MTN 87:9-10 Fidelity of Male Olive Ridley Sea Turtles to a Breeding Ground

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Fidelity of Male Olive Ridley Sea Turtles to a Breeding Ground

Bivash Pandav, K. Banugopan, Dipani Sutaria & B. C. Choudhury
Wildlife Institute of India, P. O. Box # 18, Chandrabani, Dehradun 248 001, U. P., India
(E-mail: pandavb@hotmail.com)

The biology of the female olive ridley sea turtle (Lepidochelys olivacea) congregating for nesting has been the subject of several studies at Gahirmatha rookery in Orissa, India (Dash & Kar 1990; Pandav et al. 1994). Tagging studies initiated by the Orissa State Forest Department between 1978 and 1983 have shown that female olive ridleys using Gahirmatha for nesting exhibit site fidelity (see Pandav & Kar 2000). Because courtship occurs at sea where there is greater difficulty in observing and capturing turtles, there have been no studies on the biology of breeding males. As part of Wildlife Institute of India’s sea turtle research programme, an offshore tagging programme was initiated to study the male olive ridley population visiting the area.

Olive ridley turtles arrive in the coastal waters off Gahirmatha by the beginning of November. After their arrival, mating takes place in the shallow coastal waters, just south of the mass nesting beach and continues until mid January. We captured ridley mating pairs over three breeding seasons (1997-99). We used a mechanised boat and a hand held triangular trap to capture the mating pairs. Most of the mating pairs were captured in a sheltered bay of roughly 25 sq. km immediately south of the Gahirmatha rookery. Over a period of 85 days during the three breeding seasons, we captured 1,767 mating pairs and tagged 1,657 males and 1,616 females (Table 1).

Some males have been recorded in courtship activity in more than one breeding season and all such recaptures were made at the same area as the male had been originally captured while courting in a previous year. For the males recorded mating in more than one year, mean remigration interval was 0.99 years (SD=0.06, range = 0.86 to 1.14 years, n = 28). Females recaptured offshore were returning after an interval of 1.01 years (SD=0.05, range = 0.96 to 1.09 years, n = 5). On the beach our tagging study carried out on the nesting females at the Rushikulya rookery in Orissa also showed a nearly annual mean remigration interval of 1.1 years (SD=0.05 range = 0.97-1.17 years n=39; Bivash Pandav, unpublished data).

Multiple capture of the same male at the same courtship site in different seasons has also been reported for green turtles (Chelonia mydas) (Balazs 1980; Fitzsimmons et al. 1995; Limpus 1983). However, the remigration interval of olive ridley males obtained in this study is much shorter compared to that of green turtles (2.08 ± 1.14 years; Limpus 1993). This nearly annual remigration interval of male olive ridleys illustrates a strong fidelity to the coastal waters off Gahirmatha.

BALAZS, G. (1980). Synopsis of biological data on the green turtle in the Hawaiian Islands. National Oceanic and Atmospheric Administration Technical Memorandum, National Marine Fisheries Service, South West Fisheries Centre 7: 1-141.

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

FITZSIMMONS, N., A. D. TUCKER & C. J. LIMPUS. 1995. Long-term breeding histories of male green turtles and fidelity to a breeding ground. Marine Turtle Newsletter 68:2-4.

LIMPUS, C. J. 1993. The green turtle, Chelonia mydas, in Queensland: breeding males in the Southern Great Barrier Reef. Wildlife Research 20:513-523.

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

PANDAV, B. & C. S. KAR. 2000. Reproductive Span of Olive Ridley Sea Turtles at Gahirmatha Rookery, Orissa, India. Marine Turtle Newsletter 87:8-9.