TY  - BOOK
AU  - Amarasinghe, U.S.
AU  - Ajith Kumara, P.A.D.	
AU  - Ariyaratne, M.H.S.
TI  - Non-conventional fishery resources in resources in reservoirs of Sri Lanka as a source of food for cage aquaculture
PY  - 2000///,
CY  - U.K.
PB  - University of Hull
N2  - The reservoir fishery of Sri Lanka is almost entirely dependent on the exotic cichlid species, most notably Oreochromis mossambicus (Peters) and O. niloticus (L.). However, small sized indigenous cyprinid species such as Amblypharyngodon melettinus (Valenciennes), Puntius filamentosus (Valenciennes), P. chola (Hamilton- Buchanan) and P. dorsalis (Jerdon), which occur in abundance in all perennial reservoirs of the country, are not exploited due to poor consumer acceptability and mesh size restrictions in the gillnet fishery. These small cyprinid species can be differentially exploited using small mesh (<52 mm) gillnets without harming juvenile tilapias which support a profitable fishery in Sri Lankan reservoirs. Periodic length frequency data of some small cyprinid species in three reservoirs of Sri Lanka, collected during January-December 1999 were analysed using FiSAT software package. Instantaneous rate of mortality of fish stocks is known to be equal to the production per biomass (P/B ratio). As such P/B ratios of these unexploited stocks, were determined from the instantaneous rates of mortality, which were estimated using growth parameters of fish. P/B ratios or turn over rates of the small cyprinid species are appreciably higher than those of major carps which usually support less productive fisheries in lakes and reservoirs, and are within the range of figures for cichlids which support highly productive fisheries. This indicates that these fish stocks have potential to withstand heavy fishing mortalities hence to sustain productive fisheries. Community-based cage aquaculture to rear fish fry upto fingerling size is a recent development in some perennial reservoirs of Sri Lanka. These fish fingerlings are used to stock in seasonal reservoirs to develop culture-enhanced fisheries. Use of farmer-made feed using locally available ingredients and fish meal prepared from small cyprinids which are caught from the reservoir itself is a feasible option to reduce cost of this aquaculture strategy. Average daily growth and survival rates of fish fingerlings reared in floating net cages in some perennial reservoirs, using the feed based on fish meal from small cyprinids, showed better performance than those in the cages with other types of feed such as commercial feed and rice bran. The small cyprinid resources in perennial reservoirs of Sri Lanka can therefore be used to prepare fish meal as the source of animal protein for making feeds for aquaculture.

KEYWORDS: aquaculture, cage culture, cichlids, cyprinids, length frequency analysis, mortality, P/B ratio, reservoirs, unexploited stocks
ER  -