MTN 87:8-9 Reproductive Span of Olive Ridley Turtles at Gahirmatha Rookery, Orissa, India

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Reproductive Span of Olive Ridley Turtles at Gahirmatha Rookery, Orissa, India

Bivash Pandav¹ & C. S. Kar²
¹Sea Turtle Research Program, Wildlife Institute of India, P.O. Box # 18, Chandrabani, Dheradun 248 001, U.P., India (E-mail: pandavb@hotmail.com)
²Research Officer, Office of the Chief Wildlife Warden, 7-Sahid Nagar, Bhubaneswar 751 007, Orissa, India

Olive ridley turtles (Lepidochelys olivacea) are the commonest species of sea turtle occurring along the east coast of India. These turtles migrate every winter to nest en-masse at three major rookeries in the Orissa State. Gahirmatha rookery, located along the northern Orissa coast, hosts the largest known nesting concentration of olive ridley turtles (Dash & Kar 1990; Pandav et al. 1994). A tagging programme was conducted at Gahirmatha by the Orissa Forest Department between 1978 and 1983. During these five seasons approximately 15,000 nesting olive ridley turtles were tagged with monel flipper tags (Dash & Kar 1990). After an interval of nearly 14 years, the Wildlife Institute of India initiated a tagging programme at Gahirmatha and since then nearly 10,000 ridleys of both sexes have been double tagged with monel tags at this rookery and in its coastal waters.

Mass nesting (arribada) of olive ridley turtles at Gahirmatha takes place between December and March with the commencement of strong southerly winds. The first arribada at Gahirmatha is normally followed by a second one of much lower intensity after a gap of 45-60 days (Dash & Kar 1990). During the 1998-99 nesting season, the first arribada at Gahirmatha started on 23 March and continued until 30 March. About 230,000 females (of which 10,000 were tagged) were estimated to have nested at this rookery during this arribada (Bivash Pandav, unpublished data).

Five of the 15,000 turtles tagged between 1978 and 1983 were recaptured while nesting in this arribada (Table 1). Besides these five recaptures, one tagged female was found dead behind the mass nesting beach. Upon examination 97 fully formed eggs were found in her oviduct. This turtle may have died due to natural causes or because of offshore fishing activities, which have been a major cause for large-scale sea turtle mortality in Orissa (Pandav & Choudhury 1999). In addition, one female ridley (bearing tag # 50; Table 1) was recaptured while mating in the coastal waters off Gahirmatha on 13 January 1999. The same turtle was also recaptured earlier while mating in the same area on 17 December 1996.

Nesting studies of tagged green turtles (Chelonia mydas) have recorded a reproductive span of more than 17 years (Carr 1983) and in the loggerhead sea turtles (Caretta caretta) females have been estimated to have a reproductive life span of up to 32 years (Frazer 1983; 1986). The present recaptures of the olive ridley turtle in India indicate that at least some individuals can be reproductively active for decades (up to 21 years).

CARR, A.F. 1983. Life lines: Old faithful. Animal Kingdom 1:49-50.

DASH, M. C. & C. S. KAR. 1990. The turtle paradise: Gahirmatha. Interprint, New Delhi. 295pp.

FRAZER, N. B. 1983. Survivorship of adult female loggerhead sea turtles, Caretta caretta, nesting on Little Cumberland Island, Georgia, USA. Herpetologica 39: 436-447.

FRAZER, N.B. 1986. Survival from egg to adulthood in a declining population of loggerhead turtles, Caretta caretta. Herpetologica 42: 47-55.

PANDAV, B. & B. C. CHOUDHURY. 1999. An update on mortality of olive ridley sea turtle in Orissa, India. Marine Turtle Newsletter 83: 10-12.

PANDAV, B., B. C. CHOUDHURY & C. S. KAR. 1994. Olive ridley sea turtle (Lepidochelys olivacea) and its nesting habitats along Orissa coast, India - A status survey. Wildlife Institute of India, Dehradun, July 1994. 48pp.