Non-native freshwater fish escaped from aquaculture in China: too much of a good thing is not always the best

Abstract

China has the world’s largest aquaculture production that partly benefits from the introduction of high-quality germplasm from both abroad and within the country. However, the rivers, lakes and reservoirs of China face a high risk of invasion by non-native freshwater fish associated with aquaculture. In this study, we used peer reviewed and grey literature in combination with a field survey to investigate the status, pathways, mechanisms and management of non-native freshwater fish for aquaculture in China. Production of non-native freshwater fish accounts for 8% of total aquaculture in China and is dominated by tilapia, bass, ictalurid, pirapitinga, salmon, trout and sturgeon. However, the escape of non-native fish resulting from unstrict farming management, fishery stocking and mercy release has been frequently reported. In total, 155 non-native freshwater fish species have escaped into natural waters. Among these species, 102 are aquacultural of which 59 translocated and 43 introduced from abroad. Introduced species have been mainly reported from southern China, whereas translocated species from the north and west of the country. Available data suggest that non-native fish associated with aquaculture have escaped into the main rivers of China. However, the real risk posed by non-native fish to native species and the ecosystem has been hardly evaluated due to the lack of basic information on population dynamics of non-native fish. Despite management strategies for non-native species having achieved substantial progress in recent years in China, development of a suitable transformation strategy for aquaculture to fulfil Sustainable Development Goals remains challenging. Academia, government and stakeholders should work jointly to develop management strategies to mitigate the risks posed by non-native species in aquaculture.