求翻译一段文字，用在线翻译工具的就不要来了

The crab class subordination crustacean (Crustacea) decapoda (Decapoda) crawls the suborder (Reptantia) short tail to send (Brachyura) the general designation.The world crab class has 4500 kinds approximately, China has the near 800 kinds approximately, in which many kinds has the important economic value.The Zhoushan fishery (29°30 ˊ ~31°00 ˊ N,125°00 ˊ west of E sea area) the sea area is widespread, the biological resources are rich, the crab class type is many, has a pair of spot , the silver light blue crab, the thin null circle foot crab, the long hand prosperous back crab, Japan , the warrior , the rust spot , three wart blue crabs, the putty foot prosperous back crab, the sharp thorn long crab and the delicate hands blue crab, in which has the high economic value crab class kind of as for example three wart blue crab (Portunus trituberculatus), the thin null circle foot crab (Ovalpes punctatus), the Japanese sturgeon (Charybdis japonica), rusts the spot (Charybdis feriatus) and so on.Since 1980s, along with the offshore first floor fish stock decline and the people living standard enhancement, the crab class resources have obtained the development use unceasingly, the status more and more are also high in the sea fishery.But in recent years along with technical developed, the humanity moved (excessive commercial fishing for, marine environment pollution and so on) as well as the environment change causes mainly to be possible directly to use the fishery type resources the failure, the catch rate reduces, the individual average body unceasingly long slightly hastens, the natural maturation period ahead of time and so on; Has created the marine life community and the sea ecosystem structure change indirectly.The sea ecologist more and more pays attention to these disturbances to affect to the marine life community, and proposed a series of targets come the quota measure community are as for the entire ecosystem dynamic change, the species multiplicity are the community biology composition structure important targets, not only it may reflect the community organization level, moreover may through the structure and the function relational indirect reflection community function characteristic, this article through to the Zhoushan fishery and the neighbor sea area crab class species multiplicity research, investigates the Chinese Communist Party in this Zhoushan fishery and the neighbor sea area to result in the crab class type 43 kinds, subordinates 10 branches, 21 is.The superiority type for the thin null circle foot crab, the double spot , three wart blue crabs, next is Japan , the red star blue crab, the red line daybreak the crab, above six kind of crabs class account for 94.58% which the crab class always catches.The crab class catches the seasonal variation, the autumn> summer> the winter> spring.The autumn crab class catch rate is highest by the Zhoushan fishery, summer the catch rate the fishery is highest by the river outside.The crab class resources compact district concentrates in the Changjiang delta fishery and north the Zhoushan fishery.This investigation compares with the end of 1990s in the East China Sea continental shelf sea area crab class resources investigation result, crab class species composition and dominant species not too big change, also is the performance is three wart blue crabs and so on the large-scale crab class resources catch rate is low, the resource base quite is frail, the thin null circle foot crab catch rate proportion is high, the resources reserves are big, should take its resources the development use.