Effects of Hydro-Climatic Fluctuations on Catchability of Fish in Vavuniya Reservoir, Sri Lanka

Abstract

Catch assessment and frame survey were performed to estimate the species wise and total catch in the Vavuniya reservoir along with hydro-climatic factors. Relationship between the hydro-climatic factors and species wise catch statistics were determined from calendar year, rainfall (RF) and water level (WL) based quarters of the annum. Irregularity in the rainfall pattern shifted the heavy rainfall based quarter from October-December to February-April in 2013. Significant variation (P<0.05) in the species composition of the catch in all the quarters, indicates the non-uniformity of the catch distribution. The WL showed a negative correlation and significant (P<0.05) relationship between catchability. However, the correlation between WL and catch per unit effort (CPUE) with respect to gear (kg/gear/day) was insignificant (P>0.05, r=-0.327) However, there was a strong negative correlation between monthly average WL and CPUE in terms of kg/fisher/day. There were 5 exotic, 13 indigenous and 1 endemic (Esomus thermoicos) species identified. Oreochromis niloticus contributed 79%, Cirrhinus mrigala (8.6%) and Channa striata (7.6%) of the catch. Data obtained from this study may be used as a baseline for the sustainable management and to achieve optimal catch.