Abstract:
Based on long-term survey data, this study analyzed resource status and distribution pattern of Japanese eel collected at Jingjiang section of the Yangtze River using a combination set-net consisting of a 40-meter net wall (mesh size: 1.8 cm) and two fyke nets (mesh size: 0.9 cm) from January 2012 to December 2017. Our results indicated that a total of 137
Anguilla japonica with an average age of (1.8±1.0) years were collected from 519 samplings within 16 years, of which 89.1% individuals were sexually immature. The average total length and body weight were (31.1±9.8) cm and (57.64±91.94) g, respectively, of which 94.9% of individuals were in yellow eel stage. The relationship between total length and body weight was
W=0.0002415\timesL^3.483 , and the coefficient of determination (
R2) was 0.9537. Japanese eels can migrate to the Jingjiang section of the Yangtze River with 0.08% by individuals and 0.69% by weight, respectively, and the abundance and incidence rates showed a declining trend with time. In addition, cross-correlation analysis showed that the abundance of Japanese eel collected in the Jingjiang section were not related to recruitment of
Anguilla japonica glass eels in the Yangtze River estuary. The results indicated that the wild
Anguilla japonica resources in the Yangtze River were extremely rare and need to be protected. The generalized additive model showed that the occurrence rate of Japanese eel was affected by water temperature, ammonia nitrogen and turbidity. Pollution of the water environment may affect the survival of glass eels successfully migrated to the Jingjiang section.