Effects of Reservoir Water Levels on Year-class Development and the Abundance of Harvestable Fish

Résumé du livre

The single most important variable affecting the production of harvestable fish is mortality. Major sources of mortality such as starvation and predation often can be reduced by manipulating water levels during the growing season. Condition (weight at a discrete length) of largemouth bass was positively correlated to average surface area in summer and maximum change in area per year. Mortality due to starvation was apparently reduced by extensive spring flooding and above-average summer water levels. Above-normal water levels in summer also may reduce predatory mortality of young fishes by providing additional refuge from predators. The degree to which a single year class of fish dominates a population apparently is influences by the extent of annual and multiyear changes in water levels. Fish exhibited boom and bust patterns of recruitment in Bull Shoals Lake, Ark., where levels changed extensively within and among the years. In contrast, annual recruitment of fish was more uniform in John H. Kerr lake, Va., where water levels varied less extensively within and among years than in Bull Shoals Lake. Originator-supplied keywords: Fisheries, Fish ecology, Hydrology, Reservoire ecology.