ISTS: Using molecular genetics and biotelemetry to study life history and long distance movement: A tale of two turtles.

Molecular genetics and biotelemetry are powerful tools that have been used to study sea turtle movements and life history (Bowen 1995) (Balazs 1994). Together they can pro- vide empirical evidence for previously stated hypotheses, increase our understanding of habitat use, migration routes, and suggest further research lines on the interrelationships between nesting and feeding areas.

Loggerhead (Caretta caretta) and black turtles (Chelonia mydas agassizii) are thought to undertake long migrations from nesting beaches in Japan (Villanueva 1991; Ramirez Cruz et al., 1991) and Michoacan, Mexico (Alvarado and Figueroa, 1992), respectively, to distinct feeding grounds along both coasts of Baja California, Mexico. Results from analysis of mtDNA control regions, from this study and presented elsewhere (Bowen et al., 1995), and from our recent satellite telemetry studies confirm these nesting beach-feeding ground relationships and suggest vastly different patterns of use of Baja California waters by each species.

We have observed that eastern Pacific loggerheads pri- marily occupy offshore areas confirming the observations of Pitman (1990), make long pelagic forays, and feed predominantly on pelagic red crabs (Pleuroncodes planipes). In contrast, black turtles utilize primarily nearshore waters, lagoons and bays, migrate along the coast, and consume sea grasses and algae. Mortality due to incidental catch is common for both species in this region (pers. obs.).

These results reiterate the need for management and protection efforts on sea turtle feeding grounds in Baja Cali- fornia, the importance of a species by species approach to turtle conservation, and the utility of multi-faceted research programs. These studies have also led to an increase in intra- and inter-regional cooperation.

ACKNOWLEDGEMENTS

Without the participation of hundreds of volunteers, the guidance of dozens of Baja California's best fishermen, and the encouragement and support of many people this research wouldn't have been possible. We appreciate support from Richard Byles, USFWS, SWFSC-NMFS, Earthwatch Institute, Wallace Genetic Foundation, PADI Foundation, American Museum of Natural History, National Geographic Television, Seaspace, Turtle Trax, Sycamore Junior High School and the E. H. Greene School.

LITERATURE CITED

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