Competition between Spotted and Largemouth Bass in Variable Pond Ecosystems

To investigate the magnitude of competitive interactions between largemouth bass Micropterus salmoides and spotted bass M. punctulatus, we stocked yearling fish at two total densities (250 and 750 fish/hectare) and several proportional combinations in Oklahoma ponds, and followed these populations for 18 months. Both species ate less, and grew more slowly, in high-density ponds whether or not the other species was present. In terms of both growth and survival, largemouth bass were more influenced by intraspecific and total fish density than spotted bass. Over all treatments, instantaneous growth rates of the two species were identical, even though largemouth bass were larger than spotted bass when stocked. The kind and amount of food available did not differ among treatments, nor did the way in which the two species utilized various kinds of available prey. Results often varied more between treatment replicates than among different treatments, and no evidence of interspecific competition could be detected against this inherent noise in the pond ecosystems.