Hawksbill Turtles in the Eastern Pacific
Studying the hawksbill turtle to reveal regional life-history strategies
The hawksbill turtle (Eretmochelys imbricata) is found in the world’s tropical and subtropical oceans, and have traditionally been associated with coral reefs, where they feed on coral, sponges, and other invertebrates. Their brightly colored shell was the primary source of the world’s tortoiseshell, which has been used in a wide variety of items, from guitar picks and knitting needles, to furniture inlays and jewelry boxes. The demand for tortoiseshell played a large role in the decline in populations of hawksbills around the world, and despite the ban of tortoiseshell trade around the world in 1973, illegal poaching, nesting beach degradation and incidental take as fishery by-catch continue to threaten this species throughout its range.
Hawksbill Turtle Research
Researchers at the Southwest Fisheries Science Center are actively engaged with partners throughout the eastern Pacific to study hawksbills. We use satellite telemetry, ultrasonic telemetry, in-water capture efforts and stable isotope analysis to study movements, habitat use, trophic status, genetic structure, migratory connectivity, and demography.
Through these research efforts, we have learned that hawksbills in the Eastern Pacific have substantially different life-history strategies than their counterparts from other regions. Coral reefs are sporadically distributed in the eastern Pacific, with only nine large coral reef systems in the entire region. The eastern Pacific hawksbills inhabit the coral reefs in the Eastern Pacific and live in estuarine mangrove habitats where they consume large quantities of mangrove seeds along with marine algae and invertebrates. We also know that hawksbills in the region nest both on open sandy beaches and inside mangrove estuaries where they deposit their eggs in the mud-sand substrate under the shade of mangrove canopies. Unlike green turtles and leatherbacks that undertake long-distance reproductive migrations spanning thousands of kilometers, hawksbill turtles in the eastern Pacific have much shorter reproductive migrations, often spanning only a few hundred kilometers. Some individuals are non-migratory and live in or near the very same estuaries where they originally hatched. These shorter migrations are consistent with genetic research that shows regional structure within the eastern Pacific.
While hawksbills continue to be endangered in the eastern Pacific, there are encouraging signs of stable nesting trends at nesting beaches in El Salvador and Nicaragua, the two largest nesting strongholds in the region.
Gaos, A.R., R.L. Lewison, M.P. Jensen, M.J. Liles, A. Henriquez, S. Chavarria, C.M. Pacheco, M. Valle, D. Melero, V. Gadea, E. Altamirano, P. Torres, F. Vallejo, C. Miranda, C. LeMarie, J. Lucero, K. Oceguera, D. Chácon, L. Fonseca, M. Abrego, J.A. Seminoff, E.E. Flores, I. Llamas, R. Donadi, B. Peña, J.P. Muñoz, D. Alarcòn Ruales, J.A. Chaves, S. Otterstrom, A. Zavala, C.E. Hart, R. Brittain, J. Alfaro-Shigueto, J. Mangel, I.L. Yañez, and P.H. Dutton. 2018. Rookery contributions, movements and conservation needs of hawksbill turtles at foraging grounds in the eastern Pacific Ocean. Marine Ecology Progress Series 586: 203–216.
Gaos, A.R., Lewison, R.L., Jensen, M.P., Liles, M.J., Henriquez, A., Chavarria, S., Pacheco, C.M., Valle, M., Melero, D., Gadea, V., Altamirano, E., Torres, P., Vallejo, F., Miranda, C., LeMarie, C., Lucero, J., Oceguera, K., Chácon, D., Fonseca, L., Abrego, M., Seminoff, J.A., Flores, E.E., Llamas, I., Donadi, R., Peña, B., Muñoz, J.P., Alarcòn-Ruales, D., Chaves, J.A., Otterstrom, S., Zavala, A., Hart, C.E., Brittain, R., Alfaro-Shigueto, J., Mangel, J., Yañez, I.L., Dutton, P.H. 2017. Natal foraging philopatry of hawksbill turtles in the eastern Pacific Ocean. Royal Society Open Science. 4: 170153. http://dx.doi.org/10.1098/rsos.170153
Liles, M.J., A.R. Gaos, A.D. Bolaños, W.A. Lopez, R. Arauz, V. Gadea, J. Urteaga, I.L. Yañez, C.M. Pacheco, J.A. Seminoff, and M.J. Peterson. 2017. Survival on the rocks: high bycatch in lobster gillnet fisheries threatens hawksbill turtles on rocky reefs along the Pacific coast of Central America. Latin American Journal of Aquatic Research. 45(3):521-539.
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Liles, M.J., M.V. Jandres, W.A. Lopez, G.I. Mariona, C.R. Hasbun, and J.A. Seminoff. 2011. Hawksbill turtles Eretmochelys imbricata in El Salvador: nesting distribution and mortality at the largest remaining nesting aggregation in the eastern Pacific Ocean. Endangered Species Research 14:23-30.
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