TEMPORAL TRENDS AND SEX-SPECIFIC VARIATION IN GROWTH CHARACTERISTICS OF COILIA NASUS IN THE TAIZHOU SECTION OF THE YANGTZE RIVER

To evaluate the ecological effects of 10-year fishing ban policy in the Yangtze River on the population recovery of <italic>Coilia nasus</italic>, this study systematically analyzed the temporal dynamics of growth characteristics using multi-model inference approaches based on information criteria. A total of 958 specimens were collected during fishing seasons in 2005, 2009, 2012, and 2024 from the Taizhou section of the Yangtze River. The results showed: (1) Population structure optimized significantly, with age composition shifting from younger to older cohorts. The proportion of 3—4 year-old individuals increased notably from 24.7% in 2009 to 72.4% in 2024, while the sex ratio (female:male) recovered from 0.69:1 to 2.66:1. (2) Morphometric parameters exhibited a typical U-shaped recovery pattern, with mean body length increasing from the historical low of 24.2 cm in 2009 to 29.6 cm in 2024, and mean body weight increasing from 58.4 to 105.0 g, representing increases of 22.3% and 79.8%, respectively. (3) The von Bertalanffy growth model showed the best fit, revealing significant sexual dimorphism in growth parameters: females exhibited greater asymptotic length than males, with <italic>L</italic>_∞ values of 39.05 cm for females and 32.63 cm for males, but lower growth coefficient, with <italic>k</italic> values of 0.41 for females and 0.56 for males, reflecting a “slow growth-large body size” life history strategy, while males adopted a “fast growth-small body size” strategy. Temporal analysis revealed U-shaped and inverted U-shaped recovery trajectories for <italic>L</italic>_∞ and <italic>k</italic>, respectively. (4) Population recovery exhibited sex-specific differences, with females fully recovering to 2005 levels and showing enhancement, while males improved but with relatively delayed recovery. This study confirms the significant positive effects of 10-year fishing ban policy in the Yangtze River on <italic>C. nasus</italic> population conservation and resource recovery, providing important empirical support for assessing the effectiveness of aquatic biodiversity conservation in the Yangtze River Basin and scientific basis for formulating adaptive management strategies for endangered anadromous fish species.