2017 Volume 11 Pages 29-40
Abstract The native piscivorous fish Opsariichthys uncirostris uncirostris, a representative vulnerable species, were investigated at the northwest shoreline of Lake Biwa, central Japan. Fourteen females and 51 males were captured; their sex ratio was biased to males. Remarkably, all of the females had empty guts. The overall empty gut ratio (0.83 overall) was higher than that in Lake Biwa in 1963 (<0.5 throughout the year). The length–weight relationship analysis found a negative allometric growth in females, though the sample size for this analysis was small. Future studies must examine the relationship between the recent reduction in catch, biased sex ratio, and negative allometric growth in females.
