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Acoustic Techniques for Estimating Fish Abundance
IEEE Transactions on Geoscience Electronics, 1972Echo counting and echo integration are two acoustic techniques for estimating the abundance of fish stocks. Mathematical models for the echo counting and echo integrating systems are presented and analyzed. Expressions for the mean squared errors of the abundance estimate obtained with each system are obtained.
J. E. Ehrenberg, D. W. Lytle
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Climate change: Large-scale abundance shifts in fishes
Current Biology, 2021Warming seas are driving a mass-scale restructuring of marine life, with observed responses expanding beyond species' range shifts. New evidence highlights large regions where ecological change has been dominated by the declining abundance of species that prefer cooler waters.
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Acoustical measurement of fish abundance
The Journal of the Acoustical Society of America, 1990The theory of echo formation provides formulas relating echo energy to physical characteristics of the target. Single-target theory (applicable to counting isolated fish) is extended to the multiple-target case relevant to schooling fish. An echo-integrator equation relates fish density to echo energy integrated over a time gate corresponding to the ...
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Target strengths of two abundant mesopelagic fish species
The Journal of the Acoustical Society of America, 2015Mesopelagic fish of the Myctophidae and Sternoptychidae families dominate the biomass of the oceanic deep scattering layers and, therefore, have important ecological roles within these ecosystems. Interest in the commercial exploitation of these fish is growing, so the development of techniques for estimating their abundance, distribution and ...
Scoulding, B.C. +3 more
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Evaluating impacts of forage fish abundance on marine predators
Conservation Biology, 2021Abstract Forage fish—small, low trophic level, pelagic fish such as herrings, sardines, and anchovies—are important prey species in marine ecosystems and also support large commercial fisheries. In many parts of the world, forage fish fisheries are managed using precautionary principles that target catch limits below the maximum ...
Christopher M. Free +2 more
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Fish abundance, distribution, and habitat use
1999The 1996 controlled flood in the Colorado River, Grand Canyon, was designed, in part, to improve conditions for juvenile native fishes by reshaping habitat and displacing non-native fishes. We examined changes in abundance and distributions of native and non-native fishes immediately before and after the controlled flood and recovery of affected ...
Timothy L. Hoffnagle +2 more
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Statistical Power of Trends in Fish Abundance
Canadian Journal of Fisheries and Aquatic Sciences, 1987Estimation errors inherent in stock assessment methods may make it difficult to estimate time trends in fish abundances correctly. Our objective was to quantify the probability that trends in abundance of recruits will be successfully identified. For this analysis, we used an empirically based simulation model of English sole (Parophrys vetulus) off ...
Randall M. Peterman, Michael J. Bradford
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Fish Abundance Information and Fishery’s Aggregate Behavior
Journal of the Association of Environmental and Resource Economists, 2020AbstractWe analyze a competitive fishery with congestion in which each skipper is privately informed about fish abundance, and we study the broader implications for the entire fishery.
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Trends in the abundance of marine fishes
Canadian Journal of Fisheries and Aquatic Sciences, 2010The Convention on Biological Diversity (CBD) established a target in 2002 to reduce the rate of biodiversity loss by 2010. Using a newly constructed global database for 207 populations (108 species), we examine whether the 2010 target has been met for marine fishes, while accounting for population biomass relative to maximum sustainable yield, BMSY ...
Jeffrey A. Hutchings +4 more
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The Effects of Fishing on Coral Reef Fish Abundance and Diversity
Journal of the Marine Biological Association of the United Kingdom, 1996The effect of artisanal fishing on the abundance and diversity of coral reef fish assemblages was investigated in the Kisite Marine National Park and Mpunguti Marine National Reserve at Shimoni, Kenya. Fishing is prohibited within the Park whereas in the Reserve artisanal fishing using traditional methods is practised.
Maggie Watson +3 more
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