By John Maloy
THE CAMBODIA DAILY
Just a few hundred meters from the Laos border, a scaly behemoth has swum the waters of the Mekong River in Stung Treng province for years.
"There is a police station near the border there and the police are scared to go in the water," joked Srun Lim Song, director of the Fisheries Administration's Inland Fisheries Research and Development Institute. "But this fish is not dangerous."
The massive fish that has spooked the police is a particularly huge Mekong giant catfish, or Pangasianodon gigas, which are currently in the middle of their annual migration from the Tonle Sap Lake to the Mekong River.
A native of Cambodia, Laos and Thailand, the giant catfish is the largest freshwater fish in the world —growing up to 2.7 meters in length and capable of weighing over 250 kg—and quite harmless, being a toothless plankton eater.
Giant catfish expert Zeb Hogan, a research professor at the University of Nevada, Reno in the US, wrote in an e-mail that there are probably only 1,000 adult catfish left, and most can be found in Cambodia. The fish is listed as critically endangered by the World Conservation Union.
Srun Lim Song said that a key part of protecting and researching Cambodia's catfish is tagging.
Fisheries Administration Director Nao Thuok said that his department follows up on catfish catches around the country—racing to the scene to examine and release the mammoth fish.
He added that almost every catfish capture occurs during the November to December migration period.
"We catch about 10 specimens a year," he said. "We have tagged and released about 40 [in total]."
The length is measured and occasionally the fish is weighed. Fisheries officials have weighed enough fish to be able to estimate the weight from the length—a method that puts far less stress on the often-exhausted fish, Srun Lim Song said.
A small piece of pectoral fin is clipped for genetic analysis, a bright green tag is applied to the dorsal fin and the tag number is put in a database.
Srun Lim Song said that, to date, all of the catfish tested in Cambodia have been genetically pure. But Hogan noted that in Thailand, the giant catfish has been interbred with a related species, Pangasianodon hypophthalmus.
If a fisherman happens to catch a tagged fish—about 4,000 fish of various species have been so marked—he can turn the tag over to his local fisheries officer and receive a reward of about $1.25, Srun Ling Son said.
He added that information about where and when the fish was re-caught is used to track the movements and distribution levels of the fish.
But the tagging process has its problems. Seven giant catfish have been caught so far this year, but in recent weeks one died a few days after it was tagged and another died after getting tangled in a research facility net.
Srun Ling Son said that researchers have now learned enough about catfish behavior to avoid the risk of tagging every fish.
Hogan said that catfish are still caught with some regularity in Cambodia, but are increasingly rare in Thailand and Laos. He added that last year, both countries agreed to stop harvesting the fish in a bid to boost their numbers.
"There is a police station near the border there and the police are scared to go in the water," joked Srun Lim Song, director of the Fisheries Administration's Inland Fisheries Research and Development Institute. "But this fish is not dangerous."
The massive fish that has spooked the police is a particularly huge Mekong giant catfish, or Pangasianodon gigas, which are currently in the middle of their annual migration from the Tonle Sap Lake to the Mekong River.
A native of Cambodia, Laos and Thailand, the giant catfish is the largest freshwater fish in the world —growing up to 2.7 meters in length and capable of weighing over 250 kg—and quite harmless, being a toothless plankton eater.
Giant catfish expert Zeb Hogan, a research professor at the University of Nevada, Reno in the US, wrote in an e-mail that there are probably only 1,000 adult catfish left, and most can be found in Cambodia. The fish is listed as critically endangered by the World Conservation Union.
Srun Lim Song said that a key part of protecting and researching Cambodia's catfish is tagging.
Fisheries Administration Director Nao Thuok said that his department follows up on catfish catches around the country—racing to the scene to examine and release the mammoth fish.
He added that almost every catfish capture occurs during the November to December migration period.
"We catch about 10 specimens a year," he said. "We have tagged and released about 40 [in total]."
The length is measured and occasionally the fish is weighed. Fisheries officials have weighed enough fish to be able to estimate the weight from the length—a method that puts far less stress on the often-exhausted fish, Srun Lim Song said.
A small piece of pectoral fin is clipped for genetic analysis, a bright green tag is applied to the dorsal fin and the tag number is put in a database.
Srun Lim Song said that, to date, all of the catfish tested in Cambodia have been genetically pure. But Hogan noted that in Thailand, the giant catfish has been interbred with a related species, Pangasianodon hypophthalmus.
If a fisherman happens to catch a tagged fish—about 4,000 fish of various species have been so marked—he can turn the tag over to his local fisheries officer and receive a reward of about $1.25, Srun Ling Son said.
He added that information about where and when the fish was re-caught is used to track the movements and distribution levels of the fish.
But the tagging process has its problems. Seven giant catfish have been caught so far this year, but in recent weeks one died a few days after it was tagged and another died after getting tangled in a research facility net.
Srun Ling Son said that researchers have now learned enough about catfish behavior to avoid the risk of tagging every fish.
Hogan said that catfish are still caught with some regularity in Cambodia, but are increasingly rare in Thailand and Laos. He added that last year, both countries agreed to stop harvesting the fish in a bid to boost their numbers.
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