Study On Age, Growth And Reproductive Biology Of Chiloscyllium Plagiosum From Southern Coast Of Fujian

The chondrichthyan is one of the oldest living groups of jawed vertebrates. They are often considered to be primitive, but their reproductive system possesses some advanced characteristics and more similar to amniotes and amphibia than teleosts. So the reproductive biology of chondrichthyan fishes attracted many researchers. Recent years, exploitation and research of sharks is becoming hot topic. In this study, age and growth estimates, spermatogenesis and oogenesis, the structure and function of oviducal gland and else aspects of reproductive biology of Chiloscyllium plagiosum (Bennett) are dealt with. The thesis aims to provide scientific materials to reveal evolutionary significance of chondrichthyan fishes and also to provide scientific basis for resources protection and fisheries management. The main results are as follows:1. Three types annuli are observed, single band, double bands and multi-bands. The annuli of the population were formed from July to December. The age composition of the population is from 0-6GRs. The percentage of group 2 GRs and 3 GRs is 27.5% and 26.4% respectively and they are the dominant groups.2. The R (centrum radius) vs. L(body length) regression equation is: Female: L = 144.8R + 189.29(r=0.9835) Male: L = 150.36R + 175.6(r=0.9852)3. The length-weight relationship is: W=3.0×10^-6×L^3.0065(R²=0.9921). The exponent (b=3.0065) is closed to 3, so it is considered be an isometry growing fish.4. Von Bertalanffy Growth Function is: Female: L_t = 966. 2(1-e^{-0. 3069(t+0.578)}) W_t = 2829. 8(1-e^{-0. 3069(t+0.578)})^3.0065 Male: L_t = 988. 1(1-e^{-0 .28(t+0.553)}) Wt = 2981. 4(1-e^{-0. 28(t+0.553)})^3.00655. From the relative growth rate, growth index and growth curve in the length and weight, we can conclude that the length growth rate is reduce gradually, but the weight growth rate is from slow to fast and then to slow again. The critical position of...