Use of geographical information systems as a tool for predicting fish yield in tropical reservoirs: case study on Sri Lankan reservoirs

Use of geographical information systems (GIS) in inland fisheries has hithe rto been essentially restricted to site evaluation for aquaculture developm ent and assessment of limnological changes in time and space in individual water bodies. The present GIS study was conducted on the land-use pattern o f the catchments of nine reservoirs in Sri Lanka, for which detailed fisher y data, viz. yield, fishing intensity, landing size of major constituent sp ecies, together with selected limnological data such as conductivity and ch lorophyll-a, were available. Potential statistical relationships (linear, c urvilinear, exponential and second-order polynomial) of fish yield (FY, in kg ha(-1) yr(-1)) to different land-use patterns, such as forest cover (FC, in km(2)) and shrub-land (SL, in km(2)), either singly, or in combination, and/or the ratio of each land type to reservoir area (RA in km(2)) and res ervoir capacity (RC in km(3)), were explored. Highly significant relationsh ips were evident between FY to the ratio of SL and/or FC+SL to RA and/or RC . Similarly, the above land-use types to RA and RC ratios were significantl y related to limnological features of the reservoirs. The relationships of FY to various parameters obtained in this study were much better correlated than those relationships of FY to limnological and biological parameters u sed in yield prediction in tropical and temperate lacustrine waters previou sly.