for National Geographic News
This time of year, fishers along the banks of the Mekong River in the village of Chiang Khong in northern Thailand wait expectant, as they have for hundreds of years, for the arrival and harvest of giant catfish. But this year the catfish may never come.
"No fish have been captured in Thailand since 2001 and the giant catfish is in danger of disappearing from Thailand completely," said Zeb Hogan, a fisheries biologist at the University of California at Davis.
Hogan leads the Mekong Fish Conservation Project, an effort to protect vulnerable populations of migratory fish in the Mekong River Basin, including the critically endangered Mekong giant catfish (Pangasianodon gigas). The catfish is one of several fish species presently endangered in the watershed.
The project is supported by the National Geographic Society's Conservation Trust, the Cambodian Department of Fisheries, and the conservation group Save Cambodia's Wildlife.
Called Pla Buek in Thai, the giant catfish can weigh as much as 650 pounds (300 kilograms) and measure up to 10 feet (3 meters) in length. They are the largest scaleless freshwater fish in the world.
Chainarong Sretthachau, director of the conservation group Southeast Asia Rivers Network in Chiang Mai, Thailand, said threats to the giant catfish include commercial fishing, their touting to tourists as a food said to impart wisdom, and dynamite blasting of their spawning ground.
"The rapids and whirlpool ecosystem in Chiang Khong-Chiang Saen is the only area in the Mekong that giant catfish use as a spawning ground and it will be destroyed by Mekong rapids blasting," said Sretthachau.
The blasting project is part of navigation channel improvements planned by the governments of China, Burma, Thailand, and Lao People's Democratic Republic. According to Sretthachau, the spawning ground rapids will be dynamited in December.
As part of their project, Hogan and his colleague Heng Kong, a researcher with Cambodia's Department of Fisheries, buy live fish from fishers in Cambodia. They weigh and measure the fish, gather DNA samples for genetic studies, tag endangered fish, and release them back into the wild.
Over the short-term, the project keeps a handful of endangered fish, including the giant catfish, alive as researchers gain insight into fish migration patterns, habitat use, and mortality rates.
"In the longer term, we hope our migration studies and environmental awareness campaign will lead toward more sustainable management of Cambodia's fisheries," said Hogan.
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