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 The Irrawaddy dolphin
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Lagt på d. 24/03-2007 14:43
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 Ekspert medlem  Antal indlæg: 2597 |
[img]http://www.bangkokpost.com/Outlook/240307_out01.jpg[/img] is not a valid Image. Irrawaddy dolphins can be found at the mouth of the Bang Pakong River in Chachoengsao province every winter. [img]http://www.bangkokpost.com/Outlook/240307_out02.jpg[/img] is not a valid Image.[img]http://www.bangkokpost.com/Outlook/240307_out04.jpg[/img] is not a valid Image.[img]http://www.bangkokpost.com/Outlook/240307_out03.jpg[/img] is not a valid Image. The mouth of the Bang Pakong River. The Irrawaddy dolphin It's an uphill struggle, but Thailand is trying to protect its marine wildlife Story by Pichaya Svasti, photos courtesy of WWF THAILAND DRIFTING ON THE SURFACE OF the clear blue water at the mouth of the Bang Pakong River one day in winter were two big creatures looking like grey torpedoes with small fins on their backs. One of them stayed on the surface for several minutes in a seemingly carefree mood. Above the water was its oval-shaped mouth. It then rolled down into the water, its V-shaped tail visible for a few seconds before vanishing into the depths of the river. They were Irrawaddy dolphins (Orcaella brevirostris) who migrate from the Gulf of Thailand to the Bang Pakong River in Chachoengsao province every November, where they stay until the end of February searching for food, a mate and to give birth to their calves. Dolphins in Chachoengsao? That may sound unbelievable, but it has been this way for at least 100 years. "The dolphins have been here since before my 80-year-old fisherman father was born," said Krieng Mahasiri, commander of Marine and Coastal Resources Patrol Vessel 801, who has been working to protect dolphin food supplies off the coast of Chachoengsao for four years. Dolphins are not fish, but mammals. They are also good indicators of the marine environment, as each dolphin consumes a lot of fish, equal to around four to nine per cent of its bodyweight each day. An Irrawaddy dolphin eats around eight kilogrammes of fish every day. The Irrawaddy dolphins can live in salt-water, brackish water and freshwater. The gestation period is about 14 months and mothers nurture their young for between three and eight years. They are also sometimes spotted along the coastline from Chon Buri to Phetchaburi, often in the mouths of the Bang Pakong, Tha Chin and Bang Taboon rivers. The mouth of the Bang Pakong is a hotspot, where as many as 20 or 30 Irrawaddy dolphins can been seen at a time, said marine biologist Surasak Thongsukdee of the Marine and Coastal Resources Research Centre for the Upper Gulf of Thailand. The centre has been conducting photo identification of dolphins and whales in the Gulf of Thailand - from Chachoengsao and Samut Sakhon to Chon Buri - for several years. Surveys by the centre in 2004 found a variety of dolphins - the Irrawaddy, humpbacked (Sousa chinensis, or loma lang nok), bottlenose (Tursiops truncatus, or loma pak khuat) - and finless porpoises (Neophocaena phocaenoides, or loma hua bart lang riab ) as well as Brydes whales (Balaenoptera edeni, or warn klaeb ) and pygmy killer whales (Feresa attenuata, or warn phetchakart khrae) in the inner Gulf of Thailand. Last year's survey by the Marine and Coastal Resources Research Centre for the Lower Gulf of Thailand found 30 Irrawaddy dolphins in Songkhla Lake. The bad news is that these dolphins are under threat from fisheries, getting tangled in fishing nets, pollution, food shortages, overfishing, soil erosion and a general degradation of the marine environment, according to WWF Thailand. The most serious threat to dolphins in the Bang Pakong is overfishing and the resulting depletion of the dolphins' food supply, Krieng said. The Irrawadddy dolphins' main food is catfish, and the catfish feed on small shrimps, or koei in Thai. Overfishing of these has destroyed the food chain and is affecting the dolphins. In Songkhla Lake, the major cause of death of Irrawaddy dolphins is entanglement in gill nets, said Santi Nilwat of the Marine and Coastal Resources Research Centre for the Lower Gulf of Thailand. Dolphins are on the list of endangered species in Appendices I and II of the Convention of International Trade in Endangered Species of Wild Fauna and Flora (Cites). Trade in animals listed in Appendix I are subject to strict regulation and is normally only permitted in exceptional circumstances, while trade in animals listed in Appendix II must be monitored through a licensing system. In 2004, Cites member countries voted to ban commercial trade in Irrawaddy dolphins by adding them to Appendix I, where they join critically endangered species like great apes and tigers. The estimated dolphin population in Asia is now under 1,000, and is still declining. In Thailand, at least 20 dolphins run ashore on beaches and die each year, according to the Office of Marine and Coastal Resources Conservation. It wasn't until 2002 that the Marine and Coastal Resources Department was assigned to protect rare aquatic animals such as dolphins, whales and turtles in Thai territorial waters. To protect the dolphins, patrol vessels will ensure that boats stay at least 30 metres away from dolphins and that there is no chasing of or running through schools of dolphins. The mouth of the Bang Pakong is significant for being where Irrawaddy dolphins mate and give birth. A survey on December 2 last year found two Irrawaddy dolphin calves there. Unfortunately, the dolphins on the Bang Pakong are under threat from phong phang (bag nets), used for catching small shrimp. According to surveys conducted by the Marine and Coastal Resources Research Centre for the Upper Gulf of Thailand, three or four dead calves, weighing under 10kg, have been found each year in this area since 2004. Thanks to persuasion by the authorities, many fishermen on the Bang Pakong have agreed to stop using the phong phang, and 30 to 40 fishing boats have been modified so they can offer dolphin sightseeing tours. It is a sound economic decision: Fishing from dusk till dawn earns fishermen 400 to 500 baht, while a dolphin sightseeing tour brings at least 600 baht in only two hours. Each boat attracts 10 to 15 tourists and charges at least 60 baht per head per trip. But shrimp boats from other provinces are still fishing the Bang Pakong, resulting in less food for the Irrawaddy dolphins, Krieng noted. The situation for some 30 Irrawaddy dolphins in Songkhla Lake is more distressing, said Santi Nilwat of the Marine and Coastal Resources Research Centre for the Lower Gulf of Thailand. According to a study, approximately four Irrawaddy dolphins die each year in the lake. Last month the bodies of six dolphins, including two calves, were recovered from the lake. The calf mortality rate has also been rising, he noted. Apart from entanglement in fishing gear, other causes of dolphin fatalities in the lake include starvation and environmental degradation resulting from sedimentation and nitrification (the oxidation of ammonium compounds found in organic material into nitrates and nitrites by bacteria), and pollution caused by shrimp and pig farms, rubber plantations and factories. The major culprit is the huge gill nets used for catching big fish like the Mekong giant catfish, or pla buek, and the striped catfish, or pla sawai, a non-indigenous species. The shrimp traps (sai nang) in the Songkhla Lake, meanwhile, obstruct the route of marine animals between the sea and the lake, disrupting the food chain. They also prevent dolphins from the sea entering the lake, resulting in inbreeding in the lake's dolphin population and weak calves. Their staple diet is the Siamese rock catfish, or pla kod hua mong. But these have become scarce due to overfishing. A local committee comprising officials and community representatives plans to declare a dolphin conservation zone covering 100km2 of the lake. But the committee admits that this is no easy task, due to resistance from the fishing industry. To raise public awareness of dolphin conservation matters, the Marine and Coastal Resources Research Centre for the Lower Gulf of Thailand has encouraged local communities to report deaths of dolphins, and local fishermen to switch to dolphin sightseeing tours. There are two operators now. Not everyone agrees with the tourism solution. Kanjana Adulyanukosol, an expert of the Phuket Marine Biological Centre, for one, said it is difficult to control tour boats. Raising awareness with the fishing communities is more effective, she said. According to Assoc Prof Nantarika Chansue, director of the Veterinary Medical Aquatic Animal Research Centre under Chulalongkorn University's Faculty of Veterinary Science, 10 to 20 dolphins are reported beached and dead each year in Thailand due to injuries and disease. Their survival rate of a sick dolphin is very low, approximately five per cent, she said. In most cases, rescued aquatic animals die in one to four weeks. The major cause of death is lung infection, partly because of bad handling - turning dolphins over improperly can cause them to breath in dirt and suffer respiratory infection. Apart from a budgetary commitment to improve the rescue operation, there is a need for veterinary training in order to boost survival rates, she added. Ideally, she said, Thailand should have mobile rescue units equipped with ultrasound and X-ray equipment. There should also be rehabilitation ponds for stranded or ailing aquatic animals. Songpol Tippayawong, head of WWF Thailand's marine unit, said the Conserving Endangered Dolphins in the Inner Gulf of Thailand Project, signed last October by the WWF Thailand, the Marine and Coastal Resources Department and the Gulf Electric Company, will use dolphins to promote marine resource conservation and as indicators of mangrove fertility, since they are at the top of the food chain. Databases will be built. Guidelines for eco-tourism and local school curriculums will include environmental studies, encouraging schools and local groups to become involved in dolphin conservation. "In two or three years, there will be a baseline on dolphin populations and migrations," said Chavalit Vidthayanon, a freshwater specialist of WWF Thailand. "This information will be used for better conservation and management." [img]http://www.bangkokpost.com/Outlook/240307_out05.gif[/img] is not a valid Image. A map featuring the distribution of dolphins in the Gulf of Thailand as shown with red and yellow spots. [url]www.bangkokpost.com/Outlook/24Mar2007_out01.php[/url] |
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