Future of giant catfish may be under threat US expert urges thorough study Anchalee Kongrut Researchers studying the giant catfish's migratory behaviour have suggested that the fish's migratory and spawning patterns be systematically recorded, in order to determine the Pak Moon dam's impact on the catfish population in the Mekong river basin.
Zeb Hogan, a fisheries biologist from the University of California, said he suspected the dam had a detrimental effect on the giant catfish and other freshwater species. There should be systematic recording of the catfish migration in the Moon river to find out whether the fish's natural fish spawning grounds have been affected by the dam.
Mr Hogan has already begun a study of Cambodia's giant catfish. Late last year, Mr Hogan and Heng Kong, a researcher from Cambodia's Department of Fisheries, tagged 13 fish with ultrasonic signallers and released them into the Mekong to track their migratory pattern.
"The Pak Moon dam may be negatively affecting the fish population and its migration in Thailand as well as in neighbouring countries,'' he said. The capture of a giant catfish in the Moon river early this year, the first after the dam was built in June 1994, might hint at linkage between the dam's impact on the fish's migratory route and spawning grounds, said Mr Hogan.
Fishermen above the dam caught the 116kg giant catfish on Jan 6, seven months after all the dam's sluice gates were fully opened. Dam opponents believe the dam is responsible for a decline in the Moon's fish population because it blocks the fish from swimming upstream to spawn. They also said dynamite explosions during the dam's construction had flattened the river bed and destroyed small caves which were spawning grounds for various fish species.
According to a study by the World Commission on Dams, an independent team sponsored by the World Bank, the number of fish species in the Moon has dropped from 256 to 96 since the dam construction was completed. The giant catfish (Pangasius gigas), or pla buek, is the world's largest freshwater fish and can reach three metres in length and 300kgs in weight when fully grown. The species is now under grave threat from overfishing, hydro-dams and other human activities.
The catfish captured on Jan 6 could have migrated from the Mekong river or been naturally bred in the dam reservoir, said Mr Hogan. "The Pak Moon dam may be negatively affecting fish population and fish migration in Thailand as well as in neighbouring countries,'' he said. The two researchers had released a number of catfish with migratory tags in Cambodia's Tonle Sap river.
Some of the fish were later recaptured some 300km up the Mekong river. Fish conservationists hope knowledge about the giant catfish's migration and spawning patterns would lead to suitable conservation methods, such as making their spawning ground a protected habitat zone under Unesco's Man and Biosphere Programme. "Researchers hope that one or more of the tagged giant catfish may be captured in the Moon river or elsewhere in Thailand during 2002,'' Mr Hogan said.
Fishermen are asked to release tagged fish captured alive back into the river or returning their dead bodies to the authority. The tagging programme is part of the Giant Catfish Conservation and Research Project, a joint study of the US-based World Wildlife Fund and Cambodia's Fisheries Department.
Source : Bangkok Post
Endangered species can also stimulate public and political support for cooperative action to restore populations and protect habitat. In border areas, the protection of such species necessitates transnational cooperation and such cooperation has led to policy formation and the establishment of international regulatory agencies.
In the Mekong River Basin, the Mekong giant catfish is a model species for promotion of cooperation at the international level because:
1. The Mekong giant catfish is well-known throughout the Mekong River Basin. The fish is migratory, transboundary, and endemic to the Mekong River.
2. Many people believe the Mekong giant catfish is a sacred fish. In Thailand and the Lao PDR, a complex ritual accompanies the fishing of this species. In Cambodia, the species is called "trey reach" or royal fish, signifying the special status of the giant catfish in the Khmer heritage.
3. The Mekong giant catfish is endangered. Populations of the Mekong giant catfish have been declining for several decades. The fish, once captured throughout the basin, is now very rare.
4. The Mekong giant catfish is one of the only Mekong species specifically mentioned in several international treaties and agreements, such as the IUCN Red List of Endangered Species and the Convention on the Conservation of Migratory Species.
5. National law supports the conservation of the Mekong giant catfish. It is illegal to capture the Mekong giant catfish in Cambodia and Thailand.
6. Scientific techniques exist to study the giant catfish. The Thai Department of Fisheries has developed a method to breed this species in the captivity and studies are also currently underway to determine the status and distribution of the species in the wild.
7. While wild population of the Mekong giant catfish appear close to extinction, research and conservation may provide a means to restore populations of giant catfish.
8. The giant catfish probably spawns in northern Thailand, the Lao PDR, Myanmar, and possibly China. This is the same area that will be impacted by the controversial Mekong navigation project.
9. The Mekong giant catfish appears to migrate out of the Tonle Sap Lake and into the mainstream Mekong River at the end of the rainy season. This migration pattern is common among fish of the Cambodian Mekong and thus the protection of the migratory pathway may benefit an entire assemblage of migratory fish.
Selected References Butler, P. 2000. Promoting protection through pride: a manual to facilitate successful conservation education programmes developed at RARE Center for Tropical Conservation. International Zoo Yearbook 37:273-283. Caro, T. and G. O'Doherty. 1998. On the use of surrogate species in conservation biology. Conservation Biology 13:805-814. Catch and Culture: 2 (4), May 1997; 3 (1), Aug. 1997; 4 (2), Dec. 1998, Supplement No. 3; 6 (3), March 2001. Dietz, J.M., A.L. Dietz, and E.Y. Nagagata. 1994. The effective use of flagship species for conservation of biodiversity: the example of lion tamarins in Brazil, pp. 32-49 in P.J.S. Olney, G.M. Mace, and A.T.C. Feistner, Eds. Creative Conservation: interactive management of captive and wild animals. Chapman and Hall, London. Dillon, T.C. and E. Wikramanayake. 1997. Parks, peace, and progress: a forum for transboundary conservation in Indochina Parks 7:36-51. Dinerstein, E., E. Wikramanayake, J. Robinson, V. Karanth, A. Rabinowitz, D. Olson, T. Mathew, P. Hedao, M. Connor, G. Hemley, and D. Bolze. 1997. A framework for identifying high priority areas and actions for the conservation of tigers in the wild. World Wildlife Fund, Washington D.C. Hogan, Z. 1998. The quiet demise of the Mekong giant catfish. Wildlife Conservation 101:12. Hogan, Z., N. Pengbun, and N. van Zalinge. 2002. The status of the Mekong giant catfish, Pangasianodon gigas, in the Tonle Sap River, Cambodia. The Natural History Bulletin of the Siam Society (in press). IUCN. 1996. IUCN Red List of threatened animals. Gland. Kottelat, M. and T. Whitten. 1996. Freshwater biodiversity in Asia with special reference to fish. World Bank Technical Paper No. 343, The World Bank, Washington D.C. Kumar, S. and P.S. Raghavaiah. 2000. New concepts in biodiversity conserva tion, publicity, and extension: an environmental education center at Tirumala and use of spiritual theme. Indian Forester 126:9-15.
Source : CITES for Mekong Protected Fish
This is the first time that wild Mekong Giant Catfish was caught in the Mun River since the Pak Mun dam was built ten years ago. There have been some Mekong Giant Catfish caught in the river but all of them were scientific fertilizing fish, which is smaller than wild fish.
It is assumed that this king of fish migrated to the Mun River during opening the Pak Mun dam gates last year. Mekong Giant Catfish is endangered species found only in the Mekong River and its tributaries. It is also listed in the Red Lists of IUCN.
In breeding season, this migratory fish travel upstream of the Mekong River and its tributaries to spawn before traveling back to their home in Ton Le Sap in Cambodia and wetlands in the lower Mekong.
Pak Mun villagers reported that wild Mekong Giant Catfish had been caught in the Mun River before the construction of Pak Mun dam. It is an important evidence to show that the Mun River is very important ecosystem for migratory fish in the Mekong River basin. Opening Pak Mun dam gates permanently will be opening opportunity to protect the king of fish from extinction.
Source : ChiangMai Mail
