Fish diversity in inland rivers of Guangdong Province

Guangdong Province is in the tropical and subtropical monsoon climate zone, being one of the most socio-economically active regions in China, rich in fish resources, but its fish diversity is under severe threat. Based on the surveys in recent decades, we systematically compiled the fish species list of 14 rivers (regions) in Guangdong Province, including the Pearl River system, the Eastern Guangdong river system, and the Western Guangdong river system. Then we analyzed the species composition and distribution, and investigated the spatial distribution pattern of fishes in Guangdong Province by using the clustering and nonmetric muti-dimensional scaling methods. The results show that a total of 353 fish species were recorded in Guangdong Province, belonging to 204 genera in 21 orders and 72 families. Among them, there are 13 species of endemic fish, 8 species of national key protected fish, 7 species of migratory fish, 28 species of freshwater rare and endangered fish, and 52 species of widespread fish distributed in the Pearl River system, the Eastern Guangdong river system, and the Western Guangdong river system. According to the results of clustering and ranking analysis, the 14 rivers (Regions) can be divided into five groups: the Pearl River system and the Hanjiang River were divided into one group with relatively similar fish species; the Western Guangdong river system and the Luhe River, the Chishi River and the Huangjiang River in Eastern Guangdong were divided into one group with relatively similar fish species; the Huanggang River, Rongjiang River and Lianjiang River in Eastern Guangdong were each divided into a separate group. The results of the similarity analysis show that the differences in the fish compositions among the groups were significant (r=0.937, p=0.001). Among the riverine fish species in Guangdong Province, 223 species, including alien populations, appeared after 2010, but about 39% of the historical indigenous species did not appear, with an obvious decline in indigenous fish resources. Fish habitat destruction and invasion of alien populations are the main threatening factors for the decline of fish diversity. In the future, it is urgent to strengthen the construction and management of protected areas, to prevent and control the expansion of alien populations, and last but not least, to utilize and manage water resources from the perspective of protecting fish habitats.