CHARACTERIZATION OF A HAWKSBILL TURTLE (ERETMOCHELYS IMBRICATA) FORAGING AGGREGATION IN A HIGH-LATITUDE REEF COMMUNITY IN SOUTHEASTERN FLORIDA, USA

A foraging aggregation of Hawksbill Turtles (Eretmochelys imbricata) on the Southeast Florida Continental Reef Tract off Palm Beach County, Florida, is the first described within the waters of the continental United States. The aggregation is the second most northerly known in the western Atlantic; its existence may be due in part to the proximity of the Florida Current. We captured 146 individual hawksbills 181 times at 44 dive sites over 5.5 y. We captured turtles on five benthic habitat types. Individuals varied from 35.7 to 83.9 cm SCLn-t and > 95% were likely to be immature; thus the site serves primarily as developmental habitat. Captures and observations of tagged turtles indicate year-round presence; average observed residency was 24.9 mo (up to 73 mo). The average distance between researcher dive initiation sites associated with sequential observations of individual turtles was 1345 m, indicating a high degree of site fidelity. Control region (mtDNA) sequences for 112 individuals showed a predominance (> 65%) of haplotypes associated with Mexican nesting beaches. The minimum size of hawksbills captured at the study site suggests that the turtles have already spent time in benthic developmental habitat elsewhere. Observation rates and growth rates were comparable to those at several Caribbean sites, indicating that this high-latitude reef system constitutes primary habitat for this species.