Emergence success of national nests for olive ridley on sandy beach, Kadongalay lsland in Myanmar

Abstract

The Kadongalay Island (15°49′N, 95°13′E) has existed since 1911. This Island is formed with deposited sand at the mouth of Bogalay River, Ayeyarwady delta in Bay of Bengal and it's close to Andaman Sea, Kadongalay Island is 5-miles length and three quarters mile in breadth, turtles laying the eggs on this island from September to March yearly. Department of Fisheries was undertaking sea turtle conservation and research started on Kadongalay Island in 1998. In Kadongalay Island, only olive ridley (Lepidochelys olivacea) attended to this Island for nesting. About 120 nests could be found each year along the sand beach. All nests have been preserved naturally. Nesting female turtles lay the eggs on the sand bank with white siliceous sand, three different kinds of places as lower slope, upper slope and dune. Data were recorded including nest location and date, and then watched until the time of hatching out. After the hatchlings were hatched out from clutches, the egg hatching rate and other parameters were examined immediately. Data for these clutches such as temperature, incubation period, emergence success and clutch sizes from three different areas were collected. The results showed that average temperature was 29.3℃, 51 days of incubation period and 96.17% of emergence success in dune. Average temperature was 28.53℃, 50 days of incubation period and 89.8 % of emergence success in upper slope. Average temperature was 27.4℃, 49 days of incubation period and 95% of emergence success lower slope. Digital thermometers and measuring tapes were used for these researches. All clutch sizes were not different from each other. Nesting turtles did not make deeply the body pits in the above mentioned sand.