Does aquaculture aggravate exotic fish invasions in the rivers of southern China?

Human-induced fish introduction in aquaculture always be considered the most important driver of biological invasions in freshwater ecosystems, yet most introduced species fail to establish though having great economic benefits. Explaining the varying success of introduced fish species is a central question both in invasion biology and aquaculture management. Southern China is a good region to test the invasion hypotheses where lots of nonnative fish species were cultured and invaded. In this study, we used four human activities related to aquaculture to test their effects on the establishment of non-native fish species in the rivers of southern China. Our results showed that: open-water aquaculture significantly increased the establishment probabilities of non-native species relative to standardised aquaculture in ponds; the establishment and spread of non-native fish species in rivers had no significant correlation to their production and distribution in standardised aquaculture; non-native fish species with low economic value were more prone to escape and establishment in natural rivers, and had higher establishment probabilities in rivers due to the lower fishing pressure. These results indicate that standardised aquaculture and cultivated species with high economic value do not always result in biological invasions. To mitigate the invasion of exotic species caused by aquaculture, stricter management practices and more optimized economic assessments should be implemented for the introduction and cultivation of non-native fish species.