Abstract: Yangpu is located in the west of Zhanzhou City in Hainan Province. Yangpu water area is a good inshore spawning ground of Beibu Gulf. Based on the bottom trawl surveys in Yangpu waters in June and December 2014, the community structure of fishery resources and the diversity were analyzed. The results indicated that 68 fishes were collected in the two surveys, which belonged to 10 orders, 37 families and 49 genera, and they were warm water and warmtemperate species. The Perciformes was the most abundant (39 species), followed by the Pleuronectiformes (9 species) and Scorpaeniformes (6 species). The main catch resources were both demersal fishes and nearbenthic fishes, which accounted for 93.7% in total species. The fish community was characterized by miniaturization and showed a remarkable seasonal change between the two surveys. There were 11 common fish species in June and December, with a similarity index of 21.8%. The dominant species were Siganus fuscescens, Cynoglossus arel and Apogon quadrifasciatus in June, and Harpadon nehereus, Cynoglossus oligolepis, Setipinna taty and Apogon quadrifasciatus in December. The average biomass was 137.66 kg·km^-2 in June and 84.67 kg·km^-2 in December, and the average abundance was 11.38×10³ ind·km^-2 in June and 3.21×10³ ind·km^-2 in December. Cluster analysis, analysis of similarity (ANOSIM) and similarity of percentage (SIMPER) showed that there existed spatiotemporal heterogeneity to some extent for the community structure of fish. Biota and environment matching showed that sea bottom temperature and sea bottom salinity were the major environmental factors dominating the fish community pattern, and depth factor had different influences in different months.

Key words: Northwestern Yunnan Plateau, temperature, precipitation, altitude gradient, dendrochronology