Abstract:

The Pak Mun Dam is the first run-of-river type dam in Thailand. It was constructed across the lower Mun River, 5 kms upstream from its confluence with the Mekong River. Upon closure of the Pak Mun Dam in 1994, a freshwater prawns (Macrobrachium rosenbergii) stocking program was initiated to increase the value of fish production in the reservoir that was drastically affected by the dam operation. The total number of freshwater prawn stocked in the reservoir was 22 million post larvae (PL30) from 1995 to 2000. As a run-of-river type dam, some of the stocked prawns were also dispersed to downstream through outflow of spillways and turbines. This study aimed to evaluate distribution and seasonal patterns of prawn production in the Pak Mun Dam. The data collected from fishermen operating in reservoir and downstream include the number and weight of prawn catch from May 1999 to April 2000. The average weight of prawn caught from the reservoir was 236.5±102.1g. Freshwater prawn production was 79.5 % from the reservoir and 20.5 % downstream. The total yield was 16,646 kg·year-1 with a value of 122,027 USD· year-1 (1USD=37 baht), contributing to 53.8 % of the total fish catch by weight (30,960 kg·year-1) and 97 % of economic value from the reservoir. Records showed that prawn could be harvested 8 months after stocking with an estimated recapture rate of 1%. This study shows that the freshwater prawn stocking program has been a successful effort in fishery management in the Pak Mun Dam.

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Date 2003/06/01

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