How satellite tracking revealed the migratory mysteries of endangered Atlantic loggerhead turtles

May 22, 2006

Their journeys are among the longest in the animal kingdom and they have largely remained a mystery until now. An international team of scientists led by the University of Exeter have uncovered the migratory secrets of endangered loggerhead turtles in West Africa and the results could have huge implications for strategies to protect them.

In a paper in the journal Current Biology, Dr Brendan Godley and an international team describe how they used satellite tracking systems to follow the journeys of ten turtles from Cape Verde, West Africa, which is one of the world's largest nesting sites for loggerheads and a hotspot for industrial fishing. What they found could turn current conservation strategies upside down, as the team discovered the turtles adopted two distinct approaches to finding food, linked to their size.

Previously it was thought that hatchlings left the coastal region to forage far out at sea before returning, later in life, to find food closer to shore. However the new findings show that the oceanic habitats contained far larger animals than was previously thought. The team tracked the turtles as they left nesting sites, following them for up to two years over ranges that covered more than half a million square kilometres.

Dr Brendan Godley, of the University of Exeter, said: "We were surprised to find such large turtles looking for food out in the open ocean, as it was previously thought that animals of this size would have moved back to forage in coastal zones. This means there are much greater numbers of the breeding population out at sea and far more that are vulnerable to the intensive longline fishing effort that occurs in that region."

Dr Michael Coyne, of Duke University, added: "From the information collected, we have been able to determine how much time these animals are spending within the sovereign boundaries of each country in the region. This research highlights how complicated the migration of marine vertebrates really is and how sophisticated our conservation efforts must be to safeguard these animals. Given the range these reptiles can cover an international cooperative effort in seven African states is needed to create a strategy that would protect them."

Research* shows that in 2000 1.4 billion hooks were cast into the world's oceans through industrial fishing. It's thought that globally more than 200,000 loggerhead turtles were incidentally caught by fisherman scouring the waters for other species such as tuna and swordfish. Of these, tens of thousands are thought to die as a result. 37% of this fishing effort was in the Atlantic and a major hotspot for fishing is found off West Africa, the region where the Cape Verdean turtles reside.

In recent years marine turtle researchers have been using satellite telemetry to track turtle migrations. Satellite transmitter tags are attached to the shell of the turtle so that every time the turtle surfaces to breathe, the tag transmits the turtle's position, as well as other information (e.g. depth and duration of dives), to satellites orbiting above, which then relay the data by e-mail to the computer of the scientist who attached the tag. For more information about tracking sea turtles, visit http://www.seaturtle.org/tracking
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Notes to Editors:

1) Contact in UK: Dr. Brendan Godley, Marine Turtle Research Group, University of Exeter Tel: +44 1326 371861, Out of hours Tel: + 44 1872 863728, E-mail: bgodley@seaturtle.org

or Press Officer Rachel Hoad-Robson, University of Exeter, Tel: +44 1392 262062

Contact in USA, Dr Michael S. Coyne, Marine Geospatial Ecology Lab, Nicholas School of the Environment, Duke University Tel: +1 919-613-8119, Out of hours Tel: +1 301-221-9952, E-mail: mcoyne@seaturtle.org

2) Photographs of the turtles and the attachment and release in Boavista, Cape Verde, are available for media use.

3) This work was carried out by a consortium of researchers from the following institutions: University of Exeter, UK Duke University, USA North Carolina Wildlife Resources Commission, Beaufort, North Carolina, USA Universidad Las Palmas de Gran Canaria, Departamento de Biolog?´a, Las Palmas de Gran Canaria Instituto Nacional de Desenvolvimento das Pescas, Sao Vicente, Islas de Cabo Verde

4) This work was funded by (in alphabetical order): the British Chelonia Group, Marine Conservation Society, Natural Environmental Research Council, People's Trust for Endangered Species, SeaWorld Busch Gardens, and Seaturtle.org. Lucy A Hawkes is supported by a University of Exeter Postgraduate Scholarship and the Anning-Morgan Bursary. Brendan J. Godley and Annette C. Broderick acknowledge the additional support of the Darwin Initiative, European Social Fund, and the Overseas Territories Environment Programme. Additional support was provided by the Large Pelagics Research Center at the University of New Hampshire through National Oceanographic and Atmospheric Agency award NA04NMF4550391.

5) The Marine Turtle Research Group (MTRG) http://www.seaturtle.org/mtrg/ is based at the University of Exeter. Its members carry out research and conservation projects regarding turtles in UK waters, Mediterranean and the UK Overseas Territories including Cayman Islands and Ascension Island. MTRG staff edit the international Marine Turtle Newsletter http://www.seaturtle.org/mtn/. Funding for MTRG participation in this project was provided by the Natural Environment Research Council (NERC) http://www.nerc.ac.uk/

6) Project Cabo Verde Natura 2000 is an NGO organisation staffed by volunteers and students from the Canary Islands, Cape Verde and other countries. http://www.tartarugasmarinas.org/

7) The Instituto Nacional Desenvolvimento das Pescas is the Cape Verde government department for Fisheries and is working for the conservation of marine turtles in the archipelago.

8) The Universidad Las Palmas, Gran Canaria, is the founder and coordinator for Cabo Verde Natura 2000.

9)* Research by Lewison et al. published in Ecology Letters, 2004, (7): 221 - 231

University of Exeter

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