Study On The Fishery Biology Of Oratosquilla Oratoria In The Coastal Waters Of Qingdao

The fishery biology of Oratosquilla oratoria in the inshore waters of Qingdao was studied. From Dec. 2007 to Nov. 2008 (except February and fishing moratorium), the setnet catches were sampled 1² times per month and 150 individuals of O.oratoria were sampled each time. A total individuals of 2668 were sampled. The study of growth, reproduction, feeding habits has enhanced our preliminary understanding of the fishery biology of O.oratoria in the coastal waters of Qingdao.The main results of this study are as follows:(1)There are power relationships between body weight and body length, total length ,carapace length, abdominal width, cercus length, which are expressed as: W_♀= 0.0151 BL2.9929 (r=0.9882),W♂= 0.0128 BL3.0792(r=0.9897),W♀♂= 0.0133 BL3.0582 (r=0.9898);W_♀= 0.0129TL2.9684 (r=0.9909),W_♂= 0.0103TL3.0759 (r=0.9897),W_{♀♂} = 0.0112TL^3.0349(r=0.9901) ; W_♀= 0.0014CL^3.0573(r=0.9768) , W_♂= 0.0013CL^3.0563(r=0.9814) , W_{♀♂} = 0.0014CL^3.0384(r=0.9793) ; W_♀= 0.0031AW^2.7379(r=0.9768) , W_♂= 0.0019Aw2.9107(r=0.9842) , W_{♀♂} = 0.0024AW^2.8321(r=0.9799);W_♀= 0.0041CL^2.9726 (r=0.9819),W_♂= 0.0062CL^2.8223 (r=0.9793),W_{♀♂} = 0.0052CL^2.8855(r=0.9785)。There are linear relationships between body length and carapace length, abdominal width, cercus length, which are expressed as: CL_♀= 2.0209BL + 0.7247(r=0.9630),CL_♂= 2.0635BL + 0.7193(r=0.9713),CL_{♀♂}= 2.0584BL + 0.5133(r=0.9660);AW_♀= 2.2936BL– 0.9328(r=0.9646),AW♂= 2.259BL– 0.5533(r=0.9722),AW_♀♂= 2.2829BL– 0.817(r=0.9674);LC_♀= 1.5625BL - 0.0534(r=0.9888),LC_♂= 1.6631BL - 0.7034(r=0.9822),LC♀♂= 1.6229BL - 0.4504(r=0.9842)(2)Condition factors of female and male O. oratoria are different, the values of male O.oratoria were bigger. From September to December, condition factors were rising gradually. After December, it decreased. From March to April, it was rising again. While after April, it decreased once again. (3)In October 2008, 2295 individuals were sampled, among which there were 1440 females and 855 males. Body length frequency distributions were analyzed both for females and males respectively, both of the distribution curves showed two peaks which were separated at 10 cm. Therefore we suggest that there were 2 age groups for O.oratoria's in the coastal waters of Qingdao.(4)According to the sex ratios, gonadosomatic index and ovarian development stages, we tend to propose that the fastigium of spawning season was about the middle of May.The individual absolute fecundity F(eggs) range from 13067 eggs to 74371 eggs (mean of 37858 eggs). The relationships between the individual absolute fecundity F(eggs) and body length (BL, cm), carapace length (CL, cm), body weight are expressed as: F=6.852BL3.6692 (r=0.9485);F=0.6502CL3.5518(r= 0.9139);F =4273.1W - 17263(r = 0.9372). The relationships between the individual relative fecundity F(eggs) and body length (cm), body weight are expressed as :F=853.01BL-5308.7(r = 0.8874);F=101.97W+1490.2(r = 0.8029)。(5)In this study, 802 stomachs were analyzed. There are 30 species in the stomach contents of O. oratoria, among which there were 15 species of crustaceans, 8 species of pisces, 2 species of polychaeta, 2 species of cephalopada,1 species of eggs,1 species of algae and 1 species of sprial shells respectively.(6)The feeding intensity shows seasonal variations. Before over-wintering, feeding intensity was rising gradually; During over-wintering, feeding intensity was decreasing gradually; After over-wintering, feeding intensity was rising gradually again. When the spawning season approached, feeding intensity reduced gradually. According to the stomach contents analysis of O.oratoria, there were obvious food selections. The main reasons may be: the availability and suitability of the diet.