关键词: 刀鲚, 长江口, 摄食习性, 季节差异, 体长

Abstract: In December 2021 and March 2022, a total of 1580 specimen of Coilia nasus were collected from the Yangtze River Estuary to analyze gastric content and their feeding habits. The results showed that a total of 28 species of prey organisms were identified in the stomach contents of C. nasus, indicating that it was an omnivorous fish mainly feeding on zooplankton. Calanus sinicus was the dominant prey organism. The body length of C. nasus and the condition of dominant preys in the sea were the main factors affecting its feeding habit. In the Yangtze River Estuary, the feeding intensity of C. nasus in spring was higher than that in winter, closely related to gonadal maturity and water temperature. Juvenile C. nasus was abundant in spring and the juveniles needed to feed a lot for growth and development. At this time, water temperature in the sea was high and bait organisms were abundant, with high feeding intensity. There were more C. nasus adults in winter samples. In this season, most C. nasus were in the late oviposition stage. The development of ovary restricted the expansion of the stomach, which, coupled with the lower water temperature, resulted in low feeding intensity. There was no period of feeding transition from copepods to decapods. Copepods dominated the preys of both juvenile and adult C. nasus, a phenomenon that might be related to the competition pressure for the living space of prey organisms and fish in the estuary caused by the fishing prohibition effect of the Yangtze River.

Key words: Coilia nasus, Yangtze River Estuary, feeding habit, seasonal variation, body length