Eretmochelys, Fitzinger, 1843

Meylan, Peter A., Meylan, Anne B. & Gray, Jennifer A., 2011, The Ecology And Migrations Of Sea Turtles 8. Tests Of The Developmental Habitat Hypothesis, Bulletin of the American Museum of Natural History 2011 (357), pp. 1-70 : 53

Eretmochelys

BERMUDA: The histogram showing the size distribution of Eretmochelys in figure 13 A has the same shape as that for C. mydas in figure 5 A, with a steep left side, approximately equal columns for size classes 20–55 cm (vs. 30–60 for C. mydas ), and a drop-off from 60–75 cm. As for C. mydas , this shape is best explained by arrival of hawksbills from the epipelagic stage into the benthic developmental stage, residency in Bermuda for much of the immature growth period, and then departure as sexual maturity is approached. The evidence for hawksbills occurring in adjacent epipelagic environments is stronger for this species than for C. mydas , with six stranded hawksbills smaller than the smallest hawksbill known from the Platform being documented by the stranding network. The smallest Eretmochelys caught on the Bermuda Platform (17.6 cm SCL) is smaller than that reported from other sites that likely serve as benthic developmental habitat for this species, but not remarkably so.

The few necropsies available of large Eretmochelys have so far revealed no turtles that were mature. The largest of these was larger that the minimum size of maturity observed to date for this species in the Atlantic. There is a single international tag return of a 50 cm SCL hawksbill tagged in 1989 in Bermuda and recaptured in Grenada in 2000.

Four studies of Eretmochelys at foraging sites in the West Atlantic (table 11) show a similar maximum size of immatures; a fifth has nesting sites adjacent to the areas where immatures were being studied.

THE LITERATURE: Studies by Nietschmann (1981), Boulon (1994), van Dam and Diez (1998a), and Meylan (1999) in the Caribbean, and Limpus (1992) in Australia reported relatively few long-distance tag returns of immature hawksbills. In some cases, howev- er, movements of immatures may be extensive. Three Eretmochelys tagged as immatures in known benthic developmental habitat in Brazil made trans-Atlantic migrations to West Africa. Marcovaldi and Filippini (1991) reported an immature hawksbill that made a developmental migration of 3680 km, from Atol das Rocas, Brazil, to Dakar, Senegal. The turtle that made this remarkable journey was 74 cm SCL when recaptured, a size at which it would be expected to begin the maturation process on the adult foraging grounds. Two additional hawksbills originally tagged at Fernando de Noronha were recaptured in Corisco Bay on the border between Equatorial Guinea and Gabon ( Grossman et al., 2007). Meylan (1999: table 1) summarized the few developmental migrations of hawksbills known from the greater Caribbean.