A snapshot of cannibalism in 0-group Atlantic cod (Gadus morhua) in a marine pond

Cannibalism in O-group Atlantic cod (Gadus morhua) was investigated in a semi-natural marine pond using stomach content analysis. About 6000 individuals were eradicated by rotenone treatment of the pond in November 1991. Total lengths of cod ranged from 7.4-28.8 cm with a median of 10.4 cm. The proportion of cannibalistic cod in the population was estimated at 1.3%. Cannibalism accounted for a daily loss of 1.1% of the population. The frequency of cod with greater than or equal to 2 cod prey per stomach was higher in the population compared with a Poisson model. Predator-prey length ratios ranged between 1.6 and 3.2 when estimated from otolith-length relationships. Chesson's 1983 alpha-index indicated that cannibalistic cod had a positive selectivity for conspecifics < 9.0 cm in total length.