Population dynamics of potential fish species for exploitation in presently underdeveloped fisheries of some perennial reservoirs in Sri Lanka

摘要

Fish resources in some perennial reservoirs of Sri Lanka are presently under exploited or unexploited mainly because these reservoirs are located in close proximity to marine fish landing sites or in urban areas where marine fish are readily available. The asymptotic length (L_(infinity), von Bertalanffy growth coefficient (K) and natural mortality coefficient (M) of fish species inhabiting five such reservoirs in the western coastal region in Sri Lanka, namely, Boralasgamuwa (16 ha), Lunuwila (14 ha), Madampe (81 ha), Mahawewa (60 ha) and Mattegoda (4 ha) reservoirs, were evaluated in order to determine the feasibility of their sustainable exploitation. Of the 17 fish species recorded, only three species had L_(infinity) values > 15 cm. L_(infinity) of two species were < 5 cm. The K values of most of the species were > 1.0/year. Since no fishing is carried out in these reservoirs, the fish are subjected to natural mortality only. The M values of all species other than three species were found to be > 2.0/year. High K and M values of most of the fish indicate that they have high production per biomass (P/B) ratios. Most of the fish species inhabiting these reservoirs could be subjected to heavy fishing mortalities. These species have a high economic value both as ornamental and food fish. The results indicate that there is a high potential to develop capture fisheries in these reservoirs to harvest both food and ornamental fish.