Importance of Reservoir Inflow in Determining White Bass Year-Class Strength in Three Virginia Reservoirs

Abstract

The relationship between spring inflows and the year-class strength of white bass Morone chrysops was examined in three main-stem Virginia reservoirs. The catch of age-1 white bass in fall gill-net samples from 1980 to 1998 was used as an index for year-class strength in Claytor Lake and Kerr Reservoir. Claytor Lake was sampled by electrofishing during the spring spawning run in 1996, and the residuals associated with catch-curve regressions were computed to estimate year-class strength. In Leesville Reservoir, white bass recruit to gill nets at age-0; therefore, the catch per effort of age-0 white bass was used as an indicator of year-class strength. Strong year-classes (≥0.03 fish/9.29 m² of gill net) were rare in each reservoir. In Claytor Lake, strong year-classes were produced in 1987 and 1993, both years of high spring inflows. Lake inflows during April were also positively related to the year-class strength of white bass in Kerr and Leesville reservoirs and explained about 90% of the variation in age-1 catch per effort. In all reservoirs, poor or missing year-classes were most common during years with low flow. If sporadic white bass year-class strength is partly due to climatic conditions, then equations derived to forecast year-class strength should facilitate decisions about stocking during low-flow years or adjusting regulations to optimize the use of available resources.