Amarasinghe, U.S. <br/><br/>
Fish Yields of Some Down-Stream Reservoirs of the Mahaweli Basin  

 - Sri Lanka,  1989, 
 - 1-16p. 
 - Presented at the National Workshop on Instream Ecology and Reserveir Preduction of the Mahaweli Basin:A Modified Ecosystem, Instute of Fundemental Studies, Kandy, Sri Lanka, 22-23 March 1989  .
<br/><br/> Fish yields and fishing pressure in down-stream reserveirs <br/>©f the Mahaweli basin vary considerably from each other. In <br/>Parakrama Samudra, where the fish yield was recorded to be one <br/>of the highest (376 kg ha , yr ) in the South East Asian region, <br/>the annual fish yield in 1985 was ^6 kg/ha. This declining trend <br/>is due to over-fishing. High fish yields (^1 kg ha , yr in <br/>1985) were recorded in Pimburettewa where the fishery is optimally <br/>exploited.<br/>Indigenous fish species such as Labeo dussumieri and Barbus <br/>sarana which have been recorded to be contributed considerably to <br/>the commercial catches during rainy seasons, are presently <br/>insignificant in the landings. Tor khudree longispines has almost <br/>entirely disappeared in the reservoir fish catches. This could <br/>possibly be due to the river damming which would interrupt <br/>reproductive strategies of indigenous riverine species.<br/>Although the major constituent in the Sri Lankan reservoir <br/>fishery is Oreochromis mossambicus, in some down-stream reservoirs <br/>of the Mahaweli basin, 0. niloticus appears to become dominant.<br/>After intensive stocking ©f 0. niloticus fingerlings, the conditions <br/>were probably more favourable in these reservoirs due to the receipt <br/>of water from the Mahaweli river diversion project. Future research <br/>needs on the reservoir ecosystems in relation to fisheries <br/>management are discussed.<br/>