Resource Surveys Of Trachidermus Fasciatus In Wendeng Natural Reserve

Trachidermus fasciatus used to be the common edible fish on the coast of Bohai Sea, Yellow Sea, and East China Sea in our country. Over several decades, the ecologial enviroment of seaside has been so highly polluted by toxic waste water, fertilizer and agricultural pesticide that the fish is hardly able to go into the water for food and grow. Furthermore, it can barely be seen owing to over-fishing, building dam and naval architect. Trachidermus fasciatus was listed as our country's secondary National Protected Animal. Currently, the only place where wild Trachidermus fasciatus exists is in the lower reaches of Qinglong River. According to practical inquiry, historical sources and the research on the Trachidermus fasciatus's growth, breeding, and other biological charactersin the lower reaches of Qinglong River and Jinghai Gulf, I have figured out its denatent routine, seasonal habitant and resources cunrrency, analyzed the reason for Trachidermus fasciatus's extinction and the needs to build Natrual Reserve to repair the Trachidermus fasciatus Resources.The Natural Reserve is located in the lower reaches and river estuary of Qinglong River. Kunlong Reservoir was built in the middle reaches of Qinglong River , which can control water storage manually to maitain the annual liquidity in the lower reaches. So that the Trachidermus fasciatus can go back to river denatantly in search for food. Bukou Gulf to the north of Jinghai Gulf abounds with reef, which provides excellent place for Trachidermus fasciatus to breed and grow for the winter. Jinghai Gulf's unique ecological system has become the existing comparatively big coastal natural reserve.Trachidermus fasciatus's natural breeding place is located in the sea outfall of Qinglong River with sea air climate. Its annual temporature is 12.0℃～12.7℃and annual isohygrotherm is 13.4℃. salinity varies from 30.17 to 31.80. Phosphor, silicon, dissolved oxygen, ph value and other chemical elements all apply to the first class seawater quality. Floating plants and animals are various. Biomass is enormous and zoobenthos are in various kinds. Besides, in the natural reserve, Trachidermus fasciatus's enemies are few, which provides a good natural breeding place for it.Scrods of Trachidermus fasciatus grow fast. It only needs one year to grow into a fish. A grown fish measures 120-170mm in length, and weighs 50-100g. It was listed as secondary National Protected Animals. Presently, the only place where wild Trachidermus fasciatus exists is in the low reaches of Qinglong River. It can hardly be found in other places. However, over these years, the number of Trachidermus fasciatus has apparently dropped comparing to the former years. Its number hasn't reached to the 10% in 1990. A swarm of Trachidermus fasciatus is rarely found in these years.From April to November, scrod and grown fish living in fresh water usually habit in places where water is clean, forage living abounds, water level is deep and they can hid. From October to November, grown fish whose sex gland is going to become mature begin to swim from fresh water basin to lay eggs in excutuar and neritic province, which is called Denatant breed. From December to the next March, they will stay in Jinghai Gulf for the winter. When they are one year old, their sex gland has become mature, the prime to lay eggs is from the next half of Feburary to the first half of March. The proper temperature for breeding is from 4℃to14℃. Salinity 30～32 and the eggs they hold vary from 5100 to 12800.Incresingly developed Naval Architect, pollution of ecological enviroment and ovrer-fishing are the main factors threating Trachidermus fasciatus. My suggestions are to build Trachidermus fasciatus Natural Reserve in Wendeng, draw the line of nuclear district and trial district, decide the date of special protection, formulate management rules and implement manual tappping. So that we can repair Trachidermus fasciatus resources.