Habitat Use Strategies Of Coilia Nasus From The Lower Reaches Of The Yangtze River Based On Otolith Microchemistry

The lower reaches of the Yangtze River are the main distribution areas of anadromous fishes include high-value Coilia nasus.The knowledge of migration patterns and habitat use strategies of the C.nasus species in this water area is very necessary for conservation and management in the future.In this study,otolith microchemistry analysis was used to determine life history and habitat use of Coilia nasus of the Chongming section in Shanghai City and the Jingjiang and Changshu sections in Jiangsu Province in the lower reaches of the Yangtze River.The main results are as follows:Life history and habitat use of C.nasus from Chongming section were very complex.All fish in this study revealed that they used freshwater habitats to different degrees in their life history.Most of fish would further move to brackish waters and sea water and then move back in freshwater habitat.Two of them seemed to just migrant near estuary regions but not yet enter to estuarine brackish water into brackish.This study revealed that the Chongming water in estuary of the Yangtze River would be important migratory routes for both C.nasus with or without anadromous life history.The C.nasus samples collected from Jingjiang section of the Yangtze River anchovies were typical anadromous C.nasus ecotype,even they could use different strategies of freshwater habitats in their life history before they moved to brackish water habitats.Especially,one fish stayed in freshwater after that migrated near to the freshwater habitats that effect by tide or flooding marine water(high salinity).The C.nasus collected from water around Changshu section are anadromous pattern of movement that utilized freshwater habitat in the early life then migrant to brackish water or seawater habitats of life history.The habitat use and life history characteristic are different with the aforementioned fish from Jiangjiang section and Chongming section.