Factors related to age-0 sport-fish abundance in four mainstem Missouri River reservoirs.

Radigan, W. J. and M. J. Fincel. In Preparation. Factors related to age-0 sport-fish abundance in four mainstem Missouri River reservoirs. Fisheries Management and Ecology.

The age-0 abundance of eight sport fish species in the four mainstem Missouri River reservoirs in South Dakota was evaluated to estimate the influence environmental and biological factors had on age-0 species abundance. Datasets (at least ten consecutive years) from each reservoir were analyzed to evaluate the effects of both monthly (i.e., gage height, temperature, and precipitation) and annual (i.e., cooling degree days and heating degree days, minimum, average, and maximum temperature, average precipitation) environmental factors. Biological factors including age-0 prey fish abundance (i.e., gizzard shad [Dorosoma cepedianum] abundance), age-0 sport fish abundance, and adult sport fish abundance were also examined. Factors were included that are known to have impacts on abundance of age-0 sport fish in other systems. The abundance of all sport fish species was stable or increasing in all reservoirs, except for black crappie (Pomoxis nigromaculatus) in Lake Francis Case and walleye (Sander vitreus) and white bass (Morone chrysops) in Lewis and Clark Lake. Findings of the current study highlight the need for species-specific management of both environmental (i.e., flow manipulation) and biological factors (i.e., harvest limits for sport fish) to increase the abundance of age-0 sport fish. Due to the dynamic nature of aquatic systems, resulting requirements for management agencies are system-specific evaluations and management approaches.