Trophic Dynamics of a Slow Growing Age-0 Largemouth Bass Cohort from a Virginia Small Impoundment

Abstract

ABSTRACT In order to identify what prey items may be important to age-0 fish growth, we monitored concurrent changes in length distribution and diet of an age-0 largemouth bass cohort from an impoundment where largemouth bass growth was severely reduced. Average size of the age-0 largemouth bass cohort increased with subsequent sampling periods, although growth rate did slow with later collections. By early November, age-0 largemouth bass averaged approximately 80 mm in total length, which ranks the impoundment among the slowest in terms of growth in the southeastern United States. Although age-0 largemouth bass did exhibit distinct shifts in diet with ontogeny, larger fish did not switch to piscivorous feeding but instead maintained a diet quite similar to smaller fish. We attribute slow growth of age-0 largemouth bass in this impoundment to restricted consumption of Diptera larvae, which has been found to be an important food resource elsewhere. Availability of Diptera larvae may be limited due to competition with panfish and aggravated by basin morphology of the impoundment.