Reduced growth and reproductive investment of Hemiculter leucisculus (Cyprinidae) in a reservoir with introduced icefish Neosalanx taihuensis (Salangidae)
Common name: Grahami minnow, Kanglang Yu (Chinese). Conservation status: Vulnerable—China Species Red List, Vol. 1 Red List (Wang and Xie 2004). Identification: Body elongated and slightly compressed; snout longer than interorbital width and caudal-peduncle depth; gill-rakers 31–39; pharyngeal teeth 3 rows, 2,4,4—5,4,2; dorsal fin with spine. Live coloration: dark on the back and silver-white below; all fins gray-white (Luo and Chen 1998). Distribution: Endemic to Fuxian Lake (24°17′–24°37′ N, 102°47′– 102°57′ E), Yunnan, China (Yang 1994). Abundance: Once abundant, the species accounted for 70–80% of the total fishery stocks, about 400 t. Since the 1990s, its population decreased sharply. In 1999 its output was less than 3 t, and this pronounced regression is still undergoing (Li et al. 2003). Habitat and ecology: Usually occurs in the middle and upper layers of water body. Larvae and juveniles inhabit in shallow coastal area, feeding on zooplankton, and move into open water with growing, feeding on zooplankton, small fishes and fish eggs (Yang 1992). Reproduction: Its fecundity is low. Spawning season is long, from March to October. Interestingly there’s a regular interval, about 7 days, between two sequent spawning populations. There are more females than males in natural populations. They spawn once every year at outlets of cave or hill springs (Yang 1992). Threats: Encountering strong competition from introduced fishes, especially Neosalanx taihuensis. Bycatch through commercial fishing is another critical threat (Li et al 2003). Conservation recommendations: It was successfully bred in 1999 by Kunming Institute of Zoology, Chinese Academy of Sciences, and Yuxi Bureau of Water Resource. About 800 000 fingerlings were released into Fuxian Lake every year since 2007 by the local government. Genetic diversity, viability and fecundity of restocked populations should be investigated, and corresponding breeding plan is necessary. Control of exotic species is also needed.