Study On The Annual Development Of Ovary And Large-Scale Artificial Propagation Of Chinese Hooksnout Carp Opsariichthys Bidens

In recent years,Opsariichthys bidens aquaculture industry has begun to develop.But the demand of fry in the market exceeds the supply,this problem has seriously hindered the development of the O.bidens industry.To solve this problem,we studied annual changes in the ovarian development of O.bidens and analyzed the effects of water temperature change on ovarian development.We explored the method of large-scale of artificial propagation of O.bidens and summarized the annual production.The aim is to improve the scheme of large-scale of artificial breeding and promote the rapid development of O.bidens industry.In the present work,we found that the annual change of female GSI in the central China region was from 1.16%to 11.65%.The breeding season of O.bidens was form the middle of April to the middle of July and the average absolute fecundity of the female fish before spawning was 6165.40 eggs.In early March,with the increase of water temperature,the ovary volume of O.bidens gradually increased and matured.And the ovaries began to degenerate in September and overwintered with stageⅢ.From October to February,GSI of O.bidens was at a low level,with a variation range of 1.16%-1.65%,but the proportion ofⅢphase oocytes in ovary increased gradually.In the large-scale artificial propagation experiment,it was found that the best dosage of hormone for female was LHRH-A₂（5μg/kg）+HCG（1000 IU/kg）,and the induced spawning rate could reach 86.96%.The results indicated that 0.3%NaCl solution is the best insemination medium and the best ratio of sperm to egg was 5.0×10⁴-1.0×10⁵:1.The average fertilization rate was 66.63%and hatching rate was 80.12%.Before the middle of May,the effect time was more than 20 h,and after that the effect time was 16h-17h,and the cumulative temperature was 400℃·h-430℃·h.When the water temperature was22.0℃-25.5℃,the incubation duration is more than 70 h.When the water temperature was more than 26℃,the incubation duration was less than 48 h,and the incubation accumulated temperature is within the range of 1200℃·h-1300℃·h.We also successfully conducted artificial spawning twice a year,and found that the effect of the second spawning was not significantly different from that of the first spawning.This study clarified the annual development rule of ovaries of O.bidens in central China and the time suitable for artificial propagation,and realized the large-scale of artificial propagation of O.bidens,which has provided a theoretical basis for further optimizing the large-scale artificial propagation program,and has laid a solid foundation for breeding and promotion of new varieties of O.bidens.It was of great significance for the development of related industries.