Hawksbill Turtles in the Eastern Pacific

Juvenile hawksbill turtle in the Gulf of California. Credit: Alexander Gaos

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

Adult female hawksbill turtle in Bahia Jiquilisco, El Salvador. Credit: Michael Liles

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. 

Shoreline near a hawksbill nursery for protecting eggs in Estero Padre Ramos, Nicaragua – notice the mangrove-lined shores in the background. Photo: JA Seminoff

Hawksbill nesting in vegetation in Estero Padre Ramos, Nicaragua. Credit: NOAA Fisheries/JA Seminoff

Select Publications

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.

Gaos, A.R., M.J. Liles, V. Gadea, A. Peña de Niz, F. Vallejo, J.J. Darquea, A. Henriquez, C.M. Pacheco, J. Urteaga, E. Altamirano, A. Rivera, S. Chavarría, D. Melero, D. Chácon, C. Miranda, C. LeMarie, J. Alfaro-Shigueto, J.C. Mangel, I.L. Yañez, and J.A. Seminoff. 2017. Living on the edge: Hawksbill turtle nesting along the eastern Pacific rim. Latin American Journal of Aquatic Research. 45(3): 572-584. 

Llamas, I., E.E. Flores, M. Abrego, J.A. Seminoff, C.E. Hart, R. Donadi, B. Peña, G. Alvarez. and A.R. Gaos. 2017. Distribution, size ranges, and growth rates of hawksbill turtles at a major foraging ground in the eastern Pacific. Latin American Journal of Aquatic Research. 45(3):597-605. 

Liles, M.J., M.J. Peterson, J.A. Seminoff, A.R. Gaos, V. Gadea, A.V. Henríquez, E. Altamirano, J. Urteaga, P. Torres, B.P. Wallace, T.R. Peterson. 2015. Potential consequences of generalizing about broad-ranging species indicated by endangered hawksbill turtles’ nest-site selection in the eastern Pacific. Biological Conservation 184:405–413.

Liles, M.J., M.J. Peterson, Y.S. Lincoln, J.A. Seminoff, A.R. Gaos, T.R. Peterson. 2014. Connecting international priorities with human wellbeing in low-income regions: lessons from hawksbill turtle conservation in El Salvador. Local Environment 20:1383–1404.

Gaos, A., Lewison, R., Wallace, B.P., Yanez, I., Liles, M., Baquero, A., Seminoff, J.A. 2012. Dive behaviour of adult hawksbills (Eretmochelys imbricata, Linnaeus 1766) in the eastern Pacific Ocean highlights shallow depth use by the species. Journal of Experimental Marine Biology and Ecology 432:171-178

Gaos, A.G., R.R. Lewison,I.L. Yañez, B.P. Wallace, M.J. Liles, W.J. Nichols, A. Baquero,C.R. Hasbún, M. Vasquez, J. Urteaga, and J.A. Seminoff. 2012. Spatial ecology of critically endangered hawksbill turtles (Eretmochelys imbricata (Linnaeus)) in the eastern Pacific Ocean. Marine Ecology Progress Series. 450:181-194.

Gaos, A.R., R.R. Lewison, I.L. Yañez, W.J. Nichols, A. Baquero, M. Liles, M. Vasquez, J. Urteaga, B.P. Wallace, and J.A. Seminoff. 2011. Shifting the life-history paradigm: discovery of novel habitat use by hawksbill turtles. Biology Letters. doi:10.1098/rsbl.2011.0603

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. 

Gaos, A.R., F.A. Abreu-Grobois, J. Alfaro-Shigueto, D. Amorocho, R. Arauz, A. Baquero, R. Briseño, D.  Chacón, C. Dueñas, C. Hasbún, M. Liles, G. Mariona, C. Muccio, J.P. Muñoz, W.J. Nichols, M. Peña, J.A. Seminoff, M. Vásquez, J. Urteaga, B.P. Wallace, I. Yañez, and P. Zárate. 2010. Signs of hope in the eastern Pacific: international collaboration reveals encouraging status for the severely depleted population of hawksbill turtles Eretmochelys imbricata. Oryx. doi:10.1017/S0030605310000773.

Seminoff, J.A., S. Karl, T. Swartz, and A. Resendiz. 2003. Hybridization of the green turtle (Chelonia mydas) and the hawksbill turtle (Eretmochelys imbricata) in the Pacific
Ocean: Indication of an absence of gender bias in the directionality of crosses. Bulletin of Marine Science 73:643-652

Seminoff, J.A., W.J. Nichols, A. Resendiz, and L. Brooks. 2003. Occurrence of hawksbill turtles, Eremochelys imbricata, near Baja California. Pacific Science 57:9-16