Authors:

Abstract

This study investigated whether allochthonous inputs generated by cattle and water buffaloes grazing in the catchment or wading in the water in small village reservoirs of Sri Lanka can make a significant effect on yields from culture-based fisheries of those reservoirs. The analysis is based on limnological data of 37 randomly selected reservoirs. As culture-based fish yield data were available over the 2002 - 2003 period only for 23 reservoirs, fish yield data from seven more reservoirs were gleaned for the present analysis. Cattle and water buffalo densities (BD) in 37 reservoirs where limnological data were available, were found to be significantly correlated to the biological productivity-related parameters such as chlorophyll-a content. Culture-based fish yield in the 30 reservoirs varied from 54.6 to 1800.8 kg ha^-1 and BD associated with the reservoirs studied varied from 0.90 number ha^-1 to 216.25 numbers ha^-1. Fish yield (FY) was significantly correlated with BD the relationship being, FY = 4.758 BD + 242.740 (R² = 0.345; p<0.001). The importance of taking into consideration factors such as grazing cattle and buffalo density in preparing management strategies for culture-based fisheries in small village reservoirs is discussed.

Keywords: Allochthonous nutrient inputs,   Exotic carps,   Inland fisheries,   Irrigation reservoirs,   Stocking-and-recapture fisheries