M.T. Driscoll, L.E. Miranda, and S.W. Raborn, 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, black bass, diet overlap, feeding
competition, null models, reservoirs
For competition to occur, two or more species must have to share a food
resource, and the resource must be limited in quantity. We measured diet overlap between
striped bass Morone saxatilis and smallmouth bass Micropterus dolomieu,
spotted bass M. punctulatus, largemouth bass M. salmoides, black crappie Pomoxis
nigromaculatus, sauger Stizostedion canadense, and walleye S. vitreum to
assess if striped bass shared their food with coexisting game fishes in Norris Reservoir.
Stomach contents of striped bass and the selected predator species were examined monthly
for a 12-month period (N = 3,584 stomachs). Pianka’s and Czechanowski’s resource
overlap indexes (0 = no overlap, 1 = full overlap) were applied to measure diet
overlap, and null models used to assess if overlap was more than expected by chance. Diet
overlap values ranged from 0 to 0.99, and varied seasonally and between species.
Significant diet overlap between striped bass and other game fishes occurred with all
species (except largemouth bass), but not in all seasons. Our results indicate that
exploitative competition between striped bass and coexisting game fishes is plausible if
the prey supply to predator demand ratio is low.