Individual Differences in Egg Cannibalism in Female Dark Chub (Pisces: Cyprinidae)

Abstract

Nine of 41 identifiable females of dark chub, Zacco temmincki, in a river cannibalized eggs of other females. There was no significant difference in body size, condition factor or the location of home range between cannibals and noncannibals. In laboratory experiments, one male and two females were introduced into an aquarium to observe the behaviour of individual females while a pair spawned. The response of 16 females to spawning was observed and 15 of 16 females exhibited egg cannibalism. The percentages of egg-eating behaviour for individual females varied from 11.1 to 81.8%, and did not change significantly over the course of the experiment. Dark chub were multiple spawners. In a river the number of spawning sequences for cannibals was significantly higher than that for noncannibals. The number of eggs laid by cannibals was estimated to be 1.55 times as many as that by noncannibals.