from the selection programme for increased body weight at harvest in red tilapia (Oreochromis spp.). They were offspring of 224 sires and 226 dams (50 sires and 60 dams per generation, on average). Linear mixed models were used to analyse body traits (weight, length, width and depth), whereas threshold generalised models assuming probit distribution were employed to examine genetic inheritance of survival rate, sexual maturity and body colour. The estimates of heritability for traits studied (body weight, standard length, body width, body depth, body colour, early sexual maturation and survival) across statistical models were moderate to high (0.13-0.45). Genetic correlations among body traits and survival were high and positive (0.68-0.96). Body length and width exhibited negative genetic correlations with body colour (- 0.47 to - 0.25). Sexual maturity was genetically correlated positively with measurements of body traits (weight and length). Direct and correlated genetic responses to selection were measured as estimated breeding values in each generation and expressed in genetic standard deviation units (σ G ). The cumulative improvement achieved for harvest body weight was 1.72 σ G after three generations or 12.5% per generation when the gain was expressed as a percentage of the base population. Selection for improved body weight also resulted in correlated increase in other body traits (length, width and depth) and survival rate (ranging from 0.25 to 0.81 genetic standard deviation units). Avoidance of black spot parent matings also improved the overall red colour of the selected population. It is concluded that the selective breeding programme for red tilapia has succeeded in achieving significant genetic improvement for a range of commercially important traits in this species, and the large genetic variation in body colour and survival also shows that

  2. A method for investigating population declines of migratory birds using stable isotopes: origins of harvested lesser scaup in North America.

    Directory of Open Access Journals (Sweden)

    Keith A Hobson

    2009-11-01

    Full Text Available Elucidating geographic locations from where migratory birds are recruited into adult breeding populations is a fundamental but largely elusive goal in conservation biology. This is especially true for species that breed in remote northern areas where field-based demographic assessments are logistically challenging.Here we used hydrogen isotopes (deltaD to determine natal origins of migrating hatch-year lesser scaup (Aythya affinis harvested by hunters in the United States from all North American flyways during the hunting seasons of 1999-2000 (n = 412 and 2000-2001 (n = 455. We combined geospatial, observational, and analytical data sources, including known scaup breeding range, deltaD values of feathers from juveniles at natal sites, models of deltaD for growing-season precipitation, and scaup band-recovery data to generate probabilistic natal origin landscapes for individual scaup. We then used Monte Carlo integration to model assignment uncertainty from among individual deltaD variance estimates from birds of known molt origin and also from band-return data summarized at the flyway level. We compared the distribution of scaup natal origin with the distribution of breeding population counts obtained from systematic long-term surveys.Our analysis revealed that the proportion of young scaup produced in the northern (above 60 degrees N versus the southern boreal and Prairie-Parkland region was inversely related to the proportions of breeding adults using these regions, suggesting that despite having a higher relative abundance of breeding adults, the northern boreal region was less productive for scaup recruitment into the harvest than more southern biomes. Our approach for evaluating population declines of migratory birds (particularly game birds synthesizes all available distributional data and exploits the advantages of intrinsic isotopic markers that link individuals to geography.

  3. Why fishing magnifies fluctuations in fish abundance.

    Science.gov (United States)

    Anderson, Christian N K; Hsieh, Chih-hao; Sandin, Stuart A; Hewitt, Roger; Hollowed, Anne; Beddington, John; May, Robert M; Sugihara, George

    2008-04-17

    It is now clear that fished populations can fluctuate more than unharvested stocks. However, it is not clear why. Here we distinguish among three major competing mechanisms for this phenomenon, by using the 50-year California Cooperative Oceanic Fisheries Investigations (CalCOFI) larval fish record. First, variable fishing pressure directly increases variability in exploited populations. Second, commercial fishing can decrease the average body size and age of a stock, causing the truncated population to track environmental fluctuations directly. Third, age-truncated or juvenescent populations have increasingly unstable population dynamics because of changing demographic parameters such as intrinsic growth rates. We find no evidence for the first hypothesis, limited evidence for the second and strong evidence for the third. Therefore, in California Current fisheries, increased temporal variability in the population does not arise from variable exploitation, nor does it reflect direct environmental tracking. More fundamentally, it arises from increased instability in dynamics. This finding has implications for resource management as an empirical example of how selective harvesting can alter the basic dynamics of exploited populations, and lead to unstable booms and busts that can precede systematic declines in stock levels.

  4. Reversing Period-Doubling Bifurcations in Models of Population Interactions Using Constant Stocking or Harvesting

    Science.gov (United States)

    James F. Selgrade; James H. Roberds

    1998-01-01

    This study considers a general class of two-dimensional, discrete population models where each per capita transition function (fitness) depends on a linear combination of the densities of the interacting populations. The fitness functions are either monotone decreasing functions (pioneer fitnesses) or one-humped functions (climax fitnesses). Conditions are derived...

  5. GENETIC VARIABILITY OF THREE POPULATIONS OF FLYING FISH, Hirundichthy oxycephalus FROM MAKASSAR STRAIT

    Directory of Open Access Journals (Sweden)

    Andi Parenrengi

    2016-03-01

    Full Text Available Flying fish, Hirundichthy oxycephalus is one of economically important marine species to Indonesia, particularly in Makassar Strait and Flores Sea. However, there is a limited published data on genetic variation in molecular marker level of this species. Random Amplified Polymorphic DNA (RAPD was employed in this study to determine the genetic variability of three populations of flying fish collected from Takalar, Pare-Pare, and Majene in Makassar Strait. Genomic DNA was isolated from preserved muscle tissue using phenol-chloroform technique. Two selected arbitrary primers (CA-01 and P-40 were performed to generate RAPD finger printing of flying fish populations. The two primers generated a total of 81 fragments (loci and 50 polymorphic fragments with size ranging from 125 to 1,250 bp. There were no significant differences in number of fragment and number of polymorphic fragment among populations. The high polymorphism (63.5±7.4% was obtained from Takalar population followed by Pare-Pare (58.3±19.6% and Majene population (57.7±0.8%. Similarity index of individuals was 0.60±0.17 for Takalar, 0.63±0.17 for Majene and 0.75±0.21 for Pare-Pare population. Seven fragments were identified as species-specific markers of H. oxycephalus. The UPGMA cluster analysis showed that the Takalar population was genetically closer to Pare-Pare population (D= 0.0812 than to Majene population (D= 0.1873.

  6. Study of physiological and genotoxic status of fish populations of Azerbaijan shore of the Caspian sea

    International Nuclear Information System (INIS)

    Kasimov, R.Yu.; Palatnikov, G.M.; Mekhtiev, A.A.

    2005-01-01

    Full text : According to the studies conducted on Ecotox program of Caspian Ecological program, littoral waters of Azerbaijan and Iran are characterized with high content of heavy metals and organic compounds. Actually, all these substances are not just toxicants but mutagens as well. Taking into account these considerations, it appears important to be aware of physiological and genotoxic status of fish populations dwelling along Azerbaijan shore of the Caspian Sea for present time. The purpose of proposed project is collecting data concerning actual physiological and genotoxic status of fish populations dwelling in the littoral zone of Azerbaijan shore of the Caspian Sea. That will present the real picture of ecological status of ichtyofauna in Azerbaijan sector of the Caspian Sea and give grounds to conduct comparative analysis of changes while conducting all kinds of activities in the sea with the data provided within this project's frames. For this purpose we offer to conduct studies of fish populations along Azerbaijan littoral zone of the Caspian Sea beginning from north ones, sharing all shore into 5-6 points where fish catches should be done. Not less than 5 specimens of attached-dwelling fish, for instance gobies, are planned to catch in each of defined points. Blood samples for genotoxic analysis and samples of muscles, livers and gills for immunochemical and histopathological analysis will be taken. Along with this in these points the analysis of water - oxygen content, ph, salinity, temperature will be realized. Physiological status of fish will be evaluated by determination of serotonin-modulating protein content in ELISA-test. This analysis gives precise estimation of serotonergic system status that is very sensitive to adverse conditions. The second test - histopathological tissue studies gives grounds to determine functional status of internal organs of caught fish. The third test - micronuclei counting in erythrocytes. This technique allows

  7. Population Dynamic Of Rabbit Fish Siganus Canaliculatus In Gulf Of Bone Luwu Regency South Sulawesi

    Directory of Open Access Journals (Sweden)

    Irman Halid

    2015-08-01

    Full Text Available Rabbitfish Siganus canaliculatus is ones of coral reef inhabitants are exploited intensively and suspected population decline so the necessary management measures was needed. The study aims to analyze aspects of the dynamics of rabbit fish populations in the Bone Gulf Luwu waters. Data was collected by Staratied Random Sampling estimation of the size structure the number of age groups and average length of fish per age group use a column diagram and Bhattacharya method. Population growth is analyzed using the Von Bertalanffy equation exponential growth the value of L K by Ford and Walford method and t0 by Pauly method. The total mortality fishing mortality the rate of exploitation and Y R were estimated by methods of Beverton and Holt and natural mortality by method of Pauly. The results showed that the population of rabbit fish in the waters of the Gulf of Bone Luwu consists of five age groups has the average length and the lenth range of 8.0904 cm and 5.7 to 9.0 cm on the relative age of one year 10.9222 cm and 9.0 to 12.3 cm on the relative age of two years from 12.3 to 15.6 cm 14.1543 cm on the relative age of three years 16.8949 cm and 15.6 to 18.9 cm on the relative age four years and 19.4906 cm and 18.9 to 20.7 cm on the relative age of five years. Maximum length Lamp8734 of 30.5814 cm and the growth rate coefficient K of 0.1572 per year while the t0 value of -1.4815 ofyear. The total mortality Z of 1.6913 per year the mortality M of 0.6109 fishing mortality t 1.0804 per year the rate of exploitation E of 0.6388 and optimal exploitation rate Eopt of 0.50 the value of Y R is now 0.0127 and the value of Y R optimal 0.0150. The conclusion that the population is dominated medium sized fish slow population growth as a result of the high mortality rate of the capture and exploitation as well as the recruitment process is not optimal.

  8. Evidence of a high density population of harvested leopards in a montane environment.

    Science.gov (United States)

    Chase Grey, Julia N; Kent, Vivien T; Hill, Russell A

    2013-01-01

    Populations of large carnivores can persist in mountainous environments following extensive land use change and the conversion of suitable habitat for agriculture and human habitation in lower lying areas of their range. The significance of these populations is poorly understood, however, and little attention has focussed on why certain mountainous areas can hold high densities of large carnivores and what the conservation implications of such populations might be. Here we use the leopard (Panthera pardus) population in the western Soutpansberg Mountains, South Africa, as a model system and show that montane habitats can support high numbers of leopards. Spatially explicit capture-recapture (SECR) analysis recorded the highest density of leopards reported outside of state-protected areas in sub-Saharan Africa. This density represents a temporally high local abundance of leopards and we explore the explanations for this alongside some of the potential conservation implications.

  9. Evidence of a high density population of harvested leopards in a montane environment.

    Directory of Open Access Journals (Sweden)

    Julia N Chase Grey

    Full Text Available Populations of large carnivores can persist in mountainous environments following extensive land use change and the conversion of suitable habitat for agriculture and human habitation in lower lying areas of their range. The significance of these populations is poorly understood, however, and little attention has focussed on why certain mountainous areas can hold high densities of large carnivores and what the conservation implications of such populations might be. Here we use the leopard (Panthera pardus population in the western Soutpansberg Mountains, South Africa, as a model system and show that montane habitats can support high numbers of leopards. Spatially explicit capture-recapture (SECR analysis recorded the highest density of leopards reported outside of state-protected areas in sub-Saharan Africa. This density represents a temporally high local abundance of leopards and we explore the explanations for this alongside some of the potential conservation implications.

  10. A moving target--incorporating knowledge of the spatial ecology of fish into the assessment and management of freshwater fish populations.

    Science.gov (United States)

    Cooke, Steven J; Martins, Eduardo G; Struthers, Daniel P; Gutowsky, Lee F G; Power, Michael; Doka, Susan E; Dettmers, John M; Crook, David A; Lucas, Martyn C; Holbrook, Christopher M; Krueger, Charles C

    2016-04-01

    Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions.

  11. THE EFFECT OF CUTANEOUS SECRETIONS OF CYPRINIDAE FISH ON PATHOGENIC BACTERIA ERYSIPELOTHRIX RHUSIOPATHIAE POPULATIONS

    Directory of Open Access Journals (Sweden)

    O. Gulay

    2014-09-01

    Full Text Available Purpose. To investigate the effect of cutaneous secretions of Cyprinidae fish on the populations of pathogenic bacteria Erysipelothrix rhusiopathiae. Methodology. Pieces of filter paper were placed on the skin of live fish. After a 1 min. exposure, they were removed and placed in glass tubes for the extraction of water-soluble components. Tap water was used as a solvent (previously settled for 48 hours; 0,1 cm3 of water were needed for 1 cm2 area of the filter paper. After extraction, the aqueous solution of fish cutaneous secretions was sterilized by filtering it through filters with pore diameter <0,2 µm. The test was carried out with cultures of E. rhusiopathiae bacteria, which were incubated on heart-brain broth at a temperature of +36,7 ± 0,3 °С for 48-hours. After adding the sterilized tap water and cultures of E. rhusiopathiae bacteria, test samples contained fish cutaneous secretions at following ratios: 1:10, 1:100, 1:1000, 1:10000. As a control, sterilized tap water and E. rhusiopathiae bacteria at ratios similar to test samples were used. In 48 hours, samples were taken from the specimens cultured at a temperature of +18...+20 °С for determination of cell density in E. rhusiopathiae populations. Findings. Aquatic environment, which contains the secretions of skin glands of certain Cyprinidae species, creates favorable conditions for the reproduction and increase in the density of pathogenic E. rhusiopathiae populations. In the conditions of freshwater ecosystems, direct topical biocenotical and trophic relations may be created between pathogenic E. rhusiopathiae bacteria and the studied fish species (рrussian carp Carassius auratus gibelio and wild carp Cyprinus. Originality. For the first time we obtained the quantitative data that demonstrate a stimulating effect of cutaneous secretions of certain fish species on pathogenic E. rhusiopathiae populations. Practical value. The stimulating effect of cutaneous secretions of some

  12. Distance, dams and drift: What structures populations of an endangered, benthic stream fish?

    Science.gov (United States)

    Roberts, James H.; Angermeier, Paul; Hallerman, Eric M.

    2013-01-01

    Spatial population structure plays an important role in species persistence, evolution and conservation. Benthic stream fishes are diverse and frequently imperilled, yet the determinants and spatial scaling of their population structure are understudied. We investigated the range-wide population genetic structure of Roanoke logperch (Percina rex), an endangered, benthic stream fish of the eastern United States. Fish were sampled from 35 sites and analysed at 11 microsatellite DNA loci. Clustering models were used to sort individuals into genetically cohesive groups and thereby estimate the spatial scaling of population structure. We then used Bayesian generalized linear mixed models (BGLMMs) to test alternative hypotheses about the environmental factors most responsible for generating structure, as measured by the differentiation statistic FST. Clustering models delineated seven discrete populations, whose boundaries coincided with agents of fragmentation, including hydroelectric dams and tailwaters. In the absence of hydrological barriers, gene flow was extensive throughout catchments, whereas there was no evidence for contemporary dispersal between catchments across barriers. In the best-supported BGLMM, FST was positively related to the spatial distance and degree of hydrological alteration between sites and negatively related to genetic diversity within sites. Whereas the effect of tailwaters was equivocal, dams strongly influenced differentiation: the effect of a dam on FST was comparable to that of a between-site distance of over 1200 km of unimpounded river. Overall, the effect of distance-mediated dispersal was negligible compared to the combined effects of fragmentation and genetic drift. The contemporary population structure of P. rex comprises a few geographically extensive ‘islands’ that are fragmented by hydroelectric projects. This information clarifies the importance of a catchment-scale perspective on conserving the species and

  13. Higher freshwater fish and sea fish intake is inversely associated with colorectal cancer risk among Chinese population: a case-control study

    OpenAIRE

    Xu, Ming; Fang, Yu-Jing; Chen, Yu-Ming; Lu, Min-Shan; Pan, Zhi-Zhong; Yan, Bo; Zhong, Xiao; Zhang, Cai-Xia

    2015-01-01

    The association between specific fish intake and colorectal cancer risk remains controversial. This study aimed to examine the association between specific fish intake and colorectal cancer risk in Chinese population in a large case control study. During July 2010 to November 2014, 1189 eligible colorectal cancer cases and 1189 frequency-matched controls (age and sex) completed in-person interviews. A validated food frequency questionnaire was used to estimate dietary intake. Multivariate log...

  14. Assessment of fish populations and habitat on Oculina Bank, a deep-sea coral marine protected area off eastern Florida

    OpenAIRE

    Harter , Stacey L.; Ribera, Marta M.; Shepard, Andrew N.; Reed, John K.

    2009-01-01

    A portion of the Oculina Bank located off eastern Florida is a marine protected area (MPA) preserved for its dense populations of the ivory tree coral (Oculina varicosa), which provides important habitat for fish. Surveys of fish assemblages and benthic habitat were conducted inside and outside the MPA in 2003 and 2005 by using remotely operated vehicle video transects and digital still imagery. Fish species composition, biodiversity, and grouper densities were used to determine w...

  15. Serum apolipoproteins in relation to intakes of fish in population of Arkhangelsk County

    Directory of Open Access Journals (Sweden)

    Petrenya Natalia

    2012-06-01

    Full Text Available Abstract Background Diets rich in omega-3 fatty acids and low in saturated fat were found beneficially associated with blood lipids and cardio-vascular health. Lean reindeer meet and local cold water white-fish species high in omega-3 are among the main sources of nutrients in the rural area of the Nenets Autonomous Okrug (NAO in Russia and are not normally consumed by the urban population from the same region. The aims of the study were firstly, to compare serum lipid profiles of residents of urban (Arkhangelsk city and rural (NAO regions of Arkhangelsk County, and secondly, to investigate the effects of fish consumption on the predictor of cardiovascular events apolipoprotein (Apo B/ApoA-I ratio in these populations. Methods A cross-sectional study conducted in Arkhangelsk County, Russia. Sample size of 249 adults: 132 subjects from Arkhangelsk city, aged 21–70 and 117 subject (87% Ethnic Nenets from NAO, aged 18–69. Results We observed more favorable lipid levels in NAO compared to Arkhangelsk participants. Age-adjusted geometric means of ApoB/ApoA-I ratio were 1.02 and 0.98 in men and women from Arkhangelsk; 0.84 and 0.91 in men and women from NAO respectively. Age and consumption of animal fat were positively associated with ApoB/ApoA-I ratio in women (pooled samples from Arkhangelsk and NAO. Body mass index and low levels of physical activity were positively associated with ApoB/ApoA-I ratio in men (pooled samples from Arkhangelsk and NAO. Reported oily fish consumption was not significantly correlated with ApoB/ApoA-I ratio. Conclusion The population sample from rural NAO, consisting largely of the indigenous Arctic population Nenets with healthier dietary sources, had a relatively less atherogenic lipid profile compared to the urban Arkhangelsk group. Fish consumption had no effect on apolipoproteins profile.

  16. Master Middle Ware: A Tool to Integrate Water Resources and Fish Population Dynamics Models

    Science.gov (United States)

    Yi, S.; Sandoval Solis, S.; Thompson, L. C.; Kilduff, D. P.

    2017-12-01

    Linking models that investigate separate components of ecosystem processes has the potential to unify messages regarding management decisions by evaluating potential trade-offs in a cohesive framework. This project aimed to improve the ability of riparian resource managers to forecast future water availability conditions and resultant fish habitat suitability, in order to better inform their management decisions. To accomplish this goal, we developed a middleware tool that is capable of linking and overseeing the operations of two existing models, a water resource planning tool Water Evaluation and Planning (WEAP) model and a habitat-based fish population dynamics model (WEAPhish). First, we designed the Master Middle Ware (MMW) software in Visual Basic for Application® in one Excel® file that provided a familiar framework for both data input and output Second, MMW was used to link and jointly operate WEAP and WEAPhish, using Visual Basic Application (VBA) macros to implement system level calls to run the models. To demonstrate the utility of this approach, hydrological, biological, and middleware model components were developed for the Butte Creek basin. This tributary of the Sacramento River, California is managed for both hydropower and the persistence of a threatened population of spring-run Chinook salmon (Oncorhynchus tschawytscha). While we have demonstrated the use of MMW for a particular watershed and fish population, MMW can be customized for use with different rivers and fish populations, assuming basic data requirements are met. This model integration improves on ad hoc linkages for managing data transfer between software programs by providing a consistent, user-friendly, and familiar interface across different model implementations. Furthermore, the data-viewing capabilities of MMW facilitate the rapid interpretation of model results by hydrologists, fisheries biologists, and resource managers, in order to accelerate learning and management decision

  17. The fate of populations of Euterpe oleracea harvested for palm heart in Colombia

    NARCIS (Netherlands)

    Vallejo, M.I.; Galeano, G.; Bernal, R.; Zuidema, P.

    2014-01-01

    Palm heart is an important non-timber forest product obtained from various palm species in tropical forests. We studied the effect of four decades of palm heart extraction from the clonal palm Euterpe oleracea at the southern Pacific coast of Colombia. We monitored populations that had been subject

  18. Artificial barriers prevent genetic recovery of small isolated populations of a low-mobility freshwater fish.

    Science.gov (United States)

    Coleman, R A; Gauffre, B; Pavlova, A; Beheregaray, L B; Kearns, J; Lyon, J; Sasaki, M; Leblois, R; Sgro, C; Sunnucks, P

    2018-01-12

    Habitat loss and fragmentation often result in small, isolated populations vulnerable to environmental disturbance and loss of genetic diversity. Low genetic diversity can increase extinction risk of small populations by elevating inbreeding and inbreeding depression, and reducing adaptive potential. Due to their linear nature and extensive use by humans, freshwater ecosystems are especially vulnerable to habitat loss and fragmentation. Although the effects of fragmentation on genetic structure have been extensively studied in migratory fishes, they are less understood in low-mobility species. We estimated impacts of instream barriers on genetic structure and diversity of the low-mobility river blackfish (Gadopsis marmoratus) within five streams separated by weirs or dams constructed 45-120 years ago. We found evidence of small-scale (barriers, as expected for a fish with low mobility. Genetic diversity was lower above barriers in small streams only, regardless of barrier age. In particular, one isolated population showed evidence of a recent bottleneck and inbreeding. Differentiation above and below the barrier (F ST  = 0.13) was greatest in this stream, but in other streams did not differ from background levels. Spatially explicit simulations suggest that short-term barrier effects would not be detected with our data set unless effective population sizes were very small (barriers is reduced and requires more genetic markers compared to panmictic populations. We also demonstrate the importance of accounting for natural population genetic structure in fragmentation studies.

  19. Fish population genetic structure shaped by hydroelectric power plants in the upper Rhine catchment.

    Science.gov (United States)

    Gouskov, Alexandre; Reyes, Marta; Wirthner-Bitterlin, Lisa; Vorburger, Christoph

    2016-02-01

    The Rhine catchment in Switzerland has been transformed by a chain of hydroelectric power stations. We addressed the impact of fragmentation on the genetic structure of fish populations by focusing on the European chub (Squalius cephalus). This fish species is not stocked and copes well with altered habitats, enabling an assessment of the effects of fragmentation per se. Using microsatellites, we genotyped 2133 chub from 47 sites within the catchment fragmented by 37 hydroelectric power stations, two weirs and the Rhine Falls. The shallow genetic population structure reflected drainage topology and was affected significantly by barriers to migration. The effect of power stations equipped with fishpasses on genetic differentiation was detectable, albeit weaker than that of man-made barriers without fishpasses. The Rhine Falls as the only long-standing natural obstacle (formed 14 000 to 17 000 years ago) also had a strong effect. Man-made barriers also exacerbated the upstream decrease in allelic diversity in the catchment, particularly when lacking fishpasses. Thus, existing fishpasses do have the desired effect of mitigating fragmentation, but barriers still reduce population connectivity in a fish that traverses fishpasses better than many other species. Less mobile species are likely to be affected more severely.

  20. Biomarkers in natural fish populations indicate adverse biological effects of offshore oil production.

    Directory of Open Access Journals (Sweden)

    Lennart Balk

    Full Text Available Despite the growing awareness of the necessity of a sustainable development, the global economy continues to depend largely on the consumption of non-renewable energy resources. One such energy resource is fossil oil extracted from the seabed at offshore oil platforms. This type of oil production causes continuous environmental pollution from drilling waste, discharge of large amounts of produced water, and accidental spills.Samples from natural populations of haddock (Melanogrammus aeglefinus and Atlantic cod (Gadus morhua in two North Sea areas with extensive oil production were investigated. Exposure to and uptake of polycyclic aromatic hydrocarbons (PAHs were demonstrated, and biomarker analyses revealed adverse biological effects, including induction of biotransformation enzymes, oxidative stress, altered fatty acid composition, and genotoxicity. Genotoxicity was reflected by a hepatic DNA adduct pattern typical for exposure to a mixture of PAHs. Control material was collected from a North Sea area without oil production and from remote Icelandic waters. The difference between the two control areas indicates significant background pollution in the North Sea.It is most remarkable to obtain biomarker responses in natural fish populations in the open sea that are similar to the biomarker responses in fish from highly polluted areas close to a point source. Risk assessment of various threats to the marine fish populations in the North Sea, such as overfishing, global warming, and eutrophication, should also take into account the ecologically relevant impact of offshore oil production.

  1. Evidence of population resistance to extreme low flows in a fluvial-dependent fish species

    Science.gov (United States)

    Katz, Rachel A.; Freeman, Mary C.

    2015-01-01

    Extreme low streamflows are natural disturbances to aquatic populations. Species in naturally intermittent streams display adaptations that enhance persistence during extreme events; however, the fate of populations in perennial streams during unprecedented low-flow periods is not well-understood. Biota requiring swift-flowing habitats may be especially vulnerable to flow reductions. We estimated the abundance and local survival of a native fluvial-dependent fish species (Etheostoma inscriptum) across 5 years encompassing historic low flows in a sixth-order southeastern USA perennial river. Based on capturemark-recapture data, the study shoal may have acted as a refuge during severe drought, with increased young-of-the-year (YOY) recruitment and occasionally high adult immigration. Contrary to expectations, summer and autumn survival rates (30 days) were not strongly depressed during low-flow periods, despite 25%-80% reductions in monthly discharge. Instead, YOY survival increased with lower minimum discharge and in response to small rain events that increased low-flow variability. Age-1+ fish showed the opposite pattern, with survival decreasing in response to increasing low-flow variability. Results from this population dynamics study of a small fish in a perennial river suggest that fluvial-dependent species can be resistant to extreme flow reductions through enhanced YOY recruitment and high survival

  2. Complex small pelagic fish population patterns arising from individual behavioral responses to their environment

    Science.gov (United States)

    Brochier, Timothée; Auger, Pierre-Amaël; Pecquerie, Laure; Machu, Eric; Capet, Xavier; Thiaw, Modou; Mbaye, Baye Cheikh; Braham, Cheikh-Baye; Ettahiri, Omar; Charouki, Najib; Sène, Ousseynou Ndaw; Werner, Francisco; Brehmer, Patrice

    2018-05-01

    Small pelagic fish (SPF) species are heavily exploited in eastern boundary upwelling systems (EBUS) as their transformation products are increasingly used in the world's food chain. Management relies on regular monitoring, but there is a lack of robust theories for the emergence of the populations' traits and their evolution in highly variable environments. This work aims to address existing knowledge gaps by combining physical and biogeochemical modelling with an individual life-cycle based model applied to round sardinella (Sardinella aurita) off northwest Africa, a key species for regional food security. Our approach focused on the processes responsible for seasonal migrations, spatio-temporal size-structure, and interannual biomass fluctuations. Emergence of preferred habitat resulted from interactions between natal homing behavior and environmental variability that impacts early life stages. Exploration of the environment by the fishes was determined by swimming capabilities, mesoscale to regional habitat structure, and horizontal currents. Fish spatio-temporal abundance variability emerged from a complex combination of distinct life-history traits. An alongshore gradient in fish size distributions is reported and validated by in situ measurements. New insights into population structure are provided, within an area where the species is abundant year-round (Mauritania) and with latitudinal migrations of variable (300-1200 km) amplitude. Interannual biomass fluctuations were linked to modulations of fish recruitment over the Sahara Bank driven by variability in alongshore current intensity. The identified processes constitute an analytical framework that can be implemented in other EBUS and used to explore impacts of regional climate change on SPF.

  3. Assessing the impact of power plant mortality on the compensatory reserve of fish populations

    International Nuclear Information System (INIS)

    Goodyear, C.P.

    1977-01-01

    A technique is presented to quantify the concepts of compensation and compensatory reserve in exploited fish populations. The technique was used to examine the impact of power plant mortality on a hypothetical striped bass population. Power plant mortality had a more severe impact on the compensation ratio and compensatory reserve for an exploited stock. The technique can be applied to determine a critical compensation ratio which could serve as a standard against which additional sources of mortality, such as those caused by power plants, could be measured

  4. Estimation of age structure of fish populations from length-frequency data

    International Nuclear Information System (INIS)

    Kumar, K.D.; Adams, S.M.

    1977-01-01

    A probability model is presented to determine the age structure of a fish population from length-frequency data. It is shown that when the age-length key is available, maximum-likelihood estimates of the age structure can be obtained. When the key is not available, approximate estimates of the age structure can be obtained. The model is used for determination of the age structure of populations of channel catfish and white crappie. Practical applications of the model to impact assessment are discussed

  5. Life cycle ecophysiology of small pelagic fish and climate-driven changes in populations

    Science.gov (United States)

    Peck, Myron A.; Reglero, Patricia; Takahashi, Motomitsu; Catalán, Ignacio A.

    2013-09-01

    Due to their population characteristics and trophodynamic role, small pelagic fishes are excellent bio-indicators of climate-driven changes in marine systems world-wide. We argue that making robust projections of future changes in the productivity and distribution of small pelagics will require a cause-and-effect understanding of historical changes based upon physiological principles. Here, we reviewed the ecophysiology of small pelagic (clupeiform) fishes including a matrix of abiotic and biotic extrinsic factors (e.g., temperature, salinity, light, and prey characteristics) and stage-specific vital rates: (1) adult spawning, (2) survival and development of eggs and yolk sac larvae, and (3) feeding and growth of larvae, post-larvae and juveniles. Emphasis was placed on species inhabiting Northwest Pacific and Northeast Atlantic (European) waters for which summary papers are particularly scarce compared to anchovy and sardine in upwelling systems. Our review revealed that thermal niches (optimal and sub-optimal ranges in temperatures) were species- and stage-specific but that temperature effects only partly explained observed changes in the distribution and/or productivity of populations in the Northwest Pacific and Northeast Atlantic; changes in temperature may be necessary but not sufficient to induce population-level shifts. Prey availability during the late larval and early juvenile period was a common, density-dependent mechanism linked to fluctuations in populations but recruitment mechanisms were system-specific suggesting that generalizations of climate drivers across systems should be avoided. We identified gaps in knowledge regarding basic elements of the growth physiology of each life stage that will require additional field and laboratory study. Avenues of research are recommended that will aid the development of models that provide more robust, physiological-based projections of the population dynamics of these and other small pelagic fish. In our

  6. 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

  7. Development of fish populations in seismostrsss conditions of the south of Russia

    Directory of Open Access Journals (Sweden)

    P. V. Lyushvin

    2009-01-01

    Full Text Available The last decades communications between reproduction of many food fishes and traditionally considered factors are lost, is unpredictable time recessions food are observed. The purpose of thepresent work to show, that in the seismo-seas of the south of Russia where there is a unloading litosheric fluids, seismo factors often are defining in reproduction fishes. Earthquakes lead to shortterm unloadings on breaks of an earth's crust through the made active volcanos and griffins of hundreds tons litosheric waters and km³ gases (metane, hydrogen, hydrogen sulphide, radon, etc.. Presence of some of these fluids even in midget concentration (less than 0.1-1 ml/½ causes destruction young fishes, infringement of reproductive functions due to what the food base crabs grows, and after their reproduction and extraction. Landslide reductions of fish populations in current decade it is caused by passage of a maximum of century cyclicity of earthquakes.

  8. 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.

  9. 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

  10. Population and harvest trends of big game and small game species: a technical document supporting the USDA Forest Service Interim Update of the 2000 RPA Assessment

    Science.gov (United States)

    Curtis H. Flather; Michael S. Knowles; Stephen J. Brady

    2009-01-01

    This technical document supports the Forest Service's requirement to assess the status of renewable natural resources as mandated by the Forest and Rangeland Renewable Resources Planning Act of 1974 (RPA). It updates past reports on national and regional trends in population and harvest estimates for species classified as big game and small game. The trends...

  11. Fish and fire: Post-wildfire sediment dynamics and implications for the viability of trout populations

    Science.gov (United States)

    Murphy, B. P.; Czuba, J. A.; Belmont, P.; Budy, P.; Finch, C.

    2017-12-01

    Episodic events in steep landscapes, such as wildfire and mass wasting, contribute large pulses of sediment to rivers and can significantly alter the quality and connectivity of fish habitat. Understanding where these sediment inputs occur, how they are transported and processed through the watershed, and their geomorphic effect on the river network is critical to predicting the impact on ecological aquatic communities. The Tushar Mountains of southern Utah experienced a severe wildfire in 2010, resulting in numerous debris flows and the extirpation of trout populations. Following many years of habitat and ecological monitoring in the field, we have developed a modeling framework that links post-wildfire debris flows, fluvial sediment routing, and population ecology in order to evaluate the impact and response of trout to wildfire. First, using the Tushar topographic and wildfire parameters, as well as stochastic precipitation generation, we predict the post-wildfire debris flow probabilities and volumes of mainstem tributaries using the Cannon et al. [2010] model. This produces episodic hillslope sediment inputs, which are delivered to a fluvial sediment, river-network routing model (modified from Czuba et al. [2017]). In this updated model, sediment transport dynamics are driven by time-varying discharge associated with the stochastic precipitation generation, include multiple grain sizes (including gravel), use mixed-size transport equations (Wilcock & Crowe [2003]), and incorporate channel slope adjustments with aggradation and degradation. Finally, with the spatially explicit adjustments in channel bed elevation and grain size, we utilize a new population viability analysis (PVA) model to predict the impact and recovery of fish populations in response to these changes in habitat. Our model provides a generalizable framework for linking physical and ecological models and for evaluating the extirpation risk of isolated fish populations throughout the

  12. The scaling of population persistence with carrying capacity does not asymptote in populations of a fish experiencing extreme climate variability.

    Science.gov (United States)

    White, Richard S A; Wintle, Brendan A; McHugh, Peter A; Booker, Douglas J; McIntosh, Angus R

    2017-06-14

    Despite growing concerns regarding increasing frequency of extreme climate events and declining population sizes, the influence of environmental stochasticity on the relationship between population carrying capacity and time-to-extinction has received little empirical attention. While time-to-extinction increases exponentially with carrying capacity in constant environments, theoretical models suggest increasing environmental stochasticity causes asymptotic scaling, thus making minimum viable carrying capacity vastly uncertain in variable environments. Using empirical estimates of environmental stochasticity in fish metapopulations, we showed that increasing environmental stochasticity resulting from extreme droughts was insufficient to create asymptotic scaling of time-to-extinction with carrying capacity in local populations as predicted by theory. Local time-to-extinction increased with carrying capacity due to declining sensitivity to demographic stochasticity, and the slope of this relationship declined significantly as environmental stochasticity increased. However, recent 1 in 25 yr extreme droughts were insufficient to extirpate populations with large carrying capacity. Consequently, large populations may be more resilient to environmental stochasticity than previously thought. The lack of carrying capacity-related asymptotes in persistence under extreme climate variability reveals how small populations affected by habitat loss or overharvesting, may be disproportionately threatened by increases in extreme climate events with global warming. © 2017 The Author(s).

  13. Heavy metal distribution and bioaccumulation in Chihuahuan Desert Rough Harvester ant (Pogonomyrmex rugosus) populations

    International Nuclear Information System (INIS)

    Del Toro, I.; Floyd, K.; Gardea-Torresdey, J.; Borrok, D.

    2010-01-01

    Heavy metal contamination can negatively impact arid ecosystems; however a thorough examination of bioaccumulation patterns has not been completed. We analyzed the distribution of As, Cd, Cu, Pb and Zn in soils, seeds and ant (Pogonomyrmex rugosus) populations of the Chihuahuan Desert near El Paso, TX, USA. Concentrations of As, Cd, Cu, and Pb in soils, seeds and ants declined as a function of distance from a now inactive Cu and Pb smelter and all five metals bioaccumulated in the granivorous ants. The average bioaccumulation factors for the metals from seeds to ants ranged from 1.04x (As) to 8.12x (Cd). The findings show bioaccumulation trends in linked trophic levels in an arid ecosystem and further investigation should focus on the impacts of heavy metal contamination at the community level. - Heavy metals bioaccumulate in desert ants.

  14. Protocol and Practice in the Adaptive Management of Waterfowl Harvests

    Directory of Open Access Journals (Sweden)

    Fred Johnson

    1999-06-01

    Full Text Available Waterfowl harvest management in North America, for all its success, historically has had several shortcomings, including a lack of well-defined objectives, a failure to account for uncertain management outcomes, and inefficient use of harvest regulations to understand the effects of management. To address these and other concerns, the U.S. Fish and Wildlife Service began implementation of adaptive harvest management in 1995. Harvest policies are now developed using a Markov decision process in which there is an explicit accounting for uncontrolled environmental variation, partial controllability of harvest, and structural uncertainty in waterfowl population dynamics. Current policies are passively adaptive, in the sense that any reduction in structural uncertainty is an unplanned by-product of the regulatory process. A generalization of the Markov decision process permits the calculation of optimal actively adaptive policies, but it is not yet clear how state-specific harvest actions differ between passive and active approaches. The Markov decision process also provides managers the ability to explore optimal levels of aggregation or "management scale" for regulating harvests in a system that exhibits high temporal, spatial, and organizational variability. Progress in institutionalizing adaptive harvest management has been remarkable, but some managers still perceive the process as a panacea, while failing to appreciate the challenges presented by this more explicit and methodical approach to harvest regulation. Technical hurdles include the need to develop better linkages between population processes and the dynamics of landscapes, and to model the dynamics of structural uncertainty in a more comprehensive fashion. From an institutional perspective, agreement on how to value and allocate harvests continues to be elusive, and there is some evidence that waterfowl managers have overestimated the importance of achievement-oriented factors in

  15. Global multi-decadal ocean climate and small-pelagic fish population

    International Nuclear Information System (INIS)

    Tourre, Yves M; Lluch-Cota, Salvador E; White, Warren B

    2007-01-01

    Ocean climate, environmental and biological conditions vary on several spatio-temporal scales. Besides climate change associated with anthropogenic activity, there is growing evidence of a natural global multi-decadal climate signal in the ocean-atmosphere-biosphere climate system. The spatio-temporal evolution of this signal is thus analyzed during the 20th century and compared to the variability of small-pelagic fish landings. It is argued that the low-frequency global ocean environment and plankton ecosystems must be modified such that small-pelagic populations vary accordingly. A small-pelagic global index or fishing 'regime indicator series' (RIS) (i.e. a small-pelagic abundance indicator) is used. RIS is derived from fish landings data in the four main fishing areas in the Pacific and Atlantic oceans. Global RIS changes phase (from positive to negative values) when SST multi-decadal anomalies are out-of-phase between the eastern Pacific and southern Atlantic. RIS also displays maxima during the mid-30s to early-40s and the late-70s to early-80s when the multi-decadal signal was approximately changing phases (Tourre and White 2006 Geophys. Res. Lett. 33 L06716). It is recognized that other factors may modulate fish stocks, including anthropogenic predation. Nevertheless it is proposed that variable climate and environment, and the low-frequency 'global synchrony' of small-pelagic landings (Schwartzlose et al 1999 S. Afr. J. Mar. Sci. 21 289-347), could be associated with the multi-decadal changes in global ocean climate conditions

  16. Monitoring of East Channel dredge areas benthic fish population and its implications

    International Nuclear Information System (INIS)

    Drabble, Ray

    2012-01-01

    Regional annual sampling of commercial fish stocks formed a high priority for monitoring studies attendant with the granting of aggregate dredging licenses in the Eastern Channel Region (ECR) which had previously not been dredged. An assessment of 4 m beam trawl sampling between 2005 and 2008 following the granting of licences in 2006 is provided. The majority of fish species have shown marked reductions in abundance since commencement of dredging. Draghead entrainment has been identified as a possible contributory cause based upon the known vulnerability of selected species (). Other environmental factors considered offer no explanation for the changes in abundance. Comparative analyses with ICES data for plaice and sole over the study period demonstrate that changes in the ECR do not result from seasonal flux in the wider populations. An alternative impact model and potential mitigation measures are suggested.

  17. Distribution and abundance of fish populations in the Middle Wabash River

    International Nuclear Information System (INIS)

    Teppen, T.C.; Gammon, J.R.

    1976-01-01

    A field investigation was made of the distribution and abundance of fish within a 161-km portion of the Wabash River to determine effects of heated effluents as well as changes in water quality on ichthyofaunal communities within the river. Twenty-six sampling stations were electrofished, sequentially, four times in 1974 with extended sampling efforts made in the vicinity of two power-generating stations studied since 1967 and 1968. During August an overall rise in river temperature of 4 0 C was observed from upstream to downstream, with several chemical factors also showing slight increases. Although the majority of species populations were influenced either negatively or positively by the gradient of river conditions available to them, the only statistically significant parameters found in the analysis of community structure involved a lower diversity by weight below Terre Haute and a greater abundance of fish above the Cayuga generating station. Decreases occurred downstream in populations of redhorse (Moxostoma sp.), sauger (Stizostedion canadense), longear sunfish (Lepomis megalotis), and gizzard shad (Dorosoma cepedianum), with increases downstream observed in flathead catfish (Pylodictis olivaris), shortnose gar (Lepisosteus platostomus), longnose gar (E. osseus), and bowfin (Amia calva) populations. Carp (Cyprinus carpio) were present in large numbers throughout the study area with a tremendous population increase evident in recent years. Although species associations were variable among the segments, overall community parameters remained relatively unaffected

  18. Comparing climate change and species invasions as drivers of coldwater fish population extirpations.

    Directory of Open Access Journals (Sweden)

    Sapna Sharma

    Full Text Available Species are influenced by multiple environmental stressors acting simultaneously. Our objective was to compare the expected effects of climate change and invasion of non-indigenous rainbow smelt (Osmerus mordax on cisco (Coregonus artedii population extirpations at a regional level. We assembled a database of over 13,000 lakes in Wisconsin, USA, summarising fish occurrence, lake morphology, water chemistry, and climate. We used A1, A2, and B1 scenarios from the Intergovernmental Panel on Climate Change (IPCC of future temperature conditions for 15 general circulation models in 2046-2065 and 2081-2100 totalling 78 projections. Logistic regression indicated that cisco tended to occur in cooler, larger, and deeper lakes. Depending upon the amount of warming, 25-70% of cisco populations are predicted to be extirpated by 2100. In addition, cisco are influenced by the invasion of rainbow smelt, which prey on young cisco. Projecting current estimates of rainbow smelt spread and impact into the future will result in the extirpation of about 1% of cisco populations by 2100 in Wisconsin. Overall, the effect of climate change is expected to overshadow that of species invasion as a driver of coldwater fish population extirpations. Our results highlight the potentially dominant role of climate change as a driver of biotic change.

  19. Modeling the fish community population dynamics and forecasting the eradication success of an exotic fish from an alpine stream

    Science.gov (United States)

    Laplanche, Christophe; Elger, Arnaud; Santoul, Frédéric; Thiede, Gary P.; Budy, Phaedra

    2018-01-01

    Management actions aimed at eradicating exotic fish species from riverine ecosystems can be better informed by forecasting abilities of mechanistic models. We illustrate this point with an example of the Logan River, Utah, originally populated with endemic cutthroat trout (Oncorhynchus clarkii utah), which compete with exotic brown trout (Salmo trutta). The coexistence equilibrium was disrupted by a large scale, experimental removal of the exotic species in 2009–2011 (on average, 8.2% of the stock each year), followed by an increase in the density of the native species. We built a spatially-explicit, reaction-diffusion model encompassing four key processes: population growth in heterogeneous habitat, competition, dispersal, and a management action. We calibrated the model with detailed long-term monitoring data (2001–2016) collected along the 35.4-km long river main channel. Our model, although simple, did a remarkable job reproducing the system steady state prior to the management action. Insights gained from the model independent predictions are consistent with available knowledge and indicate that the exotic species is more competitive; however, the native species still occupies more favorable habitat upstream. Dynamic runs of the model also recreated the observed increase of the native species following the management action. The model can simulate two possible distinct long-term outcomes: recovery or eradication of the exotic species. The processing of available knowledge using Bayesian methods allowed us to conclude that the chance for eradication of the invader was low at the beginning of the experimental removal (0.7% in 2009) and increased (20.5% in 2016) by using more recent monitoring data. We show that accessible mathematical and numerical tools can provide highly informative insights for managers (e.g., outcome of their conservation actions), identify knowledge gaps, and provide testable theory for researchers.

  20. Population structure, fluctuating asymmetry and genetic variability in an endemic and highly isolated Astyanax fish population (Characidae

    Directory of Open Access Journals (Sweden)

    Maria Claudia Gross

    2004-01-01

    Full Text Available Morphological and chromosomal markers were used to infer the structure and genetic variability of a population of fish of the genus Astyanax, geographically isolated at sinkhole 2 of Vila Velha State Park, Paraná, Brazil. Two morphotypes types were observed, the standard phenotype I and phenotype II which showed an anatomical alteration probably due to an inbreeding process. Fluctuating asymmetry (FA analysis of different characters showed low levels of morphological variation among the population from sinkhole 2 and in another population from the Tibagi river (Paraná, Brazil. The Astyanax karyotype was characterized in terms of chromosomal morphology, constitutive heterochromatin and nucleolar organizer regions. Males and females presented similar karyotypes (2n=48, 6M+18SM+14ST+10A with no evidence of a sex chromosome system. One female from sinkhole 2 was a natural triploid with 2n=3x=72 chromosomes (9M+27SM+21ST+15A. The data are discussed regarding the maintenance of population structure and their evolutionary importance, our data suggesting that Astyanax from the Vila Velha State Park sinkhole 2 is a recently isolated population.

  1. Learning and adaptation in the management of waterfowl harvests

    Science.gov (United States)

    Johnson, Fred A.

    2011-01-01

    A formal framework for the adaptive management of waterfowl harvests was adopted by the U.S. Fish and Wildlife Service in 1995. The process admits competing models of waterfowl population dynamics and harvest impacts, and relies on model averaging to compute optimal strategies for regulating harvest. Model weights, reflecting the relative ability of the alternative models to predict changes in population size, are used in the model averaging and are updated each year based on a comparison of model predictions and observations of population size. Since its inception the adaptive harvest program has focused principally on mallards (Anas platyrhynchos), which constitute a large portion of the U.S. waterfowl harvest. Four competing models, derived from a combination of two survival and two reproductive hypotheses, were originally assigned equal weights. In the last year of available information (2007), model weights favored the weakly density-dependent reproductive hypothesis over the strongly density-dependent one, and the additive mortality hypothesis over the compensatory one. The change in model weights led to a more conservative harvesting policy than what was in effect in the early years of the program. Adaptive harvest management has been successful in many ways, but nonetheless has exposed the difficulties in defining management objectives, in predicting and regulating harvests, and in coping with the tradeoffs inherent in managing multiple waterfowl stocks exposed to a common harvest. The key challenge now facing managers is whether adaptive harvest management as an institution can be sufficiently adaptive, and whether the knowledge and experience gained from the process can be reflected in higher-level policy decisions.

  2. Discovering and differentiating new and emerging clonal populations of Chlamydia trachomatis with a novel shotgun cell culture harvest assay.

    Science.gov (United States)

    Somboonna, Naraporn; Mead, Sally; Liu, Jessica; Dean, Deborah

    2008-03-01

    Chlamydia trachomatis is the leading cause of preventable blindness and bacterial sexually transmitted diseases worldwide. Plaque assays have been used to clonally segregate laboratory-adapted C. trachomatis strains from mixed infections, but no assays have been reported to segregate clones from recent clinical samples. We developed a novel shotgun cell culture harvest assay for this purpose because we found that recent clinical samples do not form plaques. Clones were strain-typed by using outer membrane protein A and 16S rRNA sequences. Surprisingly, ocular trachoma reference strain A/SA-1 contained clones of Chlamydophila abortus. C. abortus primarily infects ruminants and pigs and has never been identified in populations where trachoma is endemic. Three clonal variants of reference strain Ba/Apache-2 were also identified. Our findings reflect the importance of clonal isolation in identifying constituents of mixed infections containing new or emerging strains and of viable clones for research to more fully understand the dynamics of in vivo strain-mixing, evolution, and disease pathogenesis.

  3. Specific IgE to fish extracts does not predict allergy to specific species within an adult fish allergic population.

    Science.gov (United States)

    Schulkes, Karlijn Jg; Klemans, Rob Jb; Knigge, Lidy; de Bruin-Weller, Marjolein; Bruijnzeel-Koomen, Carla Afm; Marknell deWitt, Asa; Lidholm, Jonas; Knulst, André C

    2014-01-01

    Fish is an important cause of food allergy. Studies on fish allergy are scarce and in most cases limited to serological evaluation. Our objective was to study patterns of self-reported allergy and tolerance to different commonly consumed fish species and its correlation to IgE sensitization to the same species. Thirty-eight adult fish allergic patients completed a questionnaire regarding atopy, age of onset and symptoms to 13 commonly consumed fish species in the Netherlands (pangasius, cod, herring, eel, hake, pollock, mackerel, tilapia, salmon, sardine, tuna, plaice and swordfish). Specific IgE to these fish extracts were analyzed by ImmunoCAP. Median age of onset of fish allergy was 8.5 years. Severe reactions were reported by the majority of patients (n = 20 (53%) respiratory and of these 20 patients, 6 also had cardiovascular symptoms). After diagnosis, 66% of the patients had eliminated all fish from their diet. Allergy to all species ever tried was reported by 59%. In relation to species ever tried, cod (84%) and herring (79%) were the most frequently reported culprit species while hake (57%) and swordfish (55%) were the least frequent. A positive sIgE (value ≥ 0.35 kUA/L) to the culprit species ranged between 50% (swordfish) and 100% (hake). In tolerant patients, a negative sIgE (value allergy or tolerance was 82% and 25%, respectively. Sensitization to cod parvalbumin (Gad c 1) was present in 77% of all patients. Serological cross-reactivity between fish species is frequent, but in a significant proportion of patients, clinical relevance appears to be limited to only certain species. A well-taken history or food challenge is required for discrimination between allergy to the different fish species.

  4. Omics and Environmental Science Genomic Approaches With Natural Fish Populations From Polluted Environments

    Science.gov (United States)

    Bozinovic, Goran; Oleksiak, Marjorie F.

    2010-01-01

    Transcriptomics and population genomics are two complementary genomic approaches that can be used to gain insight into pollutant effects in natural populations. Transcriptomics identify altered gene expression pathways while population genomics approaches more directly target the causative genomic polymorphisms. Neither approach is restricted to a pre-determined set of genes or loci. Instead, both approaches allow a broad overview of genomic processes. Transcriptomics and population genomic approaches have been used to explore genomic responses in populations of fish from polluted environments and have identified sets of candidate genes and loci that appear biologically important in response to pollution. Often differences in gene expression or loci between polluted and reference populations are not conserved among polluted populations suggesting a biological complexity that we do not yet fully understand. As genomic approaches become less expensive with the advent of new sequencing and genotyping technologies, they will be more widely used in complimentary studies. However, while these genomic approaches are immensely powerful for identifying candidate gene and loci, the challenge of determining biological mechanisms that link genotypes and phenotypes remains. PMID:21072843

  5. 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.

  6. Higher freshwater fish and sea fish intake is inversely associated with colorectal cancer risk among Chinese population: a case-control study.

    Science.gov (United States)

    Xu, Ming; Fang, Yu-Jing; Chen, Yu-Ming; Lu, Min-Shan; Pan, Zhi-Zhong; Yan, Bo; Zhong, Xiao; Zhang, Cai-Xia

    2015-08-12

    The association between specific fish intake and colorectal cancer risk remains controversial. This study aimed to examine the association between specific fish intake and colorectal cancer risk in Chinese population in a large case control study. During July 2010 to November 2014, 1189 eligible colorectal cancer cases and 1189 frequency-matched controls (age and sex) completed in-person interviews. A validated food frequency questionnaire was used to estimate dietary intake. Multivariate logistical regression models were used to estimate the odds ratio (OR) and 95% confidence interval (95% CI) after adjusting for various confounders. A strong inverse association was found between freshwater fish intake and colorectal cancer risk. Compared with the lowest quartile, the highest quartile intake showed a risk reduction of 53% (OR 0.47, 95% CI = 0.36-0.60, Ptrend colorectal cancer risk. These results indicate that higher consumption of freshwater fish, sea fish and fresh fish is associated with a lower risk of colorectal caner.

  7. Population changes in a biofilm reactor for phosphorus removal as evidenced by the use of FISH

    DEFF Research Database (Denmark)

    Falkentoft, C.M.; Müller, E.; Arnz, P.

    2002-01-01

    as in the first run was seen after one month, although the phase lengths had not been varied. Hence, the decrease after 1 month in the first and second run should be seen as a start-up phenomenon. FISH could detect a noticeable shift in the microbial population mainly within the first 2 weeks ofoperation. Almost...... hybridised to the dominant bacterial groups in the reactors investigated. No noticeable changes were detected in the aerobic bench-scale reactor during this period, indicating that the observed changes in the lab-scale reactor were caused by the changed environment. r 2002 Elsevier Science Ltd. All rights...

  8. Does mobility explain variation in colonisation and population recovery among stream fishes?

    Science.gov (United States)

    Angermeier, Paul L.; Albanese, Brett; Peterson, James T.

    2009-01-01

    1. Colonisation and population recovery are crucial to species persistence in environmentally variable ecosystems, but are poorly understood processes. After documenting movement rates for several species of stream fish, we predicted that this variable would influence colonisation rates more strongly than local abundance, per cent occupancy, body size and taxonomic family. We also predicted that populations of species with higher movement rates would recover more rapidly than species with lower movement rates and that assemblage structure would change accordingly. 2. To test these predictions, we removed fishes from a headwater and a mainstem creek in southwest Virginia and monitored colonisation over a 2-year period. Using an information–theoretic approach, we evaluated the relative plausibility of 15 alternative models containing different combinations of our predictor variables. Our best-supported model contained movement rate and abundance and was 41 times more likely to account for observed patterns in colonisation rates than the next-best model. Movement rate and abundance were both positively related to colonisation rates and explained 88% of the variation in colonisation rates among species. 3. Population recovery, measured as the per cent of initial abundance restored, was also positively associated with movement rate. One species recovered within 3 months, most recovered within 2 years, but two species still had not recovered after 2 years. Despite high variation in recovery, the removal had only a slight impact on assemblage structure because species that were abundant in pre-removal samples were also abundant in post-removal samples. 4. The significance of interspecific variation in colonisation and recovery rates has been underappreciated because of the widely documented recovery of stream fish assemblages following fish kills and small-scale experimental defaunations. Our results indicate that recovery of the overall assemblage does not imply

  9. Visual Basic, Excel-based fish population modeling tool - The pallid sturgeon example

    Science.gov (United States)

    Moran, Edward H.; Wildhaber, Mark L.; Green, Nicholas S.; Albers, Janice L.

    2016-02-10

    The model presented in this report is a spreadsheet-based model using Visual Basic for Applications within Microsoft Excel (http://dx.doi.org/10.5066/F7057D0Z) prepared in cooperation with the U.S. Army Corps of Engineers and U.S. Fish and Wildlife Service. It uses the same model structure and, initially, parameters as used by Wildhaber and others (2015) for pallid sturgeon. The difference between the model structure used for this report and that used by Wildhaber and others (2015) is that variance is not partitioned. For the model of this report, all variance is applied at the iteration and time-step levels of the model. Wildhaber and others (2015) partition variance into parameter variance (uncertainty about the value of a parameter itself) applied at the iteration level and temporal variance (uncertainty caused by random environmental fluctuations with time) applied at the time-step level. They included implicit individual variance (uncertainty caused by differences between individuals) within the time-step level.The interface developed for the model of this report is designed to allow the user the flexibility to change population model structure and parameter values and uncertainty separately for every component of the model. This flexibility makes the modeling tool potentially applicable to any fish species; however, the flexibility inherent in this modeling tool makes it possible for the user to obtain spurious outputs. The value and reliability of the model outputs are only as good as the model inputs. Using this modeling tool with improper or inaccurate parameter values, or for species for which the structure of the model is inappropriate, could lead to untenable management decisions. By facilitating fish population modeling, this modeling tool allows the user to evaluate a range of management options and implications. The goal of this modeling tool is to be a user-friendly modeling tool for developing fish population models useful to natural resource

  10. Do fish have rights in artisanal fisheries?

    Directory of Open Access Journals (Sweden)

    Mustapha MK

    2013-09-01

    Full Text Available Artisanal fishers in developing world are unaware that fish are capable of suffering or discomfort, though researches have shown that fish do feel pain. Five fish welfare domains have been identified which constitute their rights in their environment. The needs of wild fish are usually provided in their natural, undisturbed and unperturbed aquatic environment, of which the fish will prefer. However, various anthropogenic activities by humans (including artisanal fisheries itself and some natural perturbations in the watershed, riparian zone, water body of the fish habitat and on the fish tend to take away these needs thereby compromising the fish welfare. These activities include environmental degradation, boat/canoe building, use of motorized engine boats/canoes, use of active and passive fishing gears, obnoxious cultural, religious and social fishing practices, fish harvesting, handling and processing among others. One way to understand the welfare needs of an individual fish is to understand its biology. Poor welfare conditions could then be assessed by how far the individual fish has deviated from the normal conditions. Non-intrusive signs based on the health, behavior, morphological anomalies, swimming, reduction in population and growth, outbreak of parasitic infections, injuries and loss of condition can be used to assess fish whose welfare has been compromised. Artisanal fishers should not only be concerned with catch, but, also the welfare of the fish being caught. This is because if the welfare of the fish is compromised, it is going to definitely affect the catch. As indispensable as fish is to humans, humans should not derive its pleasure at the expense of fish suffering. Human activities that impinge on the welfare of wild fish may not necessarily be stopped, but at least minimized in order to have continued sustainable artisanal exploitation of the fisheries.

  11. Coalbed gas environmental resource information project : fish population and habitat study review : Similkameen and Tulameen coalfields : final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-03-15

    This paper provided an overview of fish and fish habitats in the Similkameen and Tulameen coalfields area. The report consisted of a literature review as well as the examination of a regional-specific database. Discussions and interviews were conducted with First Nations, members of the oil and gas industry, and various governmental and non-governmental organizations. The report identified fish species in the region, and provided details of fish distribution and habitat, and obstructions and constraints to fish populations. Information on sensitive species was also provided. Watershed and hydrological overviews were provided, as well as summary tables for all relevant data. Online mapping and resource databases were used to prepare a profile of fish and fish habitat studies. Sensitive species information was obtained from online governmental mapping resources. The acquired data were then used to produce resource lists and habitat tables for streams and rivers residing within or transiting through the area. Four fish species were identified as species at risk, and an additional fish species was considered to be endangered. It was concluded that a centralized and mandatory reporting system must be developed to ensure that all documents are deposited within a single central library. Approximately 80 per cent of the information gathered for the report did not exist in the Environmental Resources Information Project (ERIP) database. 16 refs., 11 tabs., 1 fig.

  12. Historical Population Estimates For Several Fish Species At Offshore Oil and Gas Structures in the US Gulf of Mexico

    Science.gov (United States)

    Gitschlag, G.

    2016-02-01

    Population estimates were calculated for four fish species occurring at offshore oil and gas structures in water depths of 14-32 m off the Louisiana and upper Texas coasts in the US Gulf of Mexico. From 1993-1999 sampling was conducted at eight offshore platforms in conjunction with explosive salvage of the structures. To estimate fish population size prior to detonation of explosives, a fish mark-recapture study was conducted. Fish were captured on rod and reel using assorted hook sizes. Traps were occasionally used to supplement catches. Fish were tagged below the dorsal fin with plastic t-bar tags using tagging guns. Only fish that were alive and in good condition were released. Recapture sampling was conducted after explosives were detonated during salvage operations. Personnel operating from inflatable boats used dip nets to collect all dead fish that floated to the surface. Divers collected representative samples of dead fish that sank to the sea floor. Data provided estimates for red snapper (Lutjanus campechanus), Atlantic spadefish (Chaetodipterus faber), gray triggerfish (Balistes capriscus), and blue runner (Caranx crysos) at one or more of the eight platforms studied. At seven platforms, population size for red snapper was calculated at 503-1,943 with a 95% CI of 478. Abundance estimates for Atlantic spadefish at three platforms ranged from 1,432-1,782 with a 95% CI of 473. At three platforms, population size of gray triggerfish was 63-129 with a 95% CI of 82. Blue runner abundance at one platform was 558. Unlike the other three species which occur close to the platforms, blue runner range widely and recapture of this species was dependent on fish schools being in close proximity to the platform at the time explosives were detonated. Tag recapture was as high as 73% for red snapper at one structure studied.

  13. Dynamics and management of stage-structured fish stocks.

    Science.gov (United States)

    Meng, Xinzhu; Lundström, Niklas L P; Bodin, Mats; Brännström, Åke

    2013-01-01

    With increasing fishing pressures having brought several stocks to the brink of collapse, there is a need for developing efficient harvesting methods that account for factors beyond merely yield or profit. We consider the dynamics and management of a stage-structured fish stock. Our work is based on a consumer-resource model which De Roos et al. (in Theor. Popul. Biol. 73, 47-62, 2008) have derived as an approximation of a physiologically-structured counterpart. First, we rigorously prove the existence of steady states in both models, that the models share the same steady states, and that there exists at most one positive steady state. Furthermore, we carry out numerical investigations which suggest that a steady state is globally stable if it is locally stable. Second, we consider multiobjective harvesting strategies which account for yield, profit, and the recovery potential of the fish stock. The recovery potential is a measure of how quickly a fish stock can recover from a major disturbance and serves as an indication of the extinction risk associated with a harvesting strategy. Our analysis reveals that a small reduction in yield or profit allows for a disproportional increase in recovery potential. We also show that there exists a harvesting strategy with yield close to the maximum sustainable yield (MSY) and profit close to that associated with the maximum economic yield (MEY). In offering a good compromise between MSY and MEY, we believe that this harvesting strategy is preferable in most instances. Third, we consider the impact of harvesting on population size structure and analytically determine the most and least harmful harvesting strategies. We conclude that the most harmful harvesting strategy consists of harvesting both adults and juveniles, while harvesting only adults is the least harmful strategy. Finally, we find that a high percentage of juvenile biomass indicates elevated extinction risk and might therefore serve as an early-warning signal of

  14. The population ecology of two tropical trees, Brachychiton diversifolius (Malvaceae) and Bombax ceiba (Bombaceae), harvested by Indigenous woodcarvers in Arnhem Land, Australia.

    Science.gov (United States)

    Koenig, Jennifer; Griffiths, Anthony

    2012-10-01

    We describe the population ecology of two tropical deciduous trees, Bombax ceiba leiocarpum A. Robyns and Brachychiton diversifolius R. Br., which are in high demand for Indigenous sculpture production in Arnhem Land, Australia. We monitored tagged populations of both species at two locations for 2 years to examine their reproduction, growth, and survival rates and their response to harvest. Both species have similar life histories: they reproduce during the dry season (June-November) producing a high seed load, seed predation was high, seeds did not survive in the soil past the following wet season to form a seed bank, and germination rates were low and variable for both species. Average annual circumference growth rates were 1.07 cm year(-1) for B. ceiba and 0.98 cm year(-1) for B. diversifolius, with most of the growth occurring during the early wet season. Most (65-88 %) of the harvested B. ceiba and B. diversifolius stems coppiced. Coppice and stem size class were the main factors influencing tree growth rates with coppice stems growing up to six times faster than similar sized non-coppice stems. The survival of B. ceiba and B. diversifolius stems was size class dependent and affected by local site factors (e.g. fire and other disturbances) so that the smaller size classes had a low probability of survival. Given the resprouting potential of both species, their wild harvest is likely to have only minimal local impact on wild populations. However, further population modelling is required to determine whether the small and disjunct B. ceiba populations can sustain harvesting at current levels.

  15. Impact of entrainment and impingement on fish populations in the Hudson River estuary. Volume I. Entrainment-impact estimates for six fish populations inhabiting the Hudson River estuary

    International Nuclear Information System (INIS)

    Boreman, J.; Barnthouse, L.W.; Vaughn, D.S.; Goodyear, C.P.; Christensen, S.W.; Kumar, K.D.; Kirk, B.L.; Van Winkle, W.

    1982-01-01

    This volume is concerned with the estimation of the direct (or annual) entrainment impact of power plants on populations of striped bass, white perch, Alosa spp. (blueback herring and alewife), American shad, Atlantic tomcod, and bay anchovy in the Hudson River estuary. Entrainment impact results from the killing of fish eggs, larvae, and young juveniles that are contained in the cooling water cycled through a power plant. An Empirical Transport Model (ETM) is presented as the means of estimating a conditional entrainment mortality rate (defined as the fraction of a year class which would be killed due to entrainment in the absence of any other source of mortality). Most of this volume is concerned with the estimation of several parameters required by the ETM: physical input parameters (e.g., power-plant withdrawal flow rates); the longitudinal distribution of ichthyoplankton in time and space; the duration of susceptibility of the vulnerable organisms; the W-factors, which express the ratios of densities of organisms in power plant intakes to densities of organisms in the river; and the entrainment mortality factors (f-factors), which express the probability that an organism will be killed if it is entrained. Once these values are obtained, the ETM is used to estimate entrainment impact for both historical and projected conditions

  16. African Urban Harvest

    International Development Research Centre (IDRC) Digital Library (Canada)

    Urban Harvest, a system-wide initiative of the Consultative Group on Agricultural ...... and urban old, using criteria of population density, land availability, and the prevalence of crop ...... Contact between milk and containers or the environment;.

  17. Impact of climate change on fish population dynamics in the baltic sea: a dynamical downscaling investigation

    DEFF Research Database (Denmark)

    Mackenzie, Brian R; Meier, H E Markus; Lindegren, Martin

    2012-01-01

    Understanding how climate change, exploitation and eutrophication will affect populations and ecosystems of the Baltic Sea can be facilitated with models which realistically combine these forcings into common frameworks. Here, we evaluate sensitivity of fish recruitment and population dynamics...... and the temperature have influenced recruitment for at least 50 years. The three Baltic Sea models estimate relatively similar developments (increases) in biomass and fishery yield during twenty-first century climate change (ca. 28 % range among models). However, this uncertainty is exceeded by the one associated...... to past and future environmental forcings provided by three ocean-biogeochemical models of the Baltic Sea. Modeled temperature explained nearly as much variability in reproductive success of sprat (Sprattus sprattus; Clupeidae) as measured temperatures during 1973-2005, and both the spawner biomass...

  18. Embryonic IGF2 expression is not associated with offspring size among populations of a placental fish.

    Directory of Open Access Journals (Sweden)

    Matthew Schrader

    Full Text Available In organisms that provision young between fertilization and birth, mothers and their developing embryos are expected to be in conflict over embryonic growth. In mammalian embryos, the expression of Insulin-like growth factor II (IGF2 plays a key role in maternal-fetal interactions and is thought to be a focus of maternal-fetal conflict. Recent studies have suggested that IGF2 is also a focus of maternal-fetal conflict in placental fish in the family Poeciliidae. However, whether the expression of IGF2 influences offspring size, the trait over which mothers and embryos are likely to be in conflict, has not been assessed in a poeciliid. We tested whether embryonic IGF2 expression varied among four populations of a placental poeciliid that display large and consistent differences in offspring size at birth. We found that IGF2 expression varied significantly among embryonic stages with expression being 50% higher in early stage embryos than late stage embryos. There were no significant differences among populations in IGF2 expression; small differences in expression between population pairs with different offspring sizes were comparable in magnitude to those between population pairs with the same offspring sizes. Our results indicate that variation in IGF2 transcript abundance does not contribute to differences in offspring size among H. formosa populations.

  19. Density regulation in Northeast Atlantic fish populations: Density dependence is stronger in recruitment than in somatic growth.

    Science.gov (United States)

    Zimmermann, Fabian; Ricard, Daniel; Heino, Mikko

    2018-05-01

    Population regulation is a central concept in ecology, yet in many cases its presence and the underlying mechanisms are difficult to demonstrate. The current paradigm maintains that marine fish populations are predominantly regulated by density-dependent recruitment. While it is known that density-dependent somatic growth can be present too, its general importance remains unknown and most practical applications neglect it. This study aimed to close this gap by for the first time quantifying and comparing density dependence in growth and recruitment over a large set of fish populations. We fitted density-dependent models to time-series data on population size, recruitment and age-specific weight from commercially exploited fish populations in the Northeast Atlantic Ocean and the Baltic Sea. Data were standardized to enable a direct comparison within and among populations, and estimated parameters were used to quantify the impact of density regulation on population biomass. Statistically significant density dependence in recruitment was detected in a large proportion of populations (70%), whereas for density dependence in somatic growth the prevalence of density dependence depended heavily on the method (26% and 69%). Despite age-dependent variability, the density dependence in recruitment was consistently stronger among age groups and between alternative approaches that use weight-at-age or weight increments to assess growth. Estimates of density-dependent reduction in biomass underlined these results: 97% of populations with statistically significant parameters for growth and recruitment showed a larger impact of density-dependent recruitment on population biomass. The results reaffirm the importance of density-dependent recruitment in marine fishes, yet they also show that density dependence in somatic growth is not uncommon. Furthermore, the results are important from an applied perspective because density dependence in somatic growth affects productivity and

  20. Lessons learned from practical approaches to reconcile mismatches between biological population structure and stock units of marine fish

    DEFF Research Database (Denmark)

    Kerr, Lisa A.; Hintzen, Niels T.; Cadrin, Steven X.

    2017-01-01

    for overexploitation of unique spawning components, which can lead to loss of productivity and reduced biodiversity along with destabilization of local and regional stock dynamics. Furthermore, ignoring complex population structure and stock connectivity can lead to misperception of the magnitude of fish productivity......, which can translate to suboptimal utilization of the resource. We describe approaches that are currently being applied to improve the assessment and management process for marine fish in situations where complex spatial structure has led to an observed mismatch between the scale of biological...... and resilience of fish species....

  1. Long-term changes in deep-water fish populations in the northeast Atlantic: a deeper reaching effect of fisheries?

    OpenAIRE

    Bailey, D.M.; Collins, M.A.; Gordon, J.D.M.; Zuur, A.F.; Priede, I.G.

    2009-01-01

    A severe scarcity of life history and population data for deep-water fishes is a major impediment to successful fisheries management. Long-term data for non-target species and those living deeper than the fishing grounds are particularly rare. We analysed a unique dataset of scientific trawls made from 1977 to 1989 and from 1997 to 2002, at depths from 800 to 4800 m. Over this time, overall fish abundance fell significantly at all depths from 800 to 2500 m, considerably deeper than the maximu...

  2. Changing Levels of Predation on Benthos as a Result of Exploitation of Fish Populations

    NARCIS (Netherlands)

    Hansson, S.; Frid, C.L.J.; Ragnarsson, S.A.; Rijnsdorp, A.; Steingrimsson, S.A.

    1999-01-01

    In many coastal areas fishing constitutes the dominant anthropogenic impact on coastal ecosystems. That fishing has altered the abundance and size spectra of fish communities is beyond doubt. We use time series of the abundance, in the North Sea, of 8 demersal fish species and data on food

  3. Potential population and assemblage influences of non-native trout on native nongame fish in Nebraska headwater streams

    Science.gov (United States)

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

    2014-01-01

    Non-native trout are currently stocked to support recreational fisheries in headwater streams throughout Nebraska. The influence of non-native trout introductions on native fish populations and their role in structuring fish assemblages in these systems is unknown. The objectives of this study were to determine (i) if the size structure or relative abundance of native fish differs in the presence and absence of non-native trout, (ii) if native fish-assemblage structure differs in the presence and absence of non-native trout and (iii) if native fish-assemblage structure differs across a gradient in abundances of non-native trout. Longnose dace Rhinichthys cataractae were larger in the presence of brown trout Salmo trutta and smaller in the presence of rainbow trout Oncorhynchus mykiss compared to sites without trout. There was also a greater proportion of larger white suckers Catostomus commersonii in the presence of brown trout. Creek chub Semotilus atromaculatus and fathead minnow Pimephales promelas size structures were similar in the presence and absence of trout. Relative abundances of longnose dace, white sucker, creek chub and fathead minnow were similar in the presence and absence of trout, but there was greater distinction in native fish-assemblage structure between sites with trout compared to sites without trout as trout abundances increased. These results suggest increased risk to native fish assemblages in sites with high abundances of trout. However, more research is needed to determine the role of non-native trout in structuring native fish assemblages in streams, and the mechanisms through which introduced trout may influence native fish populations.

  4. Projected risk of population declines for native fish species in the Upper Mississippi River

    Science.gov (United States)

    Crimmins, S.M.; Boma, P.; Thogmartin, W.E.

    2015-01-01

    Conservationists are in need of objective metrics for prioritizing the management of habitats. For individual species, the threat of extinction is often used to prioritize what species are in need of conservation action. Using long-term monitoring data, we applied a Bayesian diffusion approximation to estimate quasi-extinction risk for 54 native fish species within six commercial navigation reaches along a 1350-km gradient of the upper Mississippi River system. We found a strong negative linear relationship between quasi-extinction risk and distance upstream. For some species, quasi-extinction estimates ranged from nearly zero in some reaches to one in others, suggesting substantial variability in threats facing individual river reaches. We found no evidence that species traits affected quasi-extinction risk across the entire system. Our results indicate that fishes within the upper Mississippi River system face localized threats that vary across river impact gradients. This suggests that conservation actions should be focused on local habitat scales but should also consider the additive effects on downstream conditions. We also emphasize the need for identification of proximate mechanisms behind observed and predicted population declines, as conservation actions will require mitigation of such mechanisms. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  5. Comparison of sampling methodologies and estimation of population parameters for a temporary fish ectoparasite

    Directory of Open Access Journals (Sweden)

    J.M. Artim

    2016-08-01

    Full Text Available Characterizing spatio-temporal variation in the density of organisms in a community is a crucial part of ecological study. However, doing so for small, motile, cryptic species presents multiple challenges, especially where multiple life history stages are involved. Gnathiid isopods are ecologically important marine ectoparasites, micropredators that live in substrate for most of their lives, emerging only once during each juvenile stage to feed on fish blood. Many gnathiid species are nocturnal and most have distinct substrate preferences. Studies of gnathiid use of habitat, exploitation of hosts, and population dynamics have used various trap designs to estimate rates of gnathiid emergence, study sensory ecology, and identify host susceptibility. In the studies reported here, we compare and contrast the performance of emergence, fish-baited and light trap designs, outline the key features of these traps, and determine some life cycle parameters derived from trap counts for the Eastern Caribbean coral-reef gnathiid, Gnathia marleyi. We also used counts from large emergence traps and light traps to estimate additional life cycle parameters, emergence rates, and total gnathiid density on substrate, and to calibrate the light trap design to provide estimates of rate of emergence and total gnathiid density in habitat not amenable to emergence trap deployment.

  6. Multi-decadal responses of a cod (Gadus morhua) population to human-induced trophic changes, fishing, and climate

    DEFF Research Database (Denmark)

    Eero, Margit; MacKenzie, Brian; Köster, Fritz

    2011-01-01

    to changes in fish populations can be analyzed with empirical data. In this study we investigate how climate variability and multiple human impacts (fishing, marine mammal hunting, eutrophication) have affected multi-decadal scale dynamics of cod in the Baltic Sea during the 20th century.We document...... significant climate-driven variations in cod recruitment production at multi-annual timescales, which had major impacts on population dynamics and the yields to commercial fisheries. We also quantify the roles of marine mammal predation, eutrophication, and exploitation on the development of the cod...

  7. Body size and geographic range do not explain long term variation in fish populations: a Bayesian phylogenetic approach to testing assembly processes in stream fish assemblages.

    Directory of Open Access Journals (Sweden)

    Stephen J Jacquemin

    Full Text Available We combine evolutionary biology and community ecology to test whether two species traits, body size and geographic range, explain long term variation in local scale freshwater stream fish assemblages. Body size and geographic range are expected to influence several aspects of fish ecology, via relationships with niche breadth, dispersal, and abundance. These traits are expected to scale inversely with niche breadth or current abundance, and to scale directly with dispersal potential. However, their utility to explain long term temporal patterns in local scale abundance is not known. Comparative methods employing an existing molecular phylogeny were used to incorporate evolutionary relatedness in a test for covariation of body size and geographic range with long term (1983 - 2010 local scale population variation of fishes in West Fork White River (Indiana, USA. The Bayesian model incorporating phylogenetic uncertainty and correlated predictors indicated that neither body size nor geographic range explained significant variation in population fluctuations over a 28 year period. Phylogenetic signal data indicated that body size and geographic range were less similar among taxa than expected if trait evolution followed a purely random walk. We interpret this as evidence that local scale population variation may be influenced less by species-level traits such as body size or geographic range, and instead may be influenced more strongly by a taxon's local scale habitat and biotic assemblages.

  8. Analysis of complex wetland ecological system: Effect of harvesting

    Directory of Open Access Journals (Sweden)

    Nilesh Kumar Thakur

    2017-12-01

    Full Text Available In this paper, we have studied interaction among diffusive phytoplankton, zooplankton and fish population with Beddington-DeAngelis type functional response for the zooplankton and Holling type III for fish. The stability analysis of the model system with diffusion and without diffusion has been analyzed. The conditions for Maximum sustainable yield and Optimal harvesting policy for non-spatial model have been discussed. Our study may be helpful to improve and manage ecosystem services provided by wetlands on an agricultural landscapes include fisheries, water conservation, climate change and many more.

  9. Use of population viability analysis to evaluate CITES trade-management options for threatened marine fishes.

    Science.gov (United States)

    Curtis, Janelle M R; Vincent, Amanda C J

    2008-10-01

    Achieving multiple conservation objectives can be challenging, particularly under high uncertainty. Having agreed to limit seahorse (Hippocampus) exports to sustainable levels, signatories to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) were offered the option of a single 10-cm minimum size limit (MSL) as an interim management measure for all Hippocampus species (> or =34). Although diverse stakeholders supported the recommended MSL, its biological and socioeconomic implications were not assessed quantitatively. We combined population viability analysis, model sensitivity analysis, and economic information to evaluate the trade-off between conservation threat to and long-term cumulative income from these exploited marine fishes of high conservation concern. We used the European long-snouted seahorse (Hippocampus guttulatus) as a representative species to compare the performance of MSLs set at alternative biological reference points. Our sensitivity analyses showed that in most of our scenarios, setting the MSL just above size at maturity (9.7 cm in H. guttulatus) would not prevent exploited populations from becoming listed as vulnerable. By contrast, the relative risk of decline and extinction were almost halved--at a cost of only a 5.6% reduction in long-term catches--by increasing the MSL to the size reached after at least one full reproductive season. On the basis of our analysis, a precautionary increase in the MSL could be compatible with sustaining fishers' livelihoods and international trade. Such management tactics that aid species conservation and have minimal effects on long term catch trends may help bolster the case for CITES trade management of other valuable marine fishes.

  10. Mercury concentrations in China's coastal waters and implications for fish consumption by vulnerable populations

    International Nuclear Information System (INIS)

    Tong, Yindong; Wang, Mengzhu; Bu, Xiaoge; Guo, Xin; Lin, Yan; Lin, Huiming; Li, Jing; Zhang, Wei; Wang, Xuejun

    2017-01-01

    We assessed mercury (Hg) pollution in China's coastal waters, including the Bohai Sea, the Yellow Sea, the East China Sea and the South China Sea, based on a nationwide dataset from 301 sampling sites. A methylmercury (MeHg) intake model for humans based on the marine food chain and human fish consumption was established to determine the linkage between water pollutants and the pollutant intake by humans. The predicted MeHg concentration in fish from the Bohai Sea was the highest among the four seas included in the study. The MeHg intake through dietary ingestion was dominant for the fish and was considerably higher than the MeHg intake through water respiration. The predicted MeHg concentrations in human blood in the coastal regions of China ranged from 1.37 to 2.77 μg/L for pregnant woman and from 0.43 to 1.00 μg/L for infants, respectively, based on different diet sources. The carnivorous fish consumption advisory for pregnant women was estimated to be 288–654 g per week to maintain MeHg concentrations in human blood at levels below the threshold level (4.4 μg/L established by the US Environmental Protection Agency). With a 50% increase in Hg concentrations in water in the Bohai Sea, the bioaccumulated MeHg concentration (4.5 μg/L) in the fish consumers will be higher than the threshold level. This study demonstrates the importance in controlling Hg pollution in China's coastal waters. An official recommendation guideline for the fish consumption rate and its sources will be necessary for vulnerable populations in China. - Graphical abstract: MeHg transfer route from the marine food chain to vulnerable population. - Highlights: • Predicted MeHg concentrations in pregnant woman and infant’s blood in China’s coastal regions are below threshold level. • The carnivorous fish consumption advisory for pregnant women is estimated to be 288–654 g per week. g • If with a 50% increase in Hg in Bohai Sea, the bioaccumulated MeHg concentration in

  11. 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

  12. Immigration Rates during Population Density Reduction in a Coral Reef Fish

    Science.gov (United States)

    Turgeon, Katrine; Kramer, Donald L.

    2016-01-01

    Although the importance of density-dependent dispersal has been recognized in theory, few empirical studies have examined how immigration changes over a wide range of densities. In a replicated experiment using a novel approach allowing within-site comparison, we examined changes in immigration rate following the gradual removal of territorial damselfish from a limited area within a much larger patch of continuous habitat. In all sites, immigration occurred at intermediate densities but did not occur before the start of removals and only rarely as density approached zero. In the combined data and in 5 of 7 sites, the number of immigrants was a hump-shaped function of density. This is the first experimental evidence for hump-shaped, density-dependent immigration. This pattern may be more widespread than previously recognized because studies over more limited density ranges have identified positive density dependence at low densities and negative density dependence at high densities. Positive density dependence at low density can arise from limits to the number of potential immigrants and from behavioral preferences for settling near conspecifics. Negative density dependence at high density can arise from competition for resources, especially high quality territories. The potential for non-linear effects of local density on immigration needs to be recognized for robust predictions of conservation reserve function, harvest impacts, pest control, and the dynamics of fragmented populations. PMID:27271081

  13. Diagnostic methodology is critical for accurately determining the prevalence of Ichthyophonus infections in wild fish populations.

    Science.gov (United States)

    Kocan, Richard; Dolan, Heather; Hershberger, Paul

    2011-04-01

    Several different techniques have been employed to detect and identify Ichthyophonus spp. in infected fish hosts; these include macroscopic observation, microscopic examination of tissue squashes, histological evaluation, in vitro culture, and molecular techniques. Examination of the peer-reviewed literature revealed that when more than 1 diagnostic method is used, they often result in significantly different results; for example, when in vitro culture was used to identify infected trout in an experimentally exposed population, 98.7% of infected trout were detected, but when standard histology was used to confirm known infected tissues from wild salmon, it detected ~50% of low-intensity infections and ~85% of high-intensity infections. Other studies on different species reported similar differences. When we examined a possible mechanism to explain the disparity between different diagnostic techniques, we observed non-random distribution of the parasite in 3-dimensionally visualized tissue sections from infected hosts, thus providing a possible explanation for the different sensitivities of commonly used diagnostic techniques. Based on experimental evidence and a review of the peer-reviewed literature, we have concluded that in vitro culture is currently the most accurate diagnostic technique for determining infection prevalence of Ichthyophonus , particularly when the exposure history of the population is not known.

  14. Relationship between snail population density and infection status of snails and fish with zoonotic trematodes in Vietnamese carp nurseries

    DEFF Research Database (Denmark)

    Clausen, Jesper Hedegaard; Madsen, Henry; Murrell, Kenneth Darwin

    2012-01-01

    ponds. Previous risk assessment on FZT transmission in the Red River Delta of Vietnam identified carp nursery ponds as major sites of transmission. In this study, we analyzed the association between snail population density and heterophyid trematode infection in snails with the rate of FZT transmission...... to juvenile fish raised in carp nurseries....

  15. Bioaccumulation of trace metals and total petroleum and genotoxicity responses in an edible fish population as indicators of marine pollution.

    Science.gov (United States)

    D'Costa, Avelyno; Shyama, S K; Praveen Kumar, M K

    2017-08-01

    The present study reports the genetic damage and the concentrations of trace metals and total petroleum hydrocarbons prevailing in natural populations of an edible fish, Arius arius in different seasons along the coast of Goa, India as an indicator of the pollution status of coastal water. Fish were collected from a suspected polluted site and a reference site in the pre-monsoon, monsoon and post-monsoon seasons. Physico-chemical parameters as well as the concentrations of total petroleum hydrocarbons (TPH) and trace metals in the water and sediment as well as the tissues of fish collected from these sites were recorded. The genotoxicity status of the fish was assessed employing the micronucleus test and comet assay. A positive correlation (p<0.001) was observed between the tail DNA and micronuclei in all the fish collected. Multiple regression analysis revealed that tissue and environmental pollutant concentrations and genotoxicity were positively associated and higher in the tissues of the fish collected from the polluted site. Pollution indicators and genotoxicity tests, combined with other physiological or biochemical parameters represent an essential integrated approach for efficient monitoring of aquatic ecosystems in Goa. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. The dynamics of fish populations in the Palancar stream, a small tributary of the river Guadalquivir, Spain

    OpenAIRE

    Bravo, R.; Soriguer, M.C.; Villar, N.; Hernando, J.A.

    2000-01-01

    The relationship between flooding and changes in the size distribution of fish populations in the Palancar stream confirms observations in other rivers. On average, density decreased by 36.2 % and biomass increased by 14.5 %, passing from a period of severe drought to one of heavier than normal rains. Precipitation is the most important of the many factors affecting the populations of the Palancar stream; the most evident changes all occurred after the drought. During the drought per...

  17. Determination of a site-specific reference dose for methylmercury for fish-eating populations.

    Science.gov (United States)

    Shipp, A M; Gentry, P R; Lawrence, G; Van Landingham, C; Covington, T; Clewell, H J; Gribben, K; Crump, K

    2000-11-01

    methylmercury, the exposures of concern for the Point Comfort site are from the chronic consumption of relatively low concentrations of methylmercury in fish. Since the publication of the USEPA RfD, several analyses of chronic exposure to methylmercury in fish-eating populations have been reported. The purpose of the analysis reported here was to evaluate the possibility of deriving an RfD for methylmercury, specifically for the case of fish ingestion, on the basis of these new studies. In order to better support the risk-management decisions associated with developing a remediation approach for the site in question, the analysis was designed to provide information on the distribution of acceptable ingestion rates across a population, which could reasonably be expected to be consistent with the results of the epidemiological studies of other fish-eating populations. Based on a review of the available literature on the effects of methylmercury, a study conducted with a population in the Seychelles Islands was selected as the critical study for this analysis. The exposures to methylmercury in this population result from chronic, multigenerational ingestion of contaminated fish. This prospective study was carefully conducted and analyzed, included a large cohort of mother-infant pairs, and was relatively free of confounding factors. The results of this study are essentially negative, and a no-observed-adverse-effect level (NOAEL) derived from the estimated exposures has recently been used by the Agency for Toxic Substances and Disease Registry (ATSDR) as the basis for a chronic oral minimal risk level (MRL) for methylmercury. In spite of the fact that no statistically significant effects were observed in this study, the data as reported are suitable for dose-response analysis using the BMD method. Evaluation of the BMD method used in this analysis, as well as in the current USEPA RfD, has demonstrated that the resulting 95% lower bound on the 10% benchmark dose (BMDL) represents a

  18. A model describing the effect of sex-reversed YY fish in an established wild population: The use of a Trojan Y chromosome to cause extinction of an introduced exotic species.

    Science.gov (United States)

    Gutierrez, Juan B; Teem, John L

    2006-07-21

    A novel means of inducing extinction of an exotic fish population is proposed using a genetic approach to shift the ratio of male to females within a population. In the proposed strategy, sex-reversed fish containing two Y chromosomes are introduced into a normal fish population. These YY fish result in the production of a disproportionate number of male fish in subsequent generations. Mathematical modeling of the system following introduction of YY fish at a constant rate reveals that female fish decline in numbers over time, leading to eventual extinction of the population.

  19. A Mixed-Method Approach for Quantifying Illegal Fishing and Its Impact on an Endangered Fish Species.

    Science.gov (United States)

    Free, Christopher M; Jensen, Olaf P; Mendsaikhan, Bud

    2015-01-01

    Illegal harvest is recognized as a widespread problem in natural resource management. The use of multiple methods for quantifying illegal harvest has been widely recommended yet infrequently applied. We used a mixed-method approach to evaluate the extent, character, and motivations of illegal gillnet fishing in Lake Hovsgol National Park, Mongolia and its impact on the lake's fish populations, especially that of the endangered endemic Hovsgol grayling (Thymallus nigrescens). Surveys for derelict fishing gear indicate that gillnet fishing is widespread and increasing and that fishers generally use 3-4 cm mesh gillnet. Interviews with resident herders and park rangers suggest that many residents fish for subsistence during the spring grayling spawning migration and that some residents fish commercially year-round. Interviewed herders and rangers generally agree that fish population sizes are decreasing but are divided on the causes and solutions. Biological monitoring indicates that the gillnet mesh sizes used by fishers efficiently target Hovsgol grayling. Of the five species sampled in the monitoring program, only burbot (Lota lota) showed a significant decrease in population abundance from 2009-2013. However, grayling, burbot, and roach (Rutilus rutilus) all showed significant declines in average body size, suggesting a negative fishing impact. Data-poor stock assessment methods suggest that the fishing effort equivalent to each resident family fishing 50-m of gillnet 11-15 nights per year would be sufficient to overexploit the grayling population. Results from the derelict fishing gear survey and interviews suggest that this level of effort is not implausible. Overall, we demonstrate the ability for a mixed-method approach to effectively describe an illegal fishery and suggest that these methods be used to assess illegal fishing and its impacts in other protected areas.

  20. Population Structure and Adaptive Divergence in a High Gene Flow Marine Fish: The Small Yellow Croaker (Larimichthys polyactis.

    Directory of Open Access Journals (Sweden)

    Bing-Jian Liu

    Full Text Available The spatial distribution of genetic diversity has been long considered as a key component of policy development for management and conservation of marine fishes. However, unraveling the population genetic structure of migratory fish species is challenging due to high potential for gene flow. Despite the shallow population differentiation revealed by putatively neutral loci, the higher genetic differentiation with panels of putatively adaptive loci could provide greater resolution for stock identification. Here, patterns of population differentiation of small yellow croaker (Larimichthys polyactis were investigated by genotyping 15 highly polymorphic microsatellites in 337 individuals of 15 geographic populations collected from both spawning and overwintering grounds. Outlier analyses indicated that the locus Lpol03 might be under directional selection, which showed a strong homology with Grid2 gene encoding the glutamate receptor δ2 protein (GluRδ2. Based on Lpol03, two distinct clusters were identified by both STRUCTURE and PCoA analyses, suggesting that there were two overwintering aggregations of L. polyactis. A novel migration pattern was suggested for L. polyactis, which was inconsistent with results of previous studies based on historical fishing yield statistics. These results provided new perspectives on the population genetic structure and migratory routes of L. polyactis, which could have significant implications for sustainable management and utilization of this important fishery resource.

  1. Large-scale, multidirectional larval connectivity among coral reef fish populations in the Great Barrier Reef Marine Park

    KAUST Repository

    Williamson, David H.

    2016-11-15

    Larval dispersal is the key process by which populations of most marine fishes and invertebrates are connected and replenished. Advances in larval tagging and genetics have enhanced our capacity to track larval dispersal, assess scales of population connectivity, and quantify larval exchange among no-take marine reserves and fished areas. Recent studies have found that reserves can be a significant source of recruits for populations up to 40 km away, but the scale and direction of larval connectivity across larger seascapes remain unknown. Here, we apply genetic parentage analysis to investigate larval dispersal patterns for two exploited coral reef groupers (Plectropomus maculatus and Plectropomus leopardus) within and among three clusters of reefs separated by 60–220 km within the Great Barrier Reef Marine Park, Australia. A total of 69 juvenile P. maculatus and 17 juvenile P. leopardus (representing 6% and 9% of the total juveniles sampled, respectively) were genetically assigned to parent individuals on reefs within the study area. We identified both short-distance larval dispersal within regions (200 m to 50 km) and long-distance, multidirectional dispersal of up to ~250 km among regions. Dispersal strength declined significantly with distance, with best-fit dispersal kernels estimating median dispersal distances of ~110 km for P. maculatus and ~190 km for P. leopardus. Larval exchange among reefs demonstrates that established reserves form a highly connected network and contribute larvae for the replenishment of fished reefs at multiple spatial scales. Our findings highlight the potential for long-distance dispersal in an important group of reef fishes, and provide further evidence that effectively protected reserves can yield recruitment and sustainability benefits for exploited fish populations.

  2. Large-scale, multidirectional larval connectivity among coral reef fish populations in the Great Barrier Reef Marine Park

    KAUST Repository

    Williamson, David H.; Harrison, Hugo B.; Almany, Glenn R.; Berumen, Michael L.; Bode, Michael; Bonin, Mary C.; Choukroun, Severine; Doherty, Peter J.; Frisch, Ashley J.; Saenz-Agudelo, Pablo; Jones, Geoffrey P.

    2016-01-01

    Larval dispersal is the key process by which populations of most marine fishes and invertebrates are connected and replenished. Advances in larval tagging and genetics have enhanced our capacity to track larval dispersal, assess scales of population connectivity, and quantify larval exchange among no-take marine reserves and fished areas. Recent studies have found that reserves can be a significant source of recruits for populations up to 40 km away, but the scale and direction of larval connectivity across larger seascapes remain unknown. Here, we apply genetic parentage analysis to investigate larval dispersal patterns for two exploited coral reef groupers (Plectropomus maculatus and Plectropomus leopardus) within and among three clusters of reefs separated by 60–220 km within the Great Barrier Reef Marine Park, Australia. A total of 69 juvenile P. maculatus and 17 juvenile P. leopardus (representing 6% and 9% of the total juveniles sampled, respectively) were genetically assigned to parent individuals on reefs within the study area. We identified both short-distance larval dispersal within regions (200 m to 50 km) and long-distance, multidirectional dispersal of up to ~250 km among regions. Dispersal strength declined significantly with distance, with best-fit dispersal kernels estimating median dispersal distances of ~110 km for P. maculatus and ~190 km for P. leopardus. Larval exchange among reefs demonstrates that established reserves form a highly connected network and contribute larvae for the replenishment of fished reefs at multiple spatial scales. Our findings highlight the potential for long-distance dispersal in an important group of reef fishes, and provide further evidence that effectively protected reserves can yield recruitment and sustainability benefits for exploited fish populations.

  3. Upper Caraş River (Danube watershed fish populations fragmentation – technical rehabilitation proposal

    Directory of Open Access Journals (Sweden)

    Voicu Răzvan

    2018-01-01

    Full Text Available We propose a technical solution for fish movement based on the flow of water over a spill threshold. Such barriers are common in the Danube system. The proposed system has a range of operating components which are easily detachable from the spill threshold, are resistant to corrosion and will not harm the fish. In fact, if designed to complement swimming abilities of target fish, it should provide adequate passage for both adults and juveniles. If implemented correctly, the design may offer a solution to help displaced fish recolonize upstream habitats.

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

    Science.gov (United States)

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

    2008-01-01

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

  5. Analysis of a Fishery Model with two competing prey species in the presence of a predator species for Optimal Harvesting

    Science.gov (United States)

    Sutimin; Khabibah, Siti; Munawwaroh, Dita Anis

    2018-02-01

    A harvesting fishery model is proposed to analyze the effects of the presence of red devil fish population, as a predator in an ecosystem. In this paper, we consider an ecological model of three species by taking into account two competing species and presence of a predator (red devil), the third species, which incorporates the harvesting efforts of each fish species. The stability of the dynamical system is discussed and the existence of biological and bionomic equilibrium is examined. The optimal harvest policy is studied and the solution is derived in the equilibrium case applying Pontryagin's maximal principle. The simulation results is presented to simulate the dynamical behavior of the model and show that the optimal equilibrium solution is globally asymptotically stable. The results show that the optimal harvesting effort is obtained regarding to bionomic and biological equilibrium.

  6. 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)

  7. Differences in the metabolic rates of exploited and unexploited fish populations: a signature of recreational fisheries induced evolution?

    Directory of Open Access Journals (Sweden)

    Jan-Michael Hessenauer

    Full Text Available Non-random mortality associated with commercial and recreational fisheries have the potential to cause evolutionary changes in fish populations. Inland recreational fisheries offer unique opportunities for the study of fisheries induced evolution due to the ability to replicate study systems, limited gene flow among populations, and the existence of unexploited reference populations. Experimental research has demonstrated that angling vulnerability is heritable in Largemouth Bass Micropterus salmoides, and is correlated with elevated resting metabolic rates (RMR and higher fitness. However, whether such differences are present in wild populations is unclear. This study sought to quantify differences in RMR among replicated exploited and unexploited populations of Largemouth Bass. We collected age-0 Largemouth Bass from two Connecticut drinking water reservoirs unexploited by anglers for almost a century, and two exploited lakes, then transported and reared them in the same pond. Field RMR of individuals from each population was quantified using intermittent-flow respirometry. Individuals from unexploited reservoirs had a significantly higher mean RMR (6% than individuals from exploited populations. These findings are consistent with expectations derived from artificial selection by angling on Largemouth Bass, suggesting that recreational angling may act as an evolutionary force influencing the metabolic rates of fishes in the wild. Reduced RMR as a result of fisheries induced evolution may have ecosystem level effects on energy demand, and be common in exploited recreational populations globally.

  8. Sex Differences in the Relationship between Sleep Behavior, Fish Consumption, and Depressive Symptoms in the General Population of South Korea.

    Science.gov (United States)

    Supartini, Atin; Oishi, Taro; Yagi, Nobuyuki

    2017-07-14

    Sleep, fish consumption, and depression have a close relationship; however, the role of sex differences in sleep, fish consumption, and depression research is not yet well-established. This study aimed to examine whether the impact of bedtime, sleep-onset latency, sleep duration, sleep quality, and fish consumption on depressive symptoms differed in women and men. An online survey was conducted in South Korea with a stratified random sample of 600 participants between the ages of 20 and 69, whose gender and age were proportional to estimates of Korea's general population. The 20-item Center for Epidemiologic Studies Depression Scale was used to measure depressive symptoms with a cut-off score of 16. The Pittsburgh Sleep Quality Index (PSQI) was applied to evaluate sleep timing, sleep-onset latency, sleep duration, and sleep quality. Our results indicated that late bedtime and short sleep duration were independently associated with depressive symptoms in women. Sleep-onset latency and poor sleep quality were independently associated with increased prevalence of depressive symptoms in both men and women. Higher fish consumption was significantly associated with decreased prevalence of depressive symptoms in men only. Our findings suggested the importance of a different approach for men and women in terms of promoting healthy sleep habits. In addition, higher fish consumption may be beneficial in the primary prevention of depression in Korean men. Further research is needed to confirm the findings from this cross-sectional study.

  9. The diet of otters ( Lutra lutra L.) in Danish freshwater habitats : comparisons of prey fish populations

    DEFF Research Database (Denmark)

    Taastrom, H.M.; Jacobsen, Lene

    1999-01-01

    Otter spraints from five Danish freshwater localities were analysed. In all localities fish was the main prey (76-99% of estimated bulk), especially in winter. Depending on locality, the prey fish mainly consisted of cyprinids (Cyprinidae), percids (Percidae) or salmonids (Salmonidae). Seasonal v...

  10. Fish consumption and plasma levels of organochlorines in a female population in Northern Norway.

    Science.gov (United States)

    Furberg, Anne-Sofie; Sandanger, Torkjel; Thune, Inger; Burkow, Ivan C; Lun, Eiliv

    2002-02-01

    Increased cancer incidence and mortality have been found among humans exposed to high levels of organochlorines (OCs), either accidentally or as industrial workers. In order to assess levels of OCs in Norwegian women north of the Arctic Circle and validate self-reported fish consumption as a surrogate measure of organochlorine body burden, concentrations of seven polychlorinated biphenyl (PCB) congeners [IUPAC Nos. CB-105, CB-118, CB-138 (+ CB-163), CB-153, CB-180, CB-183, CB-187], beta-hexachlorocyclohexane (beta-HCH), 2,2'-bis(p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) and cis- and trains-chlordane (c-CD and t-CD) were examined in plasma samples of middle-aged women attending for health screening. Altogether, 47 of those invited (81%) completed a questionnaire and donated a suitable blood sample. The ability of questionnaire data to predict plasma levels of OCs was tested in linear and logistic regression analyses. Measured plasma concentrations were in the range reported for the general female population of other Western countries and the relative amounts of PCBs were similar to the circumpolar pattern. Intake of seagulls' eggs was a predictor of PCB congeners CB-138 (+CB-163) (p<0.05) and CB-153 (p<0.01). No other food category was positively associated with any compound. In contrast, duration of residence in the study municipality, body mass index (BMI) and lifetime lactation (months) were the best univariate predictors. There was an increase in beta-HCH, p,p'-DDE and most of the PCBs (p<0.05 for all) with increasing length of time a subject had lived in the municipality. BMI was a positive predictor for beta-HCH (OR=3.10, 95% CI 1.50-6.43, per 5 kgm(-2)), chlordane (OR=2.13, 95% CI 1.12-4.05, per 5 kgm(-2)) and CB-105 and CB-153 (p<0.05 for both). Lactation was negatively associated with all OCs (p<0.05), except chlordane and two of the PCB congeners. Time living in the municipality and lactation explained 34%, of the variance in concentration of total

  11. Consequences of the size structure of fish populations for their effects on a generalist avian predator.

    Science.gov (United States)

    Kloskowski, Janusz

    2011-06-01

    Size-structured interspecific interactions can shift between predation and competition, depending on ontogenetic changes in size relationships. I examined the effects of common carp (Cyprinus carpio), an omnivorous fish, on the reproductive success of the red-necked grebe (Podiceps grisegena), an avian gape-limited predator, along a fish size gradient created by stocking distinct age-cohorts in seminatural ponds. Young-of-the-year (0+) carp were an essential food source for young grebes. Only adult birds were able to consume 1-year-old (1+) fish, while 2-year-old (2+) fish attained a size refuge from grebes. Amphibian larvae were the principal alternative prey to fish, followed by macroinvertebrates, but the abundance of both dramatically decreased along the carp size gradient. Fledging success was 2.8 times greater in ponds with 0+ versus 1+ carp; in ponds with 1+ carp, chicks received on average 2.6-3 times less prey biomass from their parents, and over 1/3 of broods suffered total failure. Breeding birds avoided settling on 2+ ponds. These results show that changes in prey fish size structure can account for shifts from positive trophic effects on the avian predator to a negative impact on the predator's alternative resources. However, competition did not fully explain the decrease in grebe food resources in the presence of large fish, as carp and grebes overlapped little in diet. In experimental cages, 1+ carp totally eliminated young larvae of amphibians palatable to fish. In field conditions, breeding adults of palatable taxa avoided ponds with 1+ and older carp. Non-trophic interactions such as habitat selection by amphibians or macroinvertebrates to avoid large fish may provide an indirect mechanism strengthening the adverse bottom-up effects of fish on birds.

  12. 62 years of population dynamics of European perch (Perca fluviatilis) in a mesotrophic lake tracked using angler diaries: The role of commercial fishing, predation and temperature

    DEFF Research Database (Denmark)

    Skov, Christian; Jansen, Teunis; Arlinghaus, Robert

    2017-01-01

    (abundance, mean size and record size) of European perch (Perca fluviatilis L.) in relation to the impact of three commercial fishers with different fishing strategies, pike (Esox lucius L.) predation and temperature. We found that anglers’ harvest rates of perch varied by a factor of 10 over time......, but it also underlines the need for supplementary data on biotic and abiotic factors to reach the full potential of angler diary data...

  13. Fish populations under stress. The example of the Lower Neckar river; Fischpopulationen unter Stress. Das Beispiel des Unteren Neckars

    Energy Technology Data Exchange (ETDEWEB)

    Braunbeck, Thomas; Brauns, Annika; Keiter, Steffen [Sektion Aquatische Oekologie und Toxikologie, Univ. Heidelberg (Germany); Hollert, Henner [Inst. fuer Umweltforschung (Biologie V), Lehr- und Forschungsgebiet Oekosystemanalyse, Rheinisch-Westfaelische Technische Hochschule Aachen, Aachen (Germany); Schwartz, Patrick [Basel Univ. (CH). Mensch-Gesellschaft-Umwelt (MGU)

    2009-04-15

    Background, aim, and scope: Reports about declines or unusual structures of fish populations in native aquatic systems in Central Europe and North America are in sharp contrast to an obvious improvement of general water quality. The Neckar River may serve as an example of a formerly severely contaminated freshwater system in Southern Germany, the ecological situation of which could be substantially improved over the last three decades. Nevertheless, there are still deficits in the composition of the fish fauna, which cannot be explained by conventional chemical-analytical, hydromorphological and limnological methodologies. Therefore, in search of explanations for ecological deficits, ecotoxicological investigations with an increasing focus on sediment contamination have been performed along the Lower Neckar River over a period of 10 years. In addition to sediment tests, fish populations were screened for genotoxic and embryotoxic effects as well as alterations in the structure of central metabolic organs such as the liver. Materials and methods: Roach (Rutilus rutilus) and gudgeon (Gobio gobio) from the Lower Neckar River were studied with respect to histo- and cytological alterations of the liver as well as the induction of genotoxicity in liver, gut, gills and blood cells by means of the comet and micronucleus assays. At the same time, both native sediments and acetonic sediment extracts were tested for toxicity to zebrafish (Danio rerio) embryos and permanent fish cell cultures. Results: Massive disturbances of the liver ultrastructure indicate severe stress in the fish from the Lower Neckar River despite good supply of nutrition. Both cyto- and embryotoxicity tests document a considerable toxic potential of sediments from the Lower Neckar River, and results of both the comet assay and the micronucleus test provide evidence of the presence of genotoxic agents in the sediments and their effects in fish. There has been no decrease of genotoxicity over the last 10

  14. Criteria for sustainable fisheries on juveniles illustrated for Mediterranean hake: control the juvenile harvest, and safeguard spawning refugia to rebuild population fecundity

    Directory of Open Access Journals (Sweden)

    John F. Caddy

    2015-09-01

    Full Text Available The paper provides a broad overview of issues relevant to management of fisheries for juvenile fish in contrast to the many stock assessments following Beverton and Holt’s (1957 approach for rational exploitation of mature fishes. A perspective on assessing these fisheries is illustrated for juvenile European hake, Merluccius merluccius, in the northwestern Mediterranean. Here, a constant natural mortality (M assumption is incorrect, as is the assumption that high fecundities are necessarily adequate for stock replacement. The high Ms-at-age for juveniles generated by the reciprocal model are shown to be a logical counterpart to the high fecundity of hake. Charnov’s criterion of intergenerational reproductive replacement is used to test for a sustainable population, analogous to a limit reference point warning of the dangers of overfishing beyond population replacement. Once peak mortality rates of age 2 hake exceed F(2=1.1-1.2, which is currently the case, reproductive replacement may be at risk. Adult exploitation by inshore trawls is low, and maturing hake surviving the fine-mesh trawl fishery migrate offshore with a reduced vulnerability to fine-mesh gears. Early research suggested that rough bottom near the shelf edge once formed a refugium protecting offshore spawners from trawling, and led to abundant recruitment of juveniles nearer shore. It may not do so if offshore fishing effort by reinforced bottom trawls, gill nets and longlines is uncontrolled. Restoring offshore refugia to protect spawners and controlling peak fishing mortality of juveniles would be a precautionary strategy aimed at restoring previous levels of recruitment to the small-mesh trawl fishery.

  15. Mercury exposure through fish consumption in riparian populations at reservoir Guri, using nuclear techniques, Bolivar State, Venezuela

    Energy Technology Data Exchange (ETDEWEB)

    Bermudez, Dario; Gali, Gladys; Carneiro, Flor; Paolini, Jorge; Venegas, Gladys; Marquez, Oscar

    2001-07-01

    The reservoir Guri located at the south of Venezuela in Bolivar State arose from damming the Caroni river and its main tributary, the Paraguay river. It was built between the years 1963 and 1986. The reservoir, whose primary use is the electric power generation followed by others beneficial uses such as water supply and recreation, was opened to commercial fishing recently. The riparian population is about 8,030 inhabitants: 7,389 toward the left side (west) and 641 toward the right side (cast) and it is distributed in populated centers, villages and in dispersed areas. The young population is the most conspicuous: 46 % and 52% on the right and left sides, respectively, with predominance of the masculine sex (86%). The reservoir Guri, the same as some reservoirs from other countries has shown what has been called 'dam effect', a term used to designate the occurrence of bioaccumulation process in reservoirs due to the high mercury levels found mainly in piscivorous fish species which are the most preferred by fish consumers. In a sample of 42 specimens of the carnivorous trophic level, the average value of total mercury was 1. 90 ppm, with a maximum value of 6.04 ppm. For the detritivorous trophic level, in a sample of 17 specimens, the average value of total mercury was 0.27 ppm, with a maximum value of 0.69 ppm, while for the omnivorous trophic level, in a sample of 6 specimens, the average value of total mercury was 0.55 ppm, with a maximum value of 0.99 ppm. The source of mercury in fishes from reservoir Guri has not been determined; however, in some sectors of the flooded area activities were carried out of exploitation of aluvional gold using metallic mercury for gold recovery and burning the amalgam at open ceiling. The objective of this research project is to determine the relationship among the ingestion of fish coming from reservoir Guri, the levels of organic mercury in hair and the appearance of signs and symptoms of neurotoxicity in a sample

  16. Mercury exposure through fish consumption in riparian populations at reservoir Guri, using nuclear techniques, Bolivar State, Venezuela

    International Nuclear Information System (INIS)

    Bermudez, Dario; Gali, Gladys; Carneiro, Flor; Paolini, Jorge; Venegas, Gladys; Marquez, Oscar

    2001-01-01

    The reservoir Guri located at the south of Venezuela in Bolivar State arose from damming the Caroni river and its main tributary, the Paraguay river. It was built between the years 1963 and 1986. The reservoir, whose primary use is the electric power generation followed by others beneficial uses such as water supply and recreation, was opened to commercial fishing recently. The riparian population is about 8,030 inhabitants: 7,389 toward the left side (west) and 641 toward the right side (cast) and it is distributed in populated centers, villages and in dispersed areas. The young population is the most conspicuous: 46 % and 52% on the right and left sides, respectively, with predominance of the masculine sex (86%). The reservoir Guri, the same as some reservoirs from other countries has shown what has been called 'dam effect', a term used to designate the occurrence of bioaccumulation process in reservoirs due to the high mercury levels found mainly in piscivorous fish species which are the most preferred by fish consumers. In a sample of 42 specimens of the carnivorous trophic level, the average value of total mercury was 1. 90 ppm, with a maximum value of 6.04 ppm. For the detritivorous trophic level, in a sample of 17 specimens, the average value of total mercury was 0.27 ppm, with a maximum value of 0.69 ppm, while for the omnivorous trophic level, in a sample of 6 specimens, the average value of total mercury was 0.55 ppm, with a maximum value of 0.99 ppm. The source of mercury in fishes from reservoir Guri has not been determined; however, in some sectors of the flooded area activities were carried out of exploitation of aluvional gold using metallic mercury for gold recovery and burning the amalgam at open ceiling. The objective of this research project is to determine the relationship among the ingestion of fish coming from reservoir Guri, the levels of organic mercury in hair and the appearance of signs and symptoms of neurotoxicity in a sample

  17. Selective exploitation of large pike Esox lucius-Effects on mercury concentrations in fish populations

    International Nuclear Information System (INIS)

    Sharma, Chhatra Mani; Borgstrom, Reidar; Huitfeldt, Jorgen Sinkaberg; Rosseland, Bjorn Olav

    2008-01-01

    The present study outlines two main trends of mercury transfer patterns through the fish community: 1) the Hg concentrations increase with increase in the trophic level, with top predators having the highest concentrations, and 2) a fast growth rate may dilute the concentrations of Hg in fish muscle tissue (growth biodilution). In 2004, an extensive reduction in number of large pike (Esox lucius L.), was initiated by selective gillnet fishing in Lake Arungen, Norway, in order to increase the pike recruitment due to an expected reduction in cannibalism. In this connection, total mercury (THg) concentrations in the fish community were studied both before (2003) and after (2005) the removal of large pike. The δ 15 N signatures and stomach content analyses indicated that pike and perch (Perca fluviatilis L.) occupied the highest trophic position, while roach (Rutilus rutilus (L.)) was at the lower level, and rudd (Scardinius erythrophthalmus L.) at the lowest. The piscivores, pike and perch, had the highest concentrations of THg. The biomagnification rate of THg through the food web in the fish community was 0.163 ( per milleδ 15 N), with the highest uptake rate (0.232) in perch. A significant decrease in THg concentrations was found in all fish species in 2005 compared to 2003. Removal of the top predators in an Hg contaminated lake might thus be an important management tool for reducing Hg levels in fish, thereby reducing health risk to humans

  18. Importance of floodplain connectivity to fish populations in the Apalachicola River, Florida

    Science.gov (United States)

    Burgess, O.T.; Pine, William E.; Walsh, S.J.

    2013-01-01

    Floodplain habitats provide critical spawning and rearing habitats for many large-river fishes. The paradigm that floodplains are essential habitats is often a key reason for restoring altered rivers to natural flow regimes. However, few studies have documented spatial and temporal utilization of floodplain habitats by adult fish of sport or commercial management interest or assessed obligatory access to floodplain habitats for species' persistence. In this study, we applied telemetry techniques to examine adult fish movements between floodplain and mainstem habitats, paired with intensive light trap sampling of larval fish in these same habitats, to assess the relationships between riverine flows and fish movement and spawning patterns in restored and unmodified floodplain distributaries of the Apalachicola River, Florida. Our intent is to inform resource managers on the relationships between the timing, magnitude and duration of flow events and fish spawning as part of river management actions. Our results demonstrate spawning by all study species in floodplain and mainstem river habitat types, apparent migratory movements of some species between these habitats, and distinct spawning events for each study species on the basis of fish movement patterns and light trap catches. Additionally, Micropterus spp., Lepomis spp. and, to a lesser degree, Minytrema melanops used floodplain channel habitat that was experimentally reconnected to the mainstem within a few weeks of completing the restoration. This result is of interest to managers assessing restoration activities to reconnect these habitats as part of riverine restoration programmes globally.

  19. The Bifurcation and Control of a Single-Species Fish Population Logistic Model with the Invasion of Alien Species

    OpenAIRE

    Zhang, Yi; Zhang, Qiaoling; Li, Jinghao; Zhang, Qingling

    2014-01-01

    The objective of this paper is to study systematically the bifurcation and control of a single-species fish population logistic model with the invasion of alien species based on the theory of singular system and bifurcation. It regards Spartina anglica as an invasive species, which invades the fisheries and aquaculture. Firstly, the stabilities of equilibria in this model are discussed. Moreover, the sufficient conditions for existence of the trans-critical bifurcation and the singularity ind...

  20. Self-recruitment in a coral reef fish population in a marine reserve

    KAUST Repository

    Herrera Sarrias, Marcela

    2014-12-01

    Marine protected areas (MPAs) have proliferated in the past decades to protect biodiversity and sustain fisheries. However, most of the MPA networks have been designed without taking into account a critical factor: the larval dispersal patterns of populations within and outside the reserves. The scale and predictability of larval dispersal, however, remain unknown due to the difficulty of measuring dispersal when larvae are minute (~ cm) compared to the potential scale of dispersal (~ km). Nevertheless, genetic approaches can now be used to make estimates of larval dispersal. The following thesis describes self-recruitment and connectivity patterns of a coral reef fish species (Centropyge bicolor) in Kimbe Bay, Papua New Guinea. To do this, microsatellite markers were developed to evaluate fine-scale genetics and recruit assignment via genetic parentage analysis. In this method, offspring are assigned to potential parents, so that larval dispersal distances can then be inferred for each individual larvae. From a total of 255 adults and 426 juveniles collected only 2 parentoffspring pairs were assigned, representing less than 1% self-recruitment. Previous data from the same study system showed that both Chaetodon vagagundus and Amphiprion percula have consistent high self-recuitment rates (~ 60%), despite having contrasting life history traits. Since C. bicolor and C. vagabundus have similar characteristics (e.g. reproductive mode, pelagic larval duration), comparable results were expected. On the contrary, the results of this study showed that dispersal patterns cannot be generalized across species. Hence the importance of studying different species and seascapes to better understand the patterns of larval dispersal. This, in turn, will be essential to improve the design and implementation of MPAs as conservation and management tools.

  1. Population connectivity among geographic variants within the Lutjanidae (Pisces of the Mexican Pacific coast through fish scale shape recognition

    Directory of Open Access Journals (Sweden)

    Ana L. Ibáñez

    2012-11-01

    Full Text Available Fish scale shape was used to identify geographic variants among Lutjanidae (Lutjanus argentiventris, L. guttatus and L. peru. Specimens were collected from three different geographic areas, north to south of the tropical Pacific coast of Mexico: Puerto Vallarta (PV, Manzanillo (MA and Caleta de Campos (CC. Configuration of landmark coordinates of fish scales were scaled, translated and rotated using generalized procrustes analysis, followed by principal components analysis of resulting shape coordinates. Principal component scores were submitted to cross-validated discriminant analysis to determine the efficacy of scale landmarks for discrimination by geographic variants. This was done with shape and form (shape plus size. PV and MA were recognized as one population different from the CC sampling area. Using only shape (without size, identification rates predicted geographic variant membership much better than chance (91.3%, 70.6% and 85.4% for L. argentiventris, L. guttatus and L. peru, respectively, and taking size into account, classification is somewhat improved (90.6%, 80.1% and 87.5% for L. argentiventris, L. guttatus and L. peru, respectively. Consistency of the two populations for the three species shows non-fortuitous events. Population discrimination confirmed previous genetic studies that show a zoogeographic barrier between the North Equatorial Current and the California Current. The method is non-destructive, fast and less expensive than genetic analysis, thus allowing screening of many individuals for traceability of fish.

  2. Characterization of reef fish populations within St. Thomas East End Reserve (STEER), USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCCOS' Center for Coastal Monitoring and Assessment (CCMA) is working closely with a number of divisions in the USVI DPNR (e.g., Divisions of Fish and Wildlife and...

  3. Coherence between harvest and habitat management -- Joint venture perspectives

    Science.gov (United States)

    Baxter, C.K.; Nelson, J.W.; Reinecke, K.J.; Stephens, S.E.

    2006-01-01

    Introduction: In recent months, an ad hoc group of waterfowl scientists, representing the International Association of Fish and Wildlife Agencies (IAFWA) Adaptive Harvest Management (ARM) Task Force and the North American Waterfowl Management Plan (NAWMP) Committee, have collaborated as a Joint Task Group (JTG) to assess options for unifying the population goals guiding waterfowl harvest management and habitat management. The JTG has been charged with bringing coherence to the population goals of the two programs. Characterizing the problem as one of coherence indicates value judgments exist regarding its significance or perhaps existence. For purposes of this paper, we characterize the lack of coherence as the absence of consistent population goals in the two related components of waterfowl conservation habitat and harvest management. Our purpose is to support continued dialogue on the respective goals of these programs and the possible implications of discordant goals to habitat joint ventures. Our objectives are two-fold: (1) illustrate how NAWMP habitat management goals and strategies have been interpreted and pursued in both breeding and wintering areas, and (2) provide perspectives on the linkages between regional habitat management programs and harvest management. The Lower Mississippi Valley and the Prairie Pothole joint ventures (LMVJV and PPJV, respectively) will be used as examples.

  4. Reduced Spill at Hydropower Dams: Opportunities for More Generation and Increased Fish Population

    Energy Technology Data Exchange (ETDEWEB)

    Coutant, Charles C [ORNL; Mann, Roger [RMecon, Davis, California; Sale, Michael J [ORNL

    2006-09-01

    This report indicates that reduction of managed spill at hydropower dams can speed implementation of technologies for fish protection and achieve economic goals. Spill of water over spillways is managed in the Columbia River basin to assist downstream-migrating juvenile salmon, and is generally believed to be the most similar to natural migration, benign and effective passage route; other routes include turbines, intake screens with bypasses, and surface bypasses. However, this belief may be misguided, because spill is becoming recognized as less than natural, with deep intakes below normal migration depths, and likely causing physical damages from severe shear on spillways, high turbulence in tail waters, and collisions with baffle blocks that lead to disorientation and predation. Some spillways induce mortalities comparable to turbines. Spill is expensive in lost generation, and controversial. Fish-passage research is leading to more fish-friendly turbines, screens and bypasses that are more effective and less damaging, and surface bypasses that offer passage of more fish per unit water volume than does spill (leaving more water for generation). Analyses by independent economists demonstrated that goals of increased fish survival over the long term and net gain to the economy can be obtained by selectively reducing spill and diverting some of the income from added power generation to research, development, and installation of fish-passage technologies. Such a plan would selectively reduce spill when and where least damaging to fish, increase electricity generation using the water not spilled and use innovative financing to direct monetary gains to improving fish passage.

  5. Population Aspects of Fishes in Geba and Sor Rivers, White Nile System in Ethiopia, East Africa

    Directory of Open Access Journals (Sweden)

    Simagegnew Melaku

    2017-01-01

    Full Text Available This study was carried out to assess the diversity, condition factor, length-weight relationship, and sex ratio of fishes in Geba and Sor Rivers located in Baro-Akobo Basin, White Nile system within Ethiopia. Fish samples were collected in one wet and one dry season. The length-weight relationships were fitted using power equation for the most abundant species. A total of 348 fish specimens were collected using gillnets and hooks. These were identified into eight species and one Garra sp. representing seven genera and four families. Family Cyprinidae was the most dominant with six species (66.7%. Labeobarbus intermedius, Labeobarbus nedgia, and Labeo cylindricus were the most abundant fish species, respectively, with 60.72%, 16.83%, and 14.66% index of relative importance (IRI. The diversity index was higher for Geba River (H′ = 1.50 than for Sor River (H′ = 1.10. All the three most abundant species had negative allometric growth. Seasonal variations in the mean Fulton condition factor (FCF were statistically significant for L. cylindricus (p<0.05. There was variation in the sex ratio with the females dominating in all the three most abundant species. Further investigation into the fish diversity, food, feeding, and reproductive behaviors of fish species especially in the tributaries of these rivers and their socioeconomic aspects is recommended.

  6. Effect and consequences of the reactor-accident in Chernobyl on the fish population in Bavaria

    Energy Technology Data Exchange (ETDEWEB)

    Luensmann, Wulf [Bayerische Landesanstalt fuer Wasserforschung, Munich (Germany)

    1986-07-01

    After the reactor-accident in Chernobyl radioactive fission products reached during the night on April 30, 1986, the south Bavarian region. They were washed out by heavy rains in the early hours of the afternoon, causing a contamination of the total biosphere. It is known from radio-ecological studies, that radionuclides concentrate in fish meat. Ionising radiation may lead to an internal radiation exposition of human beings via food chains. It was for that reason necessary to follow up the temporal development in order to prevent injuries through ionising radiation. The Bavarian Institute for Water Research started on May 5, a project in connection with fish consumption and investigated fish meat for radioactivity, originated from 3 different biotopes: a) rivers b) fish-farms c) lakes in the prealpine region. Altogether approximately 700 fishes were examined until the end of October. Fish-meat contained until the middle of May besides Cs134 and Cs137 also the short-living radionuclides J131 and Te132 (20-30 Bq/kg fresh meat). After that date could only Cs134 and Cs137 be demonstrated. Since both cesium-isotopes in the Chernobyl-fallout occur in a 1:2 ratio, only the result of Cs137 are reported.

  7. Effect and consequences of the reactor-accident in Chernobyl on the fish population in Bavaria

    International Nuclear Information System (INIS)

    Luensmann, Wulf

    1986-01-01

    After the reactor-accident in Chernobyl radioactive fission products reached during the night on April 30, 1986, the south Bavarian region. They were washed out by heavy rains in the early hours of the afternoon, causing a contamination of the total biosphere. It is known from radio-ecological studies, that radionuclides concentrate in fish meat. Ionising radiation may lead to an internal radiation exposition of human beings via food chains. It was for that reason necessary to follow up the temporal development in order to prevent injuries through ionising radiation. The Bavarian Institute for Water Research started on May 5, a project in connection with fish consumption and investigated fish meat for radioactivity, originated from 3 different biotopes: a) rivers b) fish-farms c) lakes in the prealpine region. Altogether approximately 700 fishes were examined until the end of October. Fish-meat contained until the middle of May besides Cs134 and Cs137 also the short-living radionuclides J131 and Te132 (20-30 Bq/kg fresh meat). After that date could only Cs134 and Cs137 be demonstrated. Since both cesium-isotopes in the Chernobyl-fallout occur in a 1:2 ratio, only the result of Cs137 are reported

  8. Population Variation in the Life History of a Land Fish, Alticus arnoldorum, and the Effects of Predation and Density.

    Directory of Open Access Journals (Sweden)

    Edward R M Platt

    Full Text Available Life history variation can often reflect differences in age-specific mortality within populations, with the general expectation that reproduction should be shifted away from ages experiencing increased mortality. Investigators of life history in vertebrates frequently focus on the impact of predation, but there is increasing evidence that predation may have unexpected impacts on population density that in turn prompt unexpected changes in life history. There are also other reasons why density might impact life history independently of predation or mortality more generally. We investigated the consequences of predation and density on life history variation among populations of the Pacific leaping blenny, Alticus arnoldorum. This fish from the island of Guam spends its adult life out of the water on rocks in the splash zone, where it is vulnerable to predation and can be expected to be sensitive to changes in population density that impact resource availability. We found populations invested more in reproduction as predation decreased, while growth rate varied primarily in response to population density. These differences in life history among populations are likely plastic given the extensive gene flow among populations revealed by a previous study. The influence of predation and density on life history was unlikely to have operated independently of each other, with predation rate tending to be associated with reduced population densities. Taken together, our results suggest predation and density can have complex influences on life history, and that plastic life history traits could allow populations to persist in new or rapidly changing environments.

  9. Geometric and morphometric analysis of fish scales to identity genera, species and populations case study: the Cyprinid family

    Directory of Open Access Journals (Sweden)

    Seyedeh Narjes Tabatabei

    2014-01-01

    Full Text Available Using fish scale to identity species and population is a rapid, safe and low cost method. Hence, this study was carried out to investigate the possibility of using geometric and morphometric methods in fish scales for rapid identification of species and populations and compare the efficiency of applying few and/or high number of landmark points. For this purpose, scales of one population of Luciobarbus capito, four populations of Alburnoides eichwaldii and two populations of Rutilus frisii kutum, all belonging to cyprinid family, were examined. On two-dimensional images of the scales 7 and 23 landmark points were digitized in two separate times using TpsDig2, respectively. Landmark data after generalized procrustes analysis were analyzed using Principal Component Analysis (PCA, Canonical Variate Analysis (CVA and Cluster Analysis. The results of both methods (using 7 and 23 landmark points showed significant differences of the shape of scales among the three species studied (P0.05. The results also showed that few number of landmarks could display the differences between scale shapes. According to the results of this study, it could be stated that the scale of each species had unique shape patterns which could be utilized as a species identification key.

  10. The dynamics of fish populations in the Palancar stream,a small tributary of the river Guadalquivir, Spain

    Science.gov (United States)

    Bravo, Ramón; Soriguer, Mila C.; Villar, Noelia; Hernando, José A.

    2001-02-01

    The relationship between flooding and changes in the size distribution of fish populations in the Palancar stream confirms observations in other rivers. On average, density decreased by 36.2 % and biomass increased by 14.5 %, passing from a period of severe drought to one of heavier than normal rains. Precipitation is the most important of the many factors affecting the populations of the Palancar stream; the most evident changes all occurred after the drought. During the drought period, the marked seasonal fluctuation in flow was the most important factor regulating the population dynamics. Fish density and biomass varied in proportion to the water volume. During the rainy period, the studied section of the river was found to be an important reproduction and nursery area, with juveniles and individuals of reproduction age dominating. The presence of Micropterus salmoides, an introduced piscivorous species, is another factor affecting the population dynamics in the Palancar stream. The observed absence of age 0+ individuals of the dominant populations is considered a direct effect of predation.

  11. The Impacts of Recently Established Fish Populations on Zooplankton Communities in a Desert Spring, and Potential Conflicts in Setting Conservation Goals

    Directory of Open Access Journals (Sweden)

    Sujan M. Henkanaththegedara

    2015-01-01

    Full Text Available Desert springs, which harbor diverse and endemic invertebrate assemblages, are often used as refuge habitats for protected fish species. Additionally, many of these springs have been colonized by invasive fish species. However, the potential impacts of recently established fish populations on invertebrate communities in desert springs have been relatively unexplored. We conducted a mesocosm experiment to assess the impact of both protected and invasive fish on community structure of spring-dwelling invertebrates focusing on zooplankton. Experimental populations of spring zooplankton communities were established and randomly assigned to one of three treatments, (1 invasive western mosquitofish (Gambusia affinis; (2 endangered Mohave tui chub (Siphateles bicolor mohavensis; and (3 fishless control. Final populations of zooplankton and fish were sampled, sorted, identified and counted. The treatment differences of zooplankton communities were analyzed by comparing the densities of six major zooplankton taxa. Further, we performed nonmetric multidimensional scaling (NMDS to visualize the patterns of zooplankton community assemblages. Four zooplankton taxa, crustacean nauplii, cladocera, calanoid and cyclopoid copepods had significantly lower densities in fish treatments compared to fishless control. Overall, invasive mosquitofish caused a 78.8% reduction in zooplankton density, while Mohave tui chub caused a 65.1% reduction. Both protected and invasive fish had similar effects on zooplankton except for cladocerans where tui chub caused a 60% reduction in density, whereas mosquitofish virtually eliminated cladocerans. The presence of fish also had a significant effect on zooplankton community structure due to population declines and local extirpations presumably due to fish predation. This work shows that conservation-translocations undertaken to conserve protected fish species may impact spring-dwelling invertebrate communities, and such impacts are

  12. Genetic population structure of European sprat (Sprattus sprattus L.): differentiation across a steep environmental gradient in a small pelagic fish

    DEFF Research Database (Denmark)

    Limborg, Morten; Pedersen, Jes S.; Hansen, Jakob Hemmer

    2009-01-01

    locations in and around the North- and Baltic Sea area and from a geographically distant population from the Adriatic Sea. Analyses of nine microsatellite loci revealed a sharp genetic division separating samples from the Northeastern Atlantic and the Baltic Sea (pairwise θ = 0.019–0.035), concurring...... with a steep salinity gradient. We found, at most, weak structure among samples within the Northeastern Atlantic region and within the Baltic Sea (pairwise θ = 0.001–0.009). The Adriatic Sea population was highly differentiated from all northern samples (pairwise θ = 0.071–0.092). Overall, the observed...... population structure resembles that of most other marine fishes studied in the North/Baltic Sea areas. Nevertheless, spatially explicit differences are observed among species, likely reflecting specific life-histories. Such fine-scale population structure should be taken into account, e.g. in ecosystem...

  13. Characteristics of Marine Recreational Fishing in the anakkale Strait (Turkey

    Directory of Open Access Journals (Sweden)

    V. UNAL

    2010-11-01

    Full Text Available The economic and harvest impacts of Marine Recreational Fishing (MRF in Çanakkale Strait were analysed along with fishing policy, sociology and habits of fishers. Data sources included field survey data carried out along the entire length of the Çanakkale strait and policy information gathered from published sources. MRF policy is commendable, even in the fishing tourism sector, and is better developed than that in many other European countries. In Çanakkale, 9.9% of the population is recreational fishers. Recreational fishers are typically men (90%, primarily those between the ages of 25 and 49 yrs. The occupation of the recreational fishers ranged from self-employed (28%, students (28%, retired persons (22% and public employees (15%, to currently-unemployed persons (7%. An analysis of diel behaviour showed that most recreational fishers preferred fishing during the day (56.1%, while the evening was the next most preferred time for fishing (18%, followed by the night-time (9.8%, while a substantial number of recreational fishers (16.1% reported that they fished at any time of day. The most popular type of fishing was shore-based (68%, followed by boat-based (21%, and underwater fishing (11%. The mean daily fishing times were 6.07 h d-1, 6.18 h d-1 4.75 d-1 for boat-based, underwater and shore-based fishing, respectively. Summer and autumn were the preferred seasons for shore-based and underwater fishing, while autumn and winter were preferred for boat-based fishing. The highest Catch per Unit Effort (CPUE was observed for boat-based fishing (2.77 kg h-1, followed by underwater (0.97 kg h-1 and shore-based fishing (0.81 kg h-1. The catch composition included 51 species, though the catch composition of each fishing type was mostly comprised of only 3 or 4 species. The impact of the MRF harvest was high (30% of commercial fishing, particularly for bluefish (Pomatomus saltatrix and picarel (Spicara smaris species. The economic impact of MRF was

  14. Argument supporting the reality of compensation in fish populations and a plea to let them exercise it

    International Nuclear Information System (INIS)

    McFadden, J.T.

    1977-01-01

    Approaching population processes of fish from the perspective of compensation one envisions an established population as one in which survival or reproduction (or both) have been vastly suppressed for the reason that the population has become large. The natural factors that operate to suppress the biotic potential are many and are complexly intertwined, including availability of food, predators, disease, and physical factors such as temperature. Many of them have greater suppressive effect when the population is large than when it is small. If some new effect that kills off part of the population is introduced, it reduces the suppressive effect of many factors in the population's environment. As a consequence, survival rate or reproductive rate becomes higher and the population compensates in part for the reduction in size. When something causes a population to either increase or decrease in size, there is a tendency for eventual return to average size when the perturbation is removed. Populations do not usually become extinct or increase to infinity, but maintain the balance of nature

  15. Source Array Support for Continuous Monitoring of Fish Population and Behavior by Instantaneous Continental-Shelf-Scale Imaging Using Ocean-Waveguide Acoustics

    National Research Council Canada - National Science Library

    Rynne, Ed; Gillette, David

    2006-01-01

    ...) Multistatic ASW Capability Enhancement Program (MACE) as the source of underwater sounds to support active bi-static sonar capabilities for monitoring fish populations and behaviors during a September/October 2006 sea test off the coast of Maine...

  16. Mercury exposure in a high fish eating Bolivian Amazonian population with intense small-scale gold-mining activities.

    Science.gov (United States)

    Barbieri, Flavia Laura; Cournil, Amandine; Gardon, Jacques

    2009-08-01

    Methylmercury exposure in Amazonian communities through fish consumption has been widely documented in Brazil. There is still a lack of data in other Amazonian countries, which is why we conducted this study in the Bolivian Amazon basin. Simple random sampling was used from a small village located in the lower Beni River, where there is intense gold mining and high fish consumption. All participants were interviewed and hair samples were taken to measure total mercury concentrations. The hair mercury geometric mean in the general population was 3.02 microg/g (CI: 2.69-3.37; range: 0.42-15.65). Age and gender were not directly associated with mercury levels. Fish consumption showed a positive relation and so did occupation, especially small-scale gold mining. Hair mercury levels were lower than those found in Brazilian studies, but still higher than in non-exposed populations. It is necessary to assess mercury exposure in the Amazonian regions where data is still lacking, using a standardized indicator.

  17. Apportioning bacterial carbon source utilization in soil using 14 C isotope analysis of FISH-targeted bacterial populations sorted by fluorescence activated cell sorting (FACS): 14 C-FISH-FACS.

    Science.gov (United States)

    Gougoulias, Christos; Meade, Andrew; Shaw, Liz J

    2018-02-19

    An unresolved need in microbial ecology is methodology to enable quantitative analysis of in situ microbial substrate carbon use at the population level. Here, we evaluated if a novel combination of radiocarbon-labelled substrate tracing, fluorescence in situ hybridisation (FISH) and fluorescence-activated cell sorting (FACS) to sort the FISH-targeted population for quantification of incorporated radioactivity ( 14 C-FISH-FACS) can address this need. Our test scenario used FISH probe PSE1284 targeting Pseudomonas spp. (and some Burkholderia spp.) and salicylic acid added to rhizosphere soil. We examined salicylic acid- 14 C fate (mineralized, cell-incorporated, extractable and non-extractable) and mass balance (0-24 h) and show that the PSE1284 population captured ∼ 50% of the Nycodenz extracted biomass 14 C. Analysis of the taxonomic distribution of the salicylic acid biodegradation trait suggested that PSE1284 population success was not due to conservation of this trait but due to competitiveness for the added carbon. Adding 50KBq of 14 C sample -1 enabled detection of 14 C in the sorted population at ∼ 60-600 times background; a sensitivity which demonstrates potential extension to analysis of rarer/less active populations. Given its sensitivity and compatibility with obtaining a C mass balance, 14 C-FISH-FACS allows quantitative dissection of C flow within the microbial biomass that has hitherto not been achieved. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

  18. Linking temporal changes in the demographic structure and individual growth to the decline in the population of a tropical fish

    Science.gov (United States)

    Sirot, Charlotte; Darnaude, Audrey M.; Guilhaumon, François; Ramos-Miranda, Julia; Flores-Hernandez, Domingo; Panfili, Jacques

    2015-11-01

    The exceptional biodiversity and productivity of tropical coastal lagoons can only be preserved by identifying the causes for the decline in the populations living in these vulnerable ecosystems. The Terminos lagoon in Mexico provided an opportunity for studying this issue as some of its fish populations, in particular the Silver Perch (Bairdiella chrysoura), have declined significantly since the 1980s. Fish sampling campaigns carried out over the whole lagoon area in 1979-81 and again in 2006-2011 revealed the mechanisms which may have been responsible for this decline. Based on biometrical data for 295 juveniles and adults from the two periods and on somatic growth derived from 173 otoliths, a study of the temporal changes in the demographic structure and life history traits (individual growth and body condition) made it possible to distinguish the causes of the decline in the B. chrysoura population. Growth models for the lagoon in 1980-1981 and 2006-2011 showed no significant change in the growth parameters of the population over the last 30 years with a logistic model giving an accurate estimate (R2 = 0.66) of the size-at-age for both periods. The decline in the B. chrysoura population could not be explained by an overall decrease in individual size and condition in the lagoon, the average standard length (SL) and Fulton index (FI) having increased slightly since 1980-1981 (4.6 mm and 0.02 for juveniles and 5.42 mm and 0.07 for adults). However, the size structure of the population in the lagoon has changed, with a significant shift in the size distribution of juveniles with a marked reduction in the proportion of juveniles ≤ 60 mm in the captures (90.9% fewer than in 1980-1981). As the otolith growth rate of fish during the first 4 months also decreased significantly between the two sampling periods (-15%), it is suggested that the main reason for the decline in the abundance and biomass of B. chrysoura within this system may be that its habitats are less

  19. Novel mobbing strategies of a fish population against a sessile annelid predator.

    Science.gov (United States)

    Lachat, Jose; Haag-Wackernagel, Daniel

    2016-09-12

    When searching for food, foraging fishes expose themselves to hidden predators. The strategies that maximize the survival of foraging fishes are not well understood. Here, we describe a novel type of mobbing behaviour displayed by foraging Scolopsis affinis. The fish direct sharp water jets towards the hidden sessile annelid predator Eunice aphroditois (Bobbit worm). We recognized two different behavioural roles for mobbers (i.e., initiator and subsequent participants). The first individual to exhibit behaviour indicating the discovery of the Bobbit directed, absolutely and per time unit, more water jets than the subsequent individuals that joined the mobbing. We found evidence that the mobbing impacted the behaviour of the Bobbit, e.g., by inducing retraction. S. affinis individuals either mob alone or form mobbing groups. We speculate that this behaviour may provide social benefits for its conspecifics by securing foraging territories for S. affinis. Our results reveal a sophisticated and complex behavioural strategy to protect against a hidden predator.

  20. 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.

  1. Harvest Management and Recovery of Snake River Salmon Stocks : Recovery Issues for Threatened and Endangered Snake River Salmon : Technical Report 7 of 11.

    Energy Technology Data Exchange (ETDEWEB)

    Lestelle, Lawrence C.; Gilbertson, Larry G.

    1993-06-01

    Management measures to regulate salmon fishing harvest have grown increasingly complex over the past decade in response to the needs for improved protection for some salmon runs and to alter harvest sharing between fisheries. The development of management plans that adequately address both needs is an immensely complicated task, one that involves a multitude of stocks, each with its own migration patterns and capacity to sustain exploitation. The fishing industry that relies on these fish populations is also highly diverse. The management task is made especially difficult because the stocks are often intermingled on the fishing grounds, creating highly mixed aggregates of stocks and species on which the fisheries operate. This situation is the one confronting harvest managers attempting to protect Snake River salmon. This report provides an overview of some of the factors that will need to be addressed in assessing the potential for using harvest management measures in the recovery of Snake River salmon stocks. The major sections of the report include the following: perspectives on harvest impacts; ocean distribution and in-river adult migration timing; description of management processes and associated fisheries of interest; and altemative harvest strategies.

  2. Functional responses of human hunters to their prey - why harvest statistics may not always reflect changes in prey population abundance

    DEFF Research Database (Denmark)

    Kahlert, Johnny Abildgaard; Fox, Anthony David; Heldbjerg, Henning

    pigeon Columba palumbus, coot Fulica atra, grey partridge Perdix perdix, roe deer Capreolus capreolus and brown hare Lepus europaeus in Denmark. If we consider hunting a form of predator-prey interaction, the annual kill can be viewed as a predator functional response to prey population size. Convergence...

  3. Estimating the size of juvenile fish populations in southeastern coastal-plain estuaries

    International Nuclear Information System (INIS)

    Kjelson, M.A.

    1977-01-01

    Understanding the ecological significance of man's activities upon fishery resources requires information on the size of affected fish stocks. The objective of this paper is to provide information to evaluate and plan sampling programs designed to obtain accurate and precise estimates of fish abundance. Nursery habitats, as marsh--tidal creeks and submerged grass beds, offer the optimal conditions for estimating natural mortality rates for young-of-the-year fish in Atlantic and Gulf of Mexico coast estuaries. The area-density method of abundance estimation using quantitative gears is more feasible than either mark-recapture or direct-count techniques. The blockage method provides the most accurate estimates, while encircling devices enable highly mobile species found in open water to be captured. Drop nets and lift nets allow samples to be taken in obstructed sites, but trawls and seines are the most economical gears. Replicate samples are necessary to improve the precision of density estimates, while evaluation and use of gear-catch efficiencies is feasible and required to improve the accuracy of density estimates. Coefficients of variation for replicate trawl samples range from 50 to 150 percent, while catch efficiencies for both trawls and seines for many juvenile fishes range from approximately 30 to 70 percent

  4. 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.

  5. Mercury concentrations in lentic fish populations related to ecosystem and watershed characteristics

    Science.gov (United States)

    Andrew L. Rypel

    2010-01-01

    Predicting mercury (Hg) concentrations of fishes at large spatial scales is a fundamental environmental challenge with the potential to improve human health. In this study, mercury concentrations were examined for five species across 161 lakes and ecosystem, and watershed parameters were investigated as explanatory variables in statistical models. For all species, Hg...

  6. 75 FR 3888 - Migratory Bird Subsistence Harvest in Alaska; Harvest Regulations for Migratory Birds in Alaska...

    Science.gov (United States)

    2010-01-25

    ...-0082; 91200-1231-9BPP-L2] RIN 1018-AW67 Migratory Bird Subsistence Harvest in Alaska; Harvest Regulations for Migratory Birds in Alaska During the 2010 Season AGENCY: Fish and Wildlife Service, Interior... Service, are reopening the public comment period on our proposed rule to establish migratory bird...

  7. Connectivity, persistence, and loss of high abundance areas of a recovering marine fish population in the Northwest Atlantic Ocean.

    Science.gov (United States)

    Boudreau, Stephanie A; Shackell, Nancy L; Carson, Stuart; den Heyer, Cornelia E

    2017-11-01

    In the early 1990s, the Northwest Atlantic Ocean underwent a fisheries-driven ecosystem shift. Today, the iconic cod ( Gadus morhua ) remains at low levels, while Atlantic halibut ( Hippoglossus hippoglossus ) has been increasing since the mid-2000s, concomitant with increasing interest from the fishing industry. Currently, our knowledge about halibut ecology is limited, and the lack of recovery in other collapsed groundfish populations has highlighted the danger of overfishing local concentrations. Here, we apply a Bayesian hierarchical spatiotemporal approach to model the spatial structure of juvenile Atlantic halibut over 36 years and three fisheries management regimes using three model parameters to characterize the resulting spatiotemporal abundance structure: persistence (similarity of spatial structure over time), connectivity (coherence of temporal pattern over space), and spatial variance (variation across the seascape). Two areas of high juvenile abundance persisted through three decades whereas two in the northeast are now diminished, despite the increased abundance and landings throughout the management units. The persistent areas overlap with full and seasonal area closures, which may act as refuges from fishing. Connectivity was estimated to be 250 km, an order of magnitude less than the distance assumed by the definition of the Canadian management units (~2,000 km). The underlying question of whether there are distinct populations within the southern stock unit cannot be answered with this model, but the smaller ~250 km scale of coherent temporal patterns suggests more complex population structure than previously thought, which should be taken into consideration by fishery management.

  8. The population size, demography and the harvest strategy for the red deer (Cervus elaphus L. in the Polish eastern Carpathians

    Directory of Open Access Journals (Sweden)

    Merta, D.

    2002-12-01

    Full Text Available Using a line intercept snow track index, the population density and numbers of red deer (Cervus elaphusL. in 8 Forest Districts (Baligród, Cisna, Dukla, Lutowiska, Komacza, Stuposiany, Rymanów and Wetlina were estimated during February 2000. The total number of red deer inhabiting the study area (134.0 thousand hectares of forest was 4,081 individuals. The average population density was 30.4 red deer/1000 ha and it ranged from 10.1 animals/1000 ha in Wetlina Forest District to 39.3 individuals/1000 ha in Dukla Forest District. In September 2000, observation records of 952 red deer indicated that male/female ratio was 1:1.6, and the calf/female index was 31 calves per 100 females. Using a population dynamics model, an annual population recruitment rate was calculated. It ranged from 10.5% to 18.1% of the population size in March and it was negatively correlated with the population density of wolves. A computer simulation of various harvest strategies showed that the low percentage of old stags in the present red deer population was caused by over-harvest of 2-5-year-old stags. Therefore, it is suggested that the percentage of young males in the hunting bag should not be higher than 30% of the total harvested males.

    [fr]
    En février 2000 nous avons estimé la densité de population et le nombre de cerfs (Cervus elaphusL. dans 8 Districts Forestiers (Baligrod, Cisn, Dukla, Lutowiska, Komancza, Stuposiany, Rymanow et Wetlina. Pour cela un index des empreintes sur la neige interceptant une ligne a été utilisé. Le nombre total de cerfs habitant dans la zone d'étude -134.000 ha de forêt- s'élevait à 4 081 animais. La densité moyenne de la population était de 30,4 cerfs par 1000 ha, chiffre oscillant entre 10,1 animais par 1000 ha dans le District Forestier de Wetlina et 39,3 individus par 1000 ha dans le District Forestier de Dukla. En Septembre 2000, les observations enregistrées pour 952 cerfs ont montré que le

  9. Paleoecological studies on variability in marine fish populations: A long-term perspective on the impacts of climatic change on marine ecosystems

    Science.gov (United States)

    Finney, Bruce P.; Alheit, Jürgen; Emeis, Kay-Christian; Field, David B.; Gutiérrez, Dimitri; Struck, Ulrich

    2010-02-01

    The use of historical fishing records to understand relationships between climatic change and fish abundance is limited by the relatively short duration of these records, and complications due to the strong influence of human activity in addition to climatic change. Sedimentary records containing scales, bones or geochemical proxies of variability in fish populations provide unique insights on long-term ecosystem dynamics and relationships with climatic change. Available records from Holocene sediments are summarized and synthesized. The records are from several widespread locations near or along the continental margins of the South Atlantic and Pacific oceans, including Alaska, USA (Pacific salmon), Saanich and Effingham Inlets, British Columbia, Canada (pelagic fish), Santa Barbara Basin, California, USA (Northern anchovies and Pacific sardines), Gulf of California, Mexico (Pacific sardines, Northern anchovies and Pacific hake), Peru upwelling system (sardines, anchovies and hake), and Benguela Current System, South Africa (sardines, anchovies and hake). These records demonstrate that fish population sizes are not constant, and varied significantly over a range of time scales prior to the advent of large-scale commercial fishing. In addition to the decadal-scale variability commonly observed in historical records, the long-term records reveal substantial variability over centennial and millennial time scales. Shifts in abundance are often, but not always, correlated with regional and/or global climatic changes. The long-term perspective reveals different patterns of variability in fish populations, as well as fish-climate relationships, than suggested by analysis of historical records. Many records suggest prominent changes in fish abundance at ca. 1000-1200 AD, during the Little Ice Age, and during the transition at the end of the Little Ice Age in the 19th century that may be correlative, and that were likely driven by major hemispheric or global

  10. Relationship between mercury levels in hair and fish consumption in a population living near a hydroelectric tropical dam.

    Science.gov (United States)

    Marrugo-Negrete, José Luis; Ruiz-Guzmán, Javier Alonso; Díez, Sergi

    2013-02-01

    In the present study, total mercury (T-Hg) concentrations were assessed in human hair samples (n = 76) and fish muscle (n = 33) collected at Urrá dam, upstream Sinú river, northwestern Colombia. Based on interviews with study participants, weekly intakes of total mercury (WIT-Hg) and methylmercury (WIMeHg) by fish consumption were also estimated. T-Hg concentrations in hair samples ranged from 0.40 to 24.56 μg/g dw. The highest concentrations were recorded in children (CH) (2-15 years old, n = 24) with significant differences (p < 0.05) with respect to women of childbearing age (WCHA) (16-49 years old, n = 29) and the rest of the population (RP) (n = 23), which were not significantly different. The highest T-Hg concentrations in muscle tissue were recorded in the carnivorous fish (0.65-2.25 μg/g wet weight, ww), with significant differences (p < 0.05) compared to non-carnivorous fish (0.16-0.54 μg/g ww). WIT-Hg recorded the highest values in CH (2.18-50.41 μg/kg/week), with significant differences (p < 0.05) with respect to WCHA (2.02-23.54 μg/kg/week) and RP (1.09-24.71 μg/kg/week), which were not significantly different. Correlation analysis showed a significant relationship between weekly fish consumption and hair T-Hg in CH (r = 0.37, p < 0.05) and WCHA (r = 0.44, p < 0.05). This association was also observed with the number of days per week with fish consumption in CH (r = 0.37, p < 0.05) and WCHA (r = 0.45, p < 0.05). These results suggest that Hg exposure in people inhabiting the Urrá dam should be carefully monitored, particularly in vulnerable groups such as CH and WCHA.

  11. Effects of changes in food supply at the time of sex differentiation on the gonadal transcriptome of juvenile fish. Implications for natural and farmed populations.

    Directory of Open Access Journals (Sweden)

    Noelia Díaz

    Full Text Available Food supply is a major factor influencing growth rates in animals. This has important implications for both natural and farmed fish populations, since food restriction may difficult reproduction. However, a study on the effects of food supply on the development of juvenile gonads has never been transcriptionally described in fish.This study investigated the consequences of growth on gonadal transcriptome of European sea bass in: 1 4-month-old sexually undifferentiated fish, comparing the gonads of fish with the highest vs. the lowest growth, to explore a possible link between transcriptome and future sex, and 2 testis from 11-month-old juveniles where growth had been manipulated through changes in food supply. The four groups used were: i sustained fast growth, ii sustained slow growth, iii accelerated growth, iv decelerated growth. The transcriptome of undifferentiated gonads was not drastically affected by initial natural differences in growth. Further, changes in the expression of genes associated with protein turnover were seen, favoring catabolism in slow-growing fish and anabolism in fast-growing fish. Moreover, while fast-growing fish took energy from glucose, as deduced from the pathways affected and the analysis of protein-protein interactions examined, in slow-growing fish lipid metabolism and gluconeogenesis was favored. Interestingly, the highest transcriptomic differences were found when forcing initially fast-growing fish to decelerate their growth, while accelerating growth of initially slow-growing fish resulted in full transcriptomic convergence with sustained fast-growing fish.Food availability during sex differentiation shapes the juvenile testis transcriptome, as evidenced by adaptations to different energy balances. Remarkably, this occurs in absence of major histological changes in the testis. Thus, fish are able to recover transcriptionally their testes if they are provided with enough food supply during sex

  12. Effects of changes in food supply at the time of sex differentiation on the gonadal transcriptome of juvenile fish. Implications for natural and farmed populations.

    Science.gov (United States)

    Díaz, Noelia; Ribas, Laia; Piferrer, Francesc

    2014-01-01

    Food supply is a major factor influencing growth rates in animals. This has important implications for both natural and farmed fish populations, since food restriction may difficult reproduction. However, a study on the effects of food supply on the development of juvenile gonads has never been transcriptionally described in fish. This study investigated the consequences of growth on gonadal transcriptome of European sea bass in: 1) 4-month-old sexually undifferentiated fish, comparing the gonads of fish with the highest vs. the lowest growth, to explore a possible link between transcriptome and future sex, and 2) testis from 11-month-old juveniles where growth had been manipulated through changes in food supply. The four groups used were: i) sustained fast growth, ii) sustained slow growth, iii) accelerated growth, iv) decelerated growth. The transcriptome of undifferentiated gonads was not drastically affected by initial natural differences in growth. Further, changes in the expression of genes associated with protein turnover were seen, favoring catabolism in slow-growing fish and anabolism in fast-growing fish. Moreover, while fast-growing fish took energy from glucose, as deduced from the pathways affected and the analysis of protein-protein interactions examined, in slow-growing fish lipid metabolism and gluconeogenesis was favored. Interestingly, the highest transcriptomic differences were found when forcing initially fast-growing fish to decelerate their growth, while accelerating growth of initially slow-growing fish resulted in full transcriptomic convergence with sustained fast-growing fish. Food availability during sex differentiation shapes the juvenile testis transcriptome, as evidenced by adaptations to different energy balances. Remarkably, this occurs in absence of major histological changes in the testis. Thus, fish are able to recover transcriptionally their testes if they are provided with enough food supply during sex differentiation; however

  13. Status and future of Lake Huron fish communities

    Science.gov (United States)

    Ebener, M.P.; Johnson, J.E.; Reid, D.M.; Payne, N.P.; Argyle, R.L.; Wright, G.M.; Krueger, K.; Baker, J.P.; Morse, T.; Weise, J.; Munawar, M.; Edsall, T.; Leach, J.

    1995-01-01

    In 1993, fishery management agencies with jurisdiction over Lake Huron fish populations developed draft fish community objectives in response to the Joint Strategic Plan for Management of Great Lakes Fisheries. The Joint Strategic Plan charged the Great Lakes Fishery Commission sponsored Lake Huron Committee to define objectives for what the fish community of Lake Huron should look like in the future, and to develop means for measuring progress toward the objectives. The overall management objective for Lake Huron is to 'over the next two decades restore an ecologically balanced fish community dominated by top predators and consisting largely of self-sustaining, indigenous and naturalized species and capable of sustaining annual harvests of 8.9 million kg'. This paper represents the first attempt at consolidating current biological information from different management agencies on a lake-wide basis for the purpose of assessing the current status and dynamics of Lake Huron fishes.

  14. Sustainability of Mangrove Harvesting: How do Harvesters' Perceptions Differ from Ecological Analysis?

    Directory of Open Access Journals (Sweden)

    Laura López-Hoffman

    2006-12-01

    Full Text Available To harvest biological resources sustainably, it is first necessary to understand what "sustainability" means in an ecological context, and what it means to the people who use the resources. As a case study, we examined the extractive logging of the mangrove Rhizophora mangle in the Río Limón area of Lake Maracaibo, in western Venezuela. The ecological definition of sustainable harvesting is harvesting that allows population numbers to be maintained or to increase over time. In interviews, the harvesters defined sustainable harvesting as levels permitting the maintenance of the mangrove population over two human generations, about 50 yr. In Río Limón, harvesters extract a combination of small adult and juvenile trees. Harvesting rates ranged from 7-35% of small adult trees. These harvesting levels would be sustainable according to the harvester's definition as long as juvenile harvesting was less than 40%. However, some harvesting levels that would be sustainable according to the harvesters were ecologically unsustainable, i.e., eventually causing declines in mangrove population numbers. It was also determined that the structure of mangrove forests was significantly affected by harvesting; even areas harvested at low, ecologically sustainable intensities had significantly fewer adult trees than undisturbed sites. Western Venezuela has no organized timber industry, so mangrove logs are used in many types of construction. A lagging economy and a lack of alternative construction materials make mangrove harvesting inevitable, and for local people, an economic necessity. This creates a trade-off between preserving the ecological characteristics of the mangrove population and responding to human needs. In order to resolve this situation, we recommended a limited and adaptive mangrove harvesting regime. We also suggest that harvesters could participate in community-based management programs as harvesting monitors.

  15. A prospective monitoring of natural and anthropical fish populations in the basin of the Trotus river

    Directory of Open Access Journals (Sweden)

    URECHE Dorel

    2006-09-01

    Full Text Available As a major part of the Siret river hidrography, though less known ichthyologically, the Trotus has a series of tributaries worth mentioning for their natural sources of water pollution (the Slanic River for sodium chloride, the Tazlau River for potassium chloride and the Tazlaul Sarat for petroleum derivatives as well as for the chemical pollution from the plants in Darmanesti and Onesti. All these in mind the impact of the pollution over the fish fauna of the above mentioned area was determined. The basinal analysis of the ichthyocenosis was performed in three locations the selection of which was based on the particulars of the habitat: upper Trotus free of chemical and urban waste, the Tazlau and middle and downstream Trotus – an area affected by chemical and urban waste upstream Comanesti. A total number of sampling stations was chosen so as to cover all particular fish breeding associations and changes in spreading of the species.

  16. Spatial genetic analyses reveal cryptic population structure and migration patterns in a continuously harvested grey wolf (Canis lupus population in north-eastern Europe.

    Directory of Open Access Journals (Sweden)

    Maris Hindrikson

    Full Text Available Spatial genetics is a relatively new field in wildlife and conservation biology that is becoming an essential tool for unravelling the complexities of animal population processes, and for designing effective strategies for conservation and management. Conceptual and methodological developments in this field are therefore critical. Here we present two novel methodological approaches that further the analytical possibilities of STRUCTURE and DResD. Using these approaches we analyse structure and migrations in a grey wolf (Canislupus population in north-eastern Europe. We genotyped 16 microsatellite loci in 166 individuals sampled from the wolf population in Estonia and Latvia that has been under strong and continuous hunting pressure for decades. Our analysis demonstrated that this relatively small wolf population is represented by four genetic groups. We also used a novel methodological approach that uses linear interpolation to statistically test the spatial separation of genetic groups. The new method, which is capable of using program STRUCTURE output, can be applied widely in population genetics to reveal both core areas and areas of low significance for genetic groups. We also used a recently developed spatially explicit individual-based method DResD, and applied it for the first time to microsatellite data, revealing a migration corridor and barriers, and several contact zones.

  17. Methylmercury determination in fish and seafood products and estimated daily intake for the Spanish population.

    Science.gov (United States)

    Sahuquillo, I; Lagarda, M J; Silvestre, M D; Farré, R

    2007-08-01

    The mercury content of 25 samples of fish and seafood products most frequently consumed in Spain was determined. A simple method comprising cold vapour and atomic absorption spectrometry was used to determine separately inorganic and organic mercury. In all samples inorganic mercury content was below 50 microg kg(-1). There was wide variability, among not only the mercury levels of different fish species, but also for different samples of the same species - with the methylmercury content ranging from below 54 to 662 microg kg(-1). The highest mean methylmercury content was found in fresh tuna. Based on an average total fish consumption of 363 g/person week(-1), the methylmercury intake was estimated to be 46.2 microg/person week(-1). Therefore, the mercury intake of Spanish people with a body weight Food Additives (JECFA) provisional tolerable weekly intake (PTWI) of 1.6 microg kg(-1) body weight, but exceeds the US National Research Council (NRC) limit of 0.7 microg kg(-1) body weight week(-1) based on a benchmark dose.

  18. Increased extinction potential of insular fish populations with reduced life history variation and low genetic diversity.

    Science.gov (United States)

    Hellmair, Michael; Kinziger, Andrew P

    2014-01-01

    Theoretical work has shown that reduced phenotypic heterogeneity leads to population instability and can increase extinction potential, yet few examples exist of natural populations that illustrate how varying levels expressed diversity may influence population persistence, particularly during periods of stochastic environmental fluctuation. In this study, we assess levels of expressed variation and genetic diversity among demographically independent populations of tidewater goby (Eucyclogobius newberryi), show that reductions in both factors typically coincide, and describe how low levels of diversity contribute to the extinction risk of these isolated populations. We illustrate that, for this annual species, continuous reproduction is a safeguard against reproductive failure by any one population segment, as natural, stochastically driven salinity increases frequently result in high mortality among juvenile individuals. Several study populations deviated from the natural pattern of year-round reproduction typical for the species, rendering those with severely truncated reproductive periods vulnerable to extinction in the event of environmental fluctuation. In contrast, demographically diverse populations are more likely to persist through such periods through the continuous presence of adults with broader physiological tolerance to abrupt salinity changes. Notably, we found a significant correlation between genetic diversity and demographic variation in the study populations, which could be the result of population stressors that restrict both of these diversity measures simultaneously, or suggestive of a causative relationship between these population characteristics. These findings demonstrate the importance of biocomplexity at the population level, and assert that the maintenance of diversity contributes to population resilience and conservation of this endangered species.

  19. Increased extinction potential of insular fish populations with reduced life history variation and low genetic diversity.

    Directory of Open Access Journals (Sweden)

    Michael Hellmair

    Full Text Available Theoretical work has shown that reduced phenotypic heterogeneity leads to population instability and can increase extinction potential, yet few examples exist of natural populations that illustrate how varying levels expressed diversity may influence population persistence, particularly during periods of stochastic environmental fluctuation. In this study, we assess levels of expressed variation and genetic diversity among demographically independent populations of tidewater goby (Eucyclogobius newberryi, show that reductions in both factors typically coincide, and describe how low levels of diversity contribute to the extinction risk of these isolated populations. We illustrate that, for this annual species, continuous reproduction is a safeguard against reproductive failure by any one population segment, as natural, stochastically driven salinity increases frequently result in high mortality among juvenile individuals. Several study populations deviated from the natural pattern of year-round reproduction typical for the species, rendering those with severely truncated reproductive periods vulnerable to extinction in the event of environmental fluctuation. In contrast, demographically diverse populations are more likely to persist through such periods through the continuous presence of adults with broader physiological tolerance to abrupt salinity changes. Notably, we found a significant correlation between genetic diversity and demographic variation in the study populations, which could be the result of population stressors that restrict both of these diversity measures simultaneously, or suggestive of a causative relationship between these population characteristics. These findings demonstrate the importance of biocomplexity at the population level, and assert that the maintenance of diversity contributes to population resilience and conservation of this endangered species.

  20. Optimal pulse fishing policy in stage-structured models with birth pulses

    International Nuclear Information System (INIS)

    Gao Shujing; Chen Lansun; Sun Lihua

    2005-01-01

    In this paper, we propose exploited models with stage structure for the dynamics in a fish population for which periodic birth pulse and pulse fishing occur at different fixed time. Using the stroboscopic map, we obtain an exact cycle of system, and obtain the threshold conditions for its stability. Bifurcation diagrams are constructed with the birth rate (or pulse fishing time or harvesting effort) as the bifurcation parameter, and these are observed to display complex dynamic behaviors, including chaotic bands with period windows, period-doubling, multi-period-halving and incomplete period-doubling bifurcation, pitch-fork and tangent bifurcation, non-unique dynamics (meaning that several attractors or attractor and chaos coexist) and attractor crisis. This suggests that birth pulse and pulse fishing provide a natural period or cyclicity that make the dynamical behaviors more complex. Moreover, we show that the pulse fishing has a strong impact on the persistence of the fish population, on the volume of mature fish stock and on the maximum annual-sustainable yield. An interesting result is obtained that, after the birth pulse, the population can sustain much higher harvesting effort if the mature fish is removed as early as possible

  1. A fully-stochasticized, age-structured population model for population viability analysis of fish: Lower Missouri River endangered pallid sturgeon example

    Science.gov (United States)

    Wildhaber, Mark L.; Albers, Janice; Green, Nicholas; Moran, Edward H.

    2017-01-01

    We develop a fully-stochasticized, age-structured population model suitable for population viability analysis (PVA) of fish and demonstrate its use with the endangered pallid sturgeon (Scaphirhynchus albus) of the Lower Missouri River as an example. The model incorporates three levels of variance: parameter variance (uncertainty about the value of a parameter itself) applied at the iteration level, temporal variance (uncertainty caused by random environmental fluctuations over time) applied at the time-step level, and implicit individual variance (uncertainty caused by differences between individuals) applied within the time-step level. We found that population dynamics were most sensitive to survival rates, particularly age-2+ survival, and to fecundity-at-length. The inclusion of variance (unpartitioned or partitioned), stocking, or both generally decreased the influence of individual parameters on population growth rate. The partitioning of variance into parameter and temporal components had a strong influence on the importance of individual parameters, uncertainty of model predictions, and quasiextinction risk (i.e., pallid sturgeon population size falling below 50 age-1+ individuals). Our findings show that appropriately applying variance in PVA is important when evaluating the relative importance of parameters, and reinforce the need for better and more precise estimates of crucial life-history parameters for pallid sturgeon.

  2. Fish Rhabdoviruses

    Science.gov (United States)

    Kurath, G.; Winton, J.

    2008-01-01

    Many important viral pathogens of fish are members of the family Rhabdoviridae. The viruses in this large group cause significant losses in populations of wild fish as well as among fish reared in aquaculture. Fish rhabdoviruses often have a wide host and geographic range, and infect aquatic animals in both freshwater and seawater. The fish rhabdoviruses comprise a diverse collection of isolates that can be placed in one of two quite different groups: isolates that are members of the established genusNovirhabdovirus, and those that are most similar to members of the genus Vesiculovirus. Because the diseases caused by fish rhabdoviruses are important to aquaculture, diagnostic methods for their detection and identification are well established. In addition to regulations designed to reduce the spread of fish viruses, a significant body of research has addressed methods for the control or prevention of diseases caused by fish rhabdoviruses, including vaccination. The number of reported fish rhabdoviruses continues to grow as a result of the expansion of aquaculture, the increase in global trade, the development of improved diagnostic methods, and heightened surveillance activities. Fish rhabdoviruses serve as useful components of model systems to study vertebrate virus disease, epidemiology, and immunology.

  3. Fish assemblages

    Science.gov (United States)

    McGarvey, Daniel J.; Falke, Jeffrey A.; Li, Hiram W.; Li, Judith; Hauer, F. Richard; Lamberti, G.A.

    2017-01-01

    Methods to sample fishes in stream ecosystems and to analyze the raw data, focusing primarily on assemblage-level (all fish species combined) analyses, are presented in this chapter. We begin with guidance on sample site selection, permitting for fish collection, and information-gathering steps to be completed prior to conducting fieldwork. Basic sampling methods (visual surveying, electrofishing, and seining) are presented with specific instructions for estimating population sizes via visual, capture-recapture, and depletion surveys, in addition to new guidance on environmental DNA (eDNA) methods. Steps to process fish specimens in the field including the use of anesthesia and preservation of whole specimens or tissue samples (for genetic or stable isotope analysis) are also presented. Data analysis methods include characterization of size-structure within populations, estimation of species richness and diversity, and application of fish functional traits. We conclude with three advanced topics in assemblage-level analysis: multidimensional scaling (MDS), ecological networks, and loop analysis.

  4. Connectivity between Migrating and Landlocked Populations of a Diadromous fish Species Investigated Using Otolith Microchemistry

    NARCIS (Netherlands)

    Tulp, I.Y.M.; Keller, A.M.; Navez, J.; Winter, H.V.; Graaf, de M.; Baeyens, W.

    2013-01-01

    Smelt Osmerus eperlanus has two different life history strategies in the Netherlands. The migrating population inhabits the Wadden Sea and spawns in freshwater areas. After the closure of the Afsluitdijk in 1932, part of the smelt population became landlocked. The fresh water smelt population has

  5. An indigenous religious ritual selects for resistance to a toxicant in a livebearing fish.

    Science.gov (United States)

    Tobler, M; Culumber, Z W; Plath, M; Winemiller, K O; Rosenthal, G G

    2011-04-23

    Human-induced environmental change can affect the evolutionary trajectory of populations. In Mexico, indigenous Zoque people annually introduce barbasco, a fish toxicant, into the Cueva del Azufre to harvest fish during a religious ceremony. Here, we investigated tolerance to barbasco in fish from sites exposed and unexposed to the ritual. We found that barbasco tolerance increases with body size and differs between the sexes. Furthermore, fish from sites exposed to the ceremony had a significantly higher tolerance. Consequently, the annual ceremony may not only affect population structure and gene flow among habitat types, but the increased tolerance in exposed fish may indicate adaptation to human cultural practices in a natural population on a very small spatial scale.

  6. Impact of black rhinoceros (Diceros bicornis minor) on a local population of Euphorbia bothae in the Great Fish River Reserve, South Africa

    NARCIS (Netherlands)

    Luske, B.L.; Mertens, T.; Lent, P.C.; Boer, de W.F.; Prins, H.H.T.

    2009-01-01

    In the Great Fish River Reserve, South Africa, black rhinoceros (Diceros bicornis minor) feed extensively on a local population of Euphorbia bothae. Maintaining the endangered black rhinoceros and the protected E. bothae population are both conservation priorities of the reserve. Therefore, the

  7. Impacts of golden alga Prymnesium parvum on fish populations in reservoirs of the upper Colorado River and Brazos River basins, Texas

    Science.gov (United States)

    VanLandeghem, Matthew M.; Farooqi, Mukhtar; Farquhar, B.; Patino, Reynaldo

    2013-01-01

    Several reservoirs in the upper Colorado River and Brazos River basins in Texas have experienced toxic blooms of golden alga Prymnesium parvum and associated fish kills since 2001. There is a paucity of information, however, regarding the population-level effects of such kills in large reservoirs, species-specific resistance to or recovery from kills, or potential differences in the patterns of impacts among basins. We used multiple before-after, control-impact analysis to determine whether repeated golden alga blooms have led to declines in the relative abundance and size structure of fish populations. Sustained declines were noted for 9 of 12 fish species surveyed in the upper Colorado River, whereas only one of eight species was impacted by golden alga in the Brazos River. In the upper Colorado River, White Bass Morone chrysops, White Crappie Pomoxis annularis, Largemouth Bass Micropterus salmoides, Bluegill Lepomis macrochirus, River Carpsucker Carpiodes carpio, Freshwater Drum Aplodinotus grunniens, Channel Catfish Ictalurus punctatus, Flathead Catfish Pylodictis olivaris, and Blue Catfish I. furcatus exhibited sustained declines in relative abundance, size structure, or both; Gizzard Shad Dorosoma cepedianum, Longnose Gar Lepisosteus osseus, and Common Carp Cyprinus carpio did not exhibit those declines. In the Brazos River, only the relative abundance of Blue Catfish was impacted. Overall, toxic golden alga blooms can negatively impact fish populations over the long-term, but the patterns of impact can vary considerably among river basins and species. In the Brazos River, populations of most fish species appear to be healthy, suggesting a positive angling outlook for this basin. In the upper Colorado River, fish populations have been severely impacted, and angling opportunities have been reduced. Basin-specific management plans aimed at improving water quality and quantity will likely reduce bloom intensity and allow recovery of fish populations to the

  8. 75 FR 79341 - Proposed Information Collection; Comment Request; Harvest of Pacific Halibut by Guided Sport...

    Science.gov (United States)

    2010-12-20

    ... Collection; Comment Request; Harvest of Pacific Halibut by Guided Sport Charter Vessel Anglers off Alaska... halibut fishing effort and harvest by all user groups, including the guided sport charter sector of the... requirements. The State of Alaska Department of Fish and Game (ADF&G) Division of Sport Fish initiated a...

  9. Effects of Changes in Food Supply at the Time of Sex Differentiation on the Gonadal Transcriptome of Juvenile Fish. Implications for Natural and Farmed Populations

    OpenAIRE

    Díaz, Noelia; Ribas, Laia; Piferrer, Francesc

    2014-01-01

    Background: Food supply is a major factor influencing growth rates in animals. This has important implications for both natural and farmed fish populations, since food restriction may difficult reproduction. However, a study on the effects of food supply on the development of juvenile gonads has never been transcriptionally described in fish. Methods and Findings: This study investigated the consequences of growth on gonadal transcriptome of European sea bass in: 1) 4-month-old sexually undif...

  10. The contribution of lakes to global inland fisheries harvest

    Science.gov (United States)

    Deines, Andrew M.; Bunnell, David B.; Rogers, Mark W.; Bennion, David; Woelmer, Whitney; Sayers, Michael J.; Grimm, Amanda G.; Shuchman, Robert A.; Raymer, Zachary B.; Brooks, Colin N.; Mychek-Londer, Justin G.; Taylor, William W.; Beard, Douglas

    2017-01-01

    Freshwater ecosystems provide numerous services for communities worldwide, including irrigation, hydropower, and municipal water; however, the services provided by inland fisheries – nourishment, employment, and recreational opportunities – are often comparatively undervalued. We provide an independent estimate of global lake harvest to improve biological and socioeconomic assessments of inland fisheries. On the basis of satellite-derived estimates of chlorophyll concentration from 80,012 globally distributed lakes, lake-specific fishing effort based on human population, and output from a Bayesian hierarchical model, we estimated that the global lake fishery harvest in the year 2011 was 8.4 million tons (mt). Our calculations excluded harvests from highly productive rivers, wetlands, and very small lakes; therefore, the true cumulative global fishery harvest from all freshwater sources likely exceeded 11 mt as reported by the Food and Agriculture Organization of the United Nations (FAO). This putative underestimate by the FAO could diminish the perceived importance of inland fisheries and perpetuate decisions that adversely affect these fisheries and millions of people.

  11. Strong population genetic structuring in an annual fish, Nothobranchius furzeri, suggests multiple savannah refugia in southern Mozambique.

    Science.gov (United States)

    Bartáková, Veronika; Reichard, Martin; Janko, Karel; Polačik, Matej; Blažek, Radim; Reichwald, Kathrin; Cellerino, Alessandro; Bryja, Josef

    2013-09-12

    Intraspecific genetic variation of African fauna has been significantly affected by pronounced climatic fluctuations in Plio-Pleistocene, but, with the exception of large mammals, very limited empirical data on diversity of natural populations are available for savanna-dwelling animals. Nothobranchius furzeri is an annual fish from south-eastern Africa, inhabiting discrete temporary savannah pools outside main river alluvia. Their dispersal is limited and population processes affecting its genetic structure are likely a combination of those affecting terrestrial and aquatic taxa. N. furzeri is a model taxon in ageing research and several populations of known geographical origin are used in laboratory studies. Here, we analysed the genetic structure, diversity, historical demography and temporal patterns of divergence in natural populations of N. furzeri across its entire distribution range. Genetic structure and historical demography of N. furzeri were analysed using a combination of mitochondrial (partial cytochrome b sequences, 687 bp) and nuclear (13 microsatellites) markers in 693 fish from 36 populations. Genetic markers consistently demonstrated strong population structuring and suggested two main genetic groups associated with river basins. The split was dated to the Pliocene (>2 Mya). The northern group inhabits savannah pools across the basin of the intermittent river Chefu in south-western Mozambique and eastern Zimbabwe. The southern group (from southernmost Mozambique) is subdivided, with the River Limpopo forming a barrier (maximum divergence time 1 Mya). A strong habitat fragmentation (isolated temporary pools) is reflected in significant genetic structuring even between adjacent pools, with a major influence of genetic drift and significant isolation-by-distance. Analysis of historical demography revealed that the expansion of both groups is ongoing, supported by frequent founder effects in marginal parts of the range and evidence of secondary

  12. The Use of Advanced Hydroelectric Turbines to Improve Water Quality and Fish Populations

    International Nuclear Information System (INIS)

    Brookshier, P.A.; Cada, G.F.; Flynn, J.V.; Rinehart, B.N.; Sale, M.J.; Sommers, G.L.

    1999-01-01

    Hydroelectric power contributes about 10 percent of the electrical energy generated in the United States, and nearly 20 percent of the worlds electrical energy. It is a renewable energy source that can contribute significantly to reduction of greenhouse gases by offsetting conventional carbon-based electricity generation. However, rather than growing in importance, hydroelectric generation has actually declined in recent years, often as a consequence of environmental concerns centering around (1) restriction of upstream and downstream fish passage by the dam, and (2) alteration of water quality and river flows by the impoundment. The Advanced Hydropower Turbine System (AHTS) Program of the U.S. Department of Energy is developing turbine technology which would help to maximize global hydropower resources while minimizing adverse environmental effects. Major technical goals for the Program are (1) the reduction of mortality among turbine-passed fish to 2 percent or less, compared to current levels ranging up to 30 percent or greater; and (2) development of aerating turbines that would ensure that water discharged from reservoirs has a dissolved oxygen concentration of at least 6 mg/L. These advanced, environmentally friendly turbines would be suitable both for new hydropower installations and for retrofitting at existing dams. Several new turbine designs that have been developed in the initial phases of the AHTS program are described

  13. Connectivity between migrating and landlocked populations of a diadromous fish species investigated using otolith microchemistry.

    Directory of Open Access Journals (Sweden)

    Ingrid Tulp

    Full Text Available Smelt Osmerus eperlanus has two different life history strategies in The Netherlands. The migrating population inhabits the Wadden Sea and spawns in freshwater areas. After the closure of the Afsluitdijk in 1932, part of the smelt population became landlocked. The fresh water smelt population has been in severe decline since 1990, and has strongly negatively impacted the numbers of piscivorous water birds relying on smelt as their main prey. The lakes that were formed after the dike closure, IJsselmeer and Markermeer have been assigned as Natura 2000 sites, based on their importance for (among others piscivorous water birds. Because of the declining fresh water smelt population, the question arose whether this population is still supported by the diadromous population. Opportunities for exchange between fresh water and the sea are however limited to discharge sluices. The relationship between the diadromous and landlocked smelt population was analysed by means of otolith microchemistry. Our interpretation of otolith strontium ((88Sr patterns from smelt specimens collected in the fresh water area of Lake IJsselmeer and Markermeer, compared to those collected in the nearby marine environment, is that there is currently no evidence for a substantial contribution from the diadromous population to the spawning stock of the landlocked population.

  14. Geographic coupling of juvenile and adult habitat shapes spatial population dynamics of a coral reef fish

    NARCIS (Netherlands)

    Huijbers, C.M.; Nagelekerken, I.; Debrot, A.O.; Jongejans, E.

    2013-01-01

    Marine spatial population dynamics are often addressed with a focus on larval dispersal, without taking into account movement behavior of individuals in later life stages. Processes occurring during demersal life stages may also drive spatial population dynamics if habitat quality is perceived

  15. Disease associated population effects of commercial fish and shellfish species (ToR g)

    DEFF Research Database (Denmark)

    Lang, T.; Alfjorden, A.; Feist, S.W.

    2015-01-01

    of the combined effects of the pathogen, host and environmental factors. Diseases may be one of several biological and non-biological factors regulating the abundance and composition of stocks or populations of aquatic organisms. Here we review evidence for population effects associated with diseases in wild......Pathogens are increasingly reported from populations of aquatic animals. Variations in the frequency and abundance of pathogens depend on spatial or temporal factors as well as those related to host effects such as age or condition. Similarly, the devel-opment of a disease is a function...... and references to key publications are pro-vided. The overview shows that the effects of diseases may occur at various life stages of affected hosts. The extent to which these effects lead to measurable popula-tion changes (e.g., in growth, reproduction, mortality, recruitment, population de...

  16. 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

  17. Within and between population variation in epidermal club cell investment in a freshwater prey fish: a cautionary tale for evolutionary ecologists.

    Directory of Open Access Journals (Sweden)

    Aditya K Manek

    Full Text Available Many prey fishes possess large club cells in their epidermis. The role of these cells has garnered considerable attention from evolutionary ecologists. These cells likely form part of the innate immune system of fishes, however, they also have an alarm function, releasing chemical cues that serve to warn nearby conspecifics of danger. Experiments aimed at understanding the selection pressures leading to the evolution of these cells have been hampered by a surprisingly large intraspecific variation in epidermal club cell (ECC investment. The goal of our current work was to explore the magnitude and nature of this variation in ECC investment. In a field survey, we documented large differences in ECC investment both within and between several populations of minnows. We then tested whether we could experimentally reduce variation in mean ECC number by raising fish under standard laboratory conditions for 4 weeks. Fish from different populations responded very differently to being held under standard laboratory conditions; some populations showed an increase in ECC investment while others remained unchanged. More importantly, we found some evidence that we could reduce within population variation in ECC investment through time, but could not reduce among-population variation in mean ECC investment. Given the large variation we observed in wild fish and our limited ability to converge mean cell number by holding the fish under standard conditions, we caution that future studies may be hard pressed to find subtle effects of various experimental manipulations; this will make elucidating the selection pressures leading to the evolution of the cells challenging.

  18. Impact of climate change and population growth on a risk assessment for endocrine disruption in fish due to steroid estrogens in England and Wales

    International Nuclear Information System (INIS)

    Keller, V.D.J.; Lloyd, P.; Terry, J.A.; Williams, R.J.

    2015-01-01

    In England and Wales, steroid estrogens: estrone, estradiol and ethinylestradiol have previously been identified as the main chemicals causing endocrine disruption in male fish. A national risk assessment is already available for intersex in fish arising from estrogens under current flow conditions. This study presents, to our knowledge, the first set of national catchment-based risk assessments for steroid estrogen under future scenarios. The river flows and temperatures were perturbed using three climate change scenarios (ranging from relatively dry to wet). The effects of demographic changes on estrogen consumption and human population served by sewage treatment works were also included. Compared to the current situation, the results indicated increased future risk:the percentage of high risk category sites, where endocrine disruption is more likely to occur, increased. These increases were mainly caused by changes in human population. This study provides regulators with valuable information to prepare for this potential increased risk. - Highlights: • Risk assessment for the 2050's including climate change and population changes. • Three climate scenarios considered (changes in river flow and river temperature). • Increased risk from fish intersex across all scenarios in England and Wales. • Population is the main factor causing the risk increase for the 2050's. - The predicted increase in risk of endocrine disruption in fish due to steroid estrogens in England and Wales in the 2050's is mainly due to human population increase rather than climate change

  19. Diverse juvenile life-history behaviours contribute to the spawning stock of an anadromous fish population

    Science.gov (United States)

    Walsworth, Timothy E.; Schindler, Daniel E.; Griffiths, Jennifer R.; Zimmerman, Christian E.

    2015-01-01

    Habitat quality often varies substantially across space and time, producing a shifting mosaic of growth and mortality trade-offs across watersheds. Traditional studies of juvenile habitat use have emphasised the evolution of single optimal strategies that maximise recruitment to adulthood and eventual fitness. However, linking the distribution of individual behaviours that contribute to recruitment at the population level has been elusive, particularly for highly fecund aquatic organisms. We examined juvenile habitat use within a population of sockeye salmon (Oncorhynchus nerka) that spawn in a watershed consisting of two interconnected lakes and a marine lagoon. Otolith microchemical analysis revealed that the productive headwater lake accounted for about half of juvenile growth for those individuals surviving to spawn in a single river in the upper watershed. However, 47% of adults had achieved more than half of their juvenile growth in the downstream less productive lake, and 3% of individuals migrated to the estuarine environment during their first summer and returned to freshwater to overwinter before migrating back to sea. These results describe a diversity of viable habitat-use strategies by juvenile sockeye salmon that may buffer the population against poor conditions in any single rearing environment, reduce density-dependent mortality and have implications for the designation of critical habitat for conservation purposes. A network of accessible alternative habitats providing trade-offs in growth and survival may be important for long-term viability of populations.

  20. Remaining questions in the case for balanced harvesting

    DEFF Research Database (Denmark)

    Burgess, Matthew G; Diekert, Florian K; Jacobsen, Nis Sand

    2016-01-01

    are controversial, including its call for extensive harvesting of juveniles and forage fish. Balanced harvesting also calls for targeting species and size-classes that are not currently marketable, possibly at a significant economic cost. Some have argued that this cost is outweighed by the ecological benefits......Balanced harvestingharvesting all species and sizes in an ecosystem in proportion to their productivity – is a fisheries management strategy that has been suggested recently to increase yields, while reducing overall ecosystem impact. However, some aspects of balanced harvesting...

  1. The Effect on Selenium Concentrations of a Randomized Intervention with Fish and Mussels in a Population with Relatively Low Habitual Dietary Selenium Intake

    DEFF Research Database (Denmark)

    Outzen, Malene; Tjønneland, Anne; Larsen, Erik Huusfeldt

    2015-01-01

    Selenium status of the Danish population is below that assumed optimal for the suggested protective effects against chronic diseases, including certain cancers. Fish and shellfish are important dietary sources of selenium in Denmark. We investigated the effect of increased fish and mussel intake...... on selenium blood concentrations in a population with relatively low habitual dietary selenium intake. We randomly assigned 102 healthy men and women (all non-smokers) aged 48-76 years to an intervention group (n = 51) or a control group (n = 51). Intervention participants received 1000 g fish and mussels....../week for 26 weeks (similar to 50 mu g selenium/day). Controls received no intervention. Non-fasting blood samples were taken and whole blood selenium was determined using inductively coupled plasma-mass spectrometry (ICP-MS), and plasma selenoprotein P (SelP) was determined by high performance liquid...

  2. Fish resources of Lagos State coastal wetlands | Ayodele | African ...

    African Journals Online (AJOL)

    Fishing is the major occupation of the people found along the coastal wetland of Lagos State. Fishing is carried out all the year round. This study examines the fishing Activities, Gear composition and fishing methods in order to obtain the fish species and harvest composition of the study area. This paper is based on the ...

  3. Individual-specific transgenerational marking of fish populations based on a barium dual-isotope procedure.

    Science.gov (United States)

    Huelga-Suarez, Gonzalo; Moldovan, Mariella; Garcia-Valiente, America; Garcia-Vazquez, Eva; Alonso, J Ignacio Garcia

    2012-01-03

    The present study focuses on the development and evaluation of an individual-specific transgenerational marking procedure using two enriched barium isotopes, (135)Ba and (137)Ba, mixed at a given and selectable molar ratio. The method is based on the deconvolution of the isotope patterns found in the sample into four molar contribution factors: natural xenon (Xe nat), natural barium (Ba nat), Ba135, and Ba137. The ratio of molar contributions between Ba137 and Ba135 is constant and independent of the contribution of natural barium in the sample. This procedure was tested in brown trout ( Salmo trutta ) kept in captivity. Trout were injected with three different Ba137/Ba135 isotopic signatures ca. 7 months and 7 days before spawning to compare the efficiency of the marking procedure at long and short term, respectively. The barium isotopic profiles were measured in the offspring by means of inductively coupled plasma mass spectrometry. Each of the three different isotopic signatures was unequivocally identified in the offspring in both whole eggs and larvae. For 9 month old offspring, the characteristic barium isotope signatures could also be detected in the otoliths even in the presence of a high and variable amount of barium of natural isotope abundance. In conclusion, it can be stated that the proposed dual-isotope marking is inheritable and can be detected after both long-term and short-term marking. Furthermore, the dual-isotope marking can be made individual-specific, so that it allows identification of offspring from a single individual or a group of individuals within a given fish group. © 2011 American Chemical Society

  4. Adoption Of Improved Fish Technologies Among Fish Farmers In ...

    African Journals Online (AJOL)

    A shortfall exists between fish supply and fish demand in the country despite the introduction of improved technology to fish farmers. This led to huge wage bill on the importation of fish to meet the protein need of the ever increasing population. This prompted this study with focus on adoption of improved fish technologies ...

  5. Temporal variation of blood and hair mercury levels in pregnancy in relation to fish consumption history in a population living along the St. Lawrence River

    International Nuclear Information System (INIS)

    Morrissette, Joeelle; Takser, Larissa; St-Amour, Genevieve; Smargiassi, Audrey; Lafond, Julie; Mergler, Donna

    2004-01-01

    Fish consumption from the Great Lakes and the St. Lawrence River has been decreasing over the last years due to advisories and increased awareness of the presence of several contaminants. Methylmercury (MeHg), a well-established neurotoxicant even at low levels of exposure, bioaccumulates to differing degrees in various fish species and can have serious adverse effects on the development and functioning of the human central nervous system, especially during prenatal exposure. Most studies on MeHg exposure have focussed on high-level consumers from local fish sources, although mercury (Hg) is also present in fresh, frozen, and canned market fish. Moreover, little information exists on the temporal variation of blood and hair Hg in pregnant women, particularly in populations with low levels of Hg. The aim of the present study was to characterize the temporal variation of Hg during pregnancy and to investigate the relation between fish consumption from various sources prior to and during pregnancy and maternal cord blood and mother's hair Hg levels. We recruited 159 pregnant women from Southwest Quebec through two prenatal clinics of the Quebec Public Health System. All women completed two detailed questionnaires concerning their fish consumption (species and frequency) prior to and during pregnancy. The women also provided blood samples for all three trimesters of pregnancy and hair samples after delivery of up to 9 cm in length. Blood and hair Hg levels were analyzed by cold-vapor atomic-absorption and -fluorescence spectrometry methods, respectively. Results showed that maternal blood and hair Hg levels decreased significantly between the second and third trimesters of pregnancy. However, cord blood Hg was significantly higher than maternal blood at birth. Maternal hair was correlated with Hg blood concentration and was highly predictive of the organic fraction in cord blood. A strong dose relation was observed between the frequency of fish consumption before and

  6. One Fish, Two Fish, Redfish, You Fish!

    Science.gov (United States)

    White, Katherine; Timmons, Maryellen; Medders, Paul

    2011-01-01

    The recreational fishing activity presented in this article provides a hands-on, problem-based experience for students; it unites biology, math, economics, environmental policy, and population dynamics concepts. In addition, the activity allows students to shape environmental policy in a realistic setting and evaluate their peers' work. By…

  7. Environmental gradients predict the genetic population structure of a coral reef fish in the Red Sea

    KAUST Repository

    Nanninga, Gerrit B.

    2014-01-20

    The relatively recent fields of terrestrial landscape and marine seascape genetics seek to identify the influence of biophysical habitat features on the spatial genetic structure of populations or individuals. Over the last few years, there has been accumulating evidence for the effect of environmental heterogeneity on patterns of gene flow and connectivity in marine systems. Here, we investigate the population genetic patterns of an anemonefish, Amphiprion bicinctus, along the Saudi Arabian coast of the Red Sea. We collected nearly one thousand samples from 19 locations, spanning approximately 1500 km, and genotyped them at 38 microsatellite loci. Patterns of gene flow appeared to follow a stepping-stone model along the northern and central Red Sea, which was disrupted by a distinct genetic break at a latitude of approximately 19°N. The Red Sea is characterized by pronounced environmental gradients along its axis, roughly separating the northern and central from the southern basin. Using mean chlorophyll-a concentrations as a proxy for this gradient, we ran tests of isolation by distance (IBD, R2 = 0.52) and isolation by environment (IBE, R2 = 0.64), as well as combined models using partial Mantel tests and multiple matrix regression with randomization (MMRR). We found that genetic structure across our sampling sites may be best explained by a combined model of IBD and IBE (Mantel: R2 = 0.71, MMRR: R2 = 0.86). Our results highlight the potential key role of environmental patchiness in shaping patterns of gene flow in species with pelagic larval dispersal. We support growing calls for the integration of biophysical habitat characteristics into future studies of population genetic structure. © 2014 John Wiley & Sons Ltd.

  8. Environmental gradients predict the genetic population structure of a coral reef fish in the Red Sea

    KAUST Repository

    Nanninga, Gerrit B.; Saenz Agudelo, Pablo; Manica, Andrea; Berumen, Michael L.

    2014-01-01

    The relatively recent fields of terrestrial landscape and marine seascape genetics seek to identify the influence of biophysical habitat features on the spatial genetic structure of populations or individuals. Over the last few years, there has been accumulating evidence for the effect of environmental heterogeneity on patterns of gene flow and connectivity in marine systems. Here, we investigate the population genetic patterns of an anemonefish, Amphiprion bicinctus, along the Saudi Arabian coast of the Red Sea. We collected nearly one thousand samples from 19 locations, spanning approximately 1500 km, and genotyped them at 38 microsatellite loci. Patterns of gene flow appeared to follow a stepping-stone model along the northern and central Red Sea, which was disrupted by a distinct genetic break at a latitude of approximately 19°N. The Red Sea is characterized by pronounced environmental gradients along its axis, roughly separating the northern and central from the southern basin. Using mean chlorophyll-a concentrations as a proxy for this gradient, we ran tests of isolation by distance (IBD, R2 = 0.52) and isolation by environment (IBE, R2 = 0.64), as well as combined models using partial Mantel tests and multiple matrix regression with randomization (MMRR). We found that genetic structure across our sampling sites may be best explained by a combined model of IBD and IBE (Mantel: R2 = 0.71, MMRR: R2 = 0.86). Our results highlight the potential key role of environmental patchiness in shaping patterns of gene flow in species with pelagic larval dispersal. We support growing calls for the integration of biophysical habitat characteristics into future studies of population genetic structure. © 2014 John Wiley & Sons Ltd.

  9. Modelling population effects of juvenile offshore fish displacement towards adult habitat

    DEFF Research Database (Denmark)

    van de Wolfshaar, K.E.; Tulp, I.; Wennhage, H.

    2015-01-01

    consequences on population dynamics through changes in resource use and competition. To explore this, a conceptual stage-structured model was developed with 3 stages and 2 resources and allowing a move of large juveniles from the shallow to the deep habitat. Large juveniles compete with small juveniles...... in shallow waters and with adults in deeper waters. Alternative stable states occur, with one state dominated by small juvenile biomass and the other dominated by adult biomass. The model results show for both states that while large juvenile biomass responds to a change in time spent in the deep habitat...

  10. Evaluation of the flathead catfish population and fishery on Lake Carl Blackwell, Oklahoma, with emphasis on the effects of noodling

    Science.gov (United States)

    Winkelman, Dana L.; Michaletz, Paul H.; Travnichek, Vincent H.

    2011-01-01

    I conducted a 3-year study at Lake Carl Blackwell, Oklahoma to estimate effects of various fishing gears on the flathead catfish Pylodictis olivaris population. Managers were particularly interested in the effect of handfishing or noodling on this population. I used a phone survey to assess angler effort and electrofishing and gill nets to calculate standard population metrics to assess composition of the current population. Survey data indicated that fishing effort and harvest were highest for trotlines and juglines and lowest for noodling. Size distribution of fish harvested by noodlers was not different from sizes that were available in the fishery and was similar to those fish harvested with other gears. Flathead catfish Sampled in Lake Carl Blackwell ranged in size from 38 to 1,220 mm total length, and 77% of the population was less than 508 mm (minimum legal size). Estimated total annual mortality was about 11%. Proportional size distribution (PSD) of flathead catfish for Lake Carl Blackwell indicates that about 70% of legal-sized flathead catfish were over the preferred size of 710 mm. Overall, the Lake Carl Blackwell flathead catfish population appeared healthy. There were a wide range of sizes and ages in the population, and PSD indicated a well-balanced population with many preferred and memorable-sized fish. Due to its rarity, noodling is probably not adversely influencing the population. Additionally, noodling at Lake Carl Blackwell does not appear to be as size-selective as previously thought. 

  11. Fish –based diet- correlations between metabolism of carbohydrates, lipidis and proteins. Study case population of the Sulina Town, Danube Delta

    Directory of Open Access Journals (Sweden)

    Georgiana ENE

    2016-06-01

    Full Text Available According to literature data, the normal values of biochemical parameters in blood vary by sex, age, geographical region, and type of diet. The aim of this study was to analyze the benefits of a fish-based diet among the population of Sulina, in the Danube Delta (3,663 individuals, by performing a comparative hepatic evaluation, lipid profile, serum glucose levels and total protein profile of these patients. Fish is an important source of protein with high biological value, containing all essential aminoacids and low lipid levels. The novelty of the research is represented by the analyzed geographical area. The Danube Delta had no medical analysis laboratory until 2010, when the RoutineMed Sulina laboratory was opened. Patients had a set of biochemical tests in the RoutineMed Sulina laboratory and declared they eat fish or fish-based products at least once a week. Tests were performed on 200 patients for the evaluation of the liver of these patients: Aspartate Amino Transferase, alanine amino transferase, de Ritis ratio, High Density Lipoprotein, Low Density Lipoprotein, total lipids, total cholesterol, triglycerides and 200 tests for the evaluation of the serum glucose levels and total protein. Both women and men were involved in the research and patients were grouped into age ranges: 20-40 years, 40-60 years, > 60 years. The values obtained were statistically analyzed using the SPSS v. 20 software and then compared to the ranges considered normal for these parameters. The results obtained showed that patients with a fish-based diet seem to be healthier than those with a diet in which fish meat is scarce, as their blood biochemical parameters values are closer to normal, which leads to the conclusion that including fish and fish products in people's regular diet is beneficial in preventing lipid, protein and carbohydrate metabolism disorders and preserving the overall health of the body.

  12. Immediate effect of intertidal non-mechanised cockle harvesting on macrobenthic communities: a comparative study

    Directory of Open Access Journals (Sweden)

    Francisco Miguel Sousa Leitão

    2007-12-01

    Full Text Available In Ria Formosa cockles (Cerastoderma edule have traditionally been harvested with a harvesting-knife (HK. However, over the last six years there has been an increase in the use of a hand-dredge (HD to exploit cockle beds. A comparative study on the impact of these harvesting methods on the benthic macrofauna was undertaken with the aim of evaluating the possible introduction of the hand-dredge in the fishery. Macrofaunal mortality was very low regardless of the gear. However, the total mortality resulting from using the HK was superior to the one observed for the HD. For the same fishing time the hand-dredge covers an area approximately five times greater that the one covered by the knife, with the former yielding 5 times the catch of the latter. Consequently, the use of hand-dredges increases the fishing effort, which may lead to the overexploitation of the cockle populations. Our results revealed that the immediate effect of both gears on macrobenthic communities was similar and minimal. Therefore, we believe that introducing the hand-dredge in the cockle fishery should only be authorised if other management measures, such as daily quotas, closed areas and limiting the number of fishing licenses, are implemented.

  13. Mercury exposure through fish consumption in riparian populations at reservoir Guri, using nuclear techniques, Bolivar State, Venezuela. Highlights and achievements

    International Nuclear Information System (INIS)

    Bermudez, Dario

    2002-01-01

    Full text: Highlights and achievements: At present, according to our results so far, we have teamed that this project has an important social component which we have to take into account. The characteristics of the population in the nearby of reservoir Guri and the changes in the circumstances economic, politic and social of this country are causing quickly and severely modifications on the living conditions of that people. It is a reality that these changes can occur in a sensible manner between the time we collect the information and when the data arrives finally to the institutions. The communities included in this project are represented by social groups consolidated for more than 200 years so even if we may observe changes in their living conditions, it is intrinsic to them the presence of subjective structures that impose both individual and group behaviors that some time do not agree with the planner interest. On the other hand we believe that was obtained a very important information related to the socioeconomic situation of the two populated centers sampled and on the habits of fish consuming. In addition, we did an approximation of the total population in these localities. In the future we have to do the same with the other communities because of the lack information up to date. The 2001 census will be available next year. We have now the selected homes and individuals to start working with the next steps of the project. In the framework of the project we promote several meeting in order to design an intercalibration program among different laboratories for metal analysis. Actually these labs are filling in a simple questionnaire to harmonize the program. This activity has had the acceptance of the Pan-American Sanitary Office, Regional Office of the World Health Organization in Venezuela. (author)

  14. Relationship between obesity, metabolic syndrome, and nonalcoholic fatty liver disease in the elderly agricultural and fishing population of Taiwan.

    Science.gov (United States)

    Shen, Hsi-Che; Zhao, Zi-Hao; Hu, Yi-Chun; Chen, Yu-Fen; Tung, Tao-Hsin

    2014-01-01

    The purpose of this study was to explore the relationship between obesity, the metabolic syndrome, and nonalcoholic fatty liver disease (NAFLD) in the elderly agricultural and fishing population of Taipei, Taiwan. The study participants comprised 6,511 (3,971 male and 2,540 female) healthy elderly subjects voluntarily attending a teaching hospital for a physical check-up in 2010. Blood samples and real-time ultrasound-proven fatty liver sonography results were collected. The prevalence of NAFLD in this elderly population was 27.2%, including mild NAFLD (16.0%), moderate NAFLD (10.3%), and severe NAFLD (0.9%). The prevalence of moderate or severe NAFLD for metabolic syndrome proved to be substantially greater (P<0.0001, χ(2) test) for one or two metabolic factors. Using multinomial logistic regression analysis, age, sex, metabolic syndrome, and higher body mass index had a statistically significant association with mild NAFLD. Age, sex, metabolic syndrome, higher body mass index, and higher alanine aminotransferase were significantly related to moderate NAFLD. In addition, higher body mass index, higher uric acid, and higher alanine aminotransferase levels were significantly related to severe NAFLD. The sensitivity and specificity of body mass index and waist circumference as markers of NAFLD were estimated to be 81% and 84%, respectively, and 77% and 69%, respectively. The prevalence of mild or moderate NAFLD was related to obesity and metabolic syndrome. Higher body mass index was also related to severe NAFLD but not to metabolic syndrome. Targeting this population for control of obesity and improved metabolic function is important.

  15. 50 CFR 300.132 - Lobster harvest limitations.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Lobster harvest limitations. 300.132... FISHERIES REGULATIONS Vessels of the United States Fishing in Colombian Treaty Waters § 300.132 Lobster harvest limitations. (a) Berried lobsters. A berried (egg-bearing) lobster in treaty waters may not be...

  16. 50 CFR 680.21 - Crab harvesting cooperatives.

    Science.gov (United States)

    2010-10-01

    ... establishes an annual catch limit of crab that is based on the collective QS holdings of the members of the... the members of the crab harvesting cooperative. (2) Contents of application for annual crab harvesting... permit may appeal the IAD using the appeals procedures described in § 680.43. (c) Restrictions on fishing...

  17. Effect of fishing effort on catch rate and catchability of largemouth bass in small impoundments

    Science.gov (United States)

    Wegener, M. G.; Schramm, Harold; Neal, J. W.; Gerard, P.D.

    2018-01-01

    Largemouth bass Micropterus salmoides (Lacepède) catch rates decline with sustained fishing effort, even without harvest. It is unclear why declines in catch rate occur, and little research has been directed at how to improve catch rate. Learning has been proposed as a reason for declining catch rate, but has never been tested on largemouth bass. If catch rate declines because fish learn to avoid lures, periods of no fishing could be a management tool for increasing catch rate. In this study, six small impoundments with established fish populations were fished for two May to October fishing seasons to evaluate the effect of fishing effort on catch rate. Closed seasons were implemented to test whether a 2‐month period of no fishing improved catch rates and to determine whether conditioning from factors other than being captured reduced catch rate. Mixed‐model analysis indicated catch rate and catchability declined throughout the fishing season. Catch rate and catchability increased after a 2‐month closure but soon declined to the lowest levels of the fishing season. These changes in catch rate and catchability support the conclusion of learned angler avoidance, but sustained catchability of fish not previously caught does not support that associative or social learning affected catchability.

  18. Precautionary harvest policies and the uncertainty paradox

    NARCIS (Netherlands)

    Cadrin, S.X.; Pastoors, M.A.

    2008-01-01

    Elements of the precautionary approach to fishery management are commonly implemented in the form of harvest control rules, with limit, threshold and target reference points for stock size and fishing mortality. However, a review of two large advisory and management systems indicates that many stock

  19. Benthic and fish population monitoring associated with a marine protected area in the nearshore waters of Grenada, Eastern Caribbean

    Directory of Open Access Journals (Sweden)

    Robert Anderson

    2012-03-01

    Full Text Available Annual benthic and fish population surveys were completed at five locations in the nearshore waters along Grenada´s southwest coast during 2008-2010. Two survey sites are located in a newly launched Marine Protected Area (MPA. Photo Quadrat (PQ and Point Line Intercept (PLI surveys were used to determine substrate cover. Algae was the primary live cover increasing significantly from 45.9% in 2008 to 52.7% in 2010 (PLI. Algae was also predominant (61.0%-59.3% in the PQ surveys although annual variation was not significant. Hard coral cover ranged from 16.5% to 15.4% (PLI and 11.4% to12.0% (PQ with no significant differences between years. Branching and encrusting corals occurred more frequently than massive corals. In the three annual surveys neither algal cover nor hard coral varied significantly between MPA and non-protected areas (PLI. Relative abundance of fishes along 30x2m belt transects did not vary significantly among years however density of fishes decreased significantly across years for most major groups. Chromis spp. dominated the survey sites at 65.2% in 2008 and 49.8% in 2010, followed by territorial damselfish,11.1% and 15.5%, wrasse increased from 7.3% to 15.5%. Both the substrate cover and fish survey data analyses indicated a stable but degraded community. Annual surveys are planned at these sites for the foreseeable future. Existing and future data from this project will be valuable in determining the efficacy of MPA management, guiding resource management decisions and monitoring the health status of Grenada’s valuable reef systemsUn estudio sobre poblaciones bentónicas y de peces fue realizado en cinco localidades en la zona costera en el suroeste de Grenada entre 2008 y 2010. Dos sitios se ubicaron en una Área Marina Portegida (AMP recientemente creada. Para determinar la cobertura se utilizaron foto-cuadrantes (FQ y transectos de intersección de puntos (TIP. Las algas fueron el principal componente del bentos

  20. Population Genetic Structure and Genetic Diversity in Twisted-Jaw Fish, Belodontichthys truncatus Kottelat & Ng, 1999 (Siluriformes: Siluridae, from Mekong Basin

    Directory of Open Access Journals (Sweden)

    Surapon Yodsiri

    2017-01-01

    Full Text Available The Mekong River and its tributaries possess the second highest diversity in fish species in the world. However, the fish biodiversity in this river is threatened by several human activities, such as hydropower plant construction. Understanding the genetic diversity and genetic structure of the species is important for natural resource management. Belodontichthys truncatus Kottelat & Ng is endemic to the Mekong River basin and is an important food source for people in this area. In this study, the genetic diversity, genetic structure, and demographic history of the twisted-jaw fish, B. truncatus, were investigated using mitochondrial cytochrome b gene sequences. A total of 124 fish specimens were collected from 10 locations in the Mekong and its tributaries. Relatively high genetic diversity was found in populations of B. truncatus compared to other catfish species in the Mekong River. The genetic structure analysis revealed that a population from the Chi River in Thailand was genetically significantly different from other populations, which is possibly due to the effect of genetic drift. Demographic history analysis indicated that B. truncatus has undergone recent demographic expansion dating back to the end of the Pleistocene glaciation.

  1. A populational survey of 45S rDNA polymorphism in the Jefferson salamander Ambystoma jeffersonianum revealed by fluorescence in situ hybridization (FISH

    Directory of Open Access Journals (Sweden)

    Jinzhong FU

    2009-04-01

    Full Text Available The chromosomal localization of 45S ribosomal RNA genes in Ambystoma jeffersonianum was determined by fluorescence in situ hybridization with 18S rDNA fragment as a probe (FISH-rDNA. Our results revealed the presence of rDNA polymorphism among A.jeffersonianum populations in terms of number, location and FISH signal intensity on the chromosomes. Nine rDNA cytotypes were found in ten geographically isolated populations and most of them contained derivative rDNA sites. Our preliminary study provides strong indication of karyotypic diversification of A.jeffersonianum that is demonstrated by intraspecific variation of 45S rDNA cytotypes. rDNA cytotype polymorphism has been described in many other caudate amphibians. We predict that habitat isolation, low dispersal ability and decline of effective population size could facilitate the fixation and accumulation of variable rDNA cytotypes during their chromosome evolution.

  2. Growth and fillet quality attributes of five genetic strains of rainbow trout (Oncorhynchus mykiss) reared in a partial water reuse system and harvested at different sizes

    Science.gov (United States)

    Genetics and environment can interact to influence fish growth performance and product quality attributes. Interaction in recirculating aquaculture systems (RAS) makes selection of fish strain and harvest sizes critical for optimizing fish quality. Definition of growth performance and quality outcom...

  3. An Evaluation of Parametric and Nonparametric Models of Fish Population Response.

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Timothy C.; Peterson, James T.; Lee, Danny C.

    1999-11-01

    Predicting the distribution or status of animal populations at large scales often requires the use of broad-scale information describing landforms, climate, vegetation, etc. These data, however, often consist of mixtures of continuous and categorical covariates and nonmultiplicative interactions among covariates, complicating statistical analyses. Using data from the interior Columbia River Basin, USA, we compared four methods for predicting the distribution of seven salmonid taxa using landscape information. Subwatersheds (mean size, 7800 ha) were characterized using a set of 12 covariates describing physiography, vegetation, and current land-use. The techniques included generalized logit modeling, classification trees, a nearest neighbor technique, and a modular neural network. We evaluated model performance using out-of-sample prediction accuracy via leave-one-out cross-validation and introduce a computer-intensive Monte Carlo hypothesis testing approach for examining the statistical significance of landscape covariates with the non-parametric methods. We found the modular neural network and the nearest-neighbor techniques to be the most accurate, but were difficult to summarize in ways that provided ecological insight. The modular neural network also required the most extensive computer resources for model fitting and hypothesis testing. The generalized logit models were readily interpretable, but were the least accurate, possibly due to nonlinear relationships and nonmultiplicative interactions among covariates. Substantial overlap among the statistically significant (P<0.05) covariates for each method suggested that each is capable of detecting similar relationships between responses and covariates. Consequently, we believe that employing one or more methods may provide greater biological insight without sacrificing prediction accuracy.

  4. Fewer but not smaller schools in declining fish and krill populations.

    Science.gov (United States)

    Brierley, Andrew S; Cox, Martin J

    2015-01-05

    Many pelagic species (species that live in the water column), including herring and krill, aggregate to form schools, shoals, or swarms (hereafter simply "schools," although the words are not synonyms). Schools provide benefits to individual members, including locomotory economy and protection from predators that prey on individuals, but paradoxically make schooling species energetically viable and commercially attractive targets for predators of groups and for fishers. Large schools are easier to find and yield greater prey/catch than small schools, and there is a requirement from fields as diverse as theoretical ecology and fisheries management to understand whether and how aggregation sizes change with changing population size. We collated data from vertical echosounder surveys of taxonomically diverse pelagic stocks from geographically diverse ecosystems. The data contain common significant positive linear stock-biomass to school-number relationships. They show that the numbers of schools in the stocks change with changing stock biomass and suggest that the distributions of school sizes do not change with stock biomass. New data that we collected using a multibeam sonar, which can image entire schools, contained the same stock-biomass to school-number relationship and confirm that the distribution of school sizes is not related to changing stock size: put simply, as stocks decline, individuals are distributed among fewer schools, not smaller schools. Since school characteristics affect catchability (the ease or difficulty with which fishers can capture target species) and availability of prey to predators, our findings have commercial and ecological implications, particularly within the aspirational framework of ecosystem-based management of marine systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Harvest facility protects and improves fishery

    International Nuclear Information System (INIS)

    Hampton, T.; Daley, W.

    1991-01-01

    This paper reports that by constructing a trap and transfer/harvest facility to control anadromous fish migration, the trout fishery on the Boardman River was protected and the salmon fishery was improved. The James P. Price Fish Trap and Transfer/Harvest Facility at Traverse City, Michigan, was constructed by the Traverse City Light and Power Department because of a licensing condition during the redevelopment of the Boardman and Sabin hydroelectric plants. The facility was constructed along with a fish ladder at the Union Street Dam to control the anadromous fish migration in lieu of constructing fish ladders at the Union Street, Sabin and Boardman Dams. The Michigan Department of Natural Resources (MDNR) and the U.S. Fish and Wildlife Service required that the fish ladders be constructed before the hydroelectric plants could be reactivated. The MDNR was also planning to introduce salmon into the Boardman River as far up as the reservoir of the Boardman Dam, which is the third dam from the mouth of the river

  6. Tolga power plant. Assessment of impacts on the evertebrate population and fish; Tolga kraftverk. Utredning av konsekvenser for bunndyr og fisk

    Energy Technology Data Exchange (ETDEWEB)

    Museth, J.; Johnsen, S.I.; Sandlund, O.T.; Arnekleiv, J.V.; Kjaerstad, G.; Kraaboel, M.

    2012-07-01

    Based on existing literature and conducted investigations of influence to the various development options for Tolga power plant estimated to comprise between Glomma Hoeyegga south of Alvdal and Rost waterfall in Os. This is a river length of about 85 km. The value of the specific areas that will be directly affected by the various development options are assessed based on the relative importance of these for the maintenance of fish / Benthic production and preservation of life history variation in the impact area as a whole. These assessments are made on the basis of the area's size and the presence of key habitats (Eg. Spawning grounds, wintering grounds, nursery areas) in the affected areas. Assessment of the effect of the various development options are made regardless of valuation. Of influence today viable populations of both trout and grayling. These two species are In addition to the stone fill and partly minnows dominant in sections with high water speed, while the proportion of species like whitefish, perch, burbot, pike and bekkenioeye increases the more the floating parties. Grayling population in the area is considered very large compared with other rivers in eastern Norway. Telemetry and genetics studies showed that there are significant fish migrations in the impact and the stretch that will be directly affected by the various development options. An overall assessment of the consequences for grayling, trout, other fish species and benthic considered to medium negative (-) for option 3A, medium / small negative (- (-) for alternative 3B and 2A and small negative (-) for Alternative 2B. This assessment assumes that the bidirectional fish walks past the dam and upstream migrations past the tunnel outlet is maintained at a high level on a problem given high priority in planning, building and the action-oriented after studies. The assessment also requires measures to reduce scope and consequences of failures of the power plant implemented. If bi fish

  7. Fish population and habitat analysis in Buck Creek, Washington, prior to recolonization by anadromous salmonids after the removal of Condit Dam

    Science.gov (United States)

    Allen, M. Brady; Burkhardt, Jeanette; Munz, Carrie; Connolly, Patrick J.

    2012-01-01

    We assessed the physical and biotic conditions in the part of Buck Creek, Washington, potentially accessible to anadromous fishes. This creek is a major tributary to the White Salmon River upstream of Condit Dam, which was breached in October 2011. Habitat and fish populations were characterized in four stream reaches. Reach breaks were based on stream gradient, water withdrawals, and fish barriers. Buck Creek generally was confined, with a single straight channel and low sinuosity. Boulders and cobble were the dominant stream substrate, with limited gravel available for spawning. Large-cobble riffles were 83 percent of the available fish habitat. Pools, comprising 15 percent of the surface area, mostly were formed by bedrock with little instream cover and low complexity. Instream wood averaged 6—10 pieces per 100 meters, 80 percent of which was less than 50 centimeters in diameter. Water temperature in Buck Creek rarely exceeded 16 degrees Celsius and did so for only 1 day at river kilometer (rkm) 3 and 11 days at rkm 0.2 in late July and early August 2009. The maximum temperature recorded was 17.2 degrees Celsius at rkm 0.2 on August 2, 2009. Minimum summer discharge in Buck Creek was 3.3 cubic feet per second downstream of an irrigation diversion (rkm 3.1) and 7.7 cubic feet per second at its confluence with the White Salmon River. Rainbow trout (Oncorhynchus mykiss) was the dominant fish species in all reaches. The abundance of age-1 or older rainbow trout was similar between reaches. However, in 2009 and 2010, the greatest abundance of age-0 rainbow trout (8 fish per meter) was in the most downstream reach. These analyses in Buck Creek are important for understanding the factors that may limit fish abundance and productivity, and they will help identify and prioritize potential restoration actions. The data collected constitute baseline information of pre-dam removal conditions that will allow assessment of changes in fish populations now that Condit Dam has

  8. [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.

  9. Three sympatric karyomorphs in the fish Astyanax fasciatus (Teleostei, Characidae do not seem to hybridize in natural populations

    Directory of Open Access Journals (Sweden)

    Maressa Ferreira-Neto

    2012-01-01

    Full Text Available Ninety individuals of the characid fish Astyanax fasciatus (Cuvier, 1819 were collected at Água da Madalena stream (Botucatu, São Paulo, Brazil and analyzed for diploid chromosome number 2n and karyotype composition as well as for the chromosomal location of the 5S and 18S ribosomal DNA (rDNA. Whereas no chromosome differences were associated with sex, three different karyomorphs with diploid chromosome numbers 2n=46, 2n=48 and 2n=50 were found. No intermediate 2n numbers were discovered. The 2n=50 karyomorph showed some differences in 18S rDNA location compared to the two other karyomorphs. Finally, all specimens with the 2n=46 karyomorph showed the presence of a partly heterochromatic macro supernumerary chromosome, which was absent in all individuals with the two other karyomorphs. All these results suggest that indviduals of the three different karyomorphs are not likely to hybridize in the examined populations. Our findings strongly suggest the presence of three separate species (sensu biological species concept easily diagnosed on the basis of differences in the diploid chromosome numbers and other chromosomal markers.

  10. 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.

  11. Effect of Planting Patterns' and Plant Population on Some of Morphological Traits, Harvest Index and Conservable Grain Yield of Sweet Corn

    Directory of Open Access Journals (Sweden)

    M. Nasrolah Alhossini

    2012-04-01

    Full Text Available Sweet corn is one of the most important crops in Iran and due to its short period of growth, it has been an important position after wheat and barley in khorasane Razavi Province. In this study two methods of planting (one raised bed and furrow planting and 3 plant densities (65000, 75000 and 85000 plant/ha was evaluated on some of Morphological Traits, harvest index and conservable grain yield of sweet Corn(Chase and KSC403su Varieties in Torbat-e-Heidarie in saline (4.060ds/m condition on 2009. The experimental design was factorial based on RCBC with 4 replications. The result of ANOVA showed significant differences between Anthesis silking interval (ASI, tassel length, plant height, ear height, stem diameter, harvest index, and conservable grain yield of sweet corn varieties that effected by planting methods. the highest harvest index was belonged to Chase in 75000 Plant/ha on one raised bed planting method with 31.75% and the lowest mean was belonged to KSC403su in 85000 Plant/ha on furrow planting method with 14.93%. In addition the highest grain yield was belonged to chase variety at 75000 plant/ha and furrow planting method with 11.912 ton/ha, while the lowest grain yield was belonged to KSC403su variety at 85000 plant/ha and raised bed planting (3.610 ton/ha. The Chase variety was better than KSC403su Due to its canopy and photo period is shorter than KSC403su. The superiority of Chase variety can be related to better distribution of leaves, highest harvest index, conservable grain yield and plant arrangement in the row.

  12. Optimal harvesting policy of a stochastic two-species competitive model with Lévy noise in a polluted environment

    Science.gov (United States)

    Zhao, Yu; Yuan, Sanling

    2017-07-01

    As well known that the sudden environmental shocks and toxicant can affect the population dynamics of fish species, a mechanistic understanding of how sudden environmental change and toxicant influence the optimal harvesting policy requires development. This paper presents the optimal harvesting of a stochastic two-species competitive model with Lévy noise in a polluted environment, where the Lévy noise is used to describe the sudden climate change. Due to the discontinuity of the Lévy noise, the classical optimal harvesting methods based on the explicit solution of the corresponding Fokker-Planck equation are invalid. The object of this paper is to fill up this gap and establish the optimal harvesting policy. By using of aggregation and ergodic methods, the approximation of the optimal harvesting effort and maximum expectation of sustainable yields are obtained. Numerical simulations are carried out to support these theoretical results. Our analysis shows that the Lévy noise and the mean stress measure of toxicant in organism may affect the optimal harvesting policy significantly.

  13. Wind energy harvesting with a piezoelectric harvester

    International Nuclear Information System (INIS)

    Wu, Nan; Wang, Quan; Xie, Xiangdong

    2013-01-01

    An energy harvester comprising a cantilever attached to piezoelectric patches and a proof mass is developed for wind energy harvesting, from a cross wind-induced vibration of the cantilever, by the electromechanical coupling effect of piezoelectric materials. The vibration of the cantilever under the cross wind is induced by the air pressure owing to a vortex shedding phenomenon that occurs on the leeward side of the cantilever. To describe the energy harvesting process, a theoretical model considering the cross wind-induced vibration on the piezoelectric coupled cantilever energy harvester is developed, to calculate the charge and the voltage from the harvester. The influences of the length and location of the piezoelectric patches as well as the proof mass on the generated electric power are investigated. Results show that the total generated electric power can be as high as 2 W when the resonant frequency of the cantilever harvester is close to the vortex shedding frequency. Moreover, a value of total generated electric power up to 1.02 W can be practically realized for a cross wind with a variable wind velocity of 9–10 m s −1 by a harvester with a length of 1.2 m. This research facilitates an effective and compact wind energy harvesting device. (paper)

  14. SE Asian freshwater fish population and networks: the impacts of climatic and environmental change on a vital resource

    Science.gov (United States)

    Santos, Rita; Parsons, Daniel; Cowx, Ian

    2016-04-01

    The Mekong River is the 10th largest freshwater river in the world, with the second highest biodiversity wealth, behind the much larger Amazon basin. The fisheries activity in the Lower Mekong countries counts for 2.7 million tons of fish per year, with an estimated value worth up to US 7 billion. For the 60 million people living in the basin, fish represent their primary source of economic income and protein intake, with an average per capita consumption estimated at 45.4 Kg. The proposed hydropower development in the basin is threatening its sustainability and resilience. Such developments affect fish migration patterns, hydrograph flood duration and magnitudes and sediment flux. Climate change is also likely to impact the basin, exacerbating the issues created by development. As a monsoonal system, the Mekong River's pronounced annual flood pulse cycle is important in creating variable habitat for fish productivity. Moreover, the annual flood also triggers fish migration and provides vital nutrients carried by the sediment flux. This paper examines the interactions between both dam development and climate change scenarios on fish habitat and habitat connectivity, with the aim of predicting how these will affect fish species composition and fisheries catch. The project will also employ Environmental DNA (eDNA) to quantify and understand the species composition of this complex and large freshwater system. By applying molecular analysis, it is possible to trace species abundance and migration patterns of fish and evaluate the ecological networks establish between an inland system. The aim of this work is to estimate, using process-informed models, the impacts of the proposed dam development and climate change scenarios on the hydrological and hydraulic conditions of habitat availability for fish. Furthermore, it will evaluate the connectivity along the Mekong and its tributaries, and the importance of maintaining these migration pathways, used by a great diversity

  15. Additive and Synergistic Impacts of Fishing and Warming on the Growth of a Temperate Marine Fish

    Science.gov (United States)

    Morrongiello, J.

    2016-02-01

    Fishing and climate change are having profound impacts on the trajectory and variability of marine populations. However, despite the wealth of work undertaken in marine environments on the causes of longer-term biological change, the effects of these two drivers have traditionally been considered in isolation or just additively. Such an approach obviously overlooks the potential for significant synergistic or antagonistic interactions between fishing and climate to occur. Indeed, it is increasingly becoming acknowledged that the direction and magnitude of biological responses to natural environmental variation and climate change can be mediated by other anthropogenic disturbances such as fishing, and vice versa. Somatic growth is an ideal candidate with which to explore the impacts of fishing and environmental variability due to its strong biological relevance and its heightened sensitivity to natural and anthropogenic drivers. I developed 19-year growth biochronologies (1980-1999) for three south-east Australian populations of a site-attached temperate reef fish, purple wrasse (Notolabrus fucicola) using individual-based growth information naturally archived in otoliths. A commercial wrasse fishery began in the early 1990s; before this there was negligible recreational or commercial fishing. The growth of older fish was proportionally higher and that of the youngest fish proportionally lower after the onset of commercial fishing; 2-year olds grew 7.4% slower, but 5-year-olds grew 10.3% and 10-year-olds 26% faster in the latter period. These results are consistent with a density dependent response to harvesting. Average growth rates across all ages increased by 6.6%.oC-1, reflecting either a direct or indirect temperature effect in this global marine 'hotspot'. Finally, the distribution of individual thermal reaction norms significantly changed post fishing, showing that fishing and temperature can have a synergetic impact on marine populations via within

  16. Invasive cyprinid fish in Europe originate from the single introduction of an admixed source population followed by a complex pattern of spread.

    Directory of Open Access Journals (Sweden)

    Andrea Simon

    Full Text Available The Asian cyprinid fish, the topmouth gudgeon (Pseudorasbora parva, was introduced into Europe in the 1960s. A highly invasive freshwater fish, it is currently found in at least 32 countries outside its native range. Here we analyse a 700 base pair fragment of the mitochondrial cytochrome b gene to examine different models of colonisation and spread within the invasive range, and to investigate the factors that may have contributed to their invasion success. Haplotype and nucleotide diversity of the introduced populations from continental Europe was higher than that of the native populations, although two recently introduced populations from the British Isles showed low levels of variability. Based on coalescent theory, all introduced and some native populations showed a relative excess of nucleotide diversity compared to haplotype diversity. This suggests that these populations are not in mutation-drift equilibrium, but rather that the relative inflated level of nucleotide diversity is consistent with recent admixture. This study elucidates the colonisation patterns of P. parva in Europe and provides an evolutionary framework of their invasion. It supports the hypothesis that their European colonisation was initiated by their introduction to a single location or small geographic area with subsequent complex pattern of spread including both long distance and stepping-stone dispersal. Furthermore, it was preceded by, or associated with, the admixture of genetically diverse source populations that may have augmented its invasive-potential.

  17. Effects of coconut and fish oils on ruminal methanogenesis, fermentation, and abundance and diversity of microbial populations in vitro.

    Science.gov (United States)

    Patra, A K; Yu, Z

    2013-03-01

    Coconut (CO) and fish (FO) oils were previously shown to inhibit rumen methanogenesis and biohydrogenation, which mitigates methane emission and helps improve beneficial fatty acids in meat and milk. This study aimed at investigating the comparative effects of CO and FO on the methanogenesis, fermentation, and microbial abundances and diversity in vitro rumen cultures containing different doses (0, 3.1, and 6.2 mL/L) of each oil and 400mg feed substrate using rumen fluid from lactating dairy cows as inocula. Increasing doses of CO and FO quadratically decreased concentrations of methane, but hydrogen concentrations were only increased quadratically by CO. Both oils linearly decreased dry matter and neutral detergent fiber digestibility of feeds but did not affect the concentration of total volatile fatty acids. However, CO reduced acetate percentage and acetate to propionate ratio and increased the percentages of propionate and butyrate to a greater extent than FO. Ammonia concentration was greater for CO than FO. As determined by quantitative real-time PCR, FO had greater inhibition to methanogens than CO, but the opposite was true for protozoal, Ruminococcus flavefaciens, and Fibrobacter succinogenes. Ruminococcus albus was not affected by either oil. Denaturing gradient gel electrophoresis (DGGE) profiles revealed that bacterial and archaeal community composition were changed differently by oil type. Based on Pareto-Lorenz evenness curve analysis of the DGGE profiles, CO noticeably changed the functional organization of archaea compared with FO. In conclusion, although both CO and FO decreased methane concentrations to a similar extent, the mode of reduction and the effect on abundances and diversity of archaeal and bacterial populations differed between the oils. Thus, the use of combination of CO and FO at a low dose may additively lower methanogenesis in the rumen while having little adverse effect on rumen fermentation. Copyright © 2013 American Dairy

  18. Fish Allergy

    Science.gov (United States)

    ... Cause Blog Vision Awards Common Allergens Fish Allergy Fish Allergy Learn about fish allergy, how to read ... that you must avoid both. Allergic Reactions to Fish Finned fish can cause severe and potentially life- ...

  19. Assess/monitor effects of MPA status on reef fish populations and spawning aggregations in the Tortugas Ecological Reserves

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We supply abundance information of fish species along multiple randomly oriented transects at the lowest possible taxonomic level. This information is collected from...

  20. Post-harvest physiology

    Science.gov (United States)

    Weather and management constraints, as well as the intended use of the harvested forage, all influence the forage harvest system selected by the producer. Generally, maximum retention of dry matter from harvested forage crops is achieved at moistures intermediate between the standing fresh crop and ...

  1. Variation in size frequency distribution of coral populations under different fishing pressures in two contrasting locations in the Indian Ocean.

    Science.gov (United States)

    Grimsditch, G; Pisapia, C; Huck, M; Karisa, J; Obura, D; Sweet, M

    2017-10-01

    This study aimed to assess how the size-frequency distributions of coral genera varied between reefs under different fishing pressures in two contrasting Indian Ocean locations (the Maldives and East Africa). Using generalized linear mixed models, we were able to demonstrate that complex interactions occurred between coral genera, coral size class and fishing pressure. In both locations, we found Acropora coral species to be more abundant in non-fished compared to fished sites (a pattern which was consistent for nearly all the assessed size classes). Coral genera classified as 'stress tolerant' showed a contrasting pattern i.e. were higher in abundance in fished compared to non-fished sites. Site specific variations were also observed. For example, Maldivian reefs exhibited a significantly higher abundance in all size classes of 'competitive' corals compared to East Africa. This possibly indicates that East African reefs have already been subjected to higher levels of stress and are therefore less suitable environments for 'competitive' corals. This study also highlights the potential structure and composition of reefs under future degradation scenarios, for example with a loss of Acropora corals and an increase in dominance of 'stress tolerant' and 'generalist' coral genera. Copyright © 2017. Published by Elsevier Ltd.

  2. 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.

  3. 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).

  4. Diet, reproduction and population structure of the introduced Amazonian fish Cichla piquiti (Perciformes: Cichlidae) in the Cachoeira Dourada reservoir (Paranaíba River, central Brazil).

    Science.gov (United States)

    Luiz, Tatiane Ferraz; Velludo, Marcela Roquetti; Peret, Alberto Carvalho; Rodrigues Filho, Jorge Luiz; Peret, André Moldenhauer

    2011-06-01

    The Blue Peacock Bass (Cichla piquiti), native to the Tocantins-Araguaia river basin of the Amazon system, was introduced into the basin of the Paranaíba River, Paraná River system. Cachoeira Dourada reservoir is one of a series of dams on the Paranaíba River in central Brazil, where this fish has become established. A study of its feeding spectrum, combined with information about its reproductive characteristics and population structure, would enable the current state of this species in the reservoir to be assessed and might provide useful data for the management of other species native to this habitat. This study showed that the peacock bass has no predators or natural competitors in the reservoir and that reproduces continuously, with high reproductive rates, and has a smaller median length at first maturity (L50) than other species of Cichla. Its successful establishment in habitats strongly affected by human activity should cause changes in the whole structure of the local fish communities. Nonetheless, in this reservoir, there appears to be some sharing of the functions of this species with native carnivorous fish, a situation that may be sustained by the presence of a wide variety of foraging fish.

  5. On the relevance of genotoxicity for fish populations I: effects of a model genotoxicant on zebrafish (Danio rerio) in a complete life-cycle test.

    Science.gov (United States)

    Diekmann, Markus; Hultsch, Veit; Nagel, Roland

    2004-05-28

    Genotoxicity may be detected in surface waters by means of various genotoxicity assays. In order to enable an ecotoxicological assessment of the consequences of such genotoxic potential for fish populations, a complete life-cycle test with zebrafish (Danio rerio) and the model genotoxicant 4-nitroquinoline-1-oxide (NQO) was conducted. Zebrafish (f1) were continuously exposed to NQO (i.e. 0.1, 0.3, 1.1, 2.9, and 14.6 microg/l, respectively) from fertilised eggs until sexual maturity. In addition to reproduction studies in the f1-generation, f2-fish were exposed to NQO during the first 6 weeks of development. Up to 2.9 microg/l NQO, fish did not display differences in survival and growth (P < 0.05). A NQO concentration of 14.6 microg/l, however, was lethal. Female fish exposed to all NQO concentrations up to 2.9 microg/l displayed a significant reduction in egg production (P < 0.05). A mathematical simulation revealed that exposure to weak concentrations of NQO is leading to an elevated extinction risk. Copyright 2004 Elsevier B.V.

  6. Diet, reproduction and population structure of the introduced Amazonian fish Cichla piquiti (Perciformes: Cichlidae in the Cachoeira Dourada reservoir (Paranaíba River, central Brazil

    Directory of Open Access Journals (Sweden)

    Tatiane Ferraz Luiz

    2011-06-01

    Full Text Available The Blue Peacock Bass (Cichla piquiti, native to the Tocantins-Araguaia river basin of the Amazon system, was introduced into the basin of the Paranaíba River, Paraná River system. Cachoeira Dourada reservoir is one of a series of dams on the Paranaíba River in central Brazil, where this fish has become established. A study of its feeding spectrum, combined with information about its reproductive characteristics and population structure, would enable the current state of this species in the reservoir to be assessed and might provide useful data for the management of other species native to this habitat. This study showed that the peacock bass has no predators or natural competitors in the reservoir and that reproduces continuously, with high reproductive rates, and has a smaller median length at first maturity (L50 than other species of Cichla. Its successful establishment in habitats strongly affected by human activity should cause changes in the whole structure of the local fish communities. Nonetheless, in this reservoir, there appears to be some sharing of the functions of this species with native carnivorous fish, a situation that may be sustained by the presence of a wide variety of foraging fish. Rev. Biol. Trop. 59 (2: 727-741. Epub 2011 June 01.

  7. The Application of Traits-Based Assessment Approaches to Estimate the Effects of Hydroelectric Turbine Passage on Fish Populations

    Energy Technology Data Exchange (ETDEWEB)

    Cada, Glenn F [ORNL; Schweizer, Peter E [ORNL

    2012-04-01

    One of the most important environmental issues facing the hydropower industry is the adverse impact of hydroelectric projects on downstream fish passage. Fish that migrate long distances as part of their life cycle include not only important diadromous species (such as salmon, shads, and eels) but also strictly freshwater species. The hydropower reservoirs that downstream-moving fish encounter differ greatly from free-flowing rivers. Many of the environmental changes that occur in a reservoir (altered water temperature and transparency, decreased flow velocities, increased predation) can reduce survival. Upon reaching the dam, downstream-migrating fish may suffer increased mortality as they pass through the turbines, spillways and other bypasses, or turbulent tailraces. Downstream from the dam, insufficient environmental flow releases may slow downstream fish passage rates or decrease survival. There is a need to refine our understanding of the relative importance of causative factors that contribute to turbine passage mortality (e.g., strike, pressure changes, turbulence) so that turbine design efforts can focus on mitigating the most damaging components. Further, present knowledge of the effectiveness of turbine improvements is based on studies of only a few species (mainly salmon and American shad). These data may not be representative of turbine passage effects for the hundreds of other fish species that are susceptible to downstream passage at hydroelectric projects. For example, there are over 900 species of fish in the United States. In Brazil there are an estimated 3,000 freshwater fish species, of which 30% are believed to be migratory (Viana et al. 2011). Worldwide, there are some 14,000 freshwater fish species (Magurran 2009), of which significant numbers are susceptible to hydropower impacts. By comparison, in a compilation of fish entrainment and turbine survival studies from over 100 hydroelectric projects in the United States, Winchell et al. (2000

  8. EDITORIAL Solar harvest Solar harvest

    Science.gov (United States)

    Demming, Anna

    2010-12-01

    investigating organic solar cell technology. In spring 2011, Nanotechnology launches a new section wholly dedicated to the coverage of new and stimulating research into energy sources based on nanoscale science and technology. There is at present considerable concern over how to fuel the planet in a sustainable manner with the increasingly energy-thirsty human population. Yet the Earth receives more solar energy in one hour than the world population consumes in one year [8]. No wonder research into photovoltaics and ways of increasing the efficiency with which this energy can be harnessed continues to hold so much fascination. References [1] Levin I and White C E 1949 J. Chem. Phys. 18 417 [2] Chirvase D, Parisi J, Hummelen J C and Dyakonov V 2004 Nanotechnology 15 1317 [3] Kwong C Y, Choy W C H, Djurišić A B, Chui P C, Cheng K W and Chan W K 2004 Nanotechnology 15 1156 [4] Krebs F C, Thomann Y, Thomann R and Andreasen J W 2008 Nanotechnology 19 424013 [5] Zeng T-W, Lin Y-Y, Lo H-H, Chen C-W, Chen C-H, Liou S-C, Huang H-Y and Su W-F 2006 Nanotechnology 17 5387 [6] Dissanayake D M N M, Hatton R A, Lutz T, Curry R J and Silva S R P 2009 Nanotechnology 20 245202 [7] Nicholson P G and Castro F A 2010 Nanotechnology 21 492001 [8] http://www.solarenergyworld.org/solar-energy-facts/

  9. Effects of landscape features on population genetic variation of a tropical stream fish, Stone lapping minnow, Garra cambodgiensis, in the upper Nan River drainage basin, northern Thailand

    Directory of Open Access Journals (Sweden)

    Chaowalee Jaisuk

    2018-03-01

    Full Text Available Spatial genetic variation of river-dwelling freshwater fishes is typically affected by the historical and contemporary river landscape as well as life-history traits. Tropical river and stream landscapes have endured extended geological change, shaping the existing pattern of genetic diversity, but were not directly affected by glaciation. Thus, spatial genetic variation of tropical fish populations should look very different from the pattern observed in temperate fish populations. These data are becoming important for designing appropriate management and conservation plans, as these aquatic systems are undergoing intense development and exploitation. This study evaluated the effects of landscape features on population genetic diversity of Garra cambodgiensis, a stream cyprinid, in eight tributary streams in the upper Nan River drainage basin (n = 30–100 individuals/location, Nan Province, Thailand. These populations are under intense fishing pressure from local communities. Based on 11 microsatellite loci, we detected moderate genetic diversity within eight population samples (average number of alleles per locus = 10.99 ± 3.00; allelic richness = 10.12 ± 2.44. Allelic richness within samples and stream order of the sampling location were negatively correlated (P < 0.05. We did not detect recent bottleneck events in these populations, but we did detect genetic divergence among populations (Global FST = 0.022, P < 0.01. The Bayesian clustering algorithms (TESS and STRUCTURE suggested that four to five genetic clusters roughly coincide with sub-basins: (1 headwater streams/main stem of the Nan River, (2 a middle tributary, (3 a southeastern tributary and (4 a southwestern tributary. We observed positive correlation between geographic distance and linearized FST (P < 0.05, and the genetic differentiation pattern can be moderately explained by the contemporary stream network (STREAMTREE analysis, R2 = 0.75. The MEMGENE analysis

  10. Predicting the effects of copper on local population decline of 2 marine organisms, cobia fish and whiteleg shrimp, based on avoidance response.

    Science.gov (United States)

    Araújo, Cristiano V M; Cedeño-Macías, Luís A; Vera-Vera, Victoria C; Salvatierra, David; Rodríguez, Elizabeth N V; Zambrano, Ufredo; Kuri, Samir

    2016-02-01

    The present study focuses on avoidance response to predict population decline of the marine fish Rachycentron canadum (cobia) and larvae of the estuarine shrimp Litopenaeus vannamei (whiteleg shrimp). Avoidance of approximately 60% was recorded for the cobia fry exposed to 1.0 mg Cu/L, 1.60 mg Cu/L, and 1.80 mg Cu/L. For the shrimp larvae, avoidance was approximately 80% for all Cu concentrations. The population decline of cobia fry was conditioned by avoidance in lower concentrations. However, in higher concentrations mortality begins to play an important role. The displacement toward uncontaminated habitats might determine shrimp population decline. A Cu-contaminated environment can determine the habitat selection of both species and, therefore, their local population decline. © 2015 SETAC.

  11. The Effect on Selenium Concentrations of a Randomized Intervention with Fish and Mussels in a Population with Relatively Low Habitual Dietary Selenium Intake

    Science.gov (United States)

    Outzen, Malene; Tjønneland, Anne; Larsen, Erik H.; Andersen, Klaus K.; Christensen, Jane; Overvad, Kim; Olsen, Anja

    2015-01-01

    Selenium status of the Danish population is below that assumed optimal for the suggested protective effects against chronic diseases, including certain cancers. Fish and shellfish are important dietary sources of selenium in Denmark. We investigated the effect of increased fish and mussel intake on selenium blood concentrations in a population with relatively low habitual dietary selenium intake. We randomly assigned 102 healthy men and women (all non-smokers) aged 48–76 years to an intervention group (n = 51) or a control group (n = 51). Intervention participants received 1000 g fish and mussels/week for 26 weeks (~50 μg selenium/day). Controls received no intervention. Non-fasting blood samples were taken and whole blood selenium was determined using inductively coupled plasma-mass spectrometry (ICP-MS), and plasma selenoprotein P (SelP) was determined by high performance liquid chromatography coupled to ICP-MS. All available observations were included in linear multiple regression analysis to evaluate the effect of the intervention. The difference in mean change for intervention compared with control persons was 14.9 ng/mL (95% CI: 10.2, 19.7) for whole blood selenium, and 7.0 ng/mL (95% CI: 3.1, 10.9) for plasma SelP (Weeks 0–26). Selenium concentrations were significantly increased after 26 weeks of intervention, albeit to a lower degree than expected. PMID:25599275

  12. Population parameters and dynamic pool models of commercial fishes in the Beibu Gulf, northern South China Sea

    Science.gov (United States)

    Wang, Xuehui; Qiu, Yongsong; Du, Feiyan; Lin, Zhaojin; Sun, Dianrong; Huang, Shuolin

    2012-01-01

    Length-frequency data of eight commercial fish species in the Beibu Gulf (Golf of Tonkin), northern South China Sea, were collected during 2006-2007. Length-weight relationships and growth and mortality parameters were analyzed using FiSAT II software. Five species had isometric growth, two species had negative allometric growth, and one species had positive allometric growth. Overall, the exploitation rates of the eight species were lower in 2006-2007 than in 1997-1999: for four species ( Saurida tumbil, Saurida undosquamis, Argyrosomus macrocephalus, and Nemipterus virgatus) it was lower in 2006-2007 than in 1997-1999, for two species ( Parargyrops edita and Trichiurus haumela) it remained the same, and for the other two species ( Trachurus japonicus and Decapterus maruadsi) it was higher in 2006-2007 than in 1997-1999. The exploitation rates might have declined because of the decline in fishing intensity caused by high crude oil prices. The optimum exploitation rate, estimated using Beverton-Holt dynamic pool models, indicated that although fishes in the Beibu Gulf could sustain high exploitation rates, the under-size fishes at first capture resulted in low yields. To increase the yield per recruitment, it is more effective to increase the size at first capture than to control fishing effort.

  13. Of Fish and Fishermen: Shifting Societal Baselines to Reduce Environmental Harm in Fisheries

    Directory of Open Access Journals (Sweden)

    Mimi E. Lam

    2012-12-01

    Full Text Available If reasonable fishery harvests and environmental harms are specified in new regulations, policies, and laws governing the exploitation of fish for food and livelihoods, then societal baselines can shift to achieve sustainable fisheries and marine conservation. Fisheries regulations can limit the environmental and social costs or harms caused by fishing by requiring the fishing industry to pay for the privilege to fish, via access fees for the opportunity to catch fish and extraction fees for fish caught; both fees can be combined with a progressive environmental tax to discourage overcapitalization and overfishing. Fisheries policies can be sustainable if predicated on an instrumental and ethical harm principle to reduce fishing harm. To protect the public trust in fisheries, environmental laws can identify the unsustainable depletion of fishery resources as ecological damage and a public nuisance to bind private fishing enterprises to a harm principle. Collaborative governance can foster sustainable fisheries if decision-making rights and responsibilities of marine stewardship are shared among government, the fishing industry, and civil society. As global food security and human welfare are threatened by accelerating human population growth and environmental impacts, decisions of how to use and protect the environment will involve collective choices in which all citizens have a stake - and a right.

  14. FRESHWATER FISH AND DECAPOD CRUSTACEAN POPULATIONS ON RÉUNION ISLAND, WITH AN ASSESSMENT OF SPECIES INTRODUCTIONS.

    Directory of Open Access Journals (Sweden)

    KEITH P.

    2002-01-01

    Full Text Available Streams of Réunion Island shelter with 26 fish species and 11 decapod crustacean species. Some species have been introduced (18%, some other are endemic to the island or to the Madagascar-Mascarenes region (16.2%, are originated from Indo-Pacific area (35.2% or from Indo-African area (27%. Gobiidae and Palaemonidae are the prevailing family in freshwaters, with the highest number of species. 16 species were introduced, mainly fishes, beginning at the turn of the 19th century, but only 4 of those have become acclimatised, while 7 have disappeared and the status of the other is uncertain.

  15. Population dynamics of calanoid copepods and the implications of their predation by clupeid fish in the Central Baltic Sea

    DEFF Research Database (Denmark)

    Möllmann, C.; Köster, Fritz

    2002-01-01

    . Additionally this study investigated the effect of predation by the major planktivorous fish species herring (Clupea harengus) and sprat (Sprattus sprattus) for the period 1977-1996 in the Gotland Basin (Central Baltic Sea). Examination of consumption by these fish species in relation to copepod production...... by sprat on CV/CVI of both copepod species in spring resulted in higher copepod mortality rates. In consequence, based on these results we suggest that the increase in the sprat stock since the late 1980s contributed to a decline of P. elongatus, and additionally prevented an even more pronounced...

  16. Thermal and maternal environments shape the value of early hatching in a natural population of a strongly cannibalistic freshwater fish

    DEFF Research Database (Denmark)

    Pagel, T.; Bekkevold, Dorte; Pohlmeier, S.

    2015-01-01

    Hatching early in the season is often assumed to elevate fitness, particularly in cannibalistic fish in which size-dependent predation mortality is a major selective force. While the importance of the thermal environment for the growth of fish is undisputed, the relevance of maternal effects...... represented by juvenile growth rate), but not female total length, to jointly contribute to explain within- and among-season size variation in juvenile pike. While there was no statistical evidence for maternal effects on offspring growth rate, fast female juvenile growth positively correlated...... in the wild and that early hatching does not generally produce size advantages in light of stochastically varying temperature conditions...

  17. Continuity and change in subsistence harvests in five Bering Sea communities: Akutan, Emmonak, Savoonga, St. Paul, and Togiak

    Science.gov (United States)

    Fall, James A.; Braem, Nicole S.; Brown, Caroline L.; Hutchinson-Scarbrough, Lisa B.; Koster, David S.; Krieg, Theodore M.

    2013-10-01

    To document and quantify subsistence harvests of fish and wildlife resources, and provide topics for subsequent key respondent interviews to collect local and traditional knowledge (LTK) about the Bering Sea ecosystem, comprehensive household harvest surveys were conducted in four Bering Sea Alaska Native communities: Akutan, Emmonak, Savoonga, and Togiak. In a fifth community, St. Paul, annual programs to document two key subsistence resources, fur seals and sea lions, continued. Surveys documented relatively high and diverse subsistence harvests, consistent with earlier research that demonstrated the continuing economic, social, and cultural importance of subsistence uses of wild resources. The research also found differences in subsistence use patterns compared to previous years' studies, such as harvest levels, harvest composition, and diversity of resources used, although differences between study years were not uniform across communities. Survey respondents, as well as key respondents in subsequent interviews, identified a complex range of personal, economic, and environmental factors when comparing subsistence uses in the study year with other years, such as increasing costs of fuel and purchased food, commercial fisheries harvests and bycatch, more persistent storms and less predictable winds, and reduced sea ice. Such conditions affect resource abundance and locations as well as access to fish and wildlife populations, and may shape long-term trends. So far, as in the past, families and communities have adapted to changing economic, social, and environmental conditions, but the future is less clear if such changes intensify or accelerate. Local community residents should be essential partners in future efforts to understand these complex processes that affect the natural resources of the Bering Sea.

  18. 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.

  19. The effect of nuclear facilities operation on fish populations and the Dukovany-Dalesice power complex under construction

    International Nuclear Information System (INIS)

    Penaz, M.

    1979-01-01

    The scope and the main results are described of the hydrobiological and ichthyological research into the Jihlava river in the neighbourhood of the Dukovany - Dalesice power plant complex. The effect of the power plant complex on the ecosystem of the affected river stretch is predicted, mainly on the fish community. (author)

  20. A Multiple Watershed Approach to Assessing the Effects of Habitat Restoration Actions on Anadromous and Resident Fish Populations, Technical Report 2003-2004.

    Energy Technology Data Exchange (ETDEWEB)

    Marmorek, David

    2004-03-01

    Habitat protection and restoration is a cornerstone of current strategies to restore ecosystems, recover endangered fish species, and rebuild fish stocks within the Columbia River Basin. Strategies featuring habitat restoration include the 2000 Biological Opinion on operation of the Federal Columbia River Power System (FCRPS BiOp) developed by the National Marine Fisheries Service (NMFS), the 2000 Biological Opinion on Bull Trout developed by the US Fish and Wildlife Service (USFWS), and Sub-Basin Plans developed under the Fish and Wildlife Program of the Northwest Power and Conservation Council (NWPCC). There is however little quantitative information about the effectiveness of different habitat restoration techniques. Such information is crucial for helping scientists and program managers allocate limited funds towards the greatest benefits for fish populations. Therefore, it is critical to systematically test the hypotheses underlying habitat restoration actions for both anadromous and resident fish populations. This pilot project was developed through a proposal to the Innovative Projects fund of the NWPCC (ESSA 2002). It was funded by the Bonneville Power Administration (BPA) following reviews by the Independent Scientific Review Panel (ISRP 2002), the Columbia Basin Fish and Wildlife Authority (CBFWA 2002), the NWPCC and BPA. The study was designed to respond directly to the above described needs for information on the effectiveness of habitat restoration actions, including legal measures specified in the 2000 FCRPS BiOp (RPA 183, pg. 9-133, NMFS 2000). Due to the urgency of addressing these measures, the timeline of the project was accelerated from a duration of 18 months to 14 months. The purpose of this pilot project was to explore methods for evaluating past habitat restoration actions and their effects on fish populations. By doing so, the project will provide a foundation of retrospective analyses, on which to build prospective, multi-watershed designs

  1. 78 FR 68780 - Treatment of Income From Indian Fishing Rights-Related Activity as Compensation

    Science.gov (United States)

    2013-11-15

    ... fishing activities is exempt from taxation. See H.R. Rep. 100-1104, at p. 77 (1988). Congress added... harvesting, processing, or transporting fish harvested in the exercise of a recognized fishing right of the... from the exercise of nonstatutory options and amounts realized when restricted stock or other property...

  2. Fog Harvesting with Harps.

    Science.gov (United States)

    Shi, Weiwei; Anderson, Mark J; Tulkoff, Joshua B; Kennedy, Brook S; Boreyko, Jonathan B

    2018-04-11

    Fog harvesting is a useful technique for obtaining fresh water in arid climates. The wire meshes currently utilized for fog harvesting suffer from dual constraints: coarse meshes cannot efficiently capture microscopic fog droplets, whereas fine meshes suffer from clogging issues. Here, we design and fabricate fog harvesters comprising an array of vertical wires, which we call "fog harps". Under controlled laboratory conditions, the fog-harvesting rates for fog harps with three different wire diameters were compared to conventional meshes of equivalent dimensions. As expected for the mesh structures, the mid-sized wires exhibited the largest fog collection rate, with a drop-off in performance for the fine or coarse meshes. In contrast, the fog-harvesting rate continually increased with decreasing wire diameter for the fog harps due to efficient droplet shedding that prevented clogging. This resulted in a 3-fold enhancement in the fog-harvesting rate for the harp design compared to an equivalent mesh.

  3. Which Fish Should I Eat? Perspectives Influencing Fish Consumption Choices

    Science.gov (United States)

    Choi, Anna L.; Karagas, Margaret R.; Mariën, Koenraad; Rheinberger, Christoph M.; Schoeny, Rita; Sunderland, Elsie; Korrick, Susan

    2012-01-01

    Background: Diverse perspectives have influenced fish consumption choices. Objectives: We summarized the issue of fish consumption choice from toxicological, nutritional, ecological, and economic points of view; identified areas of overlap and disagreement among these viewpoints; and reviewed effects of previous fish consumption advisories. Methods: We reviewed published scientific literature, public health guidelines, and advisories related to fish consumption, focusing on advisories targeted at U.S. populations. However, our conclusions apply to groups having similar fish consumption patterns. Discussion: There are many possible combinations of matters related to fish consumption, but few, if any, fish consumption patterns optimize all domains. Fish provides a rich source of protein and other nutrients, but because of contamination by methylmercury and other toxicants, higher fish intake often leads to greater toxicant exposure. Furthermore, stocks of wild fish are not adequate to meet the nutrient demands of the growing world population, and fish consumption choices also have a broad economic impact on the fishing industry. Most guidance does not account for ecological and economic impacts of different fish consumption choices. Conclusion: Despite the relative lack of information integrating the health, ecological, and economic impacts of different fish choices, clear and simple guidance is necessary to effect desired changes. Thus, more comprehensive advice can be developed to describe the multiple impacts of fish consumption. In addition, policy and fishery management inter-ventions will be necessary to ensure long-term availability of fish as an important source of human nutrition. PMID:22534056

  4. Life-history diversity and its importance to population stability and persistence of a migratory fish: steelhead in two large North American watersheds.

    Science.gov (United States)

    Moore, Jonathan W; Yeakel, Justin D; Peard, Dean; Lough, Jeff; Beere, Mark

    2014-09-01

    Life-history strategies can buffer individuals and populations from environmental variability. For instance, it is possible that asynchronous dynamics among different life histories can stabilize populations through portfolio effects. Here, we examine life-history diversity and its importance to stability for an iconic migratory fish species. In particular, we examined steelhead (Oncorhynchus mykiss), an anadromous and iteroparous salmonid, in two large, relatively pristine, watersheds, the Skeena and Nass, in north-western British Columbia, Canada. We synthesized life-history information derived from scales collected from adult steelhead (N = 7227) in these watersheds across a decade. These migratory fishes expressed 36 different manifestations of the anadromous life-history strategy, with 16 different combinations of freshwater and marine ages, 7·6% of fish performing multiple spawning migrations, and up to a maximum of four spawning migrations per lifetime. Furthermore, in the Nass watershed, various life histories were differently prevalent through time - three different life histories were the most prevalent in a given year, and no life history ever represented more than 45% of the population. These asynchronous dynamics among life histories decreased the variability of numerical abundance and biomass of the aggregated population so that it was > 20% more stable than the stability of the weighted average of specific life histories: evidence of a substantial portfolio effect. Year of ocean entry was a key driver of dynamics; the median correlation coefficient of abundance of life histories that entered the ocean the same year was 2·5 times higher than the median pairwise coefficient of life histories that entered the ocean at different times. Simulations illustrated how different elements of life-history diversity contribute to stability and persistence of populations. This study provides evidence that life-history diversity can dampen fluctuations in

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  6. Population connectivity and the effectiveness of marine protected areas to protect vulnerable, exploited and endemic coral reef fishes at an endemic hotspot

    KAUST Repository

    Van Der Meer, Martin H.

    2014-12-23

    Marine protected areas (MPAs) aim to mitigate anthropogenic impacts by conserving biodiversity and preventing overfishing. The effectiveness of MPAs depends on population connectivity patterns between protected and non-protected areas. Remote islands are endemism hotspots for coral reef fishes and provide rare examples of coral reefs with limited fishing pressure. This study explored population genetic connectivity across a network of protected and non-protected areas for the endemic wrasse, Coris bulbifrons, which is listed as “vulnerable” by the IUCN due to its small, decreasing geographic range and declining abundance. Mitochondrial DNA (mtDNA) and microsatellite DNA (msatDNA) markers were used to estimate historic and contemporary gene flow to determine the level of population self-replenishment and to measure genetic and genotypic diversity among all four locations in the species range (south-west Pacific Ocean)—Middleton Reef (MR), Elizabeth Reef (ER), Lord Howe Island (LHI) and Norfolk Island (NI). MPAs exist at MR and LHI and are limited or non-existent at ER and NI, respectively. There was no obvious differentiation in mtDNA among locations, however, msatDNA revealed differentiation between the most peripheral (NI) and all remaining locations (MR, ER and LHI). Despite high mtDNA connectivity (M = 259–1,144), msatDNA connectivity was limited (M = 3–9) with high self-replenishment (68–93 %) at all locations. NI is the least connected and heavily reliant on self-replenishment, and the absence of MPAs at NI needs to be rectified to ensure the persistence of endemic species at this location. Other endemic fishes exhibit similar patterns of high self-replenishment across the four locations, indicating that a single spatial management approach consisting of a MPA network protecting part of each location could provide reasonable protection for these species. Thus, the existing network of MPAs at this endemic hotspot appears adequate at some locations

  7. Population connectivity and the effectiveness of marine protected areas to protect vulnerable, exploited and endemic coral reef fishes at an endemic hotspot

    Science.gov (United States)

    van der Meer, M. H.; Berumen, M. L.; Hobbs, J.-P. A.; van Herwerden, L.

    2015-06-01

    Marine protected areas (MPAs) aim to mitigate anthropogenic impacts by conserving biodiversity and preventing overfishing. The effectiveness of MPAs depends on population connectivity patterns between protected and non-protected areas. Remote islands are endemism hotspots for coral reef fishes and provide rare examples of coral reefs with limited fishing pressure. This study explored population genetic connectivity across a network of protected and non-protected areas for the endemic wrasse, Coris bulbifrons, which is listed as "vulnerable" by the IUCN due to its small, decreasing geographic range and declining abundance. Mitochondrial DNA (mtDNA) and microsatellite DNA (msatDNA) markers were used to estimate historic and contemporary gene flow to determine the level of population self-replenishment and to measure genetic and genotypic diversity among all four locations in the species range (south-west Pacific Ocean)—Middleton Reef (MR), Elizabeth Reef (ER), Lord Howe Island (LHI) and Norfolk Island (NI). MPAs exist at MR and LHI and are limited or non-existent at ER and NI, respectively. There was no obvious differentiation in mtDNA among locations, however, msatDNA revealed differentiation between the most peripheral (NI) and all remaining locations (MR, ER and LHI). Despite high mtDNA connectivity ( M = 259-1,144), msatDNA connectivity was limited ( M = 3-9) with high self-replenishment (68-93 %) at all locations. NI is the least connected and heavily reliant on self-replenishment, and the absence of MPAs at NI needs to be rectified to ensure the persistence of endemic species at this location. Other endemic fishes exhibit similar patterns of high self-replenishment across the four locations, indicating that a single spatial management approach consisting of a MPA network protecting part of each location could provide reasonable protection for these species. Thus, the existing network of MPAs at this endemic hotspot appears adequate at some locations, but not

  8. Diet, reproduction and population structure of the introduced Amazonian fish Cichla piquiti (Perciformes: Cichlidae) in the Cachoeira Dourada reservoir (Paranaíba River, central Brazil)

    OpenAIRE

    Ferraz Luiz, Tatiane; Roquetti Velludo, Marcela; Carvalho Peret, Alberto; Rodrigues Filho, Jorge Luiz; Moldenhauer Peret, André

    2011-01-01

    The Blue Peacock Bass (Cichla piquiti), native to the Tocantins-Araguaia river basin of the Amazon system, was introduced into the basin of the Paranaíba River, Paraná River system. Cachoeira Dourada reservoir is one of a series of dams on the Paranaíba River in central Brazil, where this fish has become established. A study of its feeding spectrum, combined with information about its reproductive characteristics and population structure, would enable the current state of this species in the ...

  9. Mercury exposure through fish consumption in riparian populations at reservoir Guri, using nuclear techniques, Bolivar State, Venezuela

    International Nuclear Information System (INIS)

    Bermudez, Dario; Gali, Gladys; Milano, S.; Paolini, J.; Venegas, Gladys; Carvajal, M.; Marquez, Oscar

    2002-01-01

    In the reservoir Guri located at the south of Venezuela in Bolivar State has occurred the bioaccumulation process. Several studies have demonstrated it. In samples of 42 specimens of carnivorous trophic level, the average value of total mercury was 1.90 mg/g with a maximum of 6.04 mg/g. As first job it was necessary to identify and classify the infrastructures of each town according to their use due to the lack of updated demographic information. In this investigation is described the home characteristics with relation to its residence conditions and work status of home bosses through the design and application of a survey by home in two communities nearby reservoir Guri: 'La Paragua' and 'El Manteco'. A simple questionnaire was also designed and applied where home bosses were asked for the weekly frequency of consumption of fish, especially those of carnivorous habits as well as the quantity in grams consumed per week. Homes were better structured at 'La Paragua' than at 'El Manteco' but in the latest the monthly income by home was bigger nevertheless, it does not meet the requirements of the basic basket in Venezuela of US $ 323 for a four people family. The overall consumption of fish per week was twice higher at 'El Manteco' (1,485 kg) than at 'La Paragua' (678 kg). The fish specie consumed as first priority at 'La Paragua' was Prochilodus rubrotaeniatus ('Coporo') which is of detritivorous alimentary habits while the second more consumed was Cichla ocellaris ('Pavon') of carnivorous alimentary habits. On the opposite side, at 'El Manteco' the first priority of fish was Cichla ocellaris ('Pavon') while the second one was for Prochilodus rubrotaeniatus ('Coporo'). Next step will be the organic mercury analysis in hair samples and the nutritional profile in individuals from the selected homes: 36 at 'La Paragua' and 50 at 'El Manteco' towns. (author)

  10. A modeling framework for integrated harvest and habitat management of North American waterfowl: Case-study of northern pintail metapopulation dynamics

    Science.gov (United States)

    Mattsson, Brady J.; Runge, M.C.; Devries, J.H.; Boomer, G.S.; Eadie, J.M.; Haukos, D.A.; Fleskes, J.P.; Koons, D.N.; Thogmartin, W.E.; Clark, R.G.

    2012-01-01

    We developed and evaluated the performance of a metapopulation model enabling managers to examine, for the first time, the consequences of alternative management strategies involving habitat conditions and hunting on both harvest opportunity and carrying capacity (i.e., equilibrium population size in the absence of harvest) for migratory waterfowl at a continental scale. Our focus is on the northern pintail (Anas acuta; hereafter, pintail), which serves as a useful model species to examine the potential for integrating waterfowl harvest and habitat management in North America. We developed submodel structure capturing important processes for pintail populations during breeding, fall migration, winter, and spring migration while encompassing spatial structure representing three core breeding areas and two core nonbreeding areas. A number of continental-scale predictions from our baseline parameterization (e.g., carrying capacity of 5.5 million, equilibrium population size of 2.9 million and harvest rate of 12% at maximum sustained yield [MSY]) were within 10% of those from the pintail harvest strategy under current use by the U.S. Fish and Wildlife Service. To begin investigating the interaction of harvest and habitat management, we examined equilibrium population conditions for pintail at the continental scale across a range of harvest rates while perturbing model parameters to represent: (1) a 10% increase in breeding habitat quality in the Prairie Pothole population (PR); and (2) a 10% increase in nonbreeding habitat quantity along in the Gulf Coast (GC). Based on our model and analysis, a greater increase in carrying capacity and sustainable harvest was seen when increasing a proxy for habitat quality in the Prairie Pothole population. This finding and underlying assumptions must be critically evaluated, however, before specific management recommendations can be made. To make such recommendations, we require (1) extended, refined submodels with additional

  11. Life history inhomogeneity in Baltic Sea whitefish populations revealed by otolith strontium signatures – identification of stocked fish

    Directory of Open Access Journals (Sweden)

    Henry Hägerstrand

    2015-11-01

    The strontium concentrations in the otolith cores of whitefish from River Tornionjoki were higher than that of the four otoliths with low core strontium from fishes caught at sea (Table 1. Supposing that this latter group represent stocked fish raised in freshwater ponds, the vast majority of River Tornionjoki whitefish is naturally reproduced fish. This is plausible because in River Tornionjoki, the major whitefish spawning river in Finland, no larger stocking have been made since 1990s (Jokikokko and Huhmarniemi 2014. In conclusion, the concentration of otolith core strontium differs in whitefish hatched in fresh-water and in whitefish hatched in river water or in brackish Baltic Sea water. This difference can be used to reveal stocked whitefish. Barium concentration may be an even better indicator in this respect than strontium, as previous results indicate (Hägerstrand et al., 2015. Stocked river spawning whitefish appear in large amount at the southern feeding grounds around the Åland Islands, as already indicated by e.g. Leskelä et al. (2009.

  12. Increasing global crop harvest frequency: recent trends and future directions

    International Nuclear Information System (INIS)

    Ray, Deepak K; Foley, Jonathan A

    2013-01-01

    The world’s agricultural systems face the challenge of meeting the rising demands from population growth, changing dietary preferences, and expanding biofuel use. Previous studies have put forward strategies for meeting this growing demand by increasing global crop production, either expanding the area under cultivation or intensifying the crop yields of our existing agricultural lands. However, another possible means for increasing global crop production has received less attention: increasing the frequency of global cropland harvested each year. Historically, many of the world’s croplands were left fallow, or had failed harvests, each year, foregoing opportunities for delivering crop production. Furthermore, many regions, particularly in the tropics, may be capable of multiple harvests per year, often more than are harvested today. Here we analyze a global compilation of agricultural statistics to show how the world’s harvested cropland has changed. Between 2000 and 2011, harvested land area grew roughly 4 times faster than total standing cropland area. Using a metric of cropland harvest frequency (CHF)—the ratio of land harvested each year to the total standing cropland—and its recent trends, we identify countries that harvest their croplands more frequently, and those that have the potential to increase their cropland harvest frequency. We suggest that a possible ‘harvest gap’ may exist in many countries that represents an opportunity to increase crop production on existing agricultural lands. However, increasing the harvest frequency of existing croplands could have significant environmental and social impacts, which need careful evaluation. (letter)

  13. 1970 Oregon timber harvest.

    Science.gov (United States)

    Brian R. Wall

    1971-01-01

    The 1970 Oregon timber harvest of 7.98 billion board feet was the lowest recorded since the recession year of 1961 when 7.41 billion board feet of timber was produced. The 1970 log production figure was 12.8 percent below the 1969 harvest, the second consecutive year of declining production in Oregon.

  14. Dietary exposure to perfluoroalkyl acids of specific French adult sub-populations: High seafood consumers, high freshwater fish consumers and pregnant women

    International Nuclear Information System (INIS)

    Yamada, A.; Bemrah, N.; Veyrand, B.; Pollono, C.; Merlo, M.; Desvignes, V.; Sirot, V.

    2014-01-01

    Perfluoroalkyl acids (PFAAs) are globally found in various media, including food and especially fishery products. In the present study, the dietary exposure to 15 perfluoroalkyl acids was assessed for 3 French adult populations, namely high seafood consumers, high freshwater fish consumers, and pregnant women. Purified food extracts were analysed by LC–MS/MS and PFBA, PFPA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFTrDA, PFTeDA, PFBS, PFHxS, PFHpS, PFOS and PFDS were monitored and quantified according to the isotope dilution principle. Under lower bound (LB) hypothesis (i.e. contamination values < LOD considered as 0), high freshwater fish consumers appear as the most exposed to PFOS (7.5 ng.kg −1 bw.d −1 ), PFUnA (1.3 ng.kg −1 bw.d −1 ), PFDA (0.4 ng.kg −1 bw.d −1 ) and PFHpS (0.03 ng.kg −1 bw.d −1 ) while high seafood consumers appear as the most exposed to PFOA (1.2 ng.kg −1 bw.d −1 ), PFNA (0.2 ng.kg −1 bw.d −1 ) and PFHxS (0.06 ng.kg −1 bw.d −1 ). For all considered populations, the major exposure contributors are fish, seafood and water under LB hypothesis, while dairy products, bread and crispbread are the main contributors under upper bound (UB) hypothesis. Besides this food exposure assessment, further studies are needed to assess the more global PFAA exposure, taking into account indoor and outdoor air, dust and cutaneous contact, which could be other important contributors for this particular class of chemicals. - Highlights: • The dietary exposure was estimated for 15 perfluoroalkyl acids. • Despite the overestimation, the FFQ remains useful to evaluate the whole diet. • The high fish consumers are the most dietary exposed population. • Fishery products are the main exposure contributors under LB hypothesis

  15. Dietary exposure to perfluoroalkyl acids of specific French adult sub-populations: High seafood consumers, high freshwater fish consumers and pregnant women

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, A., E-mail: ami.s.yamada@gmail.com [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); Bemrah, N., E-mail: nawel.bemrah@anses.fr [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); Veyrand, B., E-mail: bruno.veyrand@oniris-nantes.fr [LUNAM Université, Oniris, Laboratoire d' Etude des Résidus et Contaminants dans les Aliments (LABERCA), USC INRA 1329, Nantes 44307 (France); Pollono, C., E-mail: charles.pollono@oniris-nantes.fr [LUNAM Université, Oniris, Laboratoire d' Etude des Résidus et Contaminants dans les Aliments (LABERCA), USC INRA 1329, Nantes 44307 (France); Merlo, M., E-mail: mathilde.merlo@anses.fr [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); Desvignes, V., E-mail: virginie.desvignes@anses.fr [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); Sirot, V., E-mail: sirotv@gmail.com [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); and others

    2014-09-01

    Perfluoroalkyl acids (PFAAs) are globally found in various media, including food and especially fishery products. In the present study, the dietary exposure to 15 perfluoroalkyl acids was assessed for 3 French adult populations, namely high seafood consumers, high freshwater fish consumers, and pregnant women. Purified food extracts were analysed by LC–MS/MS and PFBA, PFPA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFTrDA, PFTeDA, PFBS, PFHxS, PFHpS, PFOS and PFDS were monitored and quantified according to the isotope dilution principle. Under lower bound (LB) hypothesis (i.e. contamination values < LOD considered as 0), high freshwater fish consumers appear as the most exposed to PFOS (7.5 ng.kg{sup −1} bw.d{sup −1}), PFUnA (1.3 ng.kg{sup −1} bw.d{sup −1}), PFDA (0.4 ng.kg{sup −1} bw.d{sup −1}) and PFHpS (0.03 ng.kg{sup −1} bw.d{sup −1}) while high seafood consumers appear as the most exposed to PFOA (1.2 ng.kg{sup −1} bw.d{sup −1}), PFNA (0.2 ng.kg{sup −1} bw.d{sup −1}) and PFHxS (0.06 ng.kg{sup −1} bw.d{sup −1}). For all considered populations, the major exposure contributors are fish, seafood and water under LB hypothesis, while dairy products, bread and crispbread are the main contributors under upper bound (UB) hypothesis. Besides this food exposure assessment, further studies are needed to assess the more global PFAA exposure, taking into account indoor and outdoor air, dust and cutaneous contact, which could be other important contributors for this particular class of chemicals. - Highlights: • The dietary exposure was estimated for 15 perfluoroalkyl acids. • Despite the overestimation, the FFQ remains useful to evaluate the whole diet. • The high fish consumers are the most dietary exposed population. • Fishery products are the main exposure contributors under LB hypothesis.

  16. Parasites of forage fishes in the vicinity of Steller sea lion (Eumetopias jubatus) habitat in Alaska.

    Science.gov (United States)

    Moles, A; Heintz, R A

    2007-07-01

    Fish serve as intermediate hosts for a number of larval parasites that have the potential of maturing in marine mammals such as Steller sea lions (Eumetopias jubatus). We examined the prevalence of parasites from 229 fish collected between March and July 2002 near two islands used by Steller sea lions in Southeast Alaska and island habitats in the Aleutian Islands. Sea lion populations have remained steady in Southeast Alaska but have been declining over the last 30 yr in the Aleutian Islands. Even though the fish samples near the Southeast Alaska haul-outs were composed of numerous small species of fish and the Aleutian Islands catch was dominated by juveniles of commercially harvested species, the parasite fauna was similar at all locations. Eleven of the 20 parasite taxa identified were in their larval stage in the fish hosts, several of which have been described from mammalian final hosts. Four species of parasite were more prevalent in Southeast Alaska fish samples, and seven parasite species, including several larval forms capable of infecting marine mammals, were more prevalent in fish from the Aleutian Islands. Nevertheless, parasites available to Steller sea lions from common fish prey are not likely to be a major factor in the decline of this marine mammal species.

  17. Maple Sugar Harvesting/Wild Rice Harvesting.

    Science.gov (United States)

    Minneapolis Public Schools, MN.

    Comprised of two separate booklets, this resource unit assists elementary teachers in explaining how the Ojibwe people harvest maple sugar and wild rice. The first booklet explains the procedure of tapping the maple trees for sap, preparation for boiling the sap, and the three forms the sugar is made into (granulated, "molded," and…

  18. Electromagnetic energy harvester for harvesting acoustic energy

    Indian Academy of Sciences (India)

    Farid U Khan

    Acoustics; energy harvesting; electromagnetic; Helmholtz resonator; sound pressure level; suspended coil. ... WSNs, which are supposed to operate for longer period of time. However ... several ambient energies such as wind, thermal, vibration, and solar are ..... textile plants in Northern India with specific reference to noise.

  19. Rice-Fish Culture in China

    International Development Research Centre (IDRC) Digital Library (Canada)

    Bumper harvests of both rice and fish provided more protein, improved ...... and photosynthesizing bacteria are the primary producers and the raw materials used ... 5-cm deep in the booting and earing stages, and about 6-cm deep in the milk ...... of fish have different shapes and feeding habits, fat contents, and distributions.

  20. Area-based management and fishing efficiency

    NARCIS (Netherlands)

    Marchal, P.; Ulrich, C.; Pastoors, M.

    2002-01-01

    The scope of this study is to investigate the extent to which area-based management may have influenced the fishing efficiency of the Danish and Dutch demersal fleets harvesting cod, plaice and sole in the North Sea. Special consideration is given to the `plaice box', a restricted area where fishing

  1. Mercury and nickel contents in fish meat

    Directory of Open Access Journals (Sweden)

    Tomas Toth

    2016-10-01

    Full Text Available The main aim of our work was to identify the content of mercury and nickel in selected fish species. Consumers today are increasingly aware of the association between diet and health, and thus in Europe consume more and more fish. Fish is a valuable source of high quality protein, minerals and vitamins, and fatty fish are also rich in omega-3-polyunsaturated fatty acids, which are normally considered to be beneficial to health. In our work we determined content of mercury and nickel harvested fish in particular were the following species: Common goldfish (Carassius auratus, L., Common roach (Rutilus rutilus, L. and Common bream (Abramis brama, L. Concentrations of mercury and nickel was analyzed and results evaluated according to current standards and compared to the values ​​established by the Codex Alimentarius of the Slovak Republic and the EU Commission Regulation no. 1881/2006, as well as in the EU Commission Regulation no. 420/2011 and no. 269/2008. In our research area we analysed 19 samples of fish muscle. Samples were taken from two water reservoirs – Golianovo and Vráble.  The highest mercury content was in sample Rutilus 1 - 0.052632 mg/kg. Lowest mercury content was in sample Abramis 2  - 0.010431 mg/kg. Largest nickel content was in meat of Abramis  - sample 2  - 0.78 mg/kg. Minimum content of nickel was in sample Carassius 1  - 0.11 mg/kg. We got out of the limit values ​​specified: Codex Alimentarius SR - Mercury 0.5 mg/kg and  Regulation of the EU Commission no. 1881/2006, no. 420/2011 and no. 629/2008. To optimize the protection of the population, it is necessary to continue to monitor the concentration of mercury in fish and fish products. Risk management strategy must focus on reducing potential exposure derived from consumption of fish. In particular, the definition of maximum levels for methylmercury, advising consumers and environmental activities oriented to reduce contamination.

  2. Temporal genetic stability and high effective population size despite fisheries-induced life-history trait evolution in the North Sea sole

    NARCIS (Netherlands)

    Cuveliers, E.L.; Volckaert, F.A.M.; Rijnsdorp, A.D.; Larmuseau, M.H.D.; Maes, G.E.

    2011-01-01

    Heavy fishing and other anthropogenic influences can have profound impact on a species’ resilience to harvesting. Besides the decrease in the census and effective population size, strong declines in mature adults and recruiting individuals may lead to almost irreversible genetic changes in

  3. Multilevel learning in the adaptive management of waterfowl harvests: 20 years and counting

    Science.gov (United States)

    Johnson, Fred A.; Boomer, G. Scott; Williams, Byron K.; Nichols, James D.; Case, David J.

    2015-01-01

    In 1995, the U.S. Fish and Wildlife Service implemented an adaptive harvest management program (AHM) for the sport harvest of midcontinent mallards (Anas platyrhynchos). The program has been successful in reducing long-standing contentiousness in the regulatory process, while integrating science and policy in a coherent, rigorous, and transparent fashion. After 20 years, much has been learned about the relationship among waterfowl populations, their environment, and hunting regulations, with each increment of learning contributing to better management decisions. At the same time, however, much has been changing in the social, institutional, and environmental arenas that provide context for the AHM process. Declines in hunter numbers, competition from more pressing conservation issues, and global-change processes are increasingly challenging waterfowl managers to faithfully reflect the needs and desires of stakeholders, to account for an increasing number of institutional constraints, and to (probabilistically) predict the consequences of regulatory policy in a changing environment. We review the lessons learned from the AHM process so far, and describe emerging challenges and ways in which they may be addressed. We conclude that the practice of AHM has greatly increased an awareness of the roles of social values, trade-offs, and attitudes toward risk in regulatory decision-making. Nevertheless, going forward the waterfowl management community will need to focus not only on the relationships among habitat, harvest, and waterfowl populations, but on the ways in which society values waterfowl and how those values can change over time. 

  4. Data-Limited Population-Status Evaluation of Two Coastal Fishes in Southern Angola Using Recreational Catch Length-Frequency Data.

    Science.gov (United States)

    Beckensteiner, Jennifer; Kaplan, David M; Potts, Warren M; Santos, Carmen V; O'Farrell, Michael R

    2016-01-01

    Excessive truncation of a population's size structure is often identified as an important deleterious effect of exploitation, yet the effect on population persistence of size-structure truncation caused by exploitation is often not quantified due to data limitations. In this study, we estimate changes in eggs per recruit (EPR) using annual length-frequency samples over a 9 year period to assess persistence of the two most important recreational fishes in southern Angola: west coast dusky kob (Argyrosomus coronus) and leerfish (Lichia amia). Using a length- and age-structured model, we improve on an existing method to fit this type of model to length-frequency data and estimate EPR. The objectives of the methodological changes are to add flexibility and robustness to the approach for assessing population status in data-limited situations. Results indicate that dusky kob presents very low levels of EPR (5%-10% of the per recruit reproductive capacity in the absence of fishing) in 2013, whereas large inter-annual variability in leerfish estimates suggest caution must be applied when drawing conclusions about its exploitation status. Using simulated length frequency data with known parameter values, we demonstrate that recruitment decline due to overexploitation leads to overestimation of EPR values. Considering the low levels of EPR estimated for the study species, recruitment limitation is not impossible and true EPR values may be even lower than our estimates. It is, therefore, likely that management action, such as the creation of Marine Protected Areas, is needed to reconstitute the west coast dusky kob population.

  5. Marine reserves and reproductive biomass: a case study of a heavily targeted reef fish.

    Directory of Open Access Journals (Sweden)

    Brett M Taylor

    Full Text Available Recruitment overfishing (the reduction of a spawning stock past a point at which the stock can no longer replenish itself is a common problem which can lead to a rapid and irreversible fishery collapse. Averting this disaster requires maintaining a sufficient spawning population to buffer stochastic fluctuations in recruitment of heavily harvested stocks. Optimal strategies for managing spawner biomass are well developed for temperate systems, yet remain uncertain for tropical fisheries, where the danger of collapse from recruitment overfishing looms largest. In this study, we explored empirically and through modeling, the role of marine reserves in maximizing spawner biomass of a heavily exploited reef fish, Lethrinus harak around Guam, Micronesia. On average, spawner biomass was 16 times higher inside the reserves compared with adjacent fished sites. Adult density and habitat-specific mean fish size were also significantly greater. We used these data in an age-structured population model to explore the effect of several management scenarios on L. harak demography. Under minimum-size limits, unlimited extraction and all rotational-closure scenarios, the model predicts that preferential mortality of larger and older fish prompt dramatic declines in spawner biomass and the proportion of male fish, as well as considerable declines in total abundance. For rotational closures this occurred because of the mismatch between the scales of recovery and extraction. Our results highlight how alternative management scenarios fall short in comparison to marine reserves in preserving reproductively viable fish populations on coral reefs.

  6. Fish allergy: in review.

    Science.gov (United States)

    Sharp, Michael F; Lopata, Andreas L

    2014-06-01

    Globally, the rising consumption of fish and its derivatives, due to its nutritional value and divergence of international cuisines, has led to an increase in reports of adverse reactions to fish. Reactions to fish are not only mediated by the immune system causing allergies, but are often caused by various toxins and parasites including ciguatera and Anisakis. Allergic reactions to fish can be serious and life threatening and children usually do not outgrow this type of food allergy. The route of exposure is not only restricted to ingestion but include manual handling and inhalation of cooking vapors in the domestic and occupational environment. Prevalence rates of self-reported fish allergy range from 0.2 to 2.29 % in the general population, but can reach up to 8 % among fish processing workers. Fish allergy seems to vary with geographical eating habits, type of fish processing, and fish species exposure. The major fish allergen characterized is parvalbumin in addition to several less well-known allergens. This contemporary review discusses interesting and new findings in the area of fish allergy including demographics, novel allergens identified, immunological mechanisms of sensitization, and innovative approaches in diagnosing and managing this life-long disease.

  7. Water-level fluctuations and metapopulation dynamics as drivers of genetic diversity in populations of three Tanganyikan cichlid fish species.

    Science.gov (United States)

    Nevado, B; Mautner, S; Sturmbauer, C; Verheyen, E

    2013-08-01

    Understanding how genetic variation is generated and maintained in natural populations, and how this process unfolds in a changing environment, remains a central issue in biological research. In this work, we analysed patterns of genetic diversity from several populations of three cichlid species from Lake Tanganyika in parallel, using the mitochondrial DNA control region. We sampled populations inhabiting the littoral rocky habitats in both very deep and very shallow areas of the lake. We hypothesized that the former would constitute relatively older, more stable and genetically more diverse populations, because they should have been less severely affected by the well-documented episodes of dramatic water-level fluctuations. In agreement with our predictions, populations of all three species sampled in very shallow shorelines showed traces of stronger population growth than populations of the same species inhabiting deep shorelines. However, contrary to our working hypothesis, we found a significant trend towards increased genetic diversity in the younger, demographically less stable populations inhabiting shallow areas, in comparison with the older and more stable populations inhabiting the deep shorelines. We interpret this finding as the result of the establishment of metapopulation dynamics in the former shorelines, by the frequent perturbation and reshuffling of individuals between populations due to the lake-level fluctuations. The repeated succession of periods of allopatric separation and secondary contact is likely to have further increased the rapid pace of speciation in lacustrine cichlids. © 2013 John Wiley & Sons Ltd.

  8. STUDY OF THE ADAPTATION PROCESS IN COMMON CARP (CYPRINUS CARPIO L.) AFTER HARVESTING

    OpenAIRE

    Milena Bušová; Kristýna Štancelová

    2013-01-01

    Fish is sensitive to exogenous and endogenous ammonia. Ammonia formed in fish as a product of metabolism of proteins may be under certain circumstances life-threatening. Ammonia autointoxication is a serious problem and can cause mass mortalities in fish farms. This study focused on the common carp Cyprinus carpio L. in large-capacity breeding farms. It was focused on monitoring the blood ammonia levels in fish blood in the period of metabolic attenuation and the influence of harvesting and h...

  9. Bundling harvester; Nippukorjausharvesteri

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, K. [Eko-Log Oy, Kuopio (Finland)

    1996-12-31

    The staring point of the project was to design and construct, by taking the silvicultural point of view into account, a harvesting and processing system especially for energy-wood, containing manually driven bundling harvester, automatizing of the harvester, and automatized loading. The equipment forms an ideal method for entrepreneur`s-line harvesting. The target is to apply the system also for owner`s-line harvesting. The profitability of the system promotes the utilization of the system in both cases. The objectives of the project were: to construct a test equipment and prototypes for all the project stages, to carry out terrain and strain tests in order to examine the usability and durability, as well as the capacity of the machine, to test the applicability of the Eko-Log system in simultaneous harvesting of energy and pulp woods, and to start the marketing and manufacturing of the products. The basic problems of the construction of the bundling harvester have been solved using terrain-tests. The prototype machine has been shown to be operable. Loading of the bundles to form sufficiently economically transportable loads has been studied, and simultaneously, the branch-biomass has been tried to be utilized without loosing the profitability of transportation. The results have been promising, and will promote the profitable utilization of wood-energy

  10. Bundling harvester; Nippukorjausharvesteri

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, K [Eko-Log Oy, Kuopio (Finland)

    1997-12-31

    The staring point of the project was to design and construct, by taking the silvicultural point of view into account, a harvesting and processing system especially for energy-wood, containing manually driven bundling harvester, automatizing of the harvester, and automatized loading. The equipment forms an ideal method for entrepreneur`s-line harvesting. The target is to apply the system also for owner`s-line harvesting. The profitability of the system promotes the utilization of the system in both cases. The objectives of the project were: to construct a test equipment and prototypes for all the project stages, to carry out terrain and strain tests in order to examine the usability and durability, as well as the capacity of the machine, to test the applicability of the Eko-Log system in simultaneous harvesting of energy and pulp woods, and to start the marketing and manufacturing of the products. The basic problems of the construction of the bundling harvester have been solved using terrain-tests. The prototype machine has been shown to be operable. Loading of the bundles to form sufficiently economically transportable loads has been studied, and simultaneously, the branch-biomass has been tried to be utilized without loosing the profitability of transportation. The results have been promising, and will promote the profitable utilization of wood-energy

  11. Gendered Disparities in Quality of Cataract Surgery in a Marginalised Population in Pakistan: The Karachi Marine Fishing Communities Eye and General Health Survey.

    Directory of Open Access Journals (Sweden)

    Khabir Ahmad

    Full Text Available Marine fishing communities are among the most marginalised and hard-to-reach groups and have been largely neglected in health research. We examined the quality of cataract surgery and its determinants, with an emphasis on gender, in marine fishing communities in Karachi, Pakistan, using multiple indicators of performance.The Karachi Marine Fishing Communities Eye and General Health Survey was a door-to-door, cross-sectional study conducted between March 2009 and April 2010 in fishing communities living on 7 islands and in coastal areas in Keamari, Karachi, located on the Arabian Sea. A population-based sample of 638 adults, aged ≥ 50 years, was studied. A total of 145 eyes (of 97 persons had undergone cataract surgery in this sample. Cataract surgical outcomes assessed included vision (presenting and best-corrected with a reduced logMAR chart, satisfaction with surgery, astigmatism, and pupil shape. Overall, 65.5% of the operated eyes had some form of visual loss (presenting visual acuity [PVA] < 6/12. 55.2%, 29.0%, and 15.9% of these had good, borderline, and poor visual outcomes based on presenting vision; with best correction, these values were: 68.3 %, 18.6%, and 13.1%, respectively. Of 7 covariates evaluated in the multivariable generalized estimating equations (GEE analyses, gender was the only significant independent predictor of visual outcome. Women's eyes were nearly 4.38 times more likely to have suboptimal visual outcome (PVA<6/18 compared with men's eyes (adjusted odds ratio 4.38, 95% CI 1.96-9.79; P<0.001 after adjusting for the effect of household financial status. A higher proportion of women's than men's eyes had an irregular pupil (26.5% vs. 14.8% or severe/very severe astigmatism (27.5% vs. 18.2%. However, these differences did not reach statistical significance. Overall, more than one fourth (44/144 of cataract surgeries resulted in dissatisfaction. The only significant predictor of satisfaction was visual outcome (P <0

  12. Fish and hydroelectricity

    International Nuclear Information System (INIS)

    Zorpette, G.

    1990-01-01

    This paper reports on the problems that hydroelectric plants have regarding fish populations. The utilities that operate these plants are finding that accommodating migrating fish presents unique engineering challenges, not the least of which involves designing and building systems to protect fish species whose migratory behavior remains something of a mystery. Where such systems cannot be built, the status of hydroelectric dams may be in doubt, as is now the case with several dams in the United States. A further twist in some regions in the possibility that certain migratory fish will be declared threatened or endangered-a development that could wreak havoc on the hydroelectric energy supply in those regions

  13. Energy harvesting for microsystems

    DEFF Research Database (Denmark)

    Xu, Ruichao

    The purpose of this project is to design and fabricate piezoelectric energy harvesters based on integration of Pb(ZrxTi1-x)O3 (PZT) thick film technology and silicon microtechnology. The fabrication processes are carried out in close collaboration with Meggitt Sensing Systems (MSS) who has...... the unique expertise to screen print piezoelectric thick film layers, thus all screen printing steps are done by MSS while the silicon micromachining is carried out at Danchip facility at DTU. The presented energy harvesters are all based on using piezoelectric thick film operating in the 31-mode to generate...... power when strained. Three archetypes of the numerous fabricated energy harvesters will be presented in detail, they represent three major milestones in this project. The first energy harvester archetype has an unimorph cantilever beam, which consists of a 20 µm silicon layer and 10-30 µm screen printed...

  14. Energy harvesting water vehicle

    KAUST Repository

    Singh, Devendra

    2018-01-01

    An efficient energy harvesting (EEH) water vehicle is disclosed. The base of the EEH water vehicle is fabricated with rolling cylindrical drums that can rotate freely in the same direction of the water medium. The drums reduce the drag

  15. Demographic evidence of illegal harvesting of an endangered asian turtle.

    Science.gov (United States)

    Sung, Yik-Hei; Karraker, Nancy E; Hau, Billy C H

    2013-12-01

    Harvesting pressure on Asian freshwater turtles is severe, and dramatic population declines of these turtles are being driven by unsustainable collection for food markets, pet trade, and traditional Chinese medicine. Populations of big-headed turtle (Platysternon megacephalum) have declined substantially across its distribution, particularly in China, because of overcollection. To understand the effects of chronic harvesting pressure on big-headed turtle populations, we examined the effects of illegal harvesting on the demography of populations in Hong Kong, where some populations still exist. We used mark-recapture methods to compare demographic characteristics between sites with harvesting histories and one site in a fully protected area. Sites with a history of illegal turtle harvesting were characterized by the absence of large adults and skewed ratios of juveniles to adults, which may have negative implications for the long-term viability of populations. These sites also had lower densities of adults and smaller adult body sizes than the protected site. Given that populations throughout most of the species' range are heavily harvested and individuals are increasingly difficult to find in mainland China, the illegal collection of turtles from populations in Hong Kong may increase over time. Long-term monitoring of populations is essential to track effects of illegal collection, and increased patrolling is needed to help control illegal harvesting of populations, particularly in national parks. Because few, if any, other completely protected populations remain in the region, our data on an unharvested population of big-headed turtles serve as an important reference for assessing the negative consequences of harvesting on populations of stream turtles. Evidencia Demográfica de la Captura Ilegal de una Tortuga Asiática en Peligro. © 2013 Society for Conservation Biology.

  16. Comparison of outcomes of permanently closed and periodically harvested coral reef reserves.

    Science.gov (United States)

    Bartlett, C Y; Manua, C; Cinner, J; Sutton, S; Jimmy, R; South, R; Nilsson, J; Raina, J

    2009-12-01

    In many areas of the developing world, the establishment of permanent marine reserves is inhibited by cultural norms or socioeconomic pressures. Community conserved areas that are periodically harvested are increasingly being implemented as fisheries management tools, but few researchers have empirically compared them with permanently closed reserves. We used a hierarchical control-impact experimental design to compare the abundance and biomass of reef fishes, invertebrates, and substrate composition in periodically harvested and permanent reserves and in openly fished (control sites) of the South Pacific island country of Vanuatu. Fished species had significantly higher biomass in periodically harvested reserves than in adjacent openly fished areas. We did not detect differences in substratum composition between permanent reserves and openly fished areas or between permanent reserves and periodically harvested reserves. Giant clams (tridacnids) and top shells (Trochus niloticus) were vulnerable to periodic harvest, and we suggest that for adequate management of these species, periodically harvested community conservation areas be used in conjunction with other management strategies. Periodic harvest within reserves is an example of adaptive and flexible management that may meet conservation goals and that is suited to the social, economic, and cultural contexts of many coastal communities in the developing world.

  17. Spatio-temporal dynamics of a fish predator: Density-dependent and hydrographic effects on Baltic Sea cod population.

    Directory of Open Access Journals (Sweden)

    Valerio Bartolino

    Full Text Available Understanding the mechanisms of spatial population dynamics is crucial for the successful management of exploited species and ecosystems. However, the underlying mechanisms of spatial distribution are generally complex due to the concurrent forcing of both density-dependent species interactions and density-independent environmental factors. Despite the high economic value and central ecological importance of cod in the Baltic Sea, the drivers of its spatio-temporal population dynamics have not been analytically investigated so far. In this paper, we used an extensive trawl survey dataset in combination with environmental data to investigate the spatial dynamics of the distribution of the Eastern Baltic cod during the past three decades using Generalized Additive Models. The results showed that adult cod distribution was mainly affected by cod population size, and to a minor degree by small-scale hydrological factors and the extent of suitable reproductive areas. As population size decreases, the cod population concentrates to the southern part of the Baltic Sea, where the preferred more marine environment conditions are encountered. Using the fitted models, we predicted the Baltic cod distribution back to the 1970s and a temporal index of cod spatial occupation was developed. Our study will contribute to the management and conservation of this important resource and of the ecosystem where it occurs, by showing the forces shaping its spatial distribution and therefore the potential response of the population to future exploitation and environmental changes.

  18. Fungi associated with post-harvest deterioration of dried Clarias ...

    African Journals Online (AJOL)

    Fungi associated with post-harvest deterioration of dried Clarias gariepinus vended in some ... Journal of Aquatic Sciences ... Results revealed that fish samples from okpokpo market contained highest number (10) of fungal isolates while samples from Afaha ... Key Words: Mycoflora, isolation, fungi, Fusarium, C. gariepinus ...

  19. Application of fisheries management techniques to assessing impacts: task I report. [Assessment of chemical, radiological, and thermal impacts of nuclear power plants on fish populations

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, D.H.; Baker, K.S.; Fickeisen, D.H.; Metzger, R.M.; Skalski, J.R.

    1979-03-01

    Task I efforts examined the available fisheries management techniques and assessed their potential application in a confirmatory monitoring program. The objective of such monitoring programs is to confirm that the prediction of an insignificant impact (usually made in the FES) was correct. Fisheries resource managers have developed several tools for assessing the fish population response to stress (exploitation) and they were thought potentially useful for detecting nuclear power plant impacts. Techniques in three categories were examined; catch removal, population dynamics, and nondestructive censuses, and the report contains their description, examples of application, advantages, and disadvantages. The techniques applied at nuclear power plant sites were examined in detail to provide information on implementation and variability of specific approaches. The most suitable techniques to incorporate into a monitoring program confirming no impact appear to be those based on Catch Per Unity Effort (CPUE) and hydroacoustic data. In some specific cases, age and growth studies and indirect census techniques may be beneficial. Recommendations for task II efforts to incorporate these techniques into monitoring program designs are presented. These include development of guidelines for; (1) designing and implementing a data collection program; (2) interpreting these data and assessing the occurrence of impact, and (3) establishment of the monitoring program's ability to detect changes in the affected populations.

  20. The Effect of Urban Sprawls on Timber Harvesting

    Science.gov (United States)

    Stephen A. Barlow; Ian A Munn; David A. Cleaves; David L. Evans

    1998-01-01

    In Mississippi and Alabama, urban population growth is pushing development into rural areas. To study the impact of urbanization on timber harvesting, census and forest inventory data were combined in a geographic information system, and a logistic regression model was used to estimate the relationship between several variables and harvest probabilities....

  1. Optimal Spatial Harvesting Strategy and Symmetry-Breaking

    International Nuclear Information System (INIS)

    Kurata, Kazuhiro; Shi Junping

    2008-01-01

    A reaction-diffusion model with logistic growth and constant effort harvesting is considered. By minimizing an intrinsic biological energy function, we obtain an optimal spatial harvesting strategy which will benefit the population the most. The symmetry properties of the optimal strategy are also discussed, and related symmetry preserving and symmetry breaking phenomena are shown with several typical examples of habitats

  2. Economic Evaluation and Overall Assessment of Water Harvesting Ponds based on Scorecard System: A Case Study

    Science.gov (United States)

    Dabral, P. P.; Kumar, Santosh; Kiku, Karmchand

    2017-12-01

    In the present study, an attempt has been made to carry out an economic analysis of three (03) water harvesting ponds situated in the district of Lakhimpur (Assam), India. Economic analysis was carried out using three important economic criteria, namely Benefit Cost Ratio (BCR), Net Present Worth (NPW) and the Internal Rate of Returns (IRR). Ponds of the study area were compared with adopting score card system. All the water harvesting ponds were found economically viable as the BCR was more than unity at 12% discount rate. Net present worth was the highest for the water harvesting pond of Radhapukheri Fish Seed Farm, Department of Fisheries, Govt. of Assam, Narayanpur and the least for water harvesting pond of St. Xavier's School, Harmoti. The IRR was found to be the highest (60%) for water harvesting ponds of St. Xavier's School, Harmoti followed by water harvesting pond of a farmer of Narayanpur (48%) and water harvesting pond of Radhapukheri Fish Seed Farm (19.2%).Water harvesting pond of Radhapukheri Fish Seed Farm, Narayanpur scored the highest score (84 marks) followed by water harvesting pond of a farmer of Narayanpur (80 marks) and St. Xavier's school, Harmoti (61 marks).

  3. Fishing down the largest coral reef fish species.

    Science.gov (United States)

    Fenner, Douglas

    2014-07-15

    Studies on remote, uninhabited, near-pristine reefs have revealed surprisingly large populations of large reef fish. Locations such as the northwestern Hawaiian Islands, northern Marianas Islands, Line Islands, U.S. remote Pacific Islands, Cocos-Keeling Atoll and Chagos archipelago have much higher reef fish biomass than islands and reefs near people. Much of the high biomass of most remote reef fish communities lies in the largest species, such as sharks, bumphead parrots, giant trevally, and humphead wrasse. Some, such as sharks and giant trevally, are apex predators, but others such as bumphead parrots and humphead wrasse, are not. At many locations, decreases in large reef fish species have been attributed to fishing. Fishing is well known to remove the largest fish first, and a quantitative measure of vulnerability to fishing indicates that large reef fish species are much more vulnerable to fishing than small fish. The removal of large reef fish by fishing parallels the extinction of terrestrial megafauna by early humans. However large reef fish have great value for various ecological roles and for reef tourism. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Perceptions of environmental changes and Lethargic crab disease among crab harvesters in a Brazilian coastal community

    Science.gov (United States)

    2011-01-01

    Background Lethargic Crab Disease (LCD) has caused significant mortalities in the population of Ucides cordatus crabs in the Mucuri estuary in Bahia State, Brazil, and has brought social and economic problems to many crab-harvesting communities that depend on this natural resource. The present work examined the perceptions of members of a Brazilian crab harvesting community concerning environmental changes and the Lethargic Crab Disease. Methods Field work was undertaken during the period between January and April/2009, with weekly or biweekly field excursions during which open and semi-structured interviews were held with local residents in the municipality of Mucuri, Bahia State, Brazil. A total of 23 individuals were interviewed, all of whom had at least 20 years of crab-collecting experience in the study region. Key-informants (more experienced crab harvesters) were selected among the interviewees using the "native specialist" criterion. Results According to the collectors, LCD reached the Mucuri mangroves between 2004 and 2005, decimating almost all crab population in the area, and in 2007, 2008 and 2009 high mortalities of U. cordatus were again observed as a result of recurrences of this disease in the region. In addition to LCD, crabs were also suffering great stock reductions due to habitat degradation caused by deforestation, landfills, sewage effluents, domestic and industrial wastes and the introduction of exotic fish in the Mucuri River estuary. The harvesting community was found to have significant ecological knowledge about the functioning of mangrove swamp ecology, the biology of crabs, and the mass mortality that directly affected the economy of this community, and this information was largely in accordance with scientific knowledge. Conclusions The study of traditional knowledge makes it possible to better understand human interactions with the environment and aids in the elaboration of appropriate strategies for natural resource conservation

  5. Perceptions of environmental changes and Lethargic crab disease among crab harvesters in a Brazilian coastal community

    Directory of Open Access Journals (Sweden)

    Firmo Angélica MS

    2011-11-01

    Full Text Available Abstract Background Lethargic Crab Disease (LCD has caused significant mortalities in the population of Ucides cordatus crabs in the Mucuri estuary in Bahia State, Brazil, and has brought social and economic problems to many crab-harvesting communities that depend on this natural resource. The present work examined the perceptions of members of a Brazilian crab harvesting community concerning environmental changes and the Lethargic Crab Disease. Methods Field work was undertaken during the period between January and April/2009, with weekly or biweekly field excursions during which open and semi-structured interviews were held with local residents in the municipality of Mucuri, Bahia State, Brazil. A total of 23 individuals were interviewed, all of whom had at least 20 years of crab-collecting experience in the study region. Key-informants (more experienced crab harvesters were selected among the interviewees using the "native specialist" criterion. Results According to the collectors, LCD reached the Mucuri mangroves between 2004 and 2005, decimating almost all crab population in the area, and in 2007, 2008 and 2009 high mortalities of U. cordatus were again observed as a result of recurrences of this disease in the region. In addition to LCD, crabs were also suffering great stock reductions due to habitat degradation caused by deforestation, landfills, sewage effluents, domestic and industrial wastes and the introduction of exotic fish in the Mucuri River estuary. The harvesting community was found to have significant ecological knowledge about the functioning of mangrove swamp ecology, the biology of crabs, and the mass mortality that directly affected the economy of this community, and this information was largely in accordance with scientific knowledge. Conclusions The study of traditional knowledge makes it possible to better understand human interactions with the environment and aids in the elaboration of appropriate strategies for natural

  6. Perceptions of environmental changes and lethargic crab disease among crab harvesters in a Brazilian coastal community.

    Science.gov (United States)

    Firmo, Angélica M S; Tognella, Mônica M P; Có, Walter L O; Barboza, Raynner R D; Alves, Rômulo R N

    2011-11-16

    Lethargic Crab Disease (LCD) has caused significant mortalities in the population of Ucides cordatus crabs in the Mucuri estuary in Bahia State, Brazil, and has brought social and economic problems to many crab-harvesting communities that depend on this natural resource. The present work examined the perceptions of members of a Brazilian crab harvesting community concerning environmental changes and the Lethargic Crab Disease. Field work was undertaken during the period between January and April/2009, with weekly or biweekly field excursions during which open and semi-structured interviews were held with local residents in the municipality of Mucuri, Bahia State, Brazil. A total of 23 individuals were interviewed, all of whom had at least 20 years of crab-collecting experience in the study region. Key-informants (more experienced crab harvesters) were selected among the interviewees using the "native specialist" criterion. According to the collectors, LCD reached the Mucuri mangroves between 2004 and 2005, decimating almost all crab population in the area, and in 2007, 2008 and 2009 high mortalities of U. cordatus were again observed as a result of recurrences of this disease in the region. In addition to LCD, crabs were also suffering great stock reductions due to habitat degradation caused by deforestation, landfills, sewage effluents, domestic and industrial wastes and the introduction of exotic fish in the Mucuri River estuary. The harvesting community was found to have significant ecological knowledge about the functioning of mangrove swamp ecology, the biology of crabs, and the mass mortality that directly affected the economy of this community, and this information was largely in accordance with scientific knowledge. The study of traditional knowledge makes it possible to better understand human interactions with the environment and aids in the elaboration of appropriate strategies for natural resource conservation.

  7. Post-harvest Proteomics and Food Security

    NARCIS (Netherlands)

    Pedreschi Plasencia, R.P.; Lurie, S.; Hertog, W.; Nicolai, B.; Mes, J.J.; Woltering, E.J.

    2013-01-01

    To guarantee sufficient food supply for a growing world population, efforts towards improving crop yield and plant resistance should be complemented with efforts to reduce postharvest losses. Post-harvest losses are substantial and occur at different stages of the food chain in developed and

  8. Firewood use in Bulamogi County, Uganda: species selection, harvesting and consumption patterns

    International Nuclear Information System (INIS)

    Tabuti, J.R.S.; Dhillion, S.S.; Lye, K.A.

    2003-01-01

    This study was carried out in Bulamogi, Uganda, with the main objective of determining preferred firewood species, their harvesting and consumption patterns. Data collected through household and key-informants interviews, using open- and close-ended questionnaires and semi-structured interviews, showed that 48 plant species in 36 genera and 20 families are used as firewood. These plants have other uses as herbal medicines and in traditional cultural rites. There is almost total dependence on firewood for domestic cooking and small-scale industries. Firewood is used to fire bricks (55%), distil spirits (26%), cure fish (10%), cook food in restaurants (6%) and to produce charcoal (3%). Firewood for domestic use is collected mainly by women, and largely comprises of dead wood. The distances travelled to firewood collection areas are short and little time is spent. The harvesting of firewood for domestic use may have a lower direct impact on the native flora, than the harvesting of fuelwood for commercial use by small-scale industries and to make charcoal, which requires large amounts of wood that is often green. According to the community response, firewood is abundant but declining. This decline may be related to increasing demands generated by the growing human population of Bulamogi, and growing national need for charcoal. Cultural taboos that have hitherto played an important role in plant conservation appear to be weakening. There is limited trading of firewood in the community. (author)

  9. Emerging viral diseases of fish and shrimp

    Science.gov (United States)

    Winton, James R.; Walker, Peter J.

    2010-01-01

    The rise of aquaculture has been one of the most profound changes in global food production of the past 100 years. Driven by population growth, rising demand for seafood and a levelling of production from capture fisheries, the practice of farming aquatic animals has expanded rapidly to become a major global industry. Aquaculture is now integral to the economies of many countries. It has provided employment and been a major driver of socio-economic development in poor rural and coastal communities, particularly in Asia, and has relieved pressure on the sustainability of the natural harvest from our rivers, lakes and oceans. However, the rapid growth of aquaculture has also been the source of anthropogenic change on a massive scale. Aquatic animals have been displaced from their natural environment, cultured in high density, exposed to environmental stress, provided artificial or unnatural feeds, and a prolific global trade has developed in both live aquatic animals and their products. At the same time, over-exploitation of fisheries and anthropogenic stress on aquatic ecosystems has placed pressure on wild fish populations. Not surprisingly, the consequence has been the emergence and spread of an increasing array of new diseases. This review examines the rise and characteristics of aquaculture, the major viral pathogens of fish and shrimp and their impacts, and the particular characteristics of disease emergence in an aquatic, rather than terrestrial, context. It also considers the potential for future disease emergence in aquatic animals as aquaculture continues to expand and faces the challenges presented by climate change.

  10. Puerto Rico Commercial Fishermen Census (2008): This dataset contains demographic, fishing practices and fishing boat and gear data about the population of active commercial fishermen in Puerto Rico (CRCP).

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data contains information on demographics, fishing practices and vessel gear characteristics of Puerto Rican commercial fishermen

  11. Fish Allergy

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Fish Allergy KidsHealth / For Parents / Fish Allergy What's in this ... Print en español Alergia al pescado About Fish Allergy A fish allergy is not exactly the same ...

  12. Lessons learned from practical approaches to reconcile mismatches between biological population structure and stock units of marine fish

    NARCIS (Netherlands)

    Kerr, Lisa A.; Hintzen, Niels T.; Cadrin, Steven X.; Clausen, Lotte Worsøe; Dickey-Collas, Mark; Goethel, Daniel R.; Hatfield, Emma M.C.; Kritzer, Jacob P.; Nash, Richard D.M.

    2016-01-01

    Recent advances in the application of stock identification methods have revealed inconsistencies between the spatial structure of biological populations and the definition of stock units used in assessment and management. From a fisheries management perspective, stocks are typically assumed to be

  13. Evolutionary mechanisms shaping the genetic population structure of marine fishes; lessons from the European flounder ( Platichthys flesus L.)

    DEFF Research Database (Denmark)

    Hansen, Jakob Hemmer; Eg Nielsen, Einar; Grønkjær, P.

    2007-01-01

    with the extreme isolation of the island population at the Faroe Islands. A sharp genetic break was associated with a change in life history from pelagic to benthic spawners in the Baltic Sea. Partial Mantel tests showed that geographical distance per se was not related with genetic structuring among Atlantic...

  14. Strong population genetic structuring in an annual fish, Nothobranchius furzeri, suggests multiple savannah refugia in southern Mozambique

    Czech Academy of Sciences Publication Activity Database

    Bartáková, V.; Reichard, M.; Janko, Karel; Polačik, M.; Blažek, R.; Reichwald, K.; Cellerino, A.; Bryja, J.

    2013-01-01

    Roč. 13, č. 196 (2013), s. 1-15 ISSN 1471-2148 Institutional support: RVO:67985904 Keywords : temporary pool * pyhlogeography * population genetics Subject RIV: EG - Zoology Impact factor: 3.407, year: 2013 http://www.biomedcentral.com/1471-2148/13/196

  15. Fishing effects on energy use by North Sea fishes

    NARCIS (Netherlands)

    Jennings, S.; Hal, van R.; Hiddink, J.G.; Maxwell, T.A.D.

    2008-01-01

    Fishing affects patterns of energy use in fish populations, as demonstrated by changes in population energy consumption and the size and age when energy demands are greatest. We compare theoretical predictions and observed patterns of energy use (expressed as the primary production required to

  16. Status and perspectives of fish industry of Azerbaijan in conditions of increased oil and gas extraction in the Caspian Sea

    International Nuclear Information System (INIS)

    Gadjiev, R.V; Kasimov, R.Yu; Akhundov, M.M; Karaev, A.I.

    2002-01-01

    Full text:The Caspian Sea plays important role in supply of the population of Azerbaijan Republic with fish products. Furthermore, the Caspian Sea is the single pond where more than 70% of sturgeons are harvested all over the world. Besides, more than 80% of the big bony fishes harvested in the ponds of Azerbaijan, are caught in the Caspian Sea. On the other hand, the entrails of the Caspian Sea contain tremendous amounts of oil and gas deposits whose extraction disturbs partially the ecological equilibrium in this unique pond. It should be noticed that since 1973-1974 the increase of sturgeon harvest was observed. The special scientific Institute of Fish Industry in Astrakhan city with its branch in Azerbaijan was founded. In the same years top amount of oil was extracted in the Caspian Sea and simultaneously high pollution level of the sea with oil and oil products, having been clearly seen in the Sea-attached Boulevard, was fixed. However, in spite of these unfavorable conditions, the sturgeon harvests, due to their reproduction in the hatcheries and following release into the sea, increased not only in Azerbaijan, but also all over the whole Caspian Sea basin. It is impossible to keep serenity today owing to the fact that broadening of oil extraction in the Caspian Sea for new deposits are situated near to the fattening areas of juveniles of valuable fish species, in the estuary of the Kura river and other small rivers where sex-mature fishes migrate. Besides, the migration ways of sturgeons the North origin pass through these zones: in autumn- from the North to the South, while in early and middle spring- in opposite direction

  17. Water harvest via dewing.

    Science.gov (United States)

    Lee, Anna; Moon, Myoung-Woon; Lim, Hyuneui; Kim, Wan-Doo; Kim, Ho-Young

    2012-07-10

    Harvesting water from humid air via dewing can provide a viable solution to a water shortage problem where liquid-phase water is not available. Here we experimentally quantify the effects of wettability and geometry of the condensation substrate on the water harvest efficiency. Uniformly hydrophilic surfaces are found to exhibit higher rates of water condensation and collection than surfaces with lower wettability. This is in contrast to a fog basking method where the most efficient surface consists of hydrophilic islands surrounded by hydrophobic background. A thin drainage path in the lower portion of the condensation substrate is revealed to greatly enhance the water collection efficiency. The optimal surface conditions found in this work can be used to design a practical device that harvests water as its biological counterpart, a green tree frog, Litoria caerulea , does during the dry season in tropical northern Australia.

  18. What is the carrying capacity for fish in the ocean? A meta analysis of population dynamics of North Atlantic cod

    DEFF Research Database (Denmark)

    Myers, R.A.; MacKenzie, Brian; Bowen, K.G.

    2001-01-01

    used empirical Bayes techniques to estimate the maximum reproductive rate and carrying capacity of each stock. In all cases, the empirical Bayes estimates were biologically reasonable, whereas a stock by stock analysis occasionally yielded nonsensical parameter estimates (e.g., infinite values). Our...... analysis showed that the carrying capacity per unit area varied by more than 20-fold among populations and that much of this variation was related to temperature. That is, the carrying capacity per square kilometre declines as temperature increases....

  19. Assessing power plant impacts on fish populations at Northeast Utilities sites: winter flounder studies at Millstone Nuclear Power Station

    International Nuclear Information System (INIS)

    Lorda, E.; Danila, D.J.; Miller, J.D.; Bireley, L.E.; Jacobsen, P.M.

    1987-01-01

    An historical view is presented of the various impact assessment approaches used to study the winter flounder, including efforts to identify and quantify compensation and to model its population dynamics. This review illustrates the need for unbiased estimates of basic life history parameters and power plant related mortalities if compensatory mechanisms are to be understood and if impact assessments are to be meaningful. 67 references, 19 figures, 10 tables

  20. Locally adapted fish populations maintain small-scale genetic differentiation despite perturbation by a catastrophic flood event.

    Science.gov (United States)

    Plath, Martin; Hermann, Bernd; Schröder, Christiane; Riesch, Rüdiger; Tobler, Michael; García de León, Francisco J; Schlupp, Ingo; Tiedemann, Ralph

    2010-08-23

    Local adaptation to divergent environmental conditions can promote population genetic differentiation even in the absence of geographic barriers and hence, lead to speciation. Perturbations by catastrophic events, however, can distort such parapatric ecological speciation processes. Here, we asked whether an exceptionally strong flood led to homogenization of gene pools among locally adapted populations of the Atlantic molly (Poecilia mexicana, Poeciliidae) in the Cueva del Azufre system in southern Mexico, where two strong environmental selection factors (darkness within caves and/or presence of toxic H2S in sulfidic springs) drive the diversification of P. mexicana. Nine nuclear microsatellites as well as heritable female life history traits (both as a proxy for quantitative genetics and for trait divergence) were used as markers to compare genetic differentiation, genetic diversity, and especially population mixing (immigration and emigration) before and after the flood. Habitat type (i.e., non-sulfidic surface, sulfidic surface, or sulfidic cave), but not geographic distance was the major predictor of genetic differentiation. Before and after the flood, each habitat type harbored a genetically distinct population. Only a weak signal of individual dislocation among ecologically divergent habitat types was uncovered (with the exception of slightly increased dislocation from the Cueva del Azufre into the sulfidic creek, El Azufre). By contrast, several lines of evidence are indicative of increased flood-induced dislocation within the same habitat type, e.g., between different cave chambers of the Cueva del Azufre. The virtual absence of individual dislocation among ecologically different habitat types indicates strong natural selection against migrants. Thus, our current study exemplifies that ecological speciation in this and other systems, in which extreme environmental factors drive speciation, may be little affected by temporary perturbations, as adaptations

  1. Strong population genetic structuring in an annual fish, Nothobranchius furzeri, suggests multiple savannah refugia in southern Mozambique

    Czech Academy of Sciences Publication Activity Database

    Bartáková, Veronika; Reichard, Martin; Janko, Karel; Polačik, Matej; Blažek, Radim; Reichwald, K.; Cellerino, A.; Bryja, Josef

    2013-01-01

    Roč. 13, č. 196 (2013), s. 196 ISSN 1471-2148 R&D Projects: GA ČR GA206/09/0815; GA ČR GBP505/12/G112 Institutional support: RVO:68081766 Keywords : Temporary pool * Phylogeography * Population genetics * Cyprinodontiformes * Senescence * Pluvials * Pleistocene climate changes * Dispersal * Founder effect * Killifish Subject RIV: EG - Zoology Impact factor: 3.407, year: 2013 http://www.biomedcentral.com/1471-2148/13/196

  2. Factors influencing reporting and harvest probabilities in North American geese

    Science.gov (United States)

    Zimmerman, G.S.; Moser, T.J.; Kendall, W.L.; Doherty, P.F.; White, Gary C.; Caswell, D.F.

    2009-01-01

    We assessed variation in reporting probabilities of standard bands among species, populations, harvest locations, and size classes of North American geese to enable estimation of unbiased harvest probabilities. We included reward (US10,20,30,50, or100) and control (0) banded geese from 16 recognized goose populations of 4 species: Canada (Branta canadensis), cackling (B. hutchinsii), Ross's (Chen rossii), and snow geese (C. caerulescens). We incorporated spatially explicit direct recoveries and live recaptures into a multinomial model to estimate reporting, harvest, and band-retention probabilities. We compared various models for estimating harvest probabilities at country (United States vs. Canada), flyway (5 administrative regions), and harvest area (i.e., flyways divided into northern and southern sections) scales. Mean reporting probability of standard bands was 0.73 (95 CI 0.690.77). Point estimates of reporting probabilities for goose populations or spatial units varied from 0.52 to 0.93, but confidence intervals for individual estimates overlapped and model selection indicated that models with species, population, or spatial effects were less parsimonious than those without these effects. Our estimates were similar to recently reported estimates for mallards (Anas platyrhynchos). We provide current harvest probability estimates for these populations using our direct measures of reporting probability, improving the accuracy of previous estimates obtained from recovery probabilities alone. Goose managers and researchers throughout North America can use our reporting probabilities to correct recovery probabilities estimated from standard banding operations for deriving spatially explicit harvest probabilities.

  3. Imprudent fishing harvests and consequent trophic cascades on the West Florida shelf over the last half century: A harbinger of increased human deaths from paralytic shellfish poisoning along the southeastern United States, in response to oligotrophication?

    Science.gov (United States)

    Walsh, J. J.; Tomas, C. R.; Steidinger, K. A.; Lenes, J. M.; Chen, F. R.; Weisberg, R. H.; Zheng, L.; Landsberg, J. H.; Vargo, G. A.; Heil, C. A.

    2011-06-01

    Within the context of ubiquitous overfishing of piscivores, recent consequent increments of jellyfish and clupeids have occurred at the zooplanktivore trophic level in the eastern Gulf of Mexico (GOM), after overfishing of one of their predators, i.e. red snapper. Initiation of a local trophic cascade thence led to declines of herbivore stocks, documented here on the West Florida shelf. These exacerbating world-wide trophic cascades have resulted in larger harmful algal blooms (HABs), already present at the base of most coastal food webs. Impacts on human health have thus far been minimal within nutrient-rich coastal regions. To provide a setting for past morbidities, consideration is given to chronologies of other trophic cascades within eutrophic, cold water marine ecosystems of the Scotian Sea, in the Gulf of Alaska, off Southwest Africa, within the Barents, White, and Black Seas, in the Gulf of Maine, and finally in the North Sea. Next, comparison is now made here of recent ten-fold increments within Florida waters of both relatively benign and saxitoxic HABs, some of which are fatal to humans. These events are placed in a perspective of other warm shelf systems of the South China and Caribbean Seas to assess prior and possible future poison toxicities of oligotrophic coastal habitats. Past wide-spread kills of fishes and sea urchins over the Caribbean Sea and the downstream GOM are examined in relation to the potential transmission of dinoflagellate saxitoxin and other epizootic poison vectors by western boundary currents over larger "commons" than local embayments. Furthermore, since some HABs produce more potent saxitoxins upon nutrient depletion, recent decisions to ban seasonal fertilizer applications to Florida lawns may have unintended consequences. In the future, human-killing phytoplankton, rather than relatively benign fish-killing HABs of the past, may be dispersed along the southeastern United States seaboard.

  4. Energy harvesting for microsystems

    Energy Technology Data Exchange (ETDEWEB)

    Ruichao Xu

    2012-05-15

    The purpose of this project is to design and fabricate piezoelectric energy harvesters based on integration of Pb(ZrxTi1-x)O3 (PZT) thick film technology and silicon microtechnology. The fabrication processes are carried out in close collaboration with Meggitt Sensing Systems (MSS) who has the unique expertise to screen print piezoelectric thick film layers, thus all screen printing steps are done by MSS while the silicon micromachining is carried out at Danchip facility at DTU. The presented energy harvesters are all based on using piezoelectric thick film operating in the 31-mode to generate power when strained. Three archetypes of the numerous fabricated energy harvesters will be presented in detail, they represent three major milestones in this project. The first energy harvester archetype has an unimorph cantilever beam, which consists of a 20 {mu}m silicon layer and 10-30 {mu}m screen printed PZT layer, anchored on a silicon frame at one end and attached to a silicon proof mass at the other. Electrodes will cover both side of the PZT layer, so the harvested energy can be collected electrically. The second archetype has a bimorph cantilever beam, which consists of two 15-35 {mu}m PZT layers, anchored on a silicon frame at the one end and attached to a silicon proof mass at the other. Electrodes are deposited below, between and above the two PZT layers. The root mean square (RMS) power output measured on this type of harvesters is as high as 37.1{mu}W at 1 g. The third archetype is similar to the first one, the screen printed PZT layer is replaced by a lead free piezoelectric material, (KxNa1-x)NbO3 (KNN). Some of the major challenges encountered during the development processes are bad adhesion, fragile structures and short circuiting through the PZT layer. All of which have being fully or partially solved in this project. The final energy harvesters are designed to be used in an energy harvester powered wireless sensing system. (Author)

  5. Genetic population structure of turbot ( Scophthalmus maximus L.) supports the presence of multiple hybrid zones for marine fishes in the transition zone between the Baltic Sea and the North Sea

    DEFF Research Database (Denmark)

    Eg Nielsen, Einar; Nielsen, P.H.; Meldrup, Dorte

    2004-01-01

    Sea, suggesting high gene flow among populations in these areas. In contrast, there was a sharp cline in genetic differentiation going from the low saline Baltic Sea to the high saline North Sea. The data were explained best by two divergent populations connected by a hybrid zone; however......, a mechanical mixing model could not be ruled out. A significant part of the genetic variance could be ascribed to variation among years within locality. Nevertheless, the population structure was relatively stable over time, suggesting that the observed pattern of genetic differentiation is biologically...... significant. This study suggests that hybrid zones are a common phenomenon for marine fishes in the transition area between the North Sea and the Baltic Sea and highlights the importance of using interspecific comparisons for inferring population structure in high gene flow species such as most marine fishes....

  6. Climate Change and Genetic Structure of Leading Edge and Rear End Populations in a Northwards Shifting Marine Fish Species, the Corkwing Wrasse (Symphodus melops).

    Science.gov (United States)

    Knutsen, Halvor; Jorde, Per Erik; Gonzalez, Enrique Blanco; Robalo, Joana; Albretsen, Jon; Almada, Vitor

    2013-01-01

    One mechanism by which marine organisms may respond to climate shifts is range shifts. The corkwing wrasse (Symphodus melops) is a temperate fish species, inhabiting the coasts of Europe, that show strong indications of current as well as historical (ice-age) range shifts towards the north. Nine neutral microsatellite DNA markers were screened to study genetic signatures and spatial population structure over the entire geographic and thermal gradient of the species from Portugal to Norway. A major genetic break (F ST  = 0.159 average among pairs) was identified between Scandinavian and more southern populations, with a marked reduction (30% or more) in levels of genetic variability in Scandinavia. The break is probably related to bottleneck(s) associated with post-glacial colonization of the Scandinavian coasts, and indicates a lack of present gene flow across the North Sea. The lack of gene flow can most likely be attributed to the species' need for rocky substrate for nesting and a relatively short pelagic larval phase, limiting dispersal by ocean currents. These findings demonstrate that long-distance dispersal may be severely limited in the corkwing wrasse, and that successful range-shifts following present climate change may be problematic for this and other species with limited dispersal abilities, even in the seemingly continuous marine environment.

  7. Harvesting heterogeneous renewable resources: uncoordinated, selfish, team-, and community-oriented strategies

    NARCIS (Netherlands)

    Brede, M.; de Vries, H.J.M.|info:eu-repo/dai/nl/068361599

    2009-01-01

    Using the example of a fishing fleet harvesting in different fishing zones with different carrying capacities and growth rates, we investigate strategies for the exploitation of distributed renewable resources by a crowd of agents without centralized coordination. In agent-based simulations we

  8. The nexus of fun and nutrition: Recreational fishing is also about food

    Science.gov (United States)

    Cooke, Steven J.; Twardek, William M.; Lennox, Robert J.; Zolderdo, Aaron J.; Bower, Shannon D.; Gutowsky, Lee F. G.; Danylchuk, Andy J.; Arlinghaus, Robert; Beard, Douglas

    2017-01-01

    Recreational fishing is a popular activity in aquatic ecosystems around the globe using a variety of gears including rod and line and to a lesser extent handlines, spears, bow and arrow, traps and nets. Similar to the propensity to engage in voluntary catch-and-release, the propensity to harvest fishes strongly varies among cultures, locations, species and fisheries. There is a misconception that because recreational fishing happens during non-work (i.e. leisure) time, the nutritional motivation is negligible; therefore, the role of recreational fishing in supporting nutrition (and thus food security) at regional, national or global scales is underappreciated. We consider the factors that influence whether fish will be harvested or released by examining the motives that underlie recreational fishing. Next, we provide an overview of the magnitude and role of recreational fishing harvest in supporting nutrition using regional case-studies. Then, we address issues such as contaminants and parasites that constrain the ability of fish harvested by recreational fishers to be consumed. Although recreational fishing is foremost a leisure activity, the harvest of fish for personal consumption by recreational fishers has contributed and will continue to contribute to human nutrition by providing an accessible, affordable and generally highly sustainable food source, notwithstanding concerns about food safety and possibly overfishing. Attempts to better quantify the role of fish harvested by recreational fishers and the relative contribution to overall food security and personal nutrition will provide resource managers and policymakers the information needed to guide management activities and policy development.

  9. Fish allergy and fish allergens

    DEFF Research Database (Denmark)

    Kuehn, A; Hilger, Christiane; Ollert, Markus

    2016-01-01

    Fish is one of the main elicitors for food allergies. For a long time, the clinical picture of fish allergy was reduced to the following features. First, fish-allergic patients suffer from a high IgE cross-reactivity among fishes so that they have to avoid all species. Second, clinically relevant...... symptoms are linked to the presence of IgE-antibodies recognizing parvalbumin, the fish panallergen. This view was challenged by results from recent studies as follows. 1. Allergic reactions which are limited to single or several fish species (mono-or oligosensitisations) apply not only to single cases...... but patients with this phenotype constitute an important sub-group among fish-allergic individuals. 2. Newly identified fish allergens, enolases, aldolases, and fish gelatin, are of high relevance as the majority of the fish-allergic individuals seem to develop specific IgE against these proteins. The present...

  10. Annual survival rate estimate of satellite transmitter–marked eastern population greater sandhill cranes

    Science.gov (United States)

    Fronczak, David L.; Andersen, David E.; Hanna, Everett E.; Cooper, Thomas R.

    2015-01-01

    Several surveys have documented the increasing population size and geographic distribution of Eastern Population greater sandhill cranes Grus canadensis tabida since the 1960s. Sport hunting of this population of sandhill cranes started in 2012 following the provisions of the Eastern Population Sandhill Crane Management Plan. However, there are currently no published estimates of Eastern Population sandhill crane survival rate that can be used to inform harvest management. As part of two studies of Eastern Population sandhill crane migration, we deployed solar-powered global positioning system platform transmitting terminals on Eastern Population sandhill cranes (n  =  42) at key concentration areas from 2009 to 2012. We estimated an annual survival rate for Eastern Population sandhill cranes from data resulting from monitoring these cranes by using the known-fates model in the MARK program. Estimated annual survival rate for adult Eastern Population sandhill cranes was 0.950 (95% confidence interval  =  0.885–0.979) during December 2009–August 2014. All fatalities (n  =  5) occurred after spring migration in late spring and early summer. We were unable to determine cause of death for crane fatalities in our study. Our survival rate estimate will be useful when combined with other population parameters such as the population index derived from the U.S. Fish and Wildlife Service fall survey, harvest, and recruitment rates to assess the effects of harvest on population size and trend and evaluate the effectiveness of management strategies.

  11. Area-based management and fishing efficiency

    DEFF Research Database (Denmark)

    Marchal, P.; Ulrich, Clara; Pastoors, M.

    2002-01-01

    The scope of this study is to investigate the extent to which area-based management may have influenced the fishing efficiency of the Danish and Dutch demersal fleets harvesting cod, plaice and sole in the North Sea. Special consideration is given to the 'plaice box', a restricted area where...... fishing is prohibited to towed-gear fleets of horsepower exceeding 300 hp. An index of fishing power is calculated as the log-ratio between the catch per unit effort (CPUE) of any vessel and some survey abundance index. Annual trends in fishing are calculated as the year-effect derived from a general...... linear model (GLM) analysis of the index of fishing power. The fishing efficiency of Danish gill-netters and, to some extent, Danish seiners, has overall increased inside the 'plaice box', whilst remaining relatively stable outside. However, the fishing efficiency of the other exemption fleets has...

  12. Simulation of socio-ecological impacts: Modeling a fishing village

    Science.gov (United States)

    Miller, Philip C.

    1982-03-01

    The interrelationship of society and environment is addressed here through the study of a remote fishing village of 750 people. An interdisciplinary study evaluated demographic, economic, and social aspects of the community, and simulation modeling was used to integrate these societal characteristics with environmental factors. The population of the village had grown gradually until the 1960's, when a decline began. Out-migration correlated with declining fish harvests and with increased communications with urban centers. Fishing had provided the greatest economic opportunity, followed by logging. A survey was conducted to investigate the costs and revenues of village fishermen. Diversification characterized the local fleet, and analysis showed that rates of return on investment in the current year were equal between vessel types. The variable levels and rate parameters of the demographic, economic, and social components of the model were specified through static and time series data. Sensitivity analysis to assess the effects of uncertainty, and validation tests against known historical changes were also conducted. Forecast scenarios identified the development options under several levels of fish abundance and investment. The weight given to ecological versus economic resource management registered disproportionate effects due to the interaction between investment and migration rates and resource stochasticity. This finding argues against a “golden mean” rule for evaluating policy trade-offs and argues for the importance of using a dynamic, socio-ecological perspective in designing development policies for rural communities.

  13. Combine Harvester Simulator

    DEFF Research Database (Denmark)

    Vilmann, Ole; Sørlie, James Arnold

    1999-01-01

    A simulator for training pilots in the operation of a modern high-tech combine harvester is presented. The new simulator application is based on DMI´s well-known DMS maritime simulator architecture. Two major challenges have been encountered in the development of the simulator: 1) interfacing the...

  14. Harvesting soil with potatoes

    DEFF Research Database (Denmark)

    Egelyng, Henrik

    2017-01-01

    Norwegian authorities demand soil leaving potato packing plants to be deposited as waste. Depositing soil from potato processing plants is associated with significant cost for Norwegian producers. Therefore CYCLE investigated potato soil harvesting from an innovation and socio-economic perspective....

  15. Evolution of boldness and life-history in response to selective harvesting

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Marty, Lise; Arlinghaus, Robert

    2018-01-01

    Whether intensive harvesting alters the behavioral repertoire of exploited fishes is currently unknown, but plausible. We extend a fish life-history model to account for boldness as a personality trait that affects foraging intensity, which affects energy intake and risk from predation and fishing...... gear. We systematically investigate life-history and behavioral trait evolution along the boldness–timidity axis in response to the full range of common selectivity and exploitation patterns in fisheries. In agreement with previous studies, we find that any type of harvesting selects for fast life...... histories and that merely elevated, yet unselective, fishing mortality favors boldness. We also find that timid-selective fishing (which can be expected in species targeted by active gear types) selects for increased boldness. By contrast, increased timidity is predicted when fishing targets bolder...

  16. Rooftop level rainwater harvesting system

    Science.gov (United States)

    Traboulsi, Hayssam; Traboulsi, Marwa

    2017-05-01

    Unfortunately, in Lebanon and other countries in the Middle East region, water becomes scarcer than ever before, and over the last decades the demand on domestic water has increased due to population and economic growth. Although rainwater harvesting is considered to be a safe and reliable alternative source for domestic water, the inconvenience or impracticalities related to the cost and space needed for the construction of ground or underground storage tanks makes this practice not widely common in rural areas and rarely implemented in urban cities. This paper introduces a new technique to rainwater harvesting which can be easily used in both rural and urban areas: it collects and stores rainwater directly in tanks already installed on building roofs and not necessarily in special ground or underground ones. If widely adopted in Lebanon, this technique could help in: (1) collecting around 23 MCM (70 % of the current deficit in the domestic water supply) of rainwater and thus increasing the available water per m2 of building by 0.4 m3 per year, (2) saving around 7 % of the amount of electric energy usually needed to pump water from an aquifer well and ground or underground tank, and (3) considerably reducing the rate of surface runoff of rainwater at the coastal zones where rainwater is not captured at all and goes directly to the sea.

  17. Designing A General Deep Web Harvester by Harvestability Factor

    NARCIS (Netherlands)

    Khelghati, Mohammadreza; van Keulen, Maurice; Hiemstra, Djoerd

    2014-01-01

    To make deep web data accessible, harvesters have a crucial role. Targeting different domains and websites enhances the need of a general-purpose harvester which can be applied to different settings and situations. To develop such a harvester, a large number of issues should be addressed. To have

  18. Estimating recreational harvest using interview-based recall survey: Implication of recalling in weight or numbers

    DEFF Research Database (Denmark)

    Sparrevohn, Claus Reedtz

    2013-01-01

    on interviewed-based surveys where fishers are asked to recall harvest within a given timeframe. However, the importance of whether fishers are requested to provide figures in weight or number is unresolved. Therefore, a recall survey aiming at estimating recreational harvest was designed, such that respondents...... could report harvest using either weight or numbers. It was found that: (1) a preference for reporting in numbers dominated; (2) reported mean individual weight of fish caught, differed between units preferences; and (3) when an estimate of total harvest in weight are calculated, these difference could...

  19. Satellite telemetry reveals higher fishing mortality rates than previously estimated, suggesting overfishing of an apex marine predator.

    Science.gov (United States)

    Byrne, Michael E; Cortés, Enric; Vaudo, Jeremy J; Harvey, Guy C McN; Sampson, Mark; Wetherbee, Bradley M; Shivji, Mahmood

    2017-08-16

    Overfishing is a primary cause of population declines for many shark species of conservation concern. However, means of obtaining information on fishery interactions and mortality, necessary for the development of successful conservation strategies, are often fisheries-dependent and of questionable quality for many species of commercially exploited pelagic sharks. We used satellite telemetry as a fisheries-independent tool to document fisheries interactions, and quantify fishing mortality of the highly migratory shortfin mako shark ( Isurus oxyrinchus ) in the western North Atlantic Ocean. Forty satellite-tagged shortfin mako sharks tracked over 3 years entered the Exclusive Economic Zones of 19 countries and were harvested in fisheries of five countries, with 30% of tagged sharks harvested. Our tagging-derived estimates of instantaneous fishing mortality rates ( F = 0.19-0.56) were 10-fold higher than previous estimates from fisheries-dependent data (approx. 0.015-0.024), suggesting data used in stock assessments may considerably underestimate fishing mortality. Additionally, our estimates of F were greater than those associated with maximum sustainable yield, suggesting a state of overfishing. This information has direct application to evaluations of stock status and for effective management of populations, and thus satellite tagging studies have potential to provide more accurate estimates of fishing mortality and survival than traditional fisheries-dependent methodology. © 2017 The Author(s).

  20. Magnetic Nanocomposite Cilia Energy Harvester

    KAUST Repository

    Khan, Mohammed Asadullah; Alfadhel, Ahmed; Kosel, Jü rgen

    2016-01-01

    An energy harvester capable of converting low frequency vibrations into electrical energy is presented. The operating principle, fabrication process and output characteristics at different frequencies are discussed. The harvester is realized

  1. 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

  2. Diet, reproduction and population structure of the introduced Amazonian fish Cichla piquiti (Perciformes: Cichlidae in the Cachoeira Dourada reservoir (Paranaíba River, central Brazil

    Directory of Open Access Journals (Sweden)

    Tatiane Ferraz Luiz

    2011-06-01

    Full Text Available The Blue Peacock Bass (Cichla piquiti, native to the Tocantins-Araguaia river basin of the Amazon system, was introduced into the basin of the Paranaíba River, Paraná River system. Cachoeira Dourada reservoir is one of a series of dams on the Paranaíba River in central Brazil, where this fish has become established. A study of its feeding spectrum, combined with information about its reproductive characteristics and population structure, would enable the current state of this species in the reservoir to be assessed and might provide useful data for the management of other species native to this habitat. This study showed that the peacock bass has no predators or natural competitors in the reservoir and that reproduces continuously, with high reproductive rates, and has a smaller median length at first maturity (L50 than other species of Cichla. Its successful establishment in habitats strongly affected by human activity should cause changes in the whole structure of the local fish communities. Nonetheless, in this reservoir, there appears to be some sharing of the functions of this species with native carnivorous fish, a situation that may be sustained by the presence of a wide variety of foraging fish. Rev. Biol. Trop. 59 (2: 727-741. Epub 2011 June 01.El pez tucunaré (Cichla piquiti, nativo del sistema de la cuenca del rio Tocantins-Araguaia, fue introducido en la cuenca del río Paranaíba, parte del sistema del río Paraná. En este ecosistema trófico de planicie aluvial, las relaciones entre comunidades de peces están definidas por diferentes factores que pueden ser modificados debido a la represa del río, y da como resultado grandes cambios en la interacción biológica en éstos hábitats. La represa de Cachoeira Dourada forma parte de una serie de represas en el río Paranaíba en el Brasil central, donde el tucunaré se ha establecido. Una investigación sobre su espectro alimentario, combinado con información sobre sus caracter

  3. Evaluation of three harvest control rules for Bigeye Tuna ( Thunnus obesus) fisheries in the Indian Ocean

    Science.gov (United States)

    Tong, Yuhe; Chen, Xinjun; Kolody, Dale

    2014-10-01

    The stock of Bigeye tuna ( Thunnus obesus) in the Indian Ocean supports an important international fishery and is considered to be fully exploited. The responsible management agency, the Indian Ocean Tuna Commission (IOTC), does not have an explicit management decision-making framework in place to prevent over-fishing. In this study, we evaluated three harvest control rules, i) constant fishing mortality (CF), from 0.2 to 0.6, ii) constant catch (CC), from 60000 to 140000 t, and iii) constant escapement (CE), from 0.3 to 0.7. The population dynamics simulated by the operating model was based on the most recent stock assessment using Stock Synthesis version III (SS3). Three simulation scenarios (low, medium and high productivity) were designed to cover possible uncertainty in the stock assessment and biological parameters. Performances of three harvest control rules were compared on the basis of three management objectives (over 3, 10 and 25 years): i) the probability of maintaining spawning stock biomass above a level that can sustain maximum sustainable yield (MSY) on average, ii) the probability of achieving average catches between 0.8 MSY and 1.0 MSY, and iii) inter-annual variability in catches. The constant escapement strategy ( CE=0.5), constant fishing mortality strategy ( F=0.4) and constant catch ( CC=80000) were the most rational among the respective management scenarios. It is concluded that the short-term annual catch is suggested at 80000 t, and the potential total allowable catch for a stable yield could be set at 120000 t once the stock had recovered successfully. All the strategies considered in this study to achieve a `tolerable' balance between resource conservation and utilization have been based around the management objectives of the IOTC.

  4. Fishing on cold water coral reefs : A bioeconomic model of habitat-fishery connections

    OpenAIRE

    Kahui, Viktoria; Armstrong, Claire W.

    2008-01-01

    This paper applies a bioeconomic model in order to study different interactions between a harvested renewable resource and a non-renewable resource without commercial value that is negatively affected by the harvesting activity. This enables the analysis of for instance cold water coral habitats and their importance to commercial fish species. The fish is harvested either in a manner that does not damage coral, such as stationary gear, or in a destructive fashion, such as botto...

  5. Length limits fail to restructure a Largemouth Bass population: A 28‐year case history

    Science.gov (United States)

    Miranda, Leandro E.; Colvin, M.E.; Shamaskin, A. C.; Bull, L. A.; Holman, T.; Jones, R.

    2017-01-01

    Length limits have been implemented by fisheries management agencies to achieve population density, size structure, and angler satisfaction objectives. By redirecting harvest towards or away from particular length‐ or age‐groups, length limits rely on harvest by anglers to maintain a population at or near a desired state. The fish population changes that follow the implementation of harvest regulations may take several years to manifest, so long‐term monitoring may be needed to adequately evaluate length limits. We used an innovative application of cluster analysis to facilitate evaluation of the effects of three consecutive length limits on a population of Largemouth Bass Micropterus salmoides over a 28‐year period in Ross Barnett Reservoir, Mississippi. A 13–16‐in protected slot length limit (10 years), followed by a 15‐in minimum length limit (MLL; 11 years), followed by a 12‐in MLL (7 years) failed to restructure the Largemouth Bass population due to what we suggest was the expansion of a voluntary catch‐and‐release attitude that started in the first decade of the study period. Various population metrics shifted towards values expected in an unharvested population, and the observed shifts can be attributed to a harvest deficit created by the prevailing catch‐and‐release attitude. Largemouth Bass harvest regulations may no longer be relevant in many waters. The utility of regulations for restructuring Largemouth Bass populations is largely dependent on harvesting attitudes that vary geographically, depending on cultural characteristics and demographics.

  6. 2005 Annual Synthesis Report, Pallid Sturgeon Population Assessment Program and Associated Fish Community Monitoring for the Missouri River

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, Eric W.; Hanrahan, Timothy P.; Harnish, Ryan A.; Bellgraph, Brian J.; Duncan, Joanne P.; Allwardt, Craig H.

    2008-08-12

    Pallid sturgeon, Scaphirhynchus albus, have declined throughout the Missouri River since dam construction and inception of the Bank Stabilization and Navigation Project in 1912. Their decline likely is due to the loss and degradation of their natural habitat as a result of changes in the river’s structure and function, as well as the pallid sturgeon’s inability to adapt to these changes. The U. S. Army Corps of Engineers has been working with state and federal agencies to develop and conduct a Pallid Sturgeon Monitoring and Assessment Program (Program), with the goal of recovering pallid sturgeon populations. The Program has organized the monitoring and assessment efforts into distinct geographic segments, with state and federal resource management agencies possessing primary responsibility for one or more segment. To date, the results from annual monitoring have been reported for individual Program segments. However, monitoring results have not been summarized or evaluated for larger spatial scales, encompassing more than one Program segment. This report describes a summary conducted by the Pacific Northwest National Laboratory (PNNL) that synthesizes the 2005 sampling year monitoring results from individual segments.

  7. 2006 Annual Synthesis Report, Pallid Sturgeon Population Assessment Program and Associated Fish Community Monitoring for the Missouri River

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, Eric W.; Hanrahan, Timothy P.; Harnish, Ryan A.; Bellgraph, Brian J.; Duncan, Joanne P.; Allwardt, Craig H.

    2008-08-12

    Pallid sturgeon, Scaphirhynchus albus, have declined throughout the Missouri River since dam construction and inception of the Bank Stabilization and Navigation Project in 1912. Their decline likely is due to the loss and degradation of their natural habitat as a result of changes in the river’s structure and function, as well as the pallid sturgeon’s inability to adapt to these changes. The U. S. Army Corps of Engineers has been working with state and federal agencies to develop and conduct a Pallid Sturgeon Monitoring and Assessment Program (Program), with the goal of recovering pallid sturgeon populations. The Program has organized the monitoring and assessment efforts into distinct geographic segments, with state and federal resource management agencies possessing primary responsibility for one or more segment. To date, the results from annual monitoring have been reported for individual Program segments. However, monitoring results have not been summarized or evaluated for larger spatial scales, encompassing more than one Program segment. This report describes a summary conducted by the Pacific Northwest National Laboratory (PNNL) that synthesizes the 2006 sampling year monitoring results from individual segments.

  8. Biochemical genetics of some Indian fishes

    Digital Repository Service at National Institute of Oceanography (India)

    Menezes, M.R.; Qasim, S.Z.

    similarities in their protein make up, whereas these taxonomically apart showed striking differences. Thus, the usefulness of employing this method was clearly demonstrated in fish taxonomy. The study of genetic struture of fish populations through the analysis...

  9. Harvest Regulations and Implementation Uncertainty in Small Game Harvest Management

    Directory of Open Access Journals (Sweden)

    Pål F. Moa

    2017-09-01

    Full Text Available A main challenge in harvest management is to set policies that maximize the probability that management goals are met. While the management cycle includes multiple sources of uncertainty, only some of these has received considerable attention. Currently, there is a large gap in our knowledge about implemention of harvest regulations, and to which extent indirect control methods such as harvest regulations are actually able to regulate harvest in accordance with intended management objectives. In this perspective article, we first summarize and discuss hunting regulations currently used in management of grouse species (Tetraonidae in Europe and North America. Management models suggested for grouse are most often based on proportional harvest or threshold harvest principles. These models are all built on theoretical principles for sustainable harvesting, and provide in the end an estimate on a total allowable catch. However, implementation uncertainty is rarely examined in empirical or theoretical harvest studies, and few general findings have been reported. Nevertheless, circumstantial evidence suggest that many of the most popular regulations are acting depensatory so that harvest bag sizes is more limited in years (or areas where game density is high, contrary to general recommendations. A better understanding of the implementation uncertainty related to harvest regulations is crucial in order to establish sustainable management systems. We suggest that scenario tools like Management System Evaluation (MSE should be more frequently used to examine robustness of currently applied harvest regulations to such implementation uncertainty until more empirical evidence is available.

  10. Managing harvest and habitat as integrated components

    Science.gov (United States)

    Osnas, Erik; Runge, Michael C.; Mattsson, Brady J.; Austin, Jane E.; Boomer, G. S.; Clark, R. G.; Devers, P.; Eadie, J. M.; Lonsdorf, E. V.; Tavernia, Brian G.

    2014-01-01

    In 2007, several important initiatives in the North American waterfowl management community called for an integrated approach to habitat and harvest management. The essence of the call for integration is that harvest and habitat management affect the same resources, yet exist as separate endeavours with very different regulatory contexts. A common modelling framework could help these management streams to better understand their mutual effects. Particularly, how does successful habitat management increase harvest potential? Also, how do regional habitat programmes and large-scale harvest strategies affect continental population sizes (a metric used to express habitat goals)? In the ensuing five years, several projects took on different aspects of these challenges. While all of these projects are still on-going, and are not yet sufficiently developed to produce guidance for management decisions, they have been influential in expanding the dialogue and producing some important emerging lessons. The first lesson has been that one of the more difficult aspects of integration is not the integration across decision contexts, but the integration across spatial and temporal scales. Habitat management occurs at local and regional scales. Harvest management decisions are made at a continental scale. How do these actions, taken at different scales, combine to influence waterfowl population dynamics at all scales? The second lesson has been that consideration of the interface of habitat and harvest management can generate important insights into the objectives underlying the decision context. Often the objectives are very complex and trade-off against one another. The third lesson follows from the second – if an understanding of the fundamental objectives is paramount, there is no escaping the need for a better understanding of human dimensions, specifically the desires of hunters and nonhunters and the role they play in conservation. In the end, the compelling question is

  11. At the forefront: evidence of the applicability of using environmental DNA to quantify the abundance of fish populations in natural lentic waters with additional sampling considerations

    Science.gov (United States)

    Klobucar, Stephen L.; Rodgers, Torrey W.; Budy, Phaedra

    2017-01-01

    Environmental DNA (eDNA) sampling has proven to be a valuable tool for detecting species in aquatic ecosystems. Within this rapidly evolving field, a promising application is the ability to obtain quantitative estimates of relative species abundance based on eDNA concentration rather than traditionally labor-intensive methods. We investigated the relationship between eDNA concentration and Arctic char (Salvelinus alpinus) abundance in five well-studied natural lakes; additionally, we examined the effects of different temporal (e.g., season) and spatial (e.g., depth) scales on eDNA concentration. Concentrations of eDNA were linearly correlated with char population estimates ( = 0.78) and exponentially correlated with char densities ( = 0.96 by area; 0.82 by volume). Across lakes, eDNA concentrations were greater and more homogeneous in the water column during mixis; however, when stratified, eDNA concentrations were greater in the hypolimnion. Overall, our findings demonstrate that eDNA techniques can produce effective estimates of relative fish abundance in natural lakes. These findings can guide future studies to improve and expand eDNA methods while informing research and management using rapid and minimally invasive sampling.

  12. Population growth, trophic level, and reproductive biology of two congeneric archer fishes (Toxotes chatareus, Hamilton 1822 and Toxotes jaculatrix, Pallas 1767) inhabiting Malaysian coastal waters.

    Science.gov (United States)

    Simon, K D; Bakar, Y; Samat, A; Zaidi, C C; Aziz, A; Mazlan, A G

    2009-12-01

    Population growth, trophic level, and some aspects of reproductive biology of two congeneric archer fish species, Toxotes chatareus and Toxotes jaculatrix, collected from Johor coastal waters, Malaysia, were studied. Growth pattern by length-weight relationship (W=aL(b)) for the sexes differed, and exhibited positive allometric growth (male, female and combined sexes of T. chatareus; female and combined sexes of T. jaculatrix) and isometric growth (male samples of T. jaculatrix only). Trophic levels of both species were analyzed based on 128 specimens. The results show that, in both species, crustaceans and insects were the most abundant prey items, and among crustaceans the red clawed crab Sesarma bidens and Formicidae family insects were the most represented taxa. The estimated mean trophic levels for T. chatareus and T. jaculatrix were 3.422+/-0.009 and 3.420+/-0.020, respectively, indicating that they are largely carnivores. Fecundity of T. chatareus ranged from 38 354 to 147 185 eggs for females with total length ranging from 14.5 to 22.5 cm and total body weight from 48.7 to 270.2 g, and T. jaculatrix 25 251 to 150 456 eggs for females with total length ranging from 12.2 to 23.0 cm and total body weight from 25.7 to 275.0 g. Differences in values of gonadosomatic and hepatosomatic indexes calculated for both species in this study may have resulted from uneven sample size ranges.

  13. Depth refuge and the impacts of SCUBA spearfishing on coral reef fishes.

    Directory of Open Access Journals (Sweden)

    Steven J Lindfield

    Full Text Available In recent decades, spearfishing with SCUBA has emerged as an efficient method for targeting reef fish in deeper waters. However, deeper waters are increasingly recognised as a potential source of refuge that may help sustain fishery resources. We used a combination of historical catch data over a 20-year time period and fishery-independent surveys to investigate the effects of SCUBA spearfishing on coral reef fish populations in the southern Mariana Islands. Two jurisdictions were studied; Guam, where SCUBA spearfishing is practiced, and the nearby Commonwealth of Northern Mariana Islands (CNMI, where SCUBA spearfishing has been banned since 2003. Fishery-independent data were collected using baited remote underwater stereo-video systems (stereo-BRUVs stratified by depth, marine protected area status and jurisdiction. Herbivores (primary consumers dominated spearfishing catches, with parrotfish (scarines and surgeonfish/unicornfish (acanthurids the main groups harvested. However, the large, endangered humphead wrasse (Cheilinus undulatus was the main species by weight landed by SCUBA spearfishers. SCUBA spearfishing was associated with declining size of scarines over time and catches shifting from a dominance of large parrotfishes to a mixed assemblage with increasing proportions of acanthurids. Comparisons between Guam and the nearby CNMI revealed differences in the assemblage of fished species and also greater size of scarines and acanthurids in deep water where SCUBA fishing is banned. These results suggest that SCUBA spearfishing impacts reef fish populations and that the restriction of this fishing method will ensure refuge for fish populations in deeper waters. We recommend a ban on SCUBA spearfishing to preserve or aid the recovery of large, functionally important coral reef species and to improve the sustainability of coral reef fisheries.

  14. Depth refuge and the impacts of SCUBA spearfishing on coral reef fishes.

    Science.gov (United States)

    Lindfield, Steven J; McIlwain, Jennifer L; Harvey, Euan S

    2014-01-01

    In recent decades, spearfishing with SCUBA has emerged as an efficient method for targeting reef fish in deeper waters. However, deeper waters are increasingly recognised as a potential source of refuge that may help sustain fishery resources. We used a combination of historical catch data over a 20-year time period and fishery-independent surveys to investigate the effects of SCUBA spearfishing on coral reef fish populations in the southern Mariana Islands. Two jurisdictions were studied; Guam, where SCUBA spearfishing is practiced, and the nearby Commonwealth of Northern Mariana Islands (CNMI), where SCUBA spearfishing has been banned since 2003. Fishery-independent data were collected using baited remote underwater stereo-video systems (stereo-BRUVs) stratified by depth, marine protected area status and jurisdiction. Herbivores (primary consumers) dominated spearfishing catches, with parrotfish (scarines) and surgeonfish/unicornfish (acanthurids) the main groups harvested. However, the large, endangered humphead wrasse (Cheilinus undulatus) was the main species by weight landed by SCUBA spearfishers. SCUBA spearfishing was associated with declining size of scarines over time and catches shifting from a dominance of large parrotfishes to a mixed assemblage with increasing proportions of acanthurids. Comparisons between Guam and the nearby CNMI revealed differences in the assemblage of fished species and also greater size of scarines and acanthurids in deep water where SCUBA fishing is banned. These results suggest that SCUBA spearfishing impacts reef fish populations and that the restriction of this fishing method will ensure refuge for fish populations in deeper waters. We recommend a ban on SCUBA spearfishing to preserve or aid the recovery of large, functionally important coral reef species and to improve the sustainability of coral reef fisheries.

  15. Piezoelectric energy harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Howells, Christopher A [Power Technology Branch, US Army, CERDEC, C2D, Ft. Belvoir, VA 22060-5816 (United States)

    2009-07-15

    Piezoelectric materials can be used to convert oscillatory mechanical energy into electrical energy. This technology, together with innovative mechanical coupling designs, can form the basis for harvesting energy from mechanical motion. Piezoelectric energy can be harvested to convert walking motion from the human body into electrical power. Recently four proof-of-concept Heel Strike Units were developed where each unit is essentially a small electric generator that utilizes piezoelectric elements to convert mechanical motion into electrical power in the form factor of the heel of a boot. The results of the testing and evaluation and the performance of this small electric generator are presented. The generator's conversion of mechanical motion into electrical power, the processes it goes through to produce useable power and commercial applications of the Heel Strike electric generator are discussed. (author)

  16. Piezoelectric energy harvesting

    International Nuclear Information System (INIS)

    Howells, Christopher A

    2009-01-01

    Piezoelectric materials can be used to convert oscillatory mechanical energy into electrical energy. This technology, together with innovative mechanical coupling designs, can form the basis for harvesting energy from mechanical motion. Piezoelectric energy can be harvested to convert walking motion from the human body into electrical power. Recently four proof-of-concept Heel Strike Units were developed where each unit is essentially a small electric generator that utilizes piezoelectric elements to convert mechanical motion into electrical power in the form factor of the heel of a boot. The results of the testing and evaluation and the performance of this small electric generator are presented. The generator's conversion of mechanical motion into electrical power, the processes it goes through to produce useable power and commercial applications of the Heel Strike electric generator are discussed.

  17. Restoration of harvested peatlands

    International Nuclear Information System (INIS)

    Saarmets, Tiit

    1999-01-01

    A short analysis of the main topics of the IPS Symposium Peatland Restoration and Reclamation, Duluth, Minnesota, USA, 1998 is given. It has been single-mindedly recommended in Estonia so far that harvested peatland surfaces should be levelled and outflows shut. But following these recommendations will lead to an unfounded formation of marshy areas with a very low growth of plants. The reclamation of harvested peatlands for agricultural purposes is expensive and there is no commercial need for agricultural land in today's Estonia now. In the author's opinion the foreflows and intermediate ditches should be left open which would favour the growth of the brushwood to grow later into the forest of commercial value. (author)

  18. A randomized trial of fish oil omega-3 fatty acids on arterial health, inflammation, and metabolic syndrome in a young healthy population

    Science.gov (United States)

    2013-01-01

    Background Long chain omega-3 fatty acids from fish oils (O3) are known to have beneficial effects on a number of vascular risk factors in at-risk populations. The effects of a highly bioavailable emulsified preparation on an overweight young adult population are less well known. Methods Young adults, age 18–30, with body mass indices (BMIs) greater than 23 (average = 28.1) were administered 1.7 g of O3 per day (N = 30) or safflower oil placebo (N = 27) in an emulsified preparation (Coromega, Inc.) for 4 weeks in a double-blind randomized design. Blood was drawn and anthropometric measurements taken before and after dosing. Hemodynamic measures (central pulse wave velocity, augmentation index, and aortic systolic blood pressure), inflammatory cytokines (IL-6, IL-8, IL-10, and tumor necrosis factor-α), red blood cell and plasma phospholipid fatty acid profiles, fasting serum lipids, glucose, and C-reactive protein were measured. Results Red cell and plasma phospholipid eicosapentaenoic acid and docosahexaenoic acid concentrations increased over the four weeks of dosing in the O3 group. Dosing with O3 did not affect central pulse wave velocity, augmentation index, or aortic systolic blood pressure. None of the five American Heart Association metabolic syndrome components improved over the dosing period. None of the inflammatory cytokines, C-reactive protein, or lipids (total or LDL cholesterol) improved over the dosing period. Conclusions No salutary effects of O3 were observed in hemodynamic, metabolic syndrome criteria or inflammatory markers as a result of this relatively short period of administration in this relatively overweight, but healthy young adult cohort. PMID:23565815

  19. Body growth and reproduction of individuals of the sciaenid fish Stellifer rastrifer in a shallow tropical bight: A cautionary tale for assumptions regarding population parameters

    Science.gov (United States)

    Pombo, Maíra; Denadai, Márcia Regina; Turra, Alexander

    2013-05-01

    Knowledge of population parameters and the ability to predict their responses to environmental changes are useful tools to aid in the appropriate management and conservation of natural resources. Samples of the sciaenid fish Stellifer rastrifer were taken from August 2003 through October 2004 in shallow areas of Caraguatatuba Bight, southeastern Brazil. The results showed a consistent presence of length-frequency classes throughout the year and low values of the gonadosomatic index of this species, indicating that the area is not used for spawning or residence of adults, but rather shelters individuals in late stages of development. The results may serve as a caveat for assessments of transitional areas such as the present one, the nursery function of which is neglected compared to estuaries and mangroves. The danger of mismanaging these areas by not considering their peculiarities is emphasized by using these data as a study case for the development of some broadly used population-parameter analyses. The individuals' body growth parameters from the von Bertalanffy model were estimated based on the most common approaches, and the best values obtained from traditional quantification methods of selection were very prone to bias. The low gonadosomatic index (GSI) estimated during the period was an important factor in stimulating us to select more reliable parameters of body growth (L∞ = 20.9, K = 0.37 and Z = 2.81), which were estimated based on assuming the existence of spatial segregation by size. The data obtained suggest that the estimated mortality rate included a high rate of migration of older individuals to deeper areas, where we assume that they completed their development.

  20. Assessments of fish catch composition of marine artisanal fishery in ...

    African Journals Online (AJOL)

    Fish is a major source of protein in human diets. Fish demand has been on the increase due to increase in human population which has resulted to wide gap between fish demand and supply. This study was carried out to elucidate the major fish species that are economically important in the study area. Assessment of fish ...

  1. Piezoelectric Energy Harvesting Solutions

    Science.gov (United States)

    Caliò, Renato; Rongala, Udaya Bhaskar; Camboni, Domenico; Milazzo, Mario; Stefanini, Cesare; de Petris, Gianluca; Oddo, Calogero Maria

    2014-01-01

    This paper reviews the state of the art in piezoelectric energy harvesting. It presents the basics of piezoelectricity and discusses materials choice. The work places emphasis on material operating modes and device configurations, from resonant to non-resonant devices and also to rotational solutions. The reviewed literature is compared based on power density and bandwidth. Lastly, the question of power conversion is addressed by reviewing various circuit solutions. PMID:24618725

  2. Harvesting contaminants from liquid

    Science.gov (United States)

    Simpson, John T.; Hunter, Scott R.

    2016-05-31

    Disclosed are examples of apparatuses for evaporative purification of a contaminated liquid. In each example, there is a vessel for storing the contaminated fluid. The vessel includes a surface coated with a layer of superhydrophobic material and the surface is at least partially in contact with the contaminated liquid. The contaminants do not adhere to the surface as the purified liquid evaporates, thus allowing the contaminants to be harvested.

  3. Fishing degrades size structure of coral reef fish communities.

    Science.gov (United States)

    Robinson, James P W; Williams, Ivor D; Edwards, Andrew M; McPherson, Jana; Yeager, Lauren; Vigliola, Laurent; Brainard, Russell E; Baum, Julia K

    2017-03-01

    Fishing pressure on coral reef ecosystems has been frequently linked to reductions of large fishes and reef fish biomass. Associated impacts on overall community structure are, however, less clear. In size-structured aquatic ecosystems, fishing impacts are commonly quantified using size spectra, which describe the distribution of individual body sizes within a community. We examined the size spectra and biomass of coral reef fish communities at 38 US-affiliated Pacific islands that ranged in human presence from near pristine to human population centers. Size spectra 'steepened' steadily with increasing human population and proximity to market due to a reduction in the relative biomass of large fishes and an increase in the dominance of small fishes. Reef fish biomass was substantially lower on inhabited islands than uninhabited ones, even at inhabited islands with the lowest levels of human presence. We found that on populated islands size spectra exponents decreased (analogous to size spectra steepening) linearly with declining biomass, whereas on uninhabited islands there was no relationship. Size spectra were steeper in regions of low sea surface temperature but were insensitive to variation in other environmental and geomorphic covariates. In contrast, reef fish biomass was highly sensitive to oceanographic conditions, being influenced by both oceanic productivity and sea surface temperature. Our results suggest that community size structure may be a more robust indicator than fish biomass to increasing human presence and that size spectra are reliable indicators of exploitation impacts across regions of different fish community compositions, environmental drivers, and fisheries types. Size-based approaches that link directly to functional properties of fish communities, and are relatively insensitive to abiotic variation across biogeographic regions, offer great potential for developing our understanding of fishing impacts in coral reef ecosystems. © 2016

  4. Terra Harvest software architecture

    Science.gov (United States)

    Humeniuk, Dave; Klawon, Kevin

    2012-06-01

    Under the Terra Harvest Program, the DIA has the objective of developing a universal Controller for the Unattended Ground Sensor (UGS) community. The mission is to define, implement, and thoroughly document an open architecture that universally supports UGS missions, integrating disparate systems, peripherals, etc. The Controller's inherent interoperability with numerous systems enables the integration of both legacy and future UGS System (UGSS) components, while the design's open architecture supports rapid third-party development to ensure operational readiness. The successful accomplishment of these objectives by the program's Phase 3b contractors is demonstrated via integration of the companies' respective plug-'n'-play contributions that include controllers, various peripherals, such as sensors, cameras, etc., and their associated software drivers. In order to independently validate the Terra Harvest architecture, L-3 Nova Engineering, along with its partner, the University of Dayton Research Institute, is developing the Terra Harvest Open Source Environment (THOSE), a Java Virtual Machine (JVM) running on an embedded Linux Operating System. The Use Cases on which the software is developed support the full range of UGS operational scenarios such as remote sensor triggering, image capture, and data exfiltration. The Team is additionally developing an ARM microprocessor-based evaluation platform that is both energy-efficient and operationally flexible. The paper describes the overall THOSE architecture, as well as the design decisions for some of the key software components. Development process for THOSE is discussed as well.

  5. Selective analysis of power plant operation on the Hudson River with emphasis on the Bowline Point Generating Station. Volume 2. [Multiple impact of power plant once-through cooling systems on fish populations

    Energy Technology Data Exchange (ETDEWEB)

    Barnthouse, L. W.; Cannon, J. B.; Christensen, S. G.

    1977-07-01

    Because of the location of the Bowline, Roseton, and Indian Point power generating facilities in the low-salinity zone of the Hudson estuary, operation of these plants with the present once-through cooling systems will adversely influence the fish populations that use the area for spawning and initial periods of growth and development. Recruitment rates and standing crops of several fish species may be lowered in response to the increased mortality caused by entrainment of nonscreenable eggs and larvae and by impingement of screenable young of the year. Entrainment and impingement data are particularly relevant for assessing which fish species have the greatest potential for being adversely affected by operation of Bowline, Roseton, and Indian Point with once-through cooling. These data from each of these three plants suggest that the six species that merit the greatest consideration are striped bass, white perch, tomcod, alewife, blueback herring, and bay anchovy. Two points of view are available for assessing the relative importance of the fish species in the Hudson River. From the fisheries point of view, the only two species of major importance are striped bass and shad. From the fish-community and ecosystem point of view, the dominant species, as determined by seasonal and regional standing crops (in numbers and biomass per hectare), are the six species most commonly entrained and impinged, namely, striped bass, white perch, tomcod, alewife, blueback herring, and anchovy.

  6. Effect of dietary fish oil supplements alone or in combination with sunflower and linseed oil on ruminal lipid metabolism and bacterial populations in lactating cows.

    Science.gov (United States)

    Kairenius, P; Leskinen, H; Toivonen, V; Muetzel, S; Ahvenjärvi, S; Vanhatalo, A; Huhtanen, P; Wallace, R J; Shingfield, K J

    2018-04-01

    Fish oil (FO) alters ruminal biohydrogenation causing trans fatty acid (FA) intermediates to accumulate, but the effects of 18-carbon polyunsaturated FA supply on ruminal long-chain FA metabolism and microbial communities in cattle fed FO are not well established. Four cows fitted with rumen cannula were used in a 4 × 4 Latin square with 21-d experimental periods to evaluate the effects of FO alone or in combination with plant oils high in 18:2n-6 or 18:3n-3 on rumen microbial ecology and flow of FA at the omasum. Treatments comprised a basal grass silage-based diet containing no additional oil (control) or supplements of FO (200 g/d) or FO (200 g/d) plus 500 g/d of sunflower oil (SFO) or linseed oil (LFO). Flow of FA was determined using the omasal sampling technique. The relative abundance of key biohydrogenating bacteria was assessed by quantitative PCR on 16S rRNA genes in omasal digesta. Fish oil-supplemented treatments increased the amounts of trans-18:1, trans-18:2, and 20- to 22-carbon polyunsaturated FA escaping the rumen. Relative to the control, oil supplements had no effect on the amount of 18:0 leaving the rumen, but LFO decreased the flow of 18:0 at the omasum compared with SFO. Both SFO and LFO increased trans-18:1 relative to FO, whereas LFO resulted in the highest trans-18:2 and 20- to 22-carbon FA flow. Supplements of FO plus plant oils shifted biohydrogenation toward trans-10 18:1 formation. Compared with FO alone, the ruminal metabolism of 22:6n-3 in the rumen of lactating cows is more extensive on diets containing higher amounts of 18-carbon polyunsaturated FA. However, the biohydrogenation of 22:5n-3 was less extensive in LFO than SFO, but showed no difference between FO and diets containing plant oils. Ruminal outflow of 20:5n-3 was not altered when plant oils were added to FO. Alterations in the amount of intermediates at the omasum or ruminal biohydrogenation pathways were not accompanied by major changes in analyzed bacterial populations

  7. Climate Change and Fish Availability

    Science.gov (United States)

    Teng, Paul P. S.; Lassa, Jonatan; Caballero-Anthony, Mely

    Human consumption of fish has been trending upwards in the past decades and this is projected to continue. The main sources of fish are from wild fisheries (marine and freshwater) and aquaculture. Climate change is anticipated to affect the availability of fish through its effect on these two sources as well as on supply chain processes such as storage, transport, processing and retail. Climate change is known to result in warmer and more acid oceans. Ocean acidification due to higher CO2 concentration levels at sea modifies the distribution of phytoplankton and zooplankton to affect wild, capture fisheries. Higher temperature causes warm-water coral reefs to respond with species replacement and bleaching, leading to coral cover loss and habitat loss. Global changes in climatic systems may also cause fish invasion, extinction and turnover. While this may be catastrophic for small scale fish farming in poor tropical communities, there are also potential effects on animal protein supply shifts at local and global scales with food security consequences. This paper discusses the potential impacts of climate change on fisheries and aquaculture in the Asian Pacific region, with special emphasis on Southeast Asia. The key question to be addressed is “What are the impacts of global climate change on global fish harvests and what does it mean to the availability of fish?”

  8. Occurrence of Vibrio cholerae in fish and water from a reservoir and a neighboring channel in Ouagadougou, Burkina Faso.

    Science.gov (United States)

    Traoré, Oumar; Martikainen, Outi; Siitonen, Anja; Traoré, Alfred S; Barro, Nicolas; Haukka, Kaisa

    2014-10-15

    Vibrio cholerae is a human pathogen and natural inhabitant of aquatic environments. In this study, we surveyed the occurrence of V. cholerae in fish harvested from a reservoir that receives discharges from the population in Ouagadougou through several channels. A total of 238 fish and 80 water samples were analyzed for the presence of V. cholerae. Altogether, 13 V. cholerae strains were isolated. They were all identified as non-O1/non-O139 V. cholerae without the ctxA gene. The strains were mostly susceptible to the antimicrobials tested. Although no strains of epidemic V. cholerae serotypes were encountered, it is important to monitor the microbiological quality of this extensively used water resource and its fish.

  9. The desperate dozen: Fishes on the brink

    Science.gov (United States)

    Welsh, Stuart A.

    2008-01-01

    as the diamond darter, are now suffering from the same water quality issues that cause harm to humans. Fishes that were once used for commercial gain, such as the Alabama sturgeon, are now too rare for harvest. We have ignored our freshwater to the point where we no longer remember that rivers used to be more common than reservoirs in the Southeast, and our diversity was a resource worth protecting. It is SFC’s goal to use this list to raise awareness of the plight of our freshwater habitats in the Southeast, which include rivers, creeks, wetlands, springs, and caves. The current crisis requires education, communication, and coordination among our neighbors. We have to learn how to prevent harm to our watersheds and develop new collaborations between private and public entities to promote wise development. By highlighting these twelve species, ranging from the spring pygmy sunfish to the Alabama sturgeon, we hope to encourage these partnerships to address the needs of our freshwater animals and hopefully prevent them from slipping quietly into extinction. SFC created a list of the most imperiled southeastern fishes by considering species with the highest risk of extinction. Criteria used, in order of importance, was distribution (a single population ranked highest), low abundance, and severity of threats. After the ranking based on level of imperilment, species were arranged in phylogenetic order so that all would receive equal attention. Experts on each species provided brief accounts on the Desperate Dozen, which include background, distribution, abundance, threats, and proposed conservation actions. The U.S. Fish and Wildlife Service (USFWS) was not consulted in SFC’s identification of the Desperate Dozen fishes, as we intentionally chose to work as an independent scientific panel under the criteria stated above.

  10. DYNAMICS OF PIKE (ESOX LUCIUS LINNAEUS, 1758 AGE STRUCTURE IN THE DNIEPER LOWER REACHES IN CONNECTION WITH FISHING

    Directory of Open Access Journals (Sweden)

    K. Geina

    2015-03-01

    Full Text Available Purpose. To analyze the dynamics of pike (Esox luceus Linnaeus, 1758 age structure of the Dnieper lower reaches in conditions of the modification of fishing pressure. Methodology. An analysis of fishing situation has been performed based on data of official fishery statistics. Fish sampling was done at control-observation posts of the Institute of Fisheries of the NAAS of Ukraine and directly in the fishery. Juvenile fish yield was determined using a complex of fry fishing gears using a stationary net-station. Field and cameral processing of the material was performed using generally accepted methods. Findings. A retrospective analysis of the situation in the Dnieper-Bug lower reach system clearly indicates on the presence of continuous tendency of catch decline of representative of native fish fauna – pike. With relatively uniform indices of the “yield” of its juveniles before Dnieper flow impoundment and in conditions of present time, its commercial catches significantly dropped. The dynamics of pike current age structure indicates on an increase of relative density of age groups, which form the recruitment of the commercial portion of the population (1-1+ and a decrease of importance of the component of the right side of age series. A discrepancy between the observed changes of the age group and commercial harvest quantities indicates on increased human pressure on this species. Originality. For the first, we analyzed the dynamics of fish juvenile “yield” and age structure of pike commercial stock of the Dnieper lower reaches in the river flow transformation process. Practical value. A decrease of the ichthyomass of piscivorous fishes in the Dnieper lower reaches results in changes of fish populations of littoral biotopes towards the prevalence of the dominance of coarse species that lead to a deterioration of forage availability for a number of valuable commercial species. An increase of the number of pike can regulate the strain

  11. ANALYSIS OF GENETIC DIVERSITY OF GALICIAN CARP POPULATION ON THE BASE OF FISH FARM "VELYKYY LYUBIN´” WITH USING MICROSATELLITE MARKERS

    Directory of Open Access Journals (Sweden)

    I. Yarova

    2017-09-01

    Full Text Available Purpose. To investigate the genetic structure of the Galician carp population using microsatellite DNA markers. Methodology. Blood samples taken from the caudal vein of the specimens of the Galician carp farm "Velykyy Lyubin", Lviv region. (N = 15 persons. When landing, they were labeled with electronic chips of the brand Aqua Pump and A-CHIP. The total DNA was isolated using the standard method, using the Gene JET Whole Blood Genomik DNA Purification Mini Kit (USA. The concentration and quality of DNA were determined on an Eppendorf Bio Photometr biophotometer. To study the genetic structure of the Galician carp population, four microsatellite markers were used: MFW 06, MFW 15, MFW 23, MFW 31. Findings. Blood samples taken from the tail vein of fish (n = 15 oz. Were used as research material. In the course of work, optimal conditions for SSR-PCR analysis have been selected. The conducted studies allowed to determine the factors that have the greatest impact on the amplification efficiency, namely: the concentration of the DNA preparation, the concentration of the primer in the reaction mixture and the number of amplification cycles. In the study group, for all 4 microsatellite loci, only 18 alleles with a molecular weight of 130-343 ng were detected. The number of alleles per locus varied from 3 to 6. The most polymorphous was the locus MFW 23 (6 alleles were detected, and the least polymorphic was the locus MFW 31 (3 alleles were detected. The effective number of alleles in the sample of genotypes studied varied from 2.14 (MFW 31 to 5.23 (MFW 23. According to calculations of allelic frequencies, the main indicators of genetic variability are determined. The maximum level of available heterozygosity is fixed for the MFW 23 locus, the lowest for the MFW locus 31. Originality. For the first time in 65 years the genetic structure of the Galician carp population has been investigated. Practical value. The results will be used in further studies of

  12. The 'fishery' in South Africa's remaining coastal stonewall fish traps ...

    African Journals Online (AJOL)

    Fishing takes place on pre-dawn, new-moon spring low tides. Fishers have replaced traditional spears with monofilament gillnets to remove fish from the vywers. Catches were and still are dominated by hardersLiza richardsonii, but occasional large harvests of elf Pomatomus saltatrix, white musselcracker Sparodon ...

  13. Meeting the food and nutrition needs of the poor: the role of fish and the opportunities and challenges emerging from the rise of aquaculture.

    Science.gov (United States)

    Beveridge, M C M; Thilsted, S H; Phillips, M J; Metian, M; Troell, M; Hall, S J

    2013-10-01

    People who are food and nutrition insecure largely reside in Asia and Sub-Saharan Africa and for many, fish represents a rich source of protein, micronutrients and essential fatty acids. The contribution of fish to household food and nutrition security depends upon availability, access and cultural and personal preferences. Access is largely determined by location, seasonality and price but at the individual level it also depends upon a person's physiological and health status and how fish is prepared, cooked and shared among household members. The sustained and rapid expansion of aquaculture over the past 30 years has resulted in >40% of all fish now consumed being derived from farming. While aquaculture produce increasingly features in the diets of many Asians, it is much less apparent among those living in Sub-Saharan Africa. Here, per capita fish consumption has grown little and despite the apparently strong markets and adequate biophysical conditions, aquaculture has yet to develop. The contribution of aquaculture to food and nutrition security is not only just an issue of where aquaculture occurs but also of what is being produced and how and whether the produce is as accessible as that from capture fisheries. The range of fish species produced by an increasingly globalized aquaculture industry differs from that derived from capture fisheries. Farmed fishes are also different in terms of their nutrient content, a result of the species being grown and of rearing methods. Farmed fish price affects access by poor consumers while the size at which fish is harvested influences both access and use. This paper explores these issues with particular reference to Asia and Africa and the technical and policy innovations needed to ensure that fish farming is able to fulfil its potential to meet the global population's food and nutrition needs. © 2013 World Fish. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the

  14. Dietary intake of fish, omega-3, omega-6 polyunsaturated fatty acids and vitamin D and the prevalence of psychotic-like symptoms in a cohort of 33,000 women from the general population.

    Science.gov (United States)

    Hedelin, Maria; Löf, Marie; Olsson, Marita; Lewander, Tommy; Nilsson, Björn; Hultman, Christina M; Weiderpass, Elisabete

    2010-05-26

    Low intake of fish, polyunsaturated fatty acids (PUFA) and vitamin D deficiency has been suggested to play a role in the development of schizophrenia. Our aim was to evaluate the association between the intake of different fish species, PUFA and vitamin D and the prevalence of psychotic-like symptoms in a population-based study among Swedish women. Dietary intake was estimated using a food frequency questionnaire among 33,623 women aged 30-49 years at enrollment (1991/92). Information on psychotic-like symptoms was derived from a follow-up questionnaire in the years 2002/03. Participants were classified into three predefined levels: low, middle and high frequency of symptoms. The association between diet and psychotic-like symptoms was summarized in terms of relative risks (RR) and corresponding 95% confidence intervals and was evaluated by energy-adjusted multinomial logistic regression. 18,411 women were classified as having a low level of psychotic-like symptoms, 14 395 as middle and 817 as having a high level. The risk of high level symptoms was 53% (95% CI, 30-69%) lower among women who ate fish 3-4 times per week compared to women who never ate fish. The risk was also lower for women with a high intake of omega-3 and omega-6 PUFA compared to women with a lower intake of these fatty acids. The effect was most pronounced for omega-6 PUFAs. The RR comparing the highest to the lowest quartile of omega-6 PUFAs intake was 0.78 (95% CI, 0.64-0.97). The associations were J-shaped with the strongest reduced risk for an intermediate intake of fish or PUFA. For fatty fish (herring/mackerel, salmon-type fish), the strongest inverse association was found for an intermediate intake (RR: 0.81, 95% CI, 0.66-0.98), whereas a high intake of fatty fish was associated with an increased risk of psychotic-like symptoms (RR: 1.90, 95% CI, 1.34-2.70). Women in the highest compared with the lowest quartile of vitamin D consumption experienced a 37% (95% CI, 22-50%) lower risk of

  15. Dietary intake of fish, omega-3, omega-6 polyunsaturated fatty acids and vitamin D and the prevalence of psychotic-like symptoms in a cohort of 33 000 women from the general population

    Directory of Open Access Journals (Sweden)

    Lewander Tommy

    2010-05-01

    Full Text Available Abstract Background Low intake of fish, polyunsaturated fatty acids (PUFA and vitamin D deficiency has been suggested to play a role in the development of schizophrenia. Our aim was to evaluate the association between the intake of different fish species, PUFA and vitamin D and the prevalence of psychotic-like symptoms in a population-based study among Swedish women. Methods Dietary intake was estimated using a food frequency questionnaire among 33 623 women aged 30-49 years at enrolment (1991/92. Information on psychotic-like symptoms was derived from a follow-up questionnaire in the years 2002/03. Participants were classified into three predefined levels: low, middle and high frequency of symptoms. The association between diet and psychotic-like symptoms was summarized in terms of relative risks (RR and corresponding 95% confidence intervals and was evaluated by energy-adjusted multinomial logistic regression. Results 18 411 women were classified as having a low level of psychotic-like symptoms, 14 395 as middle and 817 as having a high level. The risk of high level symptoms was 53% (95% CI, 30-69% lower among women who ate fish 3-4 times per week compared to women who never ate fish. The risk was also lower for women with a high intake of omega-3 and omega-6 PUFA compared to women with a lower intake of these fatty acids. The effect was most pronounced for omega-6 PUFAs. The RR comparing the highest to the lowest quartile of omega-6 PUFAs intake was 0.78 (95% CI, 0.64-0.97. The associations were J-shaped with the strongest reduced risk for an intermediate intake of fish or PUFA. For fatty fish (herring/mackerel, salmon-type fish, the strongest inverse association was found for an intermediate intake (RR: 0.81, 95% CI, 0.66-0.98, whereas a high intake of fatty fish was associated with an increased risk of psychotic-like symptoms (RR: 1.90, 95% CI, 1.34-2.70. Women in the highest compared with the lowest quartile of vitamin D consumption

  16. The Effect of Plant Cultivar, Growth Media, Harvest Method and Post Harvest Treatment on the Microbiology of Edible Crops

    Science.gov (United States)

    Hummerick, Mary P.; Gates, Justin R.; Nguyen, Bao-Thang; Massa, Gioia D.; Wheeler, Raymond M.

    2011-01-01

    Systems for the growth of crops in closed environments are being developed and tested for potential use in space applications to provide a source of fresh food. Plant growth conditions, growth media composition and harvest methods can have an effect on the microbial population of the plant, and therefore should be considered along with the optimization of plant growth and harvest yields to ensure a safe and palatable food crop. This work examines the effect of plant cultivar, growth media, and harvest method on plant microbial populations. Twelve varieties of leafy greens and herbs were grown on a mixture of Fafard #2 and Arcillite in the pillow root containment system currently being considered for the VEGGIE plant growth unit developed by Orbitec. In addition, ,Sierra and Outredgeous lettuce varieties were grown in three different mixtures (Fafard #2, Ardllite, and Perlite/Vermiculite). The plants were analyzed for microbial density. Two harvest methods, "cut and come again" (CACA) and terminal harvest were also compared. In one set ofexpe'riments red leaf lettuce and mizuna were grown in pots in a Biomass Production System for education. Plants were harvested every two weeks by either method. Another set of experiments was performed using the rooting pillows to grow 5 varieties of leafy greens and cut harvesting at different intervals. Radishes were harvested and replanted at two-week intervals. Results indicate up to a 3 IOglO difference in microbial counts between some varieties of plants. Rooting medium resulted in an approximately 2 IOglO lower count in the lettuce grown in arscillite then those grown in the other mixtures. Harvest method and frequency had less impact on microbial counts only showing a significant increase in one variety of plant. Post harvest methods to decrease the bacterial counts on edible crops were investigated in these and other experiments. The effectiveness of PRO-SAN and UV-C radiation is compared.

  17. Differential fat harvesting

    Directory of Open Access Journals (Sweden)

    Sebastian Torres Farr

    2014-12-01

    Full Text Available Aim: Volume replacement with fillers is regularly performed with the use of diverse volumetric materials to correct different structures around the face, depending on the volume enhancement required and the thickness of the soft tissue envelope. Differential fat harvesting and posterior grafting is performed to place the correct fat parcel size for each target area, expanding the potential applications of fat. Methods: Sixty patients consecutively recruited on a first come basis undergone a facial fat grafting procedure, in private practice setting between March 2012 and October 2013. Fat grafting quantity and quality was predicted for each case. Differential harvesting was performed, with 2 fat parcels size. Processing was performed through washing. Fat infiltration was carried out through small cannulas or needles depending on the treated area. Outcomes were analysed both by the physicians and the patients at 7 days, 1 month, 3 months and 6 months through a perceived satisfaction questionnaire. Parameters considered were downtime or discomfort, skin benefits, volume restoration, reabsorption rate estimated and overall improvement. Results: Full facial differential fat grafting procedure lasted an average of 1.5-2.5 h. Average downtime was 3-4 days. Follow-up was performed to a minimum of 6 months. Both patient and physician overall satisfaction rates were mostly excellent. Adverse events like lumps or irregularities were not encountered. Conclusion: Differential fat harvesting and posterior grafting is a valid alternative, to expand the repertoire of fat use, allow a more homogeneous effect, reduce the potential complications, speed up the process, improve graft survival, and to enhance overall aesthetic outcome.

  18. Nanostructured piezoelectric energy harvesters

    CERN Document Server

    Briscoe, Joe

    2014-01-01

    This book covers a range of devices that use piezoelectricity to convert mechanical deformation into electrical energy and relates their output capabilities to a range of potential applications. Starting with a description of the fundamental principles and properties of piezo- and ferroelectric materials, where applications of bulk materials are well established, the book shows how nanostructures of these materials are being developed for energy harvesting applications. The authors show how a nanostructured device can be produced, and put in context some of the approaches that are being invest

  19. Micro energy harvesting

    CERN Document Server

    Briand, Danick; Roundy, Shad

    2015-01-01

    With its inclusion of the fundamentals, systems and applications, this reference provides readers with the basics of micro energy conversion along with expert knowledge on system electronics and real-life microdevices. The authors address different aspects of energy harvesting at the micro scale with a focus on miniaturized and microfabricated devices. Along the way they provide an overview of the field by compiling knowledge on the design, materials development, device realization and aspects of system integration, covering emerging technologies, as well as applications in power management, e

  20. Accidental close-down of the Trollheim hydropower plant in July 2008. Effects on the fish populations in the river Surna; Utfall av Trollheim kraftverk i juli 2008. Effekter av fiskebestandene i Surna

    Energy Technology Data Exchange (ETDEWEB)

    Forseth, T.; Stickler, M.; Ugedal, O.; Sundt, H.; Bremset, G.; Linnansaari, T.; Hvidsten, N.A.; Harby, A.; Bongard, T.; Alfredsen, K.

    2009-01-15

    An accidental stop in the turbine in the Trollheim Hydropower Plant on 27th July 2008 caused a drop in downstream discharge in the River Surna from 21 to 3 m3/s during 100 min. River discharge was reestablished after three hours. The drop caused large dewatered areas (26 % of total wet area before the drop), but HEC-RAS simulations indicated that the ramping rates were relatively low (less than 20 cm per hour for the whole drop period in the modeled transects). Thus, a high proportion of the fish may have avoided stranding. Stranding mortality was estimated at approximately 14.000 0+ salmon and 3.600 older juveniles (70 % 1+), or the equivalent of approximately 3000 smolts. The loss constitutes less than 3% of the future smolt production downstream the power station (estimated by up-scaling from densities at electrofishing station, via mesohabitats to the whole river stretch) during 2009-2012. About one third of the smolts in the River Surna has been estimated to be produced in areas below the power plant. Between 3000 and 15 000 0+, and an unknown number of older brown trout likely also died from stranding, and the effect was probably larger for the juvenile population of brown trout than Atlantic salmon. All the above estimates are uncertain. Additional releases of water from the reservoir during, and one week after the drop, likely had no effects on the fish populations. The diversity of the zoobenthos communities in the river below the outlet of the power plant is low, likely due to large and frequent variation in discharge. The accidental stop in 2008 was probably particularly damaging, due to the large dewatered areas and low minimum discharge (far below the minimum allowed residual flow at 15 m3/s). This may temporarily reduce biomass and diversity of zoobenthos and thus prey availability for fish. Analysis of discharge data during the period from 2000 to 2008, show that despite measures implemented in the power plant (from 2006), there are several events

  1. Consumption patterns and why people fish

    International Nuclear Information System (INIS)

    Burger, Joanna

    2002-01-01

    Recreational and subsistence fishing play major roles in the lives of any people, although their importance in urban areas is often underestimated. There are fish and shellfish consumption advisories in the new York-New Jersey harbor estuary, particularly in the waters of the Newark Bay Complex. This paper examines fishing behavior, consumption patterns, and the reasons that people fish in the Newark Bay Complex. I test the null hypotheses that there are no differences among Asians, Blacks, Hispanics, and whites in consumption patterns for fish and crabs and in the reasons that they fish or crab. Most people either fished or crabbed, but not both. People who fish and crab ate more grams of crab than fish in a given meal; people who crab only consumed more grams of crab at a meal than those who fish only consumed of fish. Although 30% or more of the people who fished and crabbed in the Newark Bay Complex did not eat their self-caught fish or crabs 8-25% of the people ate more than 1500 g/month. Some people angling in the Newark Bay Complex are eating crabs at a rate well over 1500 g/month, and about 70% are eating crabs even though there is a total ban on both harvest and consumption because of the health risks from dioxin. Consumption patterns were negatively correlated with mean income and positively correlated with mean age. Most people rated relaxation and being outdoors the highest reasons or angling, although on an open-ended question they usually listed recreation. There were no ethnic differences in reasons for angling, although other studies have shown ethnic differences in consumption. Obtaining fish or crabs to eat, give away, trade, or sell were rated low, suggesting that consumption advisories fail partly because people are not primarily fishing or food

  2. Digging the pupfish out of its hole: risk analyses to guide harvest of Devils Hole pupfish for captive breeding

    Directory of Open Access Journals (Sweden)

    Steven R. Beissinger

    2014-09-01

    Full Text Available The Devils Hole pupfish is restricted to one wild population in a single aquifer-fed thermal pool in the Desert National Wildlife Refuge Complex. Since 1995 the pupfish has been in a nearly steady decline, where it was perched on the brink of extinction at 35–68 fish in 2013. A major strategy for conserving the pupfish has been the establishment of additional captive or “refuge” populations, but all ended in failure. In 2013 a new captive propagation facility designed specifically to breed pupfish was opened. I examine how a captive population can be initiated by removing fish from the wild without unduly accelerating extinction risk for the pupfish in Devils Hole. I construct a count-based PVA model, parameterized from estimates of the intrinsic rate of increase and its variance using counts in spring and fall from 1995–2013, to produce the first risk assessment for the pupfish. Median time to extinction was 26 and 27 years from spring and fall counts, respectively, and the probability of extinction in 20 years was 26–33%. Removing individuals in the fall had less risk to the wild population than harvest in spring. For both spring and fall harvest, risk increased rapidly when levels exceeded six adult pupfish per year for three years. Extinction risk was unaffected by the apportionment of total harvest among years. A demographic model was used to examine how removal of different stage classes affects the dynamics of the wild population based on reproductive value (RV and elasticity. Removing eggs had the least impact on the pupfish in Devils Hole; RV of an adult was roughly 25 times that of an egg. To evaluate when it might be prudent to remove all pupfish from Devils Hole for captive breeding, I used the count-based model to examine how extinction risk related to pupfish population size. Risk accelerated when initial populations were less than 30 individuals. Results are discussed in relation to the challenges facing pupfish recovery

  3. Effect of increased intake of fish and mussels on exposure to toxic trace elements in a healthy, middle-aged population

    DEFF Research Database (Denmark)

    Outzen, Malene; Tjønneland, Anne; Larsen, Erik Huusfeldt

    2015-01-01

    Fish and shellfish are rich in essential nutrients, but are also a source of exposure to environmental contaminants. We aimed to investigate the effect of increased fish and mussel intake on mercury, arsenic, lead and cadmium blood concentrations. We randomly assigned 102 healthy men and women (all...... non-smokers) aged 48-76 years to an intervention group (n = 51) or a control group (n = 51). Intervention participants received a high amount of fish and mussels for 26 weeks (1 kg week(-1)). Controls received no intervention and were expected to eat less than 300 g of fish and mussels per week. Whole...

  4. 78 FR 66683 - Fisheries in the Western Pacific; Special Coral Reef Ecosystem Fishing Permit

    Science.gov (United States)

    2013-11-06

    ... the Western Pacific; Special Coral Reef Ecosystem Fishing Permit AGENCY: National Marine Fisheries... special coral reef ecosystem fishing permit. SUMMARY: NMFS issued a Special Coral Reef Ecosystem Fishing Permit that authorizes Kampachi Farms, LLC, to culture and harvest a coral reef ecosystem management unit...

  5. 78 FR 49258 - Fisheries in the Western Pacific; Special Coral Reef Ecosystem Fishing Permit

    Science.gov (United States)

    2013-08-13

    ... the Western Pacific; Special Coral Reef Ecosystem Fishing Permit AGENCY: National Marine Fisheries... Reef Ecosystem Fishing Permit that would authorize Kampachi Farms, LLC, to culture and harvest a coral reef ecosystem management unit fish species in a floating pen moored about 5.5 nm off the west coast of...

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

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  7. Thermoelectrics and its energy harvesting

    National Research Council Canada - National Science Library

    Rowe, David Michael

    2012-01-01

    .... It details the latest techniques for the preparation of thermoelectric materials employed in energy harvesting, together with advances in the thermoelectric characterisation of nanoscale material...

  8. Fish health and fish quality

    DEFF Research Database (Denmark)

    Ingerslev, Hans-Christian

    Aquaculture is an expanding worldwide industry producing an increasing amount of fish every year. The quality of the fish meat is dependent upon many biological and non-biological factors. Infectious diseases are known to cause bleedings and damage of the muscle tissue that may lead to scarring...... are poorly described in fish. The present work in this thesis focused on: 1) examination of potential changes in the quality regarding texture of the muscle tissue in rainbow trout (Oncorhynchus mykiss) after previous infection with the bacterial pathogens Yersinia ruckeri and Vibrio anguillarum; 2...... of these studies showed that previous infections by Yersinia ruckeri and Vibrio anguillarum gave rise to subsequent changes regarding textural quality parameters in fresh fish meat, while no differences were seen for cold-smoked meat from the same fish. The texture in previous infected fish was less flaky and less...

  9. Stand, Harvest, and Equipment Interactions in Simulated Harvesting Prescriptions

    Science.gov (United States)

    Jingxin Wang; W. Dale Greene; Bryce J. Stokes

    1998-01-01

    We evaluated potential interactions of stand type, harvesting method, and equipment in an experiment using interactive simulation. We examined three felling methods (chain saw, feller-buncher, harvester) and two extraction methods (grapple skidder and forwarder) performing clearcuts, sheltenvood cuts, and single-tree selection cuts in both an uneven-aged natural stand...

  10. Population trends, bend use relative to available habitat and within-river-bend habitat use of eight indicator species of Missouri and Lower Kansas River benthic fishes: 15 years after baseline assessment

    Science.gov (United States)

    Wildhaber, Mark L.; Yang, Wen-Hsi; Arab, Ali

    2016-01-01

    A baseline assessment of the Missouri River fish community and species-specific habitat use patterns conducted from 1996 to 1998 provided the first comprehensive analysis of Missouri River benthic fish population trends and habitat use in the Missouri and Lower Yellowstone rivers, exclusive of reservoirs, and provided the foundation for the present Pallid Sturgeon Population Assessment Program (PSPAP). Data used in such studies are frequently zero inflated. To address this issue, the zero-inflated Poisson (ZIP) model was applied. This follow-up study is based on PSPAP data collected up to 15 years later along with new understanding of how habitat characteristics among and within bends affect habitat use of fish species targeted by PSPAP, including pallid sturgeon. This work demonstrated that a large-scale, large-river, PSPAP-type monitoring program can be an effective tool for assessing population trends and habitat usage of large-river fish species. Using multiple gears, PSPAP was effective in monitoring shovelnose and pallid sturgeons, sicklefin, shoal and sturgeon chubs, sand shiner, blue sucker and sauger. For all species, the relationship between environmental variables and relative abundance differed, somewhat, among river segments suggesting the importance of the overall conditions of Upper and Middle Missouri River and Lower Missouri and Kansas rivers on the habitat usage patterns exhibited. Shoal and sicklefin chubs exhibited many similar habitat usage patterns; blue sucker and shovelnose sturgeon also shared similar responses. For pallid sturgeon, the primary focus of PSPAP, relative abundance tended to increase in Upper and Middle Missouri River paralleling stocking efforts, whereas no evidence of an increasing relative abundance was found in the Lower Missouri River despite stocking.

  11. Variability in connectivity patterns of fish with ontogenetic migrations: Modelling effects of abiotic and biotic factors

    Directory of Open Access Journals (Sweden)

    Susanne Eva Tanner

    2015-10-01

    Full Text Available Connectivity is a critical property of marine fish populations as it drives population replenishment, determines colonization patterns and the resilience of populations to harvest. Understanding connectivity patterns is particularly important in species that present ontogenetic migrations and segregated habitat use during their life history, such as marine species with estuarine nursery areas. Albeit challenging, fish movement can be estimated and quantified using different methodologies depending on the life history stages of interest (e.g. biophysical modelling, otolith chemistry, genetic markers. Relative contributions from estuarine nursery areas to the adult coastal populations were determined using otolith elemental composition and maximum likelihood estimation for four commercially important species (Dicentrarchus labrax, Plathichtys flesus, Solea senegalensis and Solea solea and showed high interannual variability. Here, the effects of abiotic and biotic factors on the observed variability in connectivity rates and extent between estuarine juvenile and coastal adult subpopulations are investigated using generalized linear models (GLM and generalized mixed models (GMM. Abiotic factors impacting both larval and juvenile life history stages are included in the models (e.g. wind force and direction, NAO, water temperature while biotic factors relative to the estuarine residency of juvenile fish are evaluated (e.g. juvenile density, food availability. Factors contributing most to the observed variability in connectivity rates are singled out and compared among species. General trends are identified and results area discussed in the general context of identifying potential management frameworks applicable to different life stages and which may prove useful for ontogenetically migrating species.

  12. 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.

  13. Dynamic optimization of combined harvesting of a two-species fishery

    International Nuclear Information System (INIS)

    Chaudhuri, K.

    1986-06-01

    In the present paper, the author considers the problem of dynamic optimization of the exploitation policy connected with the combined harvesting of two competing fish species, each of which obeys the logistic growth law. The singular extremal trajectory in the phase plane is derived by taking the harvesting effort as a dynamic variable. Biological or bioeconomic interpretations of the constraints required for this singular extremal are also given. (author)

  14. Fish pelleting

    African Journals Online (AJOL)

    PUBLICATIONS1

    fish meal pelletizing machine utilized 4kg of ingredients to produce 3.77kg pellets at an effi- ciency of .... Design and fabrication of fish meal pellet processing machine ... 53 ... horsepower for effective torque application on .... two edges were tacked with a spot weld to hold ... then welded on to the shaft making sure that the.

  15. Fish parasites

    DEFF Research Database (Denmark)

    This book contains 22 chapters on some of the most important parasitic diseases in wild and farmed fish. International experts give updated reviews and provide solutions to the problems......This book contains 22 chapters on some of the most important parasitic diseases in wild and farmed fish. International experts give updated reviews and provide solutions to the problems...

  16. Fish reproduction

    National Research Council Canada - National Science Library

    Rocha, Maria João; Arukwe, Augustine; Kapoor, B. G

    2008-01-01

    ... of reproductive systems is essential for such studies. Fishes comprise over 28,000 species, with a remarkable variability in morphology, physiology and environmental adaptation. Knowledge on fish reproduction is scattered across numerous sources that shows a dynamic research field. The Editors believe it to be an opportune moment for a...

  17. Microalgae harvesting techniques: A review.

    Science.gov (United States)

    Singh, Gulab; Patidar, S K

    2018-07-01

    Microalgae with wide range of commercial applications have attracted a lot of attention of the researchers in the last few decades. However, microalgae utilization is not economically sustainable due to high cost of harvesting. A wide range of solid - liquid separation techniques are available for microalgae harvesting. The techniques include coagulation and flocculation, flotation, centrifugation and filtration or a combination of various techniques. Despite the importance of harvesting to the economics and energy balance, there is no universal harvesting technique for microalgae. Therefore, this review focuses on assessing technical, economical and application potential of various harvesting techniques so as to allow selection of an appropriate technology for cost effectively harvesting of microalgae from their culture medium. Various