Abstract: According to the survey of fish resources and environmental factors on May, August, October in 2013 and 2014, analyses were performed on the species composition and biomass of fish resources in Tianjin sea area. Furthermore, the relationship between the fish biomass and environmental factors was studied based on the generalized additive model（GAM）. The results showed that: there were 7 orders, 17 families and 26 species of fishes in Tianjin sea area, and the preponderance of the species belonged to perciformes. The average biomass was 3.37 kg/h, and the biomass had dropped by 90.39%, compared with the results of Tianjin multipurpose investigation of the coastal zone and tidal wetland resources（1983）. The maximum number of biomass appeared in August, followed by that in October, and the minimum number appeared in May. This study selected 11 environmental factors as predictor variables, and the biomass of fishes were mainly affected by four factors based on GAM, namely, salinity, temperature, fish larvae density and Longitude. The effects of the foregoing three factor were significant, while the effect of longitude was significant on the level p<0.1. The accumulation of deviance explained by the optimized GAM to the fish biomass was 44.2%. According to Akaike information criterion（AIC）, the model including the four factors was optimal. Salinity had the greatest influence on the biomass of fish resources, followed by temperature and fish larval density, longitude had the smallest effect on fish resources.

Key words: Tianjin sea area, fish resources, generalized additive model（GAM）, environmental factors