engleski

Sex ratios of juvenile loggerhead sea turtles, Caretta caretta, in the eastern Adriatic Sea and implications for conservation

We examined sexes of 33 juvenile loggerheads by morphological and histological analysis of gonads Visual examination of gonads resulted in a 1:1 ratio, while histology gave a slightly male-biased sex ratio, but not significantly different from a 1:1 ratio (chi-sq.= 2.00, p = 1.157). Our results are in discordance with the strong female-biased loggerhead hatchlings production on the Mediterranean nesting beaches. However, they confirm results on male-skewed sex ratios of juvenile loggerheads from central Mediterranean, supporting the theory on male-biased immigration of juveniles from north-western Atlantic populations into the Mediterranean. If we consider that about 50% of pelagic juveniles in the Mediterranean originate from NW Atlantic, most of them being males, such male-skewed immigration is likely to buffer the original female-bias of the Mediterranean juvenile populations. The sex ratio in our study suggests that the male-biased dispersal of NW Atlantic juveniles reaches the Adriatic Sea, classifying these waters as a habitat shared by juveniles belonging to both Mediterranean and NW Atlantic populations. As in juvenile loggerheads males seem to disperse farther than females, considering a higher reproductive value of females, human impact, such as fishery, would affect more populations from closer nesting sites than the distant ones. Therefore, high by-catch in Adriatic fisheries would have the most detrimental effect for juvenile loggerheads from the regional nesting grounds.

sea turtles; sex ratios; migrations; conservation

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