Andaman and Nicobar Islands Environment Team
Madras Crocodile Bank Trust/Centre for Herpetology
Post Bag-4, Mamallapuram, Tami Nadu- 603 104, India.
The pre tsunami status and distribution of the leatherback turtle (Dermochelys coriacea), hawksbill turtle (Eretmochelys imbricata), green turtle (Chelonia mydas) and olive ridley (Lepidochelys olivacea) in the Andaman and Nicobar islands has been documented over the last two decades (see Bhaskar, 1979, 1993; Sivasundar & Devi Prasad, 1996), Andrews (2000), Andrews & Shanker, 2002 and Andrews et al. (2006). Bhaskar (1993) and Andrews et al. (2006) have also discussed the historical records of marine turtles in these islands. Bhaskar & Andrews (1993) formulated an action plan for the four species in the islands.
The leatherback and hawksbill populations nesting in the Andamans and Nicobars are the largest for India and most important for the Northern Indian Ocean region. The leatherback nesting population in the Nicobar islands was one of the few colonies that exceeds over 1000 nesting individuals in the Indo-Pacific, and hence of global significance (Andrews & Shanker, 2002). Andrews & Tripathy (2004) and Andrews et al. (2006) recorded 30 nesting sites in North Andamans, 27 in Middle Andamans, 21 in South Andamans, six sites in Little Andaman Island and 26 sites in the Nicobar group.
The 26th December 2004 M 9 quake caused the subsidence of the Nicobar Islands and areas around South Andaman Island, besides an upheaval, by an average of 1 m, on Little Andaman Island, northwestern South Andaman, entire Middle and North Andaman Islands including Landfall Island. The subsidence of the Nicobars and South Andaman Island by an average of 1 m caused high tides reaching inland and flooding of coastal lowlands. In the Nicobars, being just north of Sumatra, coastal habitats in all the 23 islands have been affected, and beaches and coastal habitats have been swept away. The impacts and ecological changes in both island groups have been discussed in detail by Andrews (2005), Sankaran (2005), Andrews & Vaughan (2005) and by Jayaraj & Andrews (2005).
Observations and assessments of the coastal habitats and beaches, and reef flats were conducted by ground surveys. Areas and islands were assessed with a local inboard, dugout canoe (Andaman dungi). Reef flats were observed onshore and offshore. In Great Nicobar Island, surveys were conducted by ground and helicopter surveys and in central Nicobars by boat and on foot. Some areas of South Andaman Island were surveyed over land. Beaches were surveyed on foot during the mornings and evenings to count turtle nests and tracks; tracks/crawls were categorized as fresh, (crawls with visible flipper marks), and old (those with either only the nest excavation mound and or faint tracks visible). The data recorded were counts made on a single walk (on occasion to and fro) along a beach to ascertain the presence or absence of turtle nesting activity, and species visiting the beach. Off shore sightings were also recorded and surveys were conducted during January-April 2005 and during January-March 2006. Two field camps were started during the second week of October 2005, for monitoring nesting, at Cuthbert Bay, north east of Middle Andaman Islands and at Rutland Island, on Jahaji beach, on the southern side of the island.
Middle and North Andaman Islands
During January-April 2005 and January- March 2006, the beaches on South Reef, Interview, North Reef, Snark, Point, Paget, Reef, West, Landfall and East islands were surveyed (Fig: 1). There was very little changes to the beaches on these islands but due to the upheaval of reef flats, many nesting beach areas have become inaccessible for turtles. The reef flats on the northern, western and the southern sides of South Reef Island, extend for roughly about 2 km². Six nests of hawksbills were recorded during the 2005 survey on this island. The beaches on the south west coast and north eastern side of Interview Island have become inaccessible for turtles to nest due to reef flat upheaval. The beach on the south west coast of Interview Island used to be one of the most favoured nesting beaches for green turtles (Bhaskar, 1984; Andrews et al., 2001). The sea grass bed on the north of Interview Island at Brasse Point had been swept away; however regeneration of small tufts, 3-4 cm high, was observed. Over 10 green turtles and three hawksbills of different size classes were sighted in this bay (Andrews & Vaughan, 2005).
Beaches on North Reef Island, on the north western and eastern sides, have minimal changes; however the beach on the south eastern side has built up. Due to exposed reefs to an extent of 4.5 km², marine turtles do not have access to these beaches for nesting and this was evident as no tracks or nests were found on these beaches. Two plastrons of green turtles were found on the west coast and no evidence was available to conclude the cause of death. However, 22 sightings of green turtles around the island, off shore and among deeper reefs, were recorded (Andrews, 2005). During the 2006 survey, a few under nourished green turtles were seen trapped in tide pools and lagoons created due to reef upheaval. The reef flats on the western, southern and eastern side of Latouche Island were also exposed and eight green turtles and three hawksbills were sighted off North reef Island.
The exposed reef flats along the northeastern side, the northern, eastern and the southern sides of West Island, is estimated to be 4.5 km². Reefs, 2- 4 m deep, were observed on the eastern and southern sides of Snark and six green turtle nests and nine tracks and four hawksbill nests were found on Snark Island. Beaches on the southern sides of Snark Island have changed very little. Due to the upheaval of reef flats, turtles do not have access to the beaches on the eastern and western sides of Point, Paget, West, Landfall and East Islands (Fig. 1). On Flat Island, no signs of nesting were observed during the 2005 season; however during the 2006 survey, two green turtle nests and one hawksbill nest were recorded. Opposite Flat Island on the main island of Middle Andaman, a beach and spit cover the coast where rocky shoal and coral reef abut the passage between Flat Island and the main island. A single hawksbill nest was recorded on this beach in 2006.
Very minor changes have occurred to beaches along the western and eastern coasts of Middle Andaman Island (Fig. 2). Most beaches were swept away only partially and high tides reached the forest though subsequently in 2006 new beach deposits were observed. These beaches include, from the south western side, Foul Bay, Tanmuguta, Yadita and Robert Bay; and on the eastern coast, Cape Vestal, Paikat Bay, Woteng and Cuthbert Bay Turtle Sanctuary. Green turtles and olive ridleys were nesting up to April 2005 at Paikat Bay, Woteng and at Cuthbert Bay.
ANET monitored turtle nesting trends during early January 2005 at Cuthbert Bay Turtle Sanctuary. After the tsunami, six green turtles were encountered and two nested. Of the 94 olive ridleys encountered, 65 nested and the one leatherback encountered also nested. Nesting on this beach ceased by 27th April 2005. During the following nesting season, October 2005 to March 2006, 118 olive ridleys were encountered and 109 nested, 16 green turtles were encountered of which eight nested and two leatherbacks were encountered, but did not nest.
Ritchie’s Archipelago and South Andamans
During March 2005, eight green turtle and three olive ridley nests were counted on Middle Button Island. Eleven green turtle and six olive ridley nests were observed on Inglis/East Island. During the 2006 survey, 21 green turtles and 3 leatherbacks were found to have nested on North Button Island. Along the South Andamans, the Madhuban Beach east of South Andaman, along Mount Harriet National Park, north of Port Blair, was surveyed during 2005 (Fig. 3). Old and fresh tracks and nests of two species of turtles, green turtles and three olive ridleys, were recorded. However, these nests could not have survived as they were being flooded during high tides.
During the 2005 survey, it was observed that the beaches on east and west Twin islands, Rutland, North and South Cinque and South Brother Islands were partially swept away and the high tide reached the forest line. The sand bar along the south western side of North Cinque was swept away by the tsunami and currently a sand bar has formed and the beach has built up. Very minor impacts on coastal forests were observed on all these islands, including Boat, Hobday, Redskin and Tarmugli Islands. There was no evidence of nesting on these islands after the tsunami in 2005.
During the last monitoring programme by ANET, between October 2005 and March 2006, the team on Rutland Island encountered 44 green turtles, of which 22 nested, and 19 olive ridleys, of which 17 nested; of the 10 hawksbills encountered, three nested and of the 12 leatherbacks that emerged on the beach, 10 nested. During November 2005, one leatherback and two green turtle nests were recorded on North Cinque Island and there was no evidence of nesting on South Cinque. During the same month, three hawksbill nests and one green turtle nest were observed on east Twin Island and nine hawksbills and four green turtle nests on west Twin Island. A second survey of the same islands conducted during March 2006 resulted in six green turtle, three hawksbill and one olive ridley nest on east Twin Island, and three green turtle, six hawksbill and four olive ridley nests on west Twin Island.
Little Andaman Island
The three major sea turtle nesting beaches surveyed during March 2005, West Bay, South Bay on the west coast and Butler Bay on the eastern coast, were all affected. These beaches were washed away partially and submerged during the high tide. There was no evidence of turtle nesting on these beaches in 2005, but observations and indications during the 2006 survey suggest significant visitation and nesting by turtles, especially leatherbacks and that these beaches are reforming. Two other large beaches were formed after the tsunami, one starting at the northern side off the mouth of Jackson Creek measuring a length of 5 km (Fig. 4). Turtle tracks and nests of three species, green turtles (four nests), olive ridleys (three nests) and leatherback (two nests), were recorded from this beach. Another 2 km long beach had formed, situated 4 km south of Jackson Creek and four nests of green turtles and two olive ridley nests were found on this beach.
During the 2006 survey, an older member of the Onge community remarked that they (the Onge from Dugong creek) had gone turtle hunting along the shore and off the mouth of Dugong Creek, after many of their women told them that they wanted to eat turtle meat. The men went out along the shore and to sea returning with a few green turtles and the women were disappointed as the turtles were lean and did not have any fat and meat. They then realized that the sea grass beds were damaged and the sea turtles did not have much to eat. The women then told the men that despite their hunger to taste sea turtles, it would be better to wait and allow the sea grass to grow so that sea turtles could feed themselves before they became food for the Onge; since then they have not hunted.
Great Nicobar and areas in the central Nicobar group of islands
The Nicobar Islands were surveyed during January – February 2005. The entire coastal area and habitats have been completely affected and destroyed impacting all coastal flora and fauna and affecting some of the mega species. In the Galathea area and the entire South Bay, the tsunami wave had gone inland to a distance of almost 1.5 km. This had destroyed all the beaches, mangroves and the entire coastal habitat of South Bay, including the areas around the light house at 51 km. Debris, consist of fallen trees, plastics, timber and other flotsam from the sea drift on to the land at each high tide. The high tide line reached the hill slope upto the forests; existing coastal trees, mangrove species and other coastal flora are drying up. During the month of April 2006, it was reported that the coasts along western Great Nicobar Island had regressed further due to continued wave action and erosion (R. Sankaran pers. comm). The same effect was observed on the west coast of Little Nicobar Island and islands in the central group and on Car Nicobar Island.
The most affected sea turtle nesting beaches along the east coast of Great Nicobar are the Galathea beach and the beach stretch from 47- 51 km (along the north – south road), and along the west coast are areas near the Alexandria and Dagmar Rivers, Rekoret and Renhong. Beaches along Little Nicobar west coast and Katchal Islands and those areas on Great Nicobar Island were prime sea turtle nesting beaches and these have been washed away. In Great Nicobar Island in South Bay, two beaches are forming, one at 43 km and at the other at 45.5 km(along the north – south road). Hawksbills and olive ridleys were observed nesting at these two beaches. However these nests were destroyed as these beaches flood at high tide. Beach deposition had taken place toward the end of 2005 from Indira Point, the southern most tip of Great Nicobar Island, to Inhingloi on the west coast. The beaches on the west coast and North eastern coast of Little Nicobar Islands were impacted; however leatherback nesting was observed up to March 2005 along the west coast at Muhincohn beach (M. Chandi, pers. comm.).
Currently no major management or conservation effort, apart from continuing sea turtle monitoring and awareness programs, is required for the Andaman and Nicobar Islands. The sea turtle beaches that have been affected will re-form after a few monsoons and other new beaches will form in the next two to three years; this will require monitoring as marine turtles will find new nesting beaches. However, the next five years will be crucial and intensive surveys and monitoring will be required to quantify nesting trends, populations and the nesting beaches forming along the islands.
Coastal planting and restoration programmes are currently not required and mangroves and Casuarina plantations may not protect from tsunamis. There is also no need for creating wind breakers, as there are other native littoral species (other than Casuarina) that can be used to reduce erosion along coast. Natural regeneration and succession of species of flora are underway that could be affected by undue human intervention. In the absence of adequate information on natural resilience and succession, human interference should be minimised. There is also an urgent need for surveys of sea grass beds to quantify impacts and extent. The growth and regeneration of sea grass beds have implications for sea turtles that rely on them for food. Further, a GIS based analysis is required to derive the actual extent of beach and reef flat loss, besides remapping the entire Andaman and Nicobar Islands and its topography.
There is an urgent need to review fisheries practices around the islands and fishing zones. Fishing should be restricted to only 5 km offshore from the high tide line of all islands. During the past several years, surveys by ANET have observed and recorded drowning and entanglement in gill nets and drifting ghost nets, leading to death of sea turtles in significant numbers. Awareness generation and enforcement of no fishing zones in vulnerable regions are required. A plan of action needs to be urgently formulated and immediately implemented for removal of feral and domestic dogs from the Andaman and the Nicobar Islands, as they predate on eggs of turtles and also on nesting turtles.
The Andaman and Nicobar Forest Department are acknowledged for their support and endorsement; we are grateful to Mr S.S. Choudhary, the Principal Chief Conservator of Forests, D.C.F. Mayabunder; Mr. S. Thomas, ACF (WL); Mr. Reddy and Dr. Trinath, DFOs Campbell Bay, Mr. T B. Chatterjee, ACF, Campbell Bay; Mr. A K. Das, RO, Campbell Bay and RO, Saw Robert Pee for all their support, help and encouragement. Much credit goes to our ANET Team mainly Saw Paung, Saw Pamwein, Saw Nelson, Saw Glen, Saw Poba and Saw Poricha, for all their help, good company and all their efforts during the long surveys and at the field stations. We thank the Wildlife Trust of India and the International Fund for Animal Welfare for their support. The Trustees and staff of the Madras Crocodile Bank Trust/ Centre for Herpetology are thanked, as always for all their continued support. Mr. Rasheed Yusuf and the Tribal Council in the Nicobars are acknowledged, as always, for their valuable support, hospitality and assistance. The Coast Guard and the Navy are acknowledged for their help and support with logistics in the Nicobar Islands.
Figure: 1. North Andaman Islands
Figure: 2. Middle Andaman Islands
Figure: 3. South Andaman Islands and Ritchie’s Archipelago
Figure: 4. Little Andaman Island
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