seaturtle.org : MTN : ARCHIVES : Sign In

On 12 March 1995, as part of the routine beach patrol, a partially decomposed sub-adult olive ridley was found on the beach in front of Satbhaya village (15 km south of the main nesting beach). Detailed morphological measurements were taken: 57 cm curved carapace length (CCL), 56 cm curved carapace width (CCW), 40 cm plastron width (PW). The upper jaw of the specimen was missing and the plastron length could not be taken because of mutila-tion. The carapace scute counts were as follows: 9 centrals, 7 left costals, 6 right costals, 8 left marginals, 8 right marginals. A close examination of the specimen revealed that the mid plastral region, as well as portions of the inframarginal scales, were very soft.

On 29 April 1995, a second sub-adult was found dead near the Ekakula Forest Rest House (3 km south of the main nesting beach). The turtle measured 58 cm CCL, 57 cm CCW, 39 cm PW, and 41 cm plastron length~. The scute counts were as follows: 6 centrals, 8 each left and right costals, 12 each left and right marginals. The inframarginal scales and the midline joining the plastron was soft. This particular character (i.e., softness in the plastron) seemed peculiar because it is our experience that neither adults nor hatchlings exhibit this character. It is possible that death was caused by incidental capture and drowning in a fishing net. About 40 mechanised trawlers were fishing in the coastal waters near Satbhaya village throughout the nesting season, including the time during which the turtle washed ashore. This area has been declared as a closed area and fishing has been banned along this coast, so these boats were operating in violation of the law.

The smallest nesting olive ridley recorded at Gahirmatha in the last 20 years measured 62.0 cm CCL, leading to speculation that this is the minimum size at which these turtles attain sexual maturity in the Bay of Bengal (Dash and Kar, 1990). The smallest nesting olive ridley measured at Galathea beach, Great Nicobar Island, was 62.5 CCL and 63.5 cm CCW (Bhaskar, 1993). Taking into account the length of the smallest nesting females at these two sites, we consider the two stranded individuals described above to be sub-adults. There is very little information in the literature relating to the size and weight of sub-adult olive ridleys. Occasionally stray individuals are captured in fishing nets or are found dead on island or mainland beaches. The only substantial sample of juvenile and sub-adult olive ridleys (21-62 cm carapace length) outside of the Indian Ocean was recorded near Japan by Nishimura et al. (1972) who proposed that since the olive ridley tended toward a demersal life style, individuals which drifted into Japanese waters would be expected to be almost exclusively sub-adults. The ovarian condition and the gut contents of a specimen recorded by Honma and Yoshie (1975) support this contention.

In other parts of the species' range, Hughes (1974) noted that no juvenile had been found in Southeast Africa except one noticeably sub-adult specimen measuring 49.2 cm and 47.4 cm straight carapace length and width, respectively. McKeown (1977) recorded a juvenile olive ridley from Makira (Solomon Islands) in July 1977, without providing information regarding size and weight. Deraniyagala (1953) provided the dimensions for two juveniles (12 months, 5 months) from Morutuva, Sri Lanka, as follows: 11.2 cm head length, 49 cm carapace length, 45 cm carapace width and 40 cm plastron length.

During his doctoral studies on olive ridleys at Gahirmatha, Chandra Sekhar Kar documented three dead sub-adults (Kar, 1980), bringing the Orissa total to five (with the two recorded in this paper). All were found during the nesting season. Coastal fishing occurs throughout the year (in contravention of state and federal law) at Gahirmatha, but neither adults nor juveniles have washed ashore dead on this beach during the non-breeding season. It is possible that immature individuals accompany adults during the breeding migration, arriving with them at the nesting beach. Cornelius (1975) has suggested that immature green turtles may accompany adults to the nesting beach, based on his finding many sub-adult turtles amongst 73 that had died from unknown causes during the nesting season in Costa Rica. Another fragment of evidence supporting this hypothesis is the report that sub-adult green turtles are frequently caught near Bocas del Tora, Panama, during the seasonal migration of adult Tortuguero (Costa Rica) bound migrants (Meylan, 1982).

We expect that further studies in this area will expand our sample size and assist us in defining the size distribution and seasonality of olive ridleys utilizing the seas near Gahirmatha.

Bhaskar, S. 1993. The status and ecology of sea turtles in the Andaman and Nicobar Islands. Centre for Herpetology Publication No. ST 1/93:1-37.

Bustard, H. R. 1976. World's largest sea turtle rookery. Tiger Paper: 3.

Cornelius, S. E. 1976. Marine turtle nesting activity at Playa Naranjo, Costa Rica. Brenesia 8: 1-27.

Dash, M. C. and C. S. Kar. 1990. The Turtle Paradise Gahirmatha: An Ecological Analysis and Conservation Strategy. Interprint, New Delhi. 295 pp.

Deraniyagala, P. E. P. 1953. A Coloured Atlas of Some Vertebrates from Ceylon. Vol. 2, Tetrapod Reptilia. Ceylon Nat. Mus. Publ. 101 pp.

Kar, C. S. and S. Bhaskar. 1982. The status of sea turtles in the Eastern Indian Ocean, p.365- 372. In: Biology and Conservation of Sea Turtles (K. A. Bjorndal, Editor). Smithsonian Institution Press, Washington D. C.

Nishimura, S. K., K. Shirai, T. Tatsuki and C. Sugihara. 1972. The Pacific ridley turtle in Japanese and adjacent waters. Publ. Seto Mar. Biol. Lab. 19:415-426.

Honma, Y. and S. Yoshie. 1975. A record of the Pacific ridley turtle, Lepidochelys olivacea, from the coast of Niigata facing the Japan sea, with description of some of the organs. Ann. Rep. Sado. Mar. Biol. Stat., Niigata Univ., No.5:1-9.

Hughes, H. R. 1974. The sea turtles of South East Africa. I. Status, morphology and distribution. II. The biology of the Tongaland loggerhead turtle, Caretta caretta L., with comments on the leatherback turtle, Dermochelys coriacea L., in the study region. Invest. Report Nos. 35 and 36. South African Assoc. Mar. Biol. Res. Oceanographic Res. Institute, Durban, South Africa.

Kar, C. S. 1980. The Gahirmatha turtle rookery along the coast of Orissa, India. Marine Turtle Newsletter 15:2-3.

Mckeown, A. 1977. Marine turtles of Solomon Islands. Ministry of Natural Resources, Fisheries Division, Honiara. 47 pp.

Meylan, A. B. 1982. Sea turtle migration - evidence from tag returns, p.91-100. In: Biology and Conservation of Sea Turtles (K. A. Bjorndal, Editor). Smithsonian Institution Press, Washington D. C.

BIVASH PANDAV and B. C. CHOUDHURY, Wildlife Institute of India, P. O. Box 18, Dehradun - 248001, Uttar Pradesh, INDIA and C. S. KAR, Research Officer, Mangrove Forest Division, Raj Nagar, Kendrapara, Orissa, INDIA.