Habitat effect on hawksbill turtle growth rates on feeding grounds at Mona and Monito Islands, Puerto Rico

Abstract

Carapace length growth data were obtained from 197 hawksbill turtles Eretmochelys imbricata which were marked and recaptured from 1992 to 2000 at feeding grounds of Mona and Monito Islands, Puerto Rico. Straight-line carapace length (SCL) upon initial capture ranged from 20.0 to 84.5 cm. SCL growth rates ranged from -0.59 to 9.08 cm yr-1, were non-monotonic, and averaged highest in turtles measuring 34 to 35 cm. Somatic growth rates varied by site within the study area, with turtles from the aggregation at Monito Island growing on average 2.1 times faster than residents of Mona Island habitats. Aggregation density and body condition index (body mass SCL-3) were also highest at Monito Island. Hawksbills recruiting to Monito Island at 23 cm SCL are expected to reach maturity less than 14.7 yr later. Growth rates in the turtles studied are similar to those reported for other Caribbean localities, but faster than hawksbills of the southern Great Barrier Reef, Australia. Hawksbills appear capable of utilizing habitats of widely varying quality, with prey abundance exerting a strong effect on somatic growth rates.