L.E. Miranda, S.W. Raborn, and M.T. Driscoll, Mississippi
Cooperative Fish and Wildlife Research Unit, P.O. Box 9691, Mississippi State, Mississippi
39762; Voice 601-325-3217; FAX 601-325-8726; E-Mail smiranda@cfr.msstate.edu or sraborn@cfr.msstate.edu
Keywords: striped bass, stocking, reservoirs, prey inadequacy,
supply-demand, fish production, bioenergetics
If density of striped bass in Norris Reservoir is reduced or eliminated
through modifications of the stocking program, additional prey would become available to
native game fishes. Such release of prey once tied up in striped bass biomass and its
maintenance, may partially or entirely be shifted to other predators. An increase in
biomass of other predators would be a function of the amount of prey that is released, the
efficiency with which that prey is captured, and the efficiency with which the prey is
transformed into additional biomass. We simulated reductions in striped bass prey demand
by reducing current levels of striped bass biomass by several levels ranging from 0 to
0.75. Capture efficiency was unknown so we modeled several values ranging from 1 to 0.125.
A bioenergetics model was used to estimate assimilation efficiency of the native species,
as well as total prey demand by the modeled biomass of striped bass. Our results indicated
that reducing striped bass biomass would increase supply-demand ratios by as much as 25%
if striped bass were removed. Such removal would increase prey supply in the reservoir by
an estimated 63.5 kg/ha. This additional supply would increase biomass of native game fish
by as much as 12.7 kg/ha, or about 20%, if capture efficiency is 1.0. Nevertheless, it is
unrealistic to assume that all the prey released by striped bass would be consumed by
other predators, thus smaller increases should be expected.
