| Zhoushan fishing ground is one of the most famous fisheries ground, and is the perfect searching bait ground and the perfect propagating ground of many economic fishes for its multitudinous islands, optimum temperature and salinity, and abundance bait creature. In recent years, the resource of many economically important fish species had declined rapidly for worsen ocean environment and over fishing. There had no fishing flood for many fishes and some fish species even become endangered. Exploiting the native and excellent resources of wild species can increase the new choice for artificial reproduction and aquaculture to satisfy the ever-growing market need on the one hand, and on the other hand, it can avoid the genetic degeneration, the low growth rate and resistancecaused by inbreeding. Moreover, exploiting native species can offer seeds for artificial enhancement and releasing, it can also contribute to restoration of the fishery resources of the East China Sea.At the present time, pelagic fishes in or along the shore were the major species in aquaculture in China. Studies on the development of utilization technologies of deep sea fishes were very limited. However, in abroad technologies of processing deep sea fish resources such as extracting fish oil or anti-cancer drugs were well developed. But these technologies depend on the over use of natural resources and unexpected destroy of marine ecosystem.. How to exploit and utilize the resource of deep sea fishes had become an important questiion. The Dentex tumifrons is one representative species which inhabit in the sea area of 80-200 meter in depth. In this study, we can accumulate basic data on scaled reproduction and form correlation technologies of reproductive control, artificial reproduction and middle cultivation by exploring the domestication, feeding, growth and development pattern, physiology, ecology and nutrition demand on the wild Dentex tumifrons. At the same time, we offered basic theories for artificial propagation of others deep sea fishes and also offered healthy seed with market competition to the culturist. 1. Histological observation on annual development of ovary of Dentex tumifronsAbout 240 D. tumifrons female individuals were captured from Zhoushan fishing ground each month in one year. The body weight was 123-244 g and the body length was 13.5-18.8 cm. After biological measurement and histological observation the gonad net weight was weighed. Paraffin sections of the ovarian tissue i were prepared to observe the development of the ovarian tissue by using microscope. The results showed that the germ cell had 5 phases and the growth of the ovarian tissue could be divided into 6 stages. The maturation index of the ovarian tissue at stageⅴwas 9.20%-14.50%, and the average was 11.55%. The reproductive season of the Dentex tumifrons was from April to May and from October to November in each year. The growth of the oocyte of the Dentex tumifrons were not isochronous, so that Dentex tumifrons could spawn many times in the same propagation-season.2. Study on embryonic development of Dentex tumifronsThe survival experiment under influence of the environmental factors on the embryonic development and on the fries was conducted and the optimum condition of the growth was obtained. The results showed that the optimum temperature influencing the survival of embryos and fries ranged from 18℃to 26℃, the fertilized eggs of the Dentex tumifrons were round and pelagic The diameter of the fertilized eggs ranged from 0.848 mm to 1.018mm, the diameter of the oil globule was 0.178-0.215 mm. The embryo was hatched for 28-30 h after fertilization at water temperature (24.5±0.5)℃and salinity 33.6, the length of the newly–hatched-larvae was 2.22 mm.3. Domestication of the broodstock and study on the technology of artificial propagationDomesticating the wild Dentex tumifrons in the controlled condition, observing the biological characteristics and inducing spawn habit, based on the growth data of the broodstock along with scale annuli identification, we found that the fecundity of 3-5 years old Dentex tumifrons individual was 8200-25400 eggs in each spawn reason. Under the artificial propagation condition. 3 years old parent Dentex tumifrons was relative suitable to propagate,and the inducing spawn was easy to succeed. Mixed hormones LHRH-A3 or LHRH-A2+DOM were very effective in promoting gonad maturation and inducing spawn on broodstock. Each hormone could induce the develop of oocytes with over 400μm diameters to keepand induce spawn. The effect of promoting spawn had close relation to the development state of the oocyte. The change of the environmental factors such as the temperature could improve the Dentex tumifrons to spawn one month earlier in spring than which inhabiting in nature sea area..4. The influence of rotifers with different nutrition to the growth of fry of Dentex tumifronsIn this experiment, enrichment of rotifers by feeding the 50-DE Microcystis adding Chlorella spp., Chlorella spp. and 50-DE Microcystis and feeding the control rotifers cultured in yeast, then examining the DHA and EPA content of the fatty acid in four type of rotifers. In the next experiment, the four types of rotifers were fed to the Dentex tumifrons fry. Results showed that the fires of the Dentex tumifrons fed with the enriched rotifers were better than that fed with the control rotifers. The survival rates were 50.5 %,24.8 %,10.8 % and 4.7 % respectively and the increase rate of the body length were 147 %,120 %,83 % and 71 % respectively. In the strengthened types, feeding with 50-DE Microcystis adding Chlorella spp. was the best way.
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