Working to save some of the world’s most critically endangered fish, an international team of scientists and fisheries professionals will release over the weekend of Mar. 4-6 a large assemblage of iconic fish species into Cambodia’s Tonle Sap Lake.

“This is the first step in an effort to restore populations of the Mekong’s largest freshwater fishes. Fish reserves have been shown to be an effective tool to protect aquatic biodiversity and boost fish biomass. It’s one action, of many that are needed, to bring these species back from the brink of extinction,” says Dr. Zeb Hogan, a fish biologist at the University of Nevada, Reno and lead the USAID-funded Wonders of the Mekong project.

Among the fish species to be released are the critically endangered Mekong giant catfish, which is the current record holder for the world’s largest freshwater fish at 293 kilos (646 pounds); the endangered striped river catfish, once a staple food in the region whose population has dramatically declined; and the critically endangered giant barb, the world’s largest carp species and Cambodia’s national fish.

More than 1,000 individual fish will be released into a government-operated fish reserve, former fishing lot No. 4 in the Tonle Sap Lake, a short drive and boat ride from the city of Siem Reap and the famous temples of Angkor Wat. The fish are mostly juveniles, ranging in size from 30cm (1 foot) to 1.6 m (over 5 feet), that have been reared by the Cambodian Fisheries Administration in partnership with the USAID-funded Wonders of the Mekong project. By tagging the fish prior to their release, researchers will have a unique opportunity to study the animals’ survival, growth, and movement.

“The purpose of this event is to reintroduce captive-reared endangered fishes back to the wild and track their fate. We need to better understand the effectiveness of fish reserves as a refuge for threatened fish; this release today will inform future conservation practices, and help us understand whether such methods are effective in supporting the restoration of these species’ wild populations,” says Dr. Ngor Peng Bun, fish ecologist and Dean of Faculty of Fisheries Science at the Royal University of Agriculture.

The Tonle Sap, Southeast Asia’s largest lake and home to over 300 species of fish, is a hotspot for freshwater biodiversity and a UNESCO Biosphere Reserve. Historically, it has served as a crucial nursery ground for endangered giant fish and for many other migratory fish populations in the Mekong River basin. In recent years, these fish have come under increasing threat from dam building upstream, overfishing, and drought.

To combat these threats to fish populations, a series of government-run fish sanctuaries and community conservation areas have been established in the Tonle Sap Lake, forming one of the largest networks of aquatic conservation zones in the world.

“The Cambodian government has taken action to establish fish sanctuaries, protect core areas of the Tonle Sap Biosphere Reserve, and formalise community fisheries and associated reserves – these actions make Cambodia an ideal place to initiate restoration of the Mekong’s endangered fish stocks. Today is part of a multi-year effort to test the efficacy of using Cambodia’s large network fish reserves for reintroduction of captive-reared endangered fishes into the wild. The ultimate goal is to protect fish until they grow large enough to reproduce, in order to support fisheries and biodiversity,” says H.E. Poum Sitha, Director General of the Cambodian Fisheries Administration.

The release of endangered species into the Tonle Sap Lake is expected to be the first of many to come, and researchers are optimistic that a sustained commitment to protecting some of the world’s most endangered freshwater giants will bear fruit.

“Assuming the supplementation programme is continued in subsequent years, and that favorable habitat and harvest conditions exist to support the full life cycle of these fishes in the wild, this research is part of longer term goals of increased population sizes, natural reproduction, and self-sustaining populations of these rare and remarkable animals,” says Hogan, adding that other actions, such as the protection of migration corridors like the Tonle Sap River and spawning grounds in the upper Cambodian Mekong, are also needed.

Source: Agency Kampuchea Press

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