Dietary changes in an introduced largemouth bass (Micropterus salmoides) with biomanipulation in Lake Shirakaba

Abstract

Many studies have reported feeding habits of the introduced largemouth bass, Micropterus salmoides, associating their presence with ecological impacts on native prey communities. However, few studies have been conducted on the dietary changes of the bass after exploitation of the native communities. In this study, we investigated the feeding habits of an introduced largemouth bass population in Lake Shirakaba, in which biomanipulation substantially depressed a planktivorous fish population and, in-turn, increased the meso-zooplankton density. Following the manipulation, the bass population shifted its diet from the planktivorous fish to the meso-zooplankton. Although the ontogenetic niche shift from planktivory to piscivory has been frequently reported in this species, few studies have reported that largemouth bass adults show strong reliance on zooplankton prey. A possible mechanism for dietary changes in this population is a flexible response to food availability in changing prey communities.