Abstract

S. Seian Morrison and Peter Vogel.

The increasing use of freshwater fish farms by water birds poses conservation and economic problems as birds compete with man. This study sought to assess bird species diversity of an artificial wetland and the impact of birds on Tilapia production. The farm had a relatively high diversity (0.714) as 16 species of birds foraged on the farm as either residents or visitors each day. Eight of these birds were previously identified as problem species on aquaculture farms and may result in large losses in fish crops. Predation loss per grow-out period (PLOP) was calculated to be 20.92% for the fish farm and was due mainly to the Brown Pelican, Great Egret, Least Tern and Snowy Egret. This was 2.95% less than the average loss per pond and may be higher as loss due to Black-crowned Night Herons at nights was not assessed. There was a positive correlation with success, fish density and distance from the farm house. The findings indicate that bird predation has a negative impact on Tilapia production. Farm construction, stocking densities, the length of the grow-out period, and the use of non-lethal depredation strategies are important factors in reducing loss associated with bird predation.