The Preliminary Research On The Releasing Of Penaeus Japonicus In Guzhenkou Bay

The cultivation of Chinese shrimp larvae become more difficult because of the happening of disease in Chinese shrimp. The department interrelated released Penaeus japonicus massively in Guzhenkou Bay in 2007. This paper make perliminary researches on the releasing of Penaeus japonicus in Guzhenkou Bay in order to ascertain the proper date to starting fishing, and supply scientific gist for the yield and management of the released Penaeus japonicus.From June 22 to July 12, 2007, they released about 51.39 million Penaeus japonicus in Guzhenkou Bay which the body-length was about 9mm. The released Penaeus japonicus were sampled periodically, and they were measured and weighed. This paper makes an investigation on the migration, growth characteristics and recapture rate of the Penaeus japonicus, and the result shows that it mainly dispersed in the shallow water zone where the water depth is less than 5m. With the declining of water temperature in September, Penaeus japonicus migrate from shallow water to the deep water. The fisherman began to recapture the Penaeus japonicus from August 20 to October 30, the average body-length of which is 131.31mm, the body-weight is 25.37g and the recapture rate is about 3.26%.This paper handled the body-length and body-weight data of Penaeus japonicus in STATISTICA 6.0, and output the relations between the body-length and body-weight, get the equations of growth and growth speed of Penaeus japonicus as follows: From the equation d2wt/d2t=0, we can get the age equation of turning point: tr=lnb/k+t0, bring the value of b,k,t0 into the equation, and get the tr of female is on the 90.9 day, the male is on the 77.0 day. The body-weight growth curve of Penaeus japonicus is a kind of asymmetry S model curve with a turning point.Researchers investigated the fishery resources condition in Guzhenkou Bay during the course of the recapture for Penaeus japonicus. The results show that the traditional economic fishery resources in Guzhenkou Bay have declined severely, and the small fish in the upper layer become the predominant species. The amount of economical invertebrate also declines greatly.