Sri Lanka has a diversity of reservoirs unparalleled elsewhere in the world. The reservoirs of Sri Lanka were and are a culturally integral part of the Sinhalese. The reservoir fishery resource in Sri Lanka remained untapped for centuries, initially perhaps due to religious reasons. With the increasing population in the dry zone where the reservoirs are almost exclusively located, since independence in 1948 the need to exploit the fish became urgent.
Sri Lanka has a depauperate fish fauna which does not contain lacustrine species (Fernando and De Silva, 1984; De Silva, 1985a). The indigenous fish fauna by itself would not have been capable of sustaining a viable fishery, if in 1952 the ‘aquatic chicken’ of the era, O.mossambicus had not being introduced. This resulted in the development of a sustainable fishery in the major perennial reservoirs in the heart of the dry zone. Gradually, the peasant and the farming communities in this region began to accept this exotic fish. With increasing colonization of the dry zone and the stepby - step resurrection of ancient reservoirs fishing activities began to spread into major reservoirs, and consequently O.mossambicus became a staple part of the diet and the main animal protein source for the dry zone community. As the fishery developed the two large indigenous cyprinid species, L.dussumieri and B.sarana, began to make an impact as secondary species in the fishery.
The estimates of yield vary significantly from reservoir to reservoir and from year to year. At present the mean yield from the major perennial reservoir amounts to 283 kg ha-1annum-1, one of the highest in the world. The fishery of major perennial reservoirs have experienced an average fourfold increase in fishing effort over the last decade. The fishery remains uniform in gear, craft and mode of operation.
There has been an increased demand for freshwater fish as a result of population increase in the dry zone and also in view of the increasing price of sea fish, and the government has placed the development of inland fisheries amongst its priorities. Possibilities of increasing the yield by exploitation of nonconventional resources, i.e. the minor cyprinids and eels, are being evaluated, and new methods of optimizing the yield studied.
Sri Lanka is blessed with a large hectarage of small reservoirs, known as seasonal tanks, which dry up for 3–4 months of the year. These seasonal reservoirs are to be utilized for fish production through an extensive culture practice of stocking and recapture. For this purpose major Indian and Chinese carps are being utilized. Initial trials have indicated a potential average yield of 1 ton ha-1 annum-1. It is believed that within the next decade the reservoir fish yield will attain 50,000 to 60,000 tons annum-1.
The Sri Lankan major reservoirs provide an ideal stage for testing the validity of existing empirical models for predicting fish yields in relation to limnological parameters, as well as for developing fresh ones.
In the dry zone the reservoir capture fishery has taken the form of a small industry. Major sociological changes have occurred in the fishing communities. The marketing strategies are likely to show major changes in the near future. The welfare facilities of reservoir fishing communities are beginning to receive attention of the authorities and major improvements are expected in the near future. The seasonal tank aquaculture programme has had an indirect benefit for the community in that the programme demands the involvement of the village as a whole bringing coherence and unity to the community.
Foreign funded development programmes on Sri Lankan reservoir fisheries have yet to include a research component. The absence of such an approach has probably delayed adoption of better scientific managerial measures, which would result in a better utilization of fish stocks. A change in this attitude is needed if development ventures in Sri Lanka are to optimally utilize fishery resources using development assistance.