The Recent Nesting Record of Female Green Turtle (Chelonia mydas) , at Pamban, Gulf of Mannar

A female green turtle was sighted at Pamban along the Gulf of Mannar just after the nesting on the beach on 15 th January 2011. Morphometric measurements of the turtle were taken and data suggests that this individual is adult. A total number of laid eggs were 109. The distance between the nesting site and the high tide line was found to be 7 m. The depth and diameter of the nesting pit was 52 and 16 cm, whereas the mean egg diameter and weight were found to be 44.3 mm and 40.5 g respectively. Pamban coast may also be considered an important place for nesting, because of the continuous mixing of waters of GOM and Palk Bay areas, which in turn create current patterns continuously throughout the year in addition to the monsoon season. Conservation of nesting habitat along Gulf of Mannar will be important to maintain the green turtle population.


Introduction
Five species of the sea turtles, Lepidochelys olivacea (Olive ridley turtle), Chelonia mydas (Green turtle), Eretemochelys imbricata (Hawksbill turtle), Caretta caretta (Loggerhead turtle) and Dermochelys coriacea (Leatherback turtle) are found along the coasts of India including Lakshadweep, Andaman and Nicobar Islands. They all are also found in the Gulf of Mannar (Kar and Bhaskar, 1982). They are categorized as endangered species in Schedule I of the Indian Wildlife (Protection) Act, 1972 and are thereby protected.
In India directed fishery of olive ridely existed in Orissa and West Bengal during the 'arribada' and fishery of green turtle in Gulf of Mannar (GOM) and Palk Bay in Tamil Nadu. However, fishing and trading of turtles were totally stopped in the early 1980 in Tamil Nadu and in 1983 in Orissa and turtles were declared as endangered species . Since then, turtles were landed as incidental catch of different gear predominantly in gillnets, hooks and lines and trawlers along the Indian coasts in different fishing operations. The sea grass and coral reef ecosystem in the GOM region, including islands, form a good habitat and a major nesting ground for several sea turtle species (CMFRI, 1977). Green turtle, locally known as 'Paer aamai' in Tamil, is predominantly herbivorous and feeds on sea grass. The name green turtle indicates the green colour of the fat.
In the Indian territorial waters there are not many information on the green turtle, except for a few nesting records (Bhaskar, 1984;Sunderraj et al., 2002;Tripathy and Choudhury, 2002;Venkatesan et al., 2004). The present account deals with a sighting of nesting of female green turtle on the Pamban fish landing centre at Rameswaram Island along GOM.

Materials and methods
The presence of one female green turtle ( Fig. 1) along with its nest were reported on the sandy beach of Pamban landing centre along the GOM on 15-01-2011 (from 05.10-06.20 hrs) (Fig. 2). Shore and near shore water of the GOM were calm. Local enquiries revealed that it laid eggs at 04.30 hrs. The nest was filled with eggs. The position of the nesting pit was noted. All the eggs were removed and counted by excavating the nesting pit with the help of Forest Department staff who were already present on the spot (Fig. 3). The nest was excavated and the depth of the nest from surface to the bottom was measured (Fig. 4). To protect from natural predators, the eggs were safely transferred and buried in pits for incubation in a beach hatchery by the Department of Forests, TamilNadu. To determine the egg size, twelve eggs randomly collected at the time of translocation were   Venkatesan V. et al./ Not Sci Biol, 2014, 6(4) 414-416 measured using a vernier caliper and each egg was then weighed with an electronic balance to the nearest 0.1 g. Morphometric measurements were also taken using a flexible tape. The distance from the shore during high tide to the nesting pit was also measured.

Results and discussion
Studies on the sighting of green turtle and its nesting from other parts of India were reported by several workers (Bhaskar, 1984;Sunderraj et al., 2002;Tripathy and Choudhury, 2002;Venkatesan et al., 2004). However, no recent information concerning the nesting of this species is available from Pamban coast. The day of observation i.e. 15 th January 2011 comes under the nesting season of green turtle in GOM as reported by other researchers (Rajagopal et al., 1996). The details of morphometric measurements of the female turtle are given in Tab.1.
The straight carapace length (SCL) of 90 cm is well within the range of adult size classes (86.5-109 cm SCL) obtained for this species from Western Somoa (Wetzell, 1982). From the morphometric measurements, it appears 415 Fig. 4 Venkatesan V. et al./ Not Sci Biol, 2014, 6(4) 414-416 nesting beach and moreover this coast is now becoming fish landing centre. Therefore, there might have chance of more and more incidental catch and intentional hunting for meat. Rajagopalan et al. (1996), studying the incidental catch of sea turtles in India, reported the same fact i.e. green turtle formed 75% of incidental catch.
Turtle meat, oils and shells were exported to different countries in the past. In the 1960, around 3000-4000 turtles were landed every year in GOM (Rajagopalan, 1996). Gill net and bottom trawl has been considered as the most impacting fishing gears for sea turtle populations in terms of number of catch per year. During 1985-1995, gill net formed 76.5%, followed by trawl net (17.8%) in total incidental catch.
Marine turtles are migratory during all stages of development (Carr, 1987) and different current pattern play a crucial role in their behaviour. Days to week after hatching, the turtle locate oceanic currents that transport them to distant nursery areas (Bolten, 2003a). The current systems of major importance in GOM and Palk Bay are those caused by the south-west and north-east monsoons. During south-west monsoon, the direction of the current is clockwise and the reverse in northeast monsoon. These currents may play an important role in drifting the sea turtle and its hatchling towards offshore. Pamban coast may also be considered an important place for nesting because it is located adjacent to the Pamban-Pass, where the continuous mixing of waters of the two areas of GOM and Palk Bay take place, which in turn create current patterns continuously throughout the year in addition to the monsoon season.

Conclusions
Artificial nesting grounds can be constructed in and around Pamban as an aid to conserving this important species. Conservation of nesting habitat along Gulf of Mannar will be important to maintain the green turtle population, even more that the recent identification of the nest in Pamban proves the importance of this place related to the green turtle reproduction. This study will help to earmark the places to be conserved for nesting.