Dietary Composition of Big Head Croaker, Collichthys lucidus, in the Early Stage of the “10-Year Fishing Ban” Policy

Big head croaker (Collichthys lucidus) is a dominant fish species in the Yangtze River estuary, with significant economic and ecological value in the local ecosystem. In this study, the dietary composition of big head croaker in the Yangtze River estuary from 2022 to 2023 was determined using stomach content analysis. Statistical methods such as cluster analysis and canonical correspondence analysis were also applied to study the ontogenetic variation in the feeding habits of big head croaker and their relationships with environmental factors. The results indicated that big head croaker in the Yangtze River estuary fed primarily on 15 prey groups and 33 prey species. Copepods were the dominant prey group, followed by mysids, shrimp, and fish. The dominant prey species included Acanthomysis longirostris, Neomysis awatschensis, and Calanus sinicus. Compared with historical studies, the proportion of large prey such as fish and crustaceans in the diet of big head croaker has increased since the implementation of the “10-Year Fishing Ban” on the Yangtze River, which reflects the improved aquatic habitat for organisms in the Yangtze River estuary to some extent. The feeding habits of big head croaker exhibited clear ontogenetic and seasonal variations. The empty stomach rate gradually decreased as the body size of big head croaker increased and their main prey shifted from small individuals such as Acetes chinensis and A. longirostris to larger individual fishes and Brachyura. In addition, big head croaker primarily fed on N. awatschensis in spring, A. longirostris in summer and autumn, and Acrocalanus gibber in winter. Canonical correspondence analysis indicated that salinity and length were the factors most strongly correlated with the feeding habits of big head croaker, followed by latitude and longitude.