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Molecular Ecology (2009) 18, 4841–4853 doi: 10.1111/j.1365-294X.2009.04403.x
Turtle groups or turtle soup: dispersal patterns of
hawksbill turtles in the Caribbean
J. M. BLUMENTHAL,*† F. A. ABREU-GROBOIS,‡ T. J. AUSTIN,* A. C. BRODERICK,†
M. W. BRUFORD,§ M. S. COYNE,†– G. EBANKS-PETRIE,* A. FORMIA,§ P. A. MEYLAN,**
A. B. MEYLAN†† and B. J. GODLEY†
*Department of Environment, Box 486, Grand Cayman KY1-1106, Cayman Islands, †Centre for Ecology and Conservation,
School of Biosciences, University of Exeter Cornwall Campus, Penryn TR10 9EZ, UK, ‡Laboratorio de Genética, Unidad
Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Mazatlán, Sinaloa 82040, México, §Biodiversity and
Ecological Processes Research Group, School of Biosciences, Cardiff University, Cardiff CF10 3TL, UK, –SEATURTLE.ORG,
Durham, NC 27705, USA, **Natural Sciences, Eckerd College, St Petersburg, FL 33711, USA, ††Florida Fish and Wildlife
Conservation Commission, Fish and Wildlife Research Institute, St Petersburg, FL 33701, USA
Introduction
Abstract
Despite intense interest in conservation of marine turtles, spatial ecology during the
oceanic juvenile phase remains relatively unknown. Here, we used mixed stock analysis
and examination of oceanic drift to elucidate movements of hawksbill turtles (Eretmochelys
imbricata) and address management implications within the Caribbean. Among
samples collected from 92 neritic juvenile hawksbills in the Cayman Islands we detected
11 mtDNA control region haplotypes. To estimate contributions to the aggregation, we
performed ‘many-to-many’ mixed stock analysis, incorporating published hawksbill
genetic and population data. The Cayman Islands aggregation represents a diverse mixed
stock: potentially contributing source rookeries spanned the Caribbean basin, delineating
a scale of recruitment of 200–2500 km. As hawksbills undergo an extended phase of
oceanic dispersal, ocean currents may drive patterns of genetic diversity observed on
foraging aggregations. Therefore, using high-resolution Aviso ocean current data, we
modelled movement of particles representing passively drifting oceanic juvenile
hawksbills. Putative distribution patterns varied markedly by origin: particles from
many rookeries were broadly distributed across the region, while others would appear to
become entrained in local gyres. Overall, we detected a significant correlation between
genetic profiles of foraging aggregations and patterns of particle distribution produced
by a hatchling drift model (Mantel test, r = 0.77, P < 0.001; linear regression, r = 0.83,
P < 0.001). Our results indicate that although there is a high degree of mixing across the
Caribbean (a ‘turtle soup’), current patterns play a substantial role in determining genetic
structure of foraging aggregations (forming turtle groups). Thus, for marine turtles and
other widely distributed marine species, integration of genetic and oceanographic data
may enhance understanding of population connectivity and management requirements.
Keywords: conservation genetics, hawksbill, marine turtle, migratory species, mixed stock,
ocean currents
Received 29 June 2009; revision received 21 September 2009; accepted 25 September 2009
Many marine vertebrates have life cycles that span wide
spatiotemporal scales – complicating research and
Correspondence: Brendan J. Godley, Fax: 44 (0) 1326 253638;
E-mail: b.j.godley@exeter.ac.uk
Ó 2009 Blackwell Publishing Ltd
management. Recently, molecular techniques have provided
insights into patterns of migration and stock resolution
in species ranging from fish (Millar 1987) to
porpoises (Andersen et al. 2001) and great whales
(Baker et al. 1999; Witteveen et al. 2004). Such stock resolution
issues are particularly important when species