Assessment of the conservation status of the leatherback turtle in the Indian Ocean and South-East Asia - 2012 Update

Since the 2006 Leatherback Assessment, a number of new initiatives have occurred across the IOSEA region. New sites have been monitored in the south-western Indian Ocean, particularly in Mozambique, satellite tags were deployed on leatherbacks in the Bay of Bengal, foraging studies (by means of aerial surveys) as well as fisheries interaction studies have been conducted around the South China Sea area, and the Western Pacific region has had a substantial number of papers and reports published between 2007 and 2011.
Many of these efforts started before the 2004 Indian Ocean tsunami and continued afterwards, and were not necessarily in response to tsunami impacts. The Bay of Bengal – East Indian Ocean rookeries were the worst affected by the tsunami, as permanent modification of the coastline took place. Effects were further observed in nesting activities, monitoring and conservation actions, especially for the two years following. Sporadic surveys of nesting beaches and foraging areas resumed throughout the region, but with inconsistent effort mostly due to financial constraints.
The present (post-2004) assessment is still deemed Data Deficient for three of the four sub-regions, namely: Western Indian Ocean, Bay of Bengal - East Indian Ocean, South-China Sea area and Western Pacific (Fig 1, page 24). However, good data have been collected consistently in the Western Indian Ocean for the last 5 seasons. The short-term population trend is deemed “stable”. The number of leatherback nests in South Africa and Mozambique has been similar over the last 15 years (<100 females).
The main documented nesting sites in the Bay of Bengal - Eastern Indian Ocean have been, and are still, in the Nicobar and Andaman Islands. Monitoring efforts on Little Andaman indicate that nest numbers have recovered to be in a similar range as before the tsunami habitat impacts. Another regional highlight was the proclamation of the Chagos Archipelago Marine Protected Area, the world’s largest no-take MPA.
The South China Sea area has had little consistent effort, generally, and the rookeries with consistent effort (e.g. Terengganu, Malaysia) have very few leatherback nests left. The low level of dispersed nesting throughout remote areas of Viet Nam makes it very difficult to assess the status of the population in that country.
Significant effort was made particularly around the West Pacific. Substantial rookeries are still doing relatively well in Papua, Papua New Guinea, and the Solomon Islands – with collective rookery size estimated to be ~ 5000 - 10,000 nests per annum. Some genetic studies have been conducted, and more than 120 satellite tags have been deployed across the Pacific region over the last decade. These studies have provided some of the best data available for leatherback turtle habitat use, suggesting a single Western Pacific genetic stock, but with clear differences in nesting and migration patterns based on summer and winter nesting events. Even though this effort has not been consistent, it was substantial and contributed to important conservation actions such as the proclamation of an area of critical habitat along the west coast of the United States, which is the foraging habitat for West Pacific leatherbacks.
More generally, little fisheries bycatch data are available for the IOSEA region, with no indication of the magnitude or trends. The paucity of information on bycatch remains an area of concern.