Preliminary Study On Fish Communities During Spring And Autumn In Water Of Beibu Gulf

Based on the data of bottom trawl surveys in the water of Beibu Gulf in April and November 2006, this paper analyzed the species composition, area types, quantity composition,dominance species,and diversity of fish community in the two sea area. In addition,the body weight and standard length (or fork length) composition of the dominance and important economical species,was also analyzed. Finally, relating to geographic and the hydrological characteristic of survey area, this paper analyzed the relationship between the two and the diversity status.The main results of study are followed:there was 199 species collected from the two voyages surveys, belongs to 76 families of 16 orders.There was 155 species, belong to 64 families of 16 orders in spring survey. The warm water fish accounts for 124 species,80.0 percent, the warm temperature fish accounts for 31 species, 20.0 percent, The mean catch rates was 8.73kg/h in spring,respectively.Top 6 species by the IRI index were Parargyrops edita,Johnius dussumieri,Polynemus sextarius,Leiognathus ruconius,Saurida tumbil,Leiognathus lineolatus in spring survey. The species richness D,Shannon diversity index H and evenness index J were 10.696,3.501 and 0.694 in spring. There was 99 species, belong to 38 families of 13 orders in spring survey. The warm water fish accounts for 81 species, 81.8 percent, and the warm temperature fish accounts for 18 species, 18.2 percent, The mean catch rates was 9.64kg/h in spring, respectively.Top 6 species by the IRI index were Leiognathus bindus, Apogonichthys lineatus, Leiognathus berbis, Elates ransonneti, Nemipterus virgatusn, Parargyrops edita in autumn survey. The species richness D,Shannon diversity index H and evenness index J were 7.682 , 3.843 and 0.836 in autumn.There are 18 kinds of pelagic fish ,31 kinds of near bottom fish and 106 kinds of bottom fish catched in spring voyage. The bottom fish and the near bottom fish accounted for 94.25 percent by weight, the pelagic fish catched 5.75 percent by weight.There are 25 kinds of pelagic fish, 22 kinds of near bottom fish and 52 kinds of bottom fish catched in autumn voyage. The bottom fish and the near bottom fish accounted for 78.76 percent by weight, the pelagic fish catched 21.24 percent by weight.The standard length composition and the body weight composition of the major species has been studied, and the final result indicated: the size of Parargyrops edita,Johnius dussumieri,Polynemus sextarius,Leiognathus ruconius,Saurida tumbil,Leiognathus lineolatus, Elates ransonneti, Nemipterus virgatusn are very small, most of which are juveniles.According to the survey data and the historic materials, and then combining with the geographic and hydrological characteristic of survey area, this paper analyzes the feature of fish community and its variety. The result shows that the feature of fish community and its variety have a frequent relationship with the geographic and hydrological characteristic of survey area.This paper provides the latest research material on fish community in the water of Beibu Gulf , which also offer the scientific basis for the fishery diversity protection and sustainable development.