Reproductive biology and conservation status of the loggerhead sea turtle (Caretta caretta) in Espirito Santo State, Brazil.

Abstract

The reproductive biology of loggerheads nesting in Espírito Santo, Brazil, is evaluated for six nesting seasons (1991/1992 through 1996/1997), through data gathered by Projeto TAMAR-IBAMA, the Brazilian sea turtle conservation program. Mean curved carapace length of nesting females was 102.7 cm (n=198). Mean clutch size for clutches with more than 50 eggs was 119.7 (n=3664), and clutch size was significantly correlated with female body size. Management practices had significant effects on hatching success and incubation time. Mean hatching success of nests left in situ was 68.3% (n=879), of undepredated nests left in situ was 79.9% (n=751), and of nests moved to hatcheries and not depredated was 67.7% (n=2786). For nests moved to hatcheries, hatching success declined significantly with increasing time interval between oviposition and transfer to the hatchery. Mean incubation time was 59.5 days for nests left in situ (n=572) and 57.2 days for nests moved to hatcheries (n=2179). Incubation time declined significantly throughout the nesting season as temperatures increased; we conclude that sex ratio of hatchlings also shifts to more females as the season progresses. There was significant annual variation for all parameters. A short review of the conservation status of loggerheads in Espírito Santo State is also presented.