Fecundity of spiny lobster Palinurus gilchristi (Decapoda: Palinuridae) off South Africa

Abstract

Fecundity of spiny lobster Palinurus gilchristi was investigated on traditional lobster fishing grounds on the Agulhas Bank, from Mossel Bay to Algoa Bay, and Port Alfred, based on early- and late-stage egg masses collected from 415 mature females (58–118mm carapace length, CL). Fecundity increased linearly with increasing CL, and was significantly lower in length-classes >80mm CL at Port Alfred than on the Agulhas Bank and Mossel Bay to Algoa Bay, where it was similar. Egg loss during incubation was estimated at 14–17%, and was consistent over the size range sampled and among areas. Females on the Agulhas Bank carried more eggs in 2000 than in 2002. Small females of 65–79mm CL contributed 93% to egg production at Port Alfred, but at fishing grounds west of Algoa Bay larger females of 70–94mm CL contributed 84% to egg production. This difference translates into a lifetime egg production per recruit (E/R) over 30 years, starting at 50% maturity, of 0.39 million eggs per female at Port Alfred compared with 0.83 million eggs west of Algoa Bay. The lower fecundity and E/R at Port Alfred, compared with sites west of Algoa Bay, are consistent with geographic trends in growth, size at sexual maturity, and average lobster size showed for P. gilchristi in earlier studies.