Thanks to advances in genetics, researchers now can ensure the diversity of the species by crossbreeding some of the 20 pairs of cultivated specimens in the hands of the Fisheries Department.

"This could be done based on our two-year-old research into the DNA of the species, covering a total of 129 artificially bred fish and 16 wild ones," Uthairat Na Nakhon, the team leader from Kasetsart University, told The Nation.

"This means we can ensure that the species will be far from extinct. In case all the wild fish in the Mekong River are gone, we'll still have the bred ones in reserve," she said.

Known locally as pla buek, the Mekong giant catfish is called the "king" of the Mekong River due to its sheer size. It can grow up to three metres in length and weigh as much as 350 kilograms.

Its numbers have, however, been steadily falling for decades. At Ban Hat Khrai in Chiang Rai's Chiang Khong district - the major fishing grounds for the species - fishermen said they couldn't even land one giant catfish in 2001 and 2003.

The record catch is 69 fish in one season, but that was made many years ago.

The World Conservation Union has put the Mekong

giant catfish on its red list of

critically endangered species.

Scientists know preciously little about the fish, except that it is mild-mannered and easily spooked. The catfish migrate upstream and there at least 10 places where they can be sighted, including China's Dali passage and Cambodia's Tonle Sap, Southeast Asia's largest freshwater lake. Chiang Rai is the only big fishing spot.

As giant-catfish fillets are prized by wild-game connoisseurs, a local tourism promotion campaign in Chiang Khong began promoting the fish.

In 1980, the Fisheries Department succeeded in artificially breeding the species, and in 2001 researchers ensured that artificially bred catfish could produce offspring without any dependence on eggs and sperm from wild ones.

Uthairat's work is regarded as the third stage of success, as researchers now can conserve most of the species' genetic diversity.

"We used a technique called micro-satellite DNA at seven sites of the base sequences. Then, we compared the results of the artificially bred fish with the wild ones and found that the two groups are almost the same," she said.

Another result was that researchers could arrange couplings of the 20 pairs so that all of the genetic diversity would be conserved permanently.

"Normally, the problem in artificial breeding is mating between cousins, scientifically called in-breeding, which would make the gene weaker in later generations," said researcher Ketnapat Sriphairoj.

"But our research found we can avoid this in-breeding by mating 20 matched pairs," she said.

The problem is some fish are now being raised in seven farms owned by state and private authorities," she said.

Apart from Uthairat's research, another study is now underway led by conservation-group scientist Zeb Hogan under the Mekong Wetland Biodiversity Programme of the Fisheries Department.

Hogan has tagged wild fish with computer chips that can monitor their location, using underwater biotelemetry technology, to study their migratory behaviour and spawning sites. The technique is also helpful for assessing the conservation value of releasing hatchery-reared fish into the Mekong.

So far, 19 fish have been tagged and released into a 400-kilometre-long stretch of the river from Chiang Rai's Golden Triangle area to Luang Prabang in Laos. The 19 fish consist of 18 raised in captivity and one wild specimen.

"Information from the tags will be transmitted via acoustic signals to recording devices or receivers, and the data will be downloaded once a month from last May to April next year," Hogan said.

"The latest data showed that most of the tagged fish are heading downstream following their release; only the wild tagged fish has made a significant [more than 30 kilometre] upstream movement," he said.

Even though both research projects are showing impressive progress, researchers agree that further studies on this mysterious species are required, especially studies of their lifecycle and risk factors for their long-run survival.

Based on Uthairat's research, one suggestion that might be made by the Fisheries Department at this level is to maintain the species genetic diversity and lift it from endangered status. Uthairat and her co-researcher rejected the idea, as well as Hogan.

"It's too risky. Even though we got to know the species' genetic makeup better releasing the hatchery fish into the wild conditions of the Mekong River could be good or bad," Uthairat said.

"Without sufficient information about the wild fish's lifecycle, the released fish could dominate and ruin the wild stock genetically," Ketnapat said.

The researchers believe that although they know much more about the species it is not enough to suggest concrete solutions for the sustainable conservation of the Mekong giant catfish.

"Efficient and practical conservation measures might not yet be a matter for scientists at this moment. They might rather depend on fishermen at Ban Hat Khrai," environmentalists say.

Thai and Laotian fishermen have agreed to stop hunting the giant catfish, even though it's their tradition to do so at this time of the year.

"It's obvious that the population is declining sharply. Stopping fishing is the best immediate solution for now," Chiang Rai Senator Tuenjai Deetet said during a ceremony to launch the campaign.

She is opposed to breeding the fish in captivity, saying they should be left to breed naturally.

The fishermen were given compensation of Bt20,000 each - Bt1.36 million in total.

Kamol Sukin 

Chiang Rai

The Nation