Giant Catfish Crisis
The giant catfish were once plentiful throughout the Mekong River system, but in the last century the population has declined 95 to 99 percent, Hogan says.
He estimates there may only be a few hundred adult giant catfish left in the system today.
In 2003 the species was listed as critically endangered by the World Conservation Union after research showed its numbers had fallen by at least 80 percent since 1990.
The decision to stop the commercial harvest of giant catfish in Thailand, where it is known as pla beuk, may be particularly important, because conservationists believe the fish may spawn in Thai waters.
"In the past, fish have been harvested during their spawning migration but before they had a chance to reproduce," Hogan said.
"The fishing ban affords migrating fish the opportunity to spawn in their natural environment."
The talks to stop the hunt in Thailand were initiated in 2004 by the Mekong Wetlands Biodiversity Program, the fishers of Chiang Kong, and the then-senator of Chiang Rai Province, Tuenjai Deetes.
Sixty-eight fishing families called the Mekong Giant Catfish Club have agreed to stop the practice.
In return, the fishers are being paid U.S. $500 for each giant-catfish net they surrender.
"This is a great commitment from the fishers," Senator Deetes told the Associated Press.
"Every fisherman will stop fishing the giant catfish forever."
The fishers are entitled to conduct a "public demonstration catch" each year to preserve the traditional culture and methods of catching the fish. A maximum of two giant catfish may be caught and then released live back into the river.
Rearing in Cambodia
The impact of the Thai fishing moratorium on the species' population remains to be seen.
Before last month's ban the catch in Thailand had already dipped dramatically from its peak in 1990, when 65 giant catfish were caught.
Only four giant catfish were caught in Thailand last year, including one 646-pound (293-kilogram) fish that is believed to be one of the largest freshwater fish ever caught.
(Read "Grizzly Bear-Size Catfish Caught in Thailand" [June 2005].)
Now neighboring Cambodia appears to be home to the largest remaining populations of wild giant catfish.
Over the past five years the giant-catfish catch there has been higher than in Thailand.
While it is illegal to catch the species in Cambodia, fishers there inadvertently harvest it as bycatch.
"The harvest [in Cambodia] is very difficult to control," Hogan said.
He says both the Cambodian and Thai areas of the Mekong have to be well managed to ensure the survival of the species.
"Cambodia and Thailand play different roles in the life cycle of giant catfish," he said.
"Northern Thailand is a spawning ground, whereas the Tonle Sap lake [in Cambodia] is a rearing area."
(See Cambodia map.)
Tag and Release
For its tracking program, Hogan's team has installed underwater receivers along the Mekong from Thailand to Laos.
"It's a beautiful stretch of river and thought to be prime spawning habitat for a variety of fish, including the Mekong giant catfish," Hogan said.
The teamwhich includes scientists from the Thai Department of Fisheries, the University of Idaho at Boise, and the Monterey Bay Aquarium in Monterey, Californiahas tagged and released 38 large fish, including 18 hatchery-reared giant catfish and 19 other endangered fish.
"The conservation value of this project is high, because it will enable greater understanding of the movement and ecological requirements of threatened migratory fish in the Mekong River Basin, of which almost nothing is currently known," Hogan added.
Early signs show that the hatchery-bred giant catfish move downstream toward the remote Xaignabouri area of Laos (see Laos map), while wild fish may move upstream to Myanmar (Burma) and China.
Hogan also tagged and released a wild giant catfish that was caught by fishers in Laos in early May.
Unfortunately it was recaptured and killed in Thailand a few hours after it had been released.
"Had the fish lived, it would have provided by far the best scientific information that's ever been available on Mekong giant catfish or any other Mekong River species," Hogan said.
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