Abstract

Population dynamics of the spotted spiny lobster, Panulirus guttatus, were examined at Looe Key Reef, Florida, USA, from April 1987 to August 1989. The 347 lobsters captured (including recaptures), ranged from 9 mm (puerulus) to 75 mm carapace length (X = 54 mm CL). Pueruli settled all year round into small holes along the underside of the reef. All lobsters recaptured were found at the site of their initial capture; one was captured four times, all on the same reef spur, over 762 days. Adults sheltered within the reef during the day and foraged on top of the reef at night. Males and females were captured in equal proportions (1.2 M:1 F) from den entrances during the day; females were numerically dominant on foraging grounds at night (3 F:1 M). Reproduction occurred all year round but peaked between March and June; minimum size at maturity was 38 mm CL for females and 48 mm CL for males. The sheltering behaviour of P. guttatus, typically found on the ceiling of dens, contrasted markedly with that of the sympatric P. argus, typically found on the floor; both species used many of the same dens, but simultaneous co-occupancy was rare.