Variation in Largemouth Bass Recruitment in Four Mainstream Impoundments of the Tennessee River

Abstract

Variation in recruitment of largemouth bass Micropterus salmoides was quantified in four mainstream impoundments along an 800-km segment of the Tennessee River and compared with various types of hydrologic and aquatic plant abundance data in an attempt to explain factors related to the formation of strong and weak year-classes. Residuals from four catch-curve regressions for age-2–11 fish collected in 1993 or 1994 were used to describe year-class strength. The formation of strong and weak year-classes was generally synchronous in these four reservoirs. Year-class strength was inversely related to average June–July discharge and positively associated with retention (reservoir volume/discharge) for data pooled from all reservoirs. Thus, weak year-classes were produced during wet early-summer conditions after largemouth bass hatched, whereas stronger year-classes were produced during dryer early-summer conditions. Late-summer aquatic plant abundance and water level fluctuations during April–May while spawning was occurring were not related to largemouth bass recruitment in these four reservoirs. We speculated that higher discharges and faster flushing rates were associated with reduced production at lower trophic levels and poorer survival of young largemouth bass that ultimately affected recruitment to adult size.