Landscape-scale survey of non-native fishes near ornamental aquaculture facilities in Florida, USA

Abstract

The Tampa Bay region of Florida exhibits the highest concentration of ornamental aquaculture facilities in the USA. Because of the diversity of aquaculture products (~800 species and varieties) and extensive production history (began in the 1930s and 1940s), this region could be a hotspot for escaped ornamental fish. We evaluated the scope of ornamental fish invasions in this region by examining (1) escape vectors and (2) the distribution of escaped fish. We investigated potential pathways of fish escape including theft/vandalism, fish transport, bird carry-off, and through effluent discharge. Fish were sampled at the effluent discharge and continued into the surrounding environment. The dominant escape vector was through farm effluents; there was no evidence that theft/vandalism, fish transport, or bird carry-off contributed to fish escape. Most captured fish were natives, especially the ubiquitous Eastern Mosquitofish (Gambusia holbrooki). Ornamental species and varieties were also captured, especially cichlids and poeciliids such as the Green Swordtail (Xiphophorus hellerii) and Southern Platyfish (Xiphophorus maculatus). Ornamental fish were often found in the immediate vicinity of fish farms but were rarely captured in the surrounding environment. Catch per unit effort and ornamental fish diversity declined when moving away from the aquaculture facility effluent and was reduced at sites with a detention pond. The observed fish distribution might be due to relatively cold water in sub-tropical Florida, predatory fish in the environment, and additional factors related to the physical or biological habitat. Ultimately, few ornamental fishes have established in this region despite a long period of extensive culture.