Objective To characterize the seasonal and spatial distribution patterns of Pennahia anea in the northern coastal waters of the Beibu Gulf and to clarify the key environmental drivers underlying its resource variability, thereby supporting resource assessment and fisheries management of economically important coastal fishes.

Methods Based on bottom trawl fishery surveys conducted in October 2023 (autumn) and March 2024 (spring), the quantified mean individual body mass, biomass density, and numerical density of P. anea to describe spatial-temporal patterns. Structural equation modeling (SEM) was then applied to evaluate the direct and indirect effects of multiple environmental factors on these resource indicators.

Results Mean individual body mass of P. anea was higher in spring than in autumn, whereas both weight density and tail density were higher in autumn. The autumn SEM identified a significant positive effect of ammonium on weight density and of inorganic nitrogen on tail density. In contrast, no significant paths linking resource densities to environmental factors were detected in spring, suggesting that reproduction-related ecological processes may exert a stronger influence on population distribution during this period. Conclution P. anea exhibits pronounced seasonal shifts in resource distribution in the northern Beibu Gulf, with population dynamics shaped by the interplay between nutrient conditions and season-specific ecological processes. These findings provide a scientific basis for targeted monitoring and adaptive management of P. anea in this region.