ARE THERE STILL ANADROMOUS THE ESTUARINE TAPERTAIL ANCHOVIES COILIA NASUS IN DONGTING LAKE?

The electron probe microanalyzer (EPMA) was used to study the element Sr and Ca microchemistry patterns in sagittal otoliths of two dried individuals of Coilia nasus collected from a fish market by the Dongting Lake in Yueyang City of China in August 2018. The results of line transect analysis indicated that the ratios of Sr/Ca×1000 in the otolith of the two individuals fluctuated significantly. The ratios from otolith core to edge of the two anchovies in turn exhibited three different phases, namely low (<3, freshwater habitat), high (>3, brackish water habitat), and low (<3, freshwater habitat) Sr/Ca×1000 ratios. These three different phases could be more visually presented in sequence by the Sr intensity maps of bluish region (low Sr level, low salinity freshwater habitat), yellowish and greenish regions (high Sr level, high salinity brackish water habitat), and bluish region (low Sr level, low salinity freshwater habitat), respectively. The fluctuation patterns of Sr/Ca×1000 and Sr level demonstrated that these two C. nasus fish were typical anadromous individuals. These results revealed that there may still be anadromous C. nasus in the Dongting Lake, about 1400 km from the mouth of the Yangtze River.