Young hawksbill turtle migrates Kenya from the Amirantes |12 October 2015
On Saturday October 3, a juvenile hawksbill turtle bearing flipper tags E4495/E4496 with the address of the Seychelles Department of Environment was intercepted just off the coast of Kenya by Casper van de Geer, manager of a Kenyan turtle conservation group called the Local Ocean Trust (LOT).
The turtle had been tagged at St Joseph Atoll by Dr Rainer von Brandis who is scientific director of the Save Our Seas, D’Arros research centre.
The tag was applied as part of a long-term study of the juvenile turtles foraging in the shallow waters of D’Arros Island and St Joseph Atoll. The turtle had travelled a straight line distance 1,400 km from St Joseph to Ngomeni, Kenya.
Dr von Brandis reports that when the turtle was tagged in St Joseph lagoon on July 2, 2013 its curved carapace measurements were 40.3 cm long and 36.0 cm wide, and it weighed 7.5 kg. When it was encountered in Kenya 27 months later it measured 40.5 cm long and 36.5 cm wide, and weighed 7.2 kg. So, although the carapace dimensions increased slightly in 27 months, the turtle actually lost some weight, probably as a result of its stressful long-distance migration to Kenya.
The Local Ocean Trust has been tagging turtles along the Kenyan coast since 1998 where they operate a By-Catch Release Programme. Kenyan fishermen usually do not target turtles, but sometimes they catch them in their gill-nets, and LOT remunerates them the cost of getting the captured turtles to them for tag and release. Without the incentive provided by the LOT many more turtles would probably be killed in Kenya.
Two other juvenile hawksbill turtles have been recorded making westward movements from Indian Ocean islands to the coast of mainland Africa. A 70cm long hawksbill tagged by Dr Jeanne Mortimer at Providence Island Seychelles in December 1996 was reported by Charles Savy (of Seychelles) to have been encountered 1,200 km away near Pemba Mozambique 5.5 years later (in September 2002). A 50cm hawksbill tagged at Cocos Keeling Islands in 2004 was recorded foraging 6,100 km away in Tanzania 5.7 years later, in 2010. The most recently recorded migration between St Joseph Atoll and Kenya actually involves the smallest sized migrating juvenile hawksbill on record (only 40 cm long).
The turtle tagging study at D’Arros and St Joseph is only one of many exciting research projects underway at the Save Our Seas, D’Arros Research Centre. For more information visit: http://saveourseas.com/centre/sosf-darros-research-centre/. Scientific studies such as those conducted at D’Arros/St Joseph, at Aldabra Atoll, and elsewhere in Seychelles have demonstrated that hawksbill turtles are slow growing animals with complicated life cycles. They are estimated to take an average of 30 to 40 years to reach maturity in the Indo-Pacific.
Dr Jeanne A. Mortimer
Turtle Action Group of Seychelles (TAGS)