Predation patterns on the inshore spawning grounds of the squid Loligo vulgaris reynaudll (Cephalopoda: Loliginidae) off the south-eastern Cape, South Africa

Abstract

The feeding patterns of fish caught on the inshore (<50 m deep) spawning grounds of chokka squid Loligo vulgaris reynaudii were investigated between November 1988 and September 1990. Fish were sampled by demersal trawl, gillnet, handline and longline. SCUBA was used to observe interactions in situ. Potential predators consisted of 16 species each of teleost and elasmobranch. Of the teleosts, five species preyed on whole squid and one appeared to have scavenged squid fragments. Of the elasmobranchs, 12 species had squid in their stomachs, nine of these with a high incidence (>33% frequency of occurrence). The squid were in spawning condition when taken and no spent squid were recovered from stomach contents. There was no evidence that squid had been moribund when ingested and no dead or moribund squid were encountered while diving during the two-year study. Cannibalism by squid was observed. Marine mammals and avian predators were rarely sighted on the spawning grounds.