Suppression of largemouth bass (Micropterus salmoides floridanus) fingerling production in 0.01 ha ponds with high blue tilapia (Tilapia aurea) densities (760-1,900 kg/ha; 1,300-2,500 fish/ha) was studied to determine if the suppression is caused by direct competition for spawning sites. Bass spawned successfully in 8 of 9 ponds with tilapia but mean (x = 340) production of bass fingerlings was 84% less than in ponds without tilapia (x = 2183; N = 3). Difference in young-of-year bass production between ponds with and without tilapia was statistically significant; however, differences between young-of-year bass production in ponds with only male and only female tilapia were non-significant (P ≥ 0.05). Since only male blue tilapia construct spawning depressions, reduced bass fingerling production was attributed primarily to interactions independent of direct competition for spawning sites or tilapia sex.
