2012 COURSE DATES: AUGUST 4 – 17, 2012 - Sirenian International

4850 J. M. BLUMENTHAL ET AL.
mixed stocks (Bowen et al. 2007b; Godfrey et al. 2007;
Mortimer et al. 2007a,b). It has been argued that harvesting
of hawksbills from foraging grounds should be
prohibited, as exploitation of mixed stocks could potentially
impact rookeries on a regional scale – or alternatively,
that sustainability of harvesting on hawksbill
foraging aggregations could be determined on a caseby-case
basis (Godfrey et al. 2007).
Many-to-many analysis and hatchling drift models
facilitate an integrative, rookery-centric approach
(Bolker et al. 2007) in which contributions of both small,
vulnerable rookeries and large, regionally important
rookeries are evaluated. Oceanic juveniles from some
rookeries appear to be dispersed among multiple foraging
grounds, while those from other rookeries appear to
be more locally constrained. This diversity of distribution
represents both a challenge and an opportunity for
marine turtle management. Broadly dispersed stocks
are difficult to manage, yet threats are often geographically
widely dispersed and their impacts on individual
stocks will depend on how they interact. In contrast, in
areas with greater levels of local or proximate recruitment,
threats – or conservation efforts – may have a
concentrated effect (Bowen et al. 2004, 2005). Indeed,
Caribbean hawksbill rookeries have experienced varying
population trends, ranging from near-extirpation
(Cayman Islands: Aiken et al. 2001) to dramatic increase
(Antigua: Richardson et al. 2006; Barbados: Beggs et al.
2007) – raising the possibility that variations in dispersal
across an oceanographically complicated region
may be a factor in these differing trajectories.
While much remains to be determined regarding
movements and management needs of hawksbill turtles,
integration of many-to-many analysis and oceanographic
data represents a promising approach. In this
study, we delineated links between regional management
units by conducting many-to-many mixed stock
analysis across the range of Caribbean hawksbill rookeries
and foraging aggregations, developed a tool with
which to illustrate a possible role of ocean currents in
determining distribution of oceanic juveniles, and highlighted
gaps in knowledge and priorities for future
sampling. Overall, results facilitate a broader understanding
of Caribbean hawksbill movements – filling an
important gap in knowledge of life-history and potentially
informing regional management.
Acknowledgments
For invaluable logistical support and assistance with fieldwork,
we thank Cayman Islands Department of Environment
research, administration, operations and enforcement staff and
numerous volunteers. For advice on analysis, we thank J. Hunt
and W. Pitchers at University of Exeter, Cornwall campus.
Vincente Guzmán (CONANP-México) and Eduardo Cuevas
(Pronature-Península de Yucatán A.C.) generously provided
information on population sizes of Campeche, Yucatán and
Quintana Roo rookeries. Work in the Cayman Islands, the UK
and the USA was generously supported by the European
Social Fund, the Darwin Initiative, the Department of Environment,
Food & Rural Affairs (DEFRA), Eckerd College, the Foreign
and Commonwealth Office for the Overseas Territories,
the Ford Foundation, the National Fish and Wildlife Foundation
(NFWF) and the Turtles in the Caribbean Overseas Territories
(TCOT) Project. We also acknowledge support to J.
Blumenthal (University of Exeter postgraduate studentship and
the Darwin Initiative). The manuscript was improved by the
input of three anonymous reviewers.
References
Abreu-Grobois FA, Horrocks JA, Formia A et al. (2006) New
mtDNA dloop primers which work for a variety of marine
turtle species may increase the resolution capacity of mixed
stock analyses. Poster presented at the 26th Annual
Symposium on Sea Turtle Biology and Conservation, Crete,
Greece, 2–8 April 2006. Available from http://www.
iucnmtsg.org/genetics/meth/primers/abreu_grobois_etal_
new_dloop_primers.pdf. Accessed 1 March 2008.
Aiken JJ, Godley BJ, Broderick AC, Austin T, Ebanks-Petrie G,
Hays GC (2001) Two hundred years after a commercial
marine turtle fishery: the current status of marine turtles
nesting in the Cayman Islands. Oryx, 35, 145–151.
Allard MW, Miyamoto MM, Bjorndal KA, Bolten AB, Bowen
BW (1994) Support for natal homing in green turtles from
mitochondrial DNA sequences. Copeia, 1994, 34–41.
Allen M, Engstrom AS, Meyers S et al. (1998) Mitochondrial
DNA sequencing of shed hairs and saliva on robbery caps:
sensitivity and matching probabilities. Journal of Forensic
Science, 43, 453–464.
Andersen LW, Ruzzante DE, Walton M et al. (2001)
Conservation genetics of harbour porpoises, Phocoena
phocoena, in eastern and central North Atlantic. Conservation
Genetics, 2, 309–324.
Baillie JEM, Hilton-Taylor C, Stuart SN (2004) IUCN red List of
Threatened Species. A Global Species Assessment. IUCN, Gland
Switzerland.
Baker CS, Patenaude NJ, Bannister JL, Robins J, Kato H (1999)
Distribution and diversity of mtDNA lineages among
southern right whales (Eubalaena australis) from Australia
and New Zealand. Marine Biology, 134, 1–7.
Bass AL (1999) Genetic analysis to elucidate the natural history
and behavior of hawksbill turtles (Eretmochelys imbricata) in
the Wider Caribbean: a review and reanalysis. Chelonian
Conservation and Biology, 3, 195–199.
Bass AL, Witzell WN (2000) Demographic composition of
immature green turtles (Chelonia mydas) from the east central
Florida coast: evidence from mtDNA markers. Herpetologica,
56, 357–367.
Bass AL, Good DA, Bjorndal KA et al. (1996) Testing models
of female reproductive migratory behavior and population
structure in the Caribbean hawksbill turtle, Eretmochelys
imbricata, with mtDNA sequences. Molecular Ecology, 5, 321–
328.
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