MTN 101:25 Olive Ridley Sea Turtles in Porto-Novo, Tamil Nadu, India, with an Observation of an Asian Giant Softshell Turtle

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Olive Ridley Sea Turtles in Porto-Novo, Tamil Nadu, India, with an Observation of an Asian Giant Softshell Turtle

I. Sujjahad Hussain
Center of Advanced Study in Marine Biology, Annamalai University, Porto-Novo 608502, Tamil Nadu, INDIA. (E-mail: sujjahad@hotmail.com)

A survey of the nesting activity of olive ridley sea turtle (Lepidochelys olivacea) was undertaken between 22 January and 15 February 2002 on the coastline in Porto-Novo, in the state Tamil Nadu, India (11° 3’ N and 79°4’ E). This period corresponds to the annual migration made by adult female olive ridley turtles from more southern areas of the Indian Ocean to their main nesting sites in the state of Orissa. Some females choose to nest in Tamil Nadu and Andhra Pradesh, which lie south of Orissa (Rajashekar 1999).

The first day of the survey (22 January) revealed six stranded adult female olive ridley turtles. Four of these females had wounds apparently caused by propellers from boats.The other two stranded turtles were too decomposed to assess any injury. On 29 January a turtle emerged from the ocean and attempted to nest, but after two unsuccessful digging attempts it returned to the sea. Before it reached the water, it was intercepted for measurement and observations. This turtle had a curved carapace length of 67.0 cm, a curved carapace width of 68.5 cm, 6 pairs of lateral scutes, and 13 pairs of marginal scutes. A number of epibionts such as Chelonibia testudinaria were collected from the carapace of the live and stranded turtles.

Another large turtle was found stranded along the Porto-Novo coast near the mouth of the Vellar estuary: an Asian giant softshell turtle (Pelochelys bibroni). This species is considered to be rather tolerant of saline conditions (Pritchard 2001), and has been reported to reach the tidal limits of the sea (Das 1985). The curved carapace length of Asian giant softshell turtles can reach and occasionally surpass the size of olive ridley turtles (Pritchard 2001). Along the coast of Gahirmatha, Orissa, this species shares nesting beaches with the olive ridley, and is often seen approaching the nesting site from the sea and the river (Das 1985). In India, the Asian giant softshell turtle is normally distributed in the states of Orissa, Tamil Nadu (Mandapam) and West Bengal (Das 1985).

Acknowledgements: Prof. Antony Fernando for his contributions in identifying the epibiont from olive ridley, Prof. T. Balasubramanian, Director, Center of Advanced Study in Marine Biology for his kind help and interest, the M.Sc students (2002 batch) for their enthusiasm during the nights.

DAS, I. 1985. Soft shell turtles. Indian turtles: A field guide. World Wild Life Fund- India (Eastern Region), Calcutta, 119 pp.

PRITCHARD, P.C.H. 2001. Observations on body size, sympatry, and niche divergence in softshell turtles (Trionychidae). Chelonian Conservation and Biology 4: 5-27.

RAJASEKHAR, P.S.R. 1999. Nesting activity of olive ridley, Lepidochelys olivacea (Eschscholtz) at important breeding habits of Andhra Pradesh coastline, India. In: H. Kalb & T. Wibbels (Eds.). Proceedings of the Nineteenth Annual Symposium on Sea Turtle Conservation and Biology. NMFS-SEFC-443. pp. 73-76.