Based on the production survey data collected from stow net survey in Lanshan Bay in January, April, August, and October of 2025, seasonal variations in the composition and diversity of catches were examined preliminarily using index of relative importance and ecological diversity indices. The results showed that a total of 15 species were captured, belonging to 3 phylums, 3 classes, 8 orders, 12 families, 14 genus. The Decapoda and the Perciformes had the highest number of species, with 4 species each. In winter, the dominant species of catches were Oratosquilla oratoria and Octopus ocellatus, with the common species being Portunus trituberculatus. In spring, the dominant species was Syngnathus acus, with the common species being Engraulis japonicus. In summer, the dominant species were Engraulis japonicus and Loligo japonica, with the common species being Larimichthys polyactis, Exopalamon carincauda, and Portunus trituberculatus. In autumn, the dominant species were Engraulis japonicus and Portunus trituberculatus, with the common species being Trachysalambria curvirostris and Octopus ocellatus. The ranges of Shannon-Wiener diversity index (H’), being highest in autumn and lowest in spring, were from 0.18 to 1.02. The ranges of the Margalef’s species richness index (D), being highest in summer and lowest in winter, were from 0.28 to 0.89. The ranges of Pielou’s evenness index (J), being highest in winter and lowest in spring, were from 0.09 to 0.79. The seasonal variations in the composition, dominant species, and diversity of stow net catches in Lanshan Bay were quite evident. The function of Lanshan Bay as a feeding ground for various fish species should still not be overlooked. It is recommended to strengthen research on the protection and utilization of dominant species, and the effective management of stow net fishing industry.