Invasive species from the highly endemic fish fauna of Lake Biwa threatening freshwater fish in rivers of the Kanto region

Abstract

The highly endemic fish fauna of Lake Biwa has not only been a source of invasive species to other Japanese freshwaters through the activities of fish stocking, but has also itself been threatened by invasive species from other freshwaters as well as by habitat destruction. In rivers of the Kanto region, an analysis of the mitochondrial cytochrome-b gene revealed that populations of the freshwater fish Zacco platypus are composed of two distinct lineages, i. e., the native Kanto and the non-indigenous L. Biwa lineage. The latter was inadvertently introduced along with the stock of the ayu Plecoglossus altivelis from the lake. Since the stocking has been reported as not contributing to the recruitment of the next generation in the rivers, terminating the stocking is advisable for preventing invasive species as well as for sustaining the ayu stock.