Reproductive population composition and physiological characteristics of Eriocheir sinensis in the Yangtze River estuary

Abstract:

To investigate the composition of the reproductive population and changes in the physiological characteristics of Eriocheir sinensis before and after mating in the Yangtze River estuary, a survey was conducted in December 2020. The size composition, sex ratio, and reproductive status of female crabs and changes in hepatopancreas index (HSI), gonadosomatic index (GSI), and Fulton´s condition index (K) before and after mating were analyzed. Results showed that in the reproductive population of E. sinensis in the Yangtze River estuary, the overall size of female crabs was smaller than that of male crabs, and the ratio of females to males was 0.39 : 1. The number of male crabs was significantly higher than that of female crabs (χ2=101.87, P<0.05). In the comparison of physiological characteristics, there was a significant difference in the HSI among female crabs of different reproductive statuses (P<0.05), among which the highest was in the egg-bearing status, and the lowest was in the mated status. The GSI and K index of female crabs in the mated status were higher than those in the unmated status (P>0.05), and the K condition index of females in the egg-bearing status was the lowest (P<0.05). The GSI of male crabs was significantly lower than that of females (P<0.05), while the K condition index was significantly higher than that of females (P<0.05). A highly significant negative correlation was found between the HSI, GSI, and carapace width in male crabs (P<0.01), while a highly significant negative correlation was only found between the HSI and GSI in females (P<0.01). These results enrich our understanding of the physiological characteristics of E. sinensis during the reproductive mating period and provide basic data for the conservation and management of E. sinensis resources.