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Harnessing Sesan river (Part 6): Dam and fish in Samse river basin

The image of fishermen casting fish nets from their small wooden boats while others throwing bits of catfish meat into the river before using small baskets made of bamboo to catch small fish has been a commonplace in Jalai islet in mid Mekong river in Satung Treng province.
Jalai islet is about 25 kms from the lower Sesan II dam. This is the passageway of fish species that swim upstream from Tonle Sap and the lower Mekong river for spawning in the upper Mekong river and its tributaries which include Sekong, Seprok and Sesan which altogether form the Samse river basin.

By Thai PBS

Stung Treng, Cambodia, May 31, 2016

Thai PBS

The image of fishermen casting fish nets from their small wooden boats while others throwing bits of catfish meat into the river before using small baskets made of bamboo to catch small fish has been a commonplace in Jalai islet in mid Mekong river in Satung Treng province.

Jalai islet is about 25 kms from the lower Sesan II dam. This is the passageway of fish species that swim upstream from Tonle Sap and the lower Mekong river for spawning in the upper Mekong river and its tributaries which include Sekong, Seprok and Sesan which altogether form the Samse river basin.

Meat Mean, a former coordinator of Samse river basin protection network, told Thai PBS that 40-50 percent of the fishes that swim upstream destine for Sekong river for spawning. But the lower Sesan II dam which is now 50 percent complete will block Sesan and Seprok rivers making it impossible for the fishes to swim upstream for spawning.

He claimed that there are as many as 300 fish species in the Sesan river and many of them are migratory fish. Local fish species such as Wa and Sa-er also spawn at the dam site and their numbers are decreasing because of the dam, he said.

Buapan, a fisherman at Jalai islet, told Thai PBS that he had noticed changes about fish in the river two years after the construction of the dam. “Normally during the third month of the year, we catch a lot of fish of different species such as tapien, bark and Sa-er. But with the dam construction, we catch less fish.”

A fish expert, meanwhile, admitted that it was difficult to determine which fish species will be affected and how many of them because there has never been a real survey of fish species in the river.

But he noted that, normally, during the first 3-5 years after water was stored in the reservoir fish population in the reservoir would increase but, after a while, the population will start to decrease because the water has become stagnant making it impossible for fish species which live in running water to survive.

But the lower Sesan II dam is not the only dam that is blocking the river. There are the Yalee and three more dams in Vietnam, about 15 kilometres from the border. It should noted that the Lomlaeng village located beside the Sesan river in Ratanakhiri province was devastated two decades ago when the Yalee dam bursted sending a huge wall of water gushing downstream destroying almost everything in its path. 37 Lomlaeng villagers were drowned.

Twenty years afterward, one of the survivors, Klan Tee, said he was yet to receive compensation from the government. He said he could not farm near the river now because of the tide which may increase or lower up to one metre within 24 hours.

The future of Cambodian rural folks in the Samse river basin can be anticipated from the painful experience of Pakmoon villagers after the construction of the Pakmoon dam in Ban Hua Wei in Khong Chiam district of Ubon Ratchathani 24 years ago.

Kriskorn Silarak, a core member of the Assembly of the Poor, said that the fishermen of Pakmoon were hardest hit because the number of fish had decreased substantially depending on the opening of the sluice gates.

But he predicted that the consequences of the dam in Sesan river would be worse than those of the Pakmoon dam because the Samse river basin is more plentiful with fish species with many rapids which are ideal for fish spawning.

The fate appears to have been set for the locals in Samse river basin which will never be the same.

This story was produced in collaboration with The Mekong Eye and Mekong Matters Journalism Network, with full editorial control to the journalist and their outlet.

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