Key Mekong fish species - migration paths

 

Pangasianodon gigas

Stations in all four countries recorded the famous giant catfish. However, its occurrence was not reported by several stations, and only fishermen at the northern stations of Bokeo and Chiang Rai provinces (the Lao PDR and Thailand, respectively) provided records on the migration of this species.

In Cambodia, it was only recorded from Kratie to Stung Treng, and local fishermen emphasised that it was very rare.

Pangasianodon gigas is occasionally caught by the dai fisheries in the Tonle Sap River during their migration out of the Tonle Sap into the Mekong during the period of receding water. However, it has not been recorded by the Khone Falls fisheries in recent years (Baird, 1998; Singanouvong et al,, 1996b).

In Northern stations, on the border between the Lao PDR and Thailand, Pangasianodon gigas migrate upstream during April-May. Tha is also the time when fishermen from that area traditionally catch giant catfish. Fisherment from Bokeo stated that they the fish at a certain site with strong current near a beach. The migration is triggered by the first rain and the resultant increase in turbidity (e.g, mentioned independently by all three interviewd fishers from Bokeo Province.

Some fishermen from Xayaboury Province in Loa PDR reported that giant catfish spend the dry season in certain deep pools in the Mekong mainstream in that province.

Although Pangasianodon gigas appears to have previously been relatively commend in other parts of the Mekong River along the Lao-Thai boder (e.g., in the area of Nong Khai), the giant catfish is now extremely are along that stretch.

Hypothesis:
There are two remaining populations of Pangasianodon gigas, one below the Khone Falls (i.el, in Cambodia and Viet Nam), and one in the northern stretch of the river.

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