Microhabitat Associations of Late Juvenile Nassau Grouper (<I>Epinephelus Striatus</I>) Off Little Cayman, BWI

Abstract

Populations of the economically and ecologically important Nassau grouper, Epinephelus striatus Bloch, 1792, have declined to the point of being declared endangered by the International Union for the Conservation of Nature. Beyond existing efforts to reduce top-down pressure from overfishing, especially on spawning aggregations, recovery of Nassau grouper could be enhanced by preventing bottom-up pressures created by degradation of essential habitats. The design of suitable protection would benefit from knowledge of ontogenetic patterns in habitat use at multiple spatial scales, and this study documented microhabitat associations for late juvenile Nassau grouper in shallow, nearshore lagoons off Little Cayman Island. In total, 82% of juvenile grouper that were 12-26 cm in total length and approximately 1 yr old associated with hardbottom rather than other equally or more widespread microhabitats, i.e., sand, seagrass, and algae. Hardbottom provided crevices, holes, ledges, and other shelters. Approximately 96% of shelters contained a single juvenile grouper, and 10%-66% of these shelters also contained one or more cleaning organisms. These results suggest that protection of hardbottom in Little Cayman Island's lagoons would maintain the >1200 patches of microhabitat suitable for late juvenile Nassau grouper.