MEPS 432:269-276 (2011)  -  DOI: https://doi.org/10.3354/meps09125

ABSTRACT: A generalized additive mixed modelling approach was used to investigate the somatic growth of hawksbill turtles Eretmochelys imbricata (23.7 to 80 cm curved carapace length [CCL]) on nearshore coral reef sites around Barbados at depths of 12 to 35 m. The effects of body size, sex, ­sampling year, recapture interval and an indicator of foraging habitat quality on growth rates were ­investigated. The model accounted for about 60% of the variance in growth rates, but only mean size and sampling year were significant predictors. The growth rate function was nonmonotonic, with peak growth (3.4 cm yr^–1) occurring in turtles with a CCL between 30 and 35 cm. The lower growth rates recorded for smaller turtles may reflect a period when sea turtles newly recruiting from pelagic to neritic habitats are adapting to a change in diet. The decline in growth rates with sampling year over the 10 yr study may reflect density-dependent effects on growth. Declining growth rates may prompt large juveniles to leave the Barbados foraging ground to settle elsewhere to grow to maturity.

KEY WORDS: Eretmochelys imbricata · Growth rate modelling · Barbados · Developmental habitat · Foraging ground · Density-dependent effect · Generalized additive mixed model