Otolith microchemistry and microsatellite DNA provide evidence for divergence between estuarine tapertail anchovy (Coilia nasus) populations from the Poyang Lake and the Yangtze River Estuary of China

Abstract

The anadromous estuarine tapertail anchovy (Coilia nasus) in the Yangtze River is ecologically important; however, its abundance has substantially declined in recent years. There is an urgent need to identify the population structure of C. nasus in the Yangtze River to gather essential information that will help to improve the understanding of the ecology of this migratory fish and thus enable the conservation of its local populations. Otolith core trace elements and microsatellite markers were used to assess the spatial and genetic population structures of C. nasus in the Yangtze River Estuary and the Poyang Lake. The mature C. nasus in the Yangtze River Estuary showed distinct otolith core microchemical signal and genetic separations from the immature C. nasus from the Yangtze River Estuary and C. nasus from Poyang Lake. The otolith microchemical and genetic analyses revealed spatial and genetic connectivity between immature C. nasus from the Yangtze River Estuary and C. nasus from the Poyang Lake. The results of this study revealed that the mature C. nasus from Yangtze River Estuary is an independent anadromous C. nasus population with a spawning/hatching habitat located close to the Yangtze River Estuary, different from the Poyang population. The Yangtze River Estuary has highly urbanized and industrialized areas where the ecological risk showed an overall increasing trend. Therefore, conservation of the C. nasus population spawning area around the Yangtze River Estuary should and must play a prominent role in the preservation of this treasured species. The results also highlight the importance of defining populations by multiple methodological approaches to facilitate our understanding of the spatial ecology and population structure of migratory fish. Knowledge of the composition of estuarine and coastal mixed-stock fisheries is essential for effective management and conservation.