Population ecology and conservation of the river terrapin, Batagur baksa (GRAY, 1831) in Myanmar, Thailand and Malaysia

Abstract

This study confirmed that Batagur baska small populations still persists in coastal regions of Mon and Rakhine states and Ayeyarwady and Tanintharyi Division in Myanmar where a combination of local religious beliefs and areas of armed conflict confer some degree of protection. Peninsular Malaysia represents the last stronghold of B.baska and this study estimates indicate that less than 50 breeding females remain in Perak River, Malaysia. A small numbers of B.baska still inhabited in Langu Canal in Satun Province, Thailand and also documented the occurrence of three wild nests and other potential nesting beaches along the river. In Satun Inland Fishery Station, under captive condition, courtship and mating took place during October and November, followed by nesting in December and January. Mean clutch size among females (n=14) was 21.7 +- 5.6 eggs (range = 18 to 25 eggs). Incubation periods ranged from 74 to 110 days depending on the method of incubation. Hatching success ranged from 40.8 % to 58.1 % depending on incubation method. In Bota Kanan Hatchery, courtship and mating takes place from August through December, while nesting and clutch deposition occurs as early as October, with a peak in January, and continues until mid-March Clutch size produced by captive female averaged 15.2+-5.7 eggs (n=10;range = 6-20). From 1993 to 2005, 1524 clutches were produced by adults maintained at BKH with hatching success ranging from 27.5 to 60.5 %. Incubation periods ranged from 71 to 92 days. Based on 79 females and 50 males, the analysis indicates that there is no significant morphological difference between B.baska among isolated populations and it could only be concluded that B.baska males had significantly narrower carapace width, shallower shells, shorter plastrons, and lighter body weight than those in females at all locations. Batagur baska populations face a variety of threats including predation, incidental capture as a result of fishing activity, habitat loss, subsistence and commercial harvest of eggs and turtles, exposure to environmental pollutants, and global climate change. Due to rapid decline of the wild population of B.baska, the conservation management is urgently needed.