Recruitment overfishing and resilience in spiny lobster populations

Abstract

Pollock D. E. Recruitment overfishing and resilience in spiny lobster populations. - ICES J mar. Sei. 50: 9-14. In many spiny lobsters, lifetime egg production per recruit, population egg production, and average larval settlement are all linked to mean size at maturity of females. Size at maturity is labile in these crustaceans, and like juvenile growth and survival rates, is greatly influenced by density-dependent factors. Changes in size at maturity of females (and hence in lifetime egg production per recruit) enables increases or decreases in population egg production to lake place, regulating average long-term larval settlement intensity, and increasing or decreasing the degree of density-dependence of juvenile growth and survival rates. The latter determines the annual rate of recruitment to the adult slock, and together with maturity size, determines the annual egg production from the population. A feed-back process is operative, such that if egg and larval production declines to a large extent (as a result of sustained environmental changes or overfishing), growth and survival rates of juveniles increase, us does mean size at maturity of females. Increased fecundity per recruit then helps to offset the reduced egg production. This process may help explain the remarkable degree of resilience which some lobster populations display in response to high exploitation rates, but also suggests that recruitment overfishing may be currently taking place in several heavily fished lobster stocks. © 1993 Conseil International pour l’Exploration de la Mer.