Spawning season of the Chinese false gudgeon, Abbottina rivularis, in Katada Naiko, Lake Biwa

Abstract

　The reproductive cycle of Abbottina rivularis was investigated at Katada Naiko on the shore of Lake Biwa in Shiga Prefecture, Japan. By casting net sampling, specimens were collected every season from August 2001 through June 2005. Of the 37 female specimens collected from November through May, 34 were mature. The females collected between late February and mid- April exhibited a large body size and high gonadosomatic index （GSI）. Of the 31 male specimens collected from October through May, 30 were mature. All the males collected between February and May had pearl organs on their pectoral fins, and some males collected between March and May exhibited a large body size and high GSI. These results suggest that at Katada Naiko, the reproductive cycle of A. rivalaris occurs over 1.5 months from late February through mid-April.