Genetic structure of the hawksbill turtle rookery and foraging aggregation in Tobago, West Indies

Abstract Mitochondrial DNA control region haplotypes of immature hawksbills feeding in Tobago waters and adult females nesting on the beaches of Tobago were characterized. Eleven haplotypes were documented among foraging aggregations and six haplotypes among nesting females, including two which were previously of unknown natal origin. The Tobago rookery is genetically distinct from all other rookeries in the region characterized to date. Significant genetic differentiation was found between the foraging aggregations on the windward and leeward sides of Tobago. Within the rookery, greater diversity was detected among samples from the North-East coast compared to samples from the South-West coast, however no significant difference was detected based on pairwise F ST. Mixed stock analysis was conducted to estimate the natal origins of immature hawksbills foraging in Tobago waters and the contribution of the Tobago rookery to regional foraging aggregations using rookery size as a constraint. The analysis estimated that the Tobago foraging aggregation is mostly composed of animals originating from Cuba, Barbados (Leeward Coast) and Puerto Rico, though this represents only a small fraction of the production from these rookeries. The impact of harvest of juveniles in Tobago is likely to be distributed across the region and not concentrated on any particular rookery. A significant proportion of individuals from the Tobago rookery contributes to the foraging aggregation of the Cayman Islands, and a large proportion of both the Cayman Islands and Puerto Rico foraging aggregations are derived from the Tobago rookery.