Fishing and Natural Mortality: Effects on the Initial Year Class of Largemouth Bass in West Point Reservoir, Albama-Georgia

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Abstract
Rates of growth, fishing mortality, and natural mortality of the initial (1975) year class of largemouth bass (Micropterus salmoides) in 10,481‐hectare West Point Reservoir were estimated over a 2‐year period by rotenone sampling, electrofishing, and tagging studies. The estimate of an initial standing stock of 1,617 largemouth bass or 28.3 kg/hectare in August 1975 was reduced to 1.5 largemouth bass or 1.6 kg/hectare by August 1977. Instantaneous annual rates of growth, fishing mortality, and natural mortality were 2.19, 1.17, and 2.78, respectively, in the first year, and 0.65, 0.92, and 2.11 in the second. Total yield from the 1975 year class was 21.4 kg/hectare, of which 95% was harvested during the first year of impoundment, through August 1976. Natural and fishing mortality reduced the standing crop of 1975 largemouth bass by 88.2% (58.6% natural, 29.6% fishing) in the first year and 86.2% (69.1% natural, 17.1% fishing) in the second. The abundant initial year class of bass was responsible for creating a fishing “boom.” Population structure change brought about by high natural mortality and fishing mortality resulted in a “bust” in largemouth bass fishing after 2 years of impoundment.

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