Age, growth, mortality and movement patterns of shortjaw tapertail anchovy, Coilia brachygnathus, in the channel connecting Dongting Lake and the Yangtze River in central China

Abstract

Shortjaw tapertail anchovy, Coilia brachygnathus, is one of the anchovy species that exclusively lives in freshwaters, which is the dominant species in Dongting Lake. In order to explain its success as a dominant species in Dongting Lake, the basic biological knowledge of this species was studied from July 2013 to July 2015 in the channel connecting Dongting Lake and the Yangtze River. A total of 11 064 samples of C. brachygnathus were collected, and their standard length ranged between 6.8 and 35.4 cm. The length–weight relationship was W = 0.0026 L3.057, and von Bertalanffy growth curve was Lt = 36.41(1 − e−0.28(t+0.8)). The exploitation rate (E) of 0.49, indicated no overfishing on this species. Its movement patterns were highly significantly and positively correlated with the rate of variation in water level, discharge and water temperature. When water level (discharge and temperatures) were rising (mainly March to July), C. brachygnathus migrated into Dongting Lake, peaking in May. When the water level (discharge and temperatures) were falling (mainly October to December), the migratory behaviour changed to exiting Dongting Lake, peaking in October. The present study suggests, fast generation time, low exploitation rate and the river–lake movements (migrations) are the possible reasons that made C. brachygnathus a dominant species in this area.