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Growth of spiny lobster palinurus gilchristi (decapoda: palinuridae) off South Africa
Abstract
Growth of spiny lobster Palinurus gilchristi was investigated on four traditional lobster fishing grounds, Agulhas Bank, St Francis, Port Elizabeth and Port Alfred, using tagging data. Of 11 144 individuals tagged in
six tagging sessions between 1988 and 1993, 1 031 (9.25 %) were recaptured by May 1995. Most P. gilchristi moult once annually, between December and February. Moult frequency decreases with increasing length, as do annual growth increments and moult increments. Males grow marginally faster than females. Annual growth increments at Port Alfred were significantly smaller than at Agulhas Bank, St Francis and Port Elizabeth, but growth
did not differ significantly between the last three areas. Growth models based on moult increment-at-size and intermoult period-at-size gave realistic descriptions of growth, but Von Bertalanffy L ∞ ‡ parameters underestimated observed maximum carapace lengths. It is suggested that regional variations in the growth of P. gilchristi result from intraspecific competition for food, which is greatest on narrow shelf regions.
six tagging sessions between 1988 and 1993, 1 031 (9.25 %) were recaptured by May 1995. Most P. gilchristi moult once annually, between December and February. Moult frequency decreases with increasing length, as do annual growth increments and moult increments. Males grow marginally faster than females. Annual growth increments at Port Alfred were significantly smaller than at Agulhas Bank, St Francis and Port Elizabeth, but growth
did not differ significantly between the last three areas. Growth models based on moult increment-at-size and intermoult period-at-size gave realistic descriptions of growth, but Von Bertalanffy L ∞ ‡ parameters underestimated observed maximum carapace lengths. It is suggested that regional variations in the growth of P. gilchristi result from intraspecific competition for food, which is greatest on narrow shelf regions.
