| Conger myriaster belongs to the family anguillidae,a species of the genus myriaster.It is a common species in the East sea,Yellow sea,Bohai sea of China.Its economic value is higher and export has huge potential to generate foreign exchange.The coastal waters of northern Zhejiang province are one of the main distribution areas of conger myriaster.Since the 1980 s,conger myriaster have been gradually developed and utilized.It is a kind of common edible fish in the bottom layer of offshore water.As the most important fishery resource in East Asia,conger myriaster has no mode of artificial cultivation,and people still rely on the natural fishing of it for consumption.So far,because of the increasing demand from consumers,they are facing the stiuation of overfishing presure and resource exhaustion.Therefore,it is necessary to carry out relevant research work on conger myriaster.In this paper,the cultivation mode of wild eel was discussed,and the method of artificial ripening was optimized.The research results are as follows:1.In order to explore the effects of artificial culture mode and hormone injection on muscle biochemical components of the Conger myriaster.The experiment was divided into two groups: the control group(no injection of hormones)and the experimental group(CPE 1mg/kg;HCG 100IU/kg),injected once a week.During the experiment,common wild fish were fed,and their behavioral characteristics observed.The eels were cultured for more than 70 days.The results showed that the eel has a strong phototaxis,timid,quiet environment,noctumal and often hides in the sand or pipe to escape danger.The fish eats ferociously,by tearing and swallowing feed.The control group?s survival rate was 80%,and the experimental group?s survival rate was 75.86%,Control group survival rate is higher than the experimental group survival rate.After hormone injection,the gonadal development of eel in the experimental group was significantly higher than that in the control group(P<0.05),and the GSI were(23.17±2.08)%,(2.88±0.37)%,respectively.In addition,the moisture,crude fat,crude protein,and ash content in eel muscle were tested,in this experiment.Compared with the first sampling(7.82±4.29)%,the crude fat content in the muscle of the experimental group was significiantly increased(P<0.05),which were respectively(20.31±4.43)% and(26.97±5.20)%.The crude protein content in the eel muscle decreased in the experimental group and the control group,but the decrease was significant in the experimental group(P<0.05),respectively(79.54±1.26)% and(58.65±5.13)%.2.In order to study the effects of different foreign aid homones on gonadal development and biological characteristics of eel.The experimental design was divided into four groups: control group(no homone treatment),experiment group A(CPE 2mg/kg),group B(HCG 200IU/kg),and group C(CPE 1mg/kg;HCG 100IU/kg).The results showed that,compared with the control group,the eyes index,fin index,and liver index of eels were increased in the experimental groups,but the changes were not obvious.In the experimental group,the gonadal development index increased significantly(P<0.05),and the GSI of the group c was the highest [(6.80±1.72)%],the GSI of the control group was(0.94±0.14)%.Through the gonad slice observation,we found that the control group cell developed up to the Ⅱ stage,but the experimental groups developed into Ⅲ-Ⅳ of the stage,even Ⅴ stage of the cell in the experimental group C was observed.Therefore,exogenous hormone injection can change the morphological characteristics of the eel,and improve the gonadal development.3.According to the experimental method in the part Ⅱ,after injection,we tested six steroid hormones in the serum and gonad,which are related to gonadaldevelopment,including testosterone(T),17-hydroxyprogesterone(OHP),17,20-dihydroxyprogesterone-4-progesterone(OHP),estrone(E1),estradiol(E2),and estriol(E3).Hormone levels were detected by enzyme linked adsorption(ELISA).The results showed that the content of E2 [(50.86±6.34)ng/L] and E3 [(125.11±12.47)ng/L] in the serum of group C was higher than other groups.There was no signficant change in the content of other hormones between groups.In the gonad,compared with the control group,the level of the OHP showed an increasing trend in the experimental group.In the last sampling,the level of the OHP and T in the control group [(2.86±0.44)nmol/g],was lower than the mixed hormone group [(4.57±0.85)nmol/g].The level of T respectively(217±31.76)ng/g,(123.24±21.05)ng/g,p<0.05.Compared with the control group,maintain a high concentration of the steroid of hormones in the gonad,this can help with the gonadal development of the eel. |
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