Initial impact on a pond community by a short term invasion of Micropterus salmoides

Abstract

Largemouth bass invaded a small pond in Northern Miyagi Prefecture. We captured all the invaded 82 individuals of largemouth bass immediately after discovery. The record of the environmental factor showed that we found the largemouth bass 13 days after the invasion. Gastric content analysis showed that each largemouth bass ate an average of 3.0 individuals of freshwater fauna such as Acheilognathus melanogaster and Paratya compressa improvisa. The total population of freshwater fauna which inhabited in the pond was estimated at about 9,000 individuals before the largemouth bass invaded. The estimate based on these results showed that the largemouth bass ate 3,172 individuals (35.2%) of prey during the 13 days. The initial influence on fauna by the invasion of the largemouth bass has been reported. This report provides important evidence about the influence of predation pressure of largemouth bass causing a decrease of freshwater fauna.