First leatherback turtle (Dermochelys coriacea) stranding for Suffolk

43 FIRST LEATHERBACK TURTLE ( D E R M O C H E L Y S COR1ACEA) STRANDING FOR SUFFOLK T. E. S. L A N G T O N , C. L. B E C K E T T A N D J. P. FOSTER. U p until January 1998, records of thc leatherback (or leathcry) turtle around the East Anglian (Norfolk, S u f f o l k and Essex) coast werc fcw and far between; in fact there had been only three. T w o turtles werc reported (and onc caught) off the Lowestoft coast in 1913, and onc was strandcd on thc North Bcach at Grcat Yarmouth in 1956 (Brongersma, 1972).

S u f f o l k ' s first leatherback turtle stranding report was rccordcd on 12 January 1998. A freshly dcad male leatherback turtle was first secn on thc shinglc beach at Sizewell, near to the Nuclcar P o w e r Station, by Mrs Dallas who was out Walking her dog. T h e turtle was securcd on the strandlinc by thc writers of this report (at O.S. grid ref. T M / 4 7 7 6 3 9 ) at around 18.00 hours, approximately 3 0 0 metres north of Sizewell B buildings, and soulh of thc R S P B reserve at M i n s m e r e (see Plate 4).

The turtle w a s recovered f r o m the beach with thc assistance of Nuclcar Electric's night shift staff and the use of a forklift truck. Thc turtle was transported to the Institute of Z o o l o g y in L o n d o n for a post m o r t e m e x a m i n a t i o n that w a s carried o u t by A n d r e w C u n n i n g h a m . Basic b o d y m e a s u r e m e n t s w e r e sent to the British M u s e u m (Natural History) w h o document all turtle strandings in Britain and to other sea turtle researchers in Britain.

T h e turtle was 2 0 9 0 m m in total length (nose to tail-tip), w e i g h i n g approximately 225 kg. The turtle carcase w a s very fresh, and found to have abrasions and cut marks on its b o d y and flippers consistent with a net or linc entanglement. A bite-sized piece of trawl net w a s f o u n d in the turtles stomach and it is considered highly probable that an entanglement with a fishing net was contributory to the turtle's death. S a m p l e s taken f r o m the turtle were sent to national experts for further study and tests, as fresh material f r o m this species is rare. A fĂźll p o s t m o r t e m report will be prepared in d u e coursc.

The Sizewell leatherback turtle w a s o n e of f o u r that were located on thc east coast of England b e t w e e n O c t o b e r 1998 and January 1999. O n e was f o u n d in a creek in Spalding, Lincolnshire, another w a s found freshly dead on a Northumbrian beach ( S e a h o u s e s ) and the last was seen alive in thc T h a m e s (Tilbury Docks) in L o n d o n , but w a s subsequently killed when hit by a large boat propeller.

Leatherback turtles regularly enter the waters off Britain and Ireland in s u m m e r and autumn m o n t h s , and arc a native species protcctcd by U K and European Law. The mortality of turtles f r o m line and net entanglcmcnts appears to be increasing (Langton, 1999). C o n c e r n for this species which breeds on tropical and sub-tropical beaches in thc Atlantic, and along the coast of Africa and thc A m e r i c a s is growing now that nesting f e m a l c numbers have been estimated at less than 35,000. Turtle mortality at sea as a rcsult of fishing practices is largcly u n d o c u m e n t e d and strandings arc thought be thc visiblc fraction of a m u c h larger problem which goes unseen; dcad turtles are thought likely to sink fairly quickly and thus go unrccordcd.

Trans. Suffolk Nal. Soc. 35 (1999)

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Suffolk Natural History, Vol. 35

Allhough lcathcrback lurllcs arc known to bc ablc lo navigatc over huge dislanccs, il is nol cxactly clcar why thcy should cxtend thcir ränge into thc North Sca. Four lurllc rccords in a little ovcr a ycar, following so fcw histoncal rccords, is notcworthy howcvcr. The eastcrn coast of Britain rcprcsents a 'turning round' point for turtles that havc travcllcd north over the tip of Scotland and possibly also turtles that have moved cast along thc English Channel. Sick or injurcd turtles may also rcmain in this area, whcre prolonged winter cold may rcduce survival prospects. Although leatherbacks exhibit warm bloodcd physiology, they will suffer from cold over protracted periods in watcr below about 5° ccntigrade. Ii is also possible that the large, deep water jellyfish prcy that leatherbacks feed on occur less frequently in waters of eastcrn Britain, but little appears to havc becn written on this.

Thc very low number of turtle rccords for thc north sea contrasts with thc much more frequent rccords of turtles in the Irish sea and off the coast of Ircland. In fact lcathcrback turtles are reported to occur in groups off Ireland, and net trawls catching morc than one turtle have been reported. This makes thc 1913 record (Pattcrson, 1914) of two turtles sighted together interesting, and suggests that not all lcatherbacks in British eastern coastal waters arc isolated individuals or in difficulty.

Further study of fresh lcatherback turtle carcases arc a vital part of learmng morc about thesc infrequently seen marine reptiles.

Acknowledgments Mrs. Dallas made a substantial donation of £2,000 towards thc costs ol post-mortem tests, microbiology and toxicology. Nuclear Electric provided £200 towards transport costs. Pete Feilden of Bramfield assisted with loading and weighing thc turtle. Frithvale net manufacturcrs (Lowestoft) assisted with identification of the picce of polypropylene twine found in thc turtle's stomach. A report on this leathcrback stranding and other information and photographs on turtle conservation were published in BBC Wildlife Magazine March 1999 issue.

References Brongersma, L. D. (1972). European Atlantic Turtles. Rijksmuseum van Natuurlijke Historie, Leiden, The Nethcrlands Langton, T. E. S. (1999). Hell for Leatheries. BBC Wildlife Magazine, March 1999.

Pattcrson, A. H. (1914) Thc capturc of a Leathery Turtle: Fauna and Flora ol Norfolk. Additions to Part iv - Fishes (Scventh List). Transactions of the Norfolk and Norwich Naturalists' Society, 9: 815-821.

Tom Langton Dircctor Hcrpctofauna Consultants International Triton Housc Bramfield Halcsworth Suffolk IP19 9AE e-mail: tom@tritonhousc.dcmon.co.uk

Trans. Suffolk Nat. Soc. 35

(1999)

Plate 4: Leatherback Turtle. Dermochelys coriacea, first stranding in Suffolk. 12th January 1998, Sizewell (p. 43).