The Fish Community Structure And Diversity In North Of Zhejiang Set-net Fishing Ground

Studies on biodiversity status of fishery community in North Zhe-Jiang province of set-net fishing coastwise were carried out, and Primary evaluations of fishery ecosystem in this area. In the community fishes of 15 oders,61 families, 95 genera and in all 119 species, In accordance with the living temperate, the was 56 species belong to warm water (Accounted for 47.1 percent), 60 species belong to warm temperate(Accounted for 50.4 percent),and 3 species belong to cold water (Accounted for 2.5 percent); In accordance with space distribution, near demelsal and demelsal fish have 91 species (accounted for 76.5 percent),pelagic fish have 28 species (accounted for 23.5 percent).Compared with the 80s of last century, except Harpadon nehereus was still the dominate species ,the other kind of dominate species have changed a lot , Collichthys lucidus and Johnius belengerii was instate by Chaeturichthys stigmatias,Odontamblyopus rubicundus and Engraulis japonicus. It maybe related with the climate change, but it is more possible by the Succession on community structure and dominates species change due to the press of over fishing.Through measurement and analysis of economic species biological in Huang Long station, compared with the 80s of last century we find out that the average weight of Larimichthys polyactis,Pampus argenteus and Trichiurus japonicus was dramatic changed. The community composition became miniaturization. The average of Larimichthys polyactis,Pampus argenteus only 1/3 average weigh of 80s last century. And the average weight of Trichiurus japonicus only half of 80s of last century.Analyzed the major of economic biology, the results show that: the average body length of Trichiurus japonicus is 87mm; the average body length of Larimichthys polyactis is 73.2mm; the average body length of Pampus argenteus is 92.2mm, that reveal these kind of fish became miniaturization and more younger.To cluster analysis of the community of the study area, according to different regions, the results of cluster analysis and NMDS sort shows: there was two type of cluster in this area, estuary type and reef type. Larger contribution to the two types of species was Setipinna taty,Harpadon nehereus and Pampus argenteud;according to different month, the results of cluster analysis and NMDS sort shows: there was two type of cluster in this area. They are type A(Jan.,Feb.,Mar.,Apr.),type B(May,Jun.,Jul.,Aug.) and type C(Sept.,Oct.,Nov.,Dec.), Larger contribution to the two types of species was Setipinna taty,Harpadon nehereus and Coilia mystus.