Effects Of Salinity On Carp Breeding And Hormone Levels Of Juvenile Growth

A trial was conducted to determine the impact of salinity on mature carp which was domesticated by sea water in a recirculating aquaculture system and for artificial insemination. The experiment focused on researching embryo development, the impact of salinity on development in the growth of the roe, oxytocin-induced serum GTH, VTG and sex hormones of carp. The results would provide experimental basis for seawater carp breeding technology and for reproductive physiology. Results were as follows:(1) The breeding situation of seawater domesticated carps, a natural spawning, fertilization rate arrived to 94.22%, the survival rate was 5.47%, the hatchability rate was 0.16%.The time lasted 90 hours and 30 minutes from fertilization to hatch and the development situation was observed through a microscope. An artificial insemination spawning, the fertilization rates of embryonic development in different salinities(0, 2, 4, 8, 12, and 16) were 96.56, 100, 94.39, 96.44, 95.76 and 95.62%, respectively. The survival rate was 17.91, 33.71, and 1.7% respectively. The hatchability rate was 18.55, 71.71 and 1.86%. The malformation rate was 14.1, 24.16 and 100%. When the salinity was 0, carp embryos had the longest diameter. The water group had the shortest short diameter. The effects of salinity on yolk diameter and egg membrane thickness had no significant difference in the groups. The last time was artificial insemination. The female egg was dead and the male semen might be normal.(2) The effects of salinity on the growth of carp fry and young carp and metabolic rate, in salinity mutation experiment, the carp fry was directly moved from the living environment(salinity was approximate 2) to salinity 16. Within 1.2 hours they all died. Moved to salinity 12, 3h began to die and within 32 h all died. Moved to salinity 8, after 27 h began to die, and till 96 h the survival rate of the carp larvae reached 82.5%. Move to 0 and 4, until the end of the experiment, the survival rate was more than 90%. The growth results as follows, in the same salt degree, with the extension of time, the larvae growth rate was first increased then decreased. In the same day, the lower salinity larvae had a long length, the higher salinity larvae had short length. The salinity gradients experiment results, with the comparison between the control and the experimental group it shown that over a period of 21 days, the length of the two groups were both increased. However, the longest full length of the couple largest fish in the control group was 12.1mm, while the experimental group was 11.1mm. The results of metabolic rate: With the increasing of salinity on 2~16, ammonia excretion rate of carp fry showed a generally downward trend and the oxygen consumption rate was upward then downward then upward again. The effect of salinity on the growth of young carp, within the same day the same group which was in the different salinity had significant difference of length. As the salinity increasing, young carp length showeg a downward trend. On the same salinity, with the time flying, the length had significant difference. In the same day, the weight on salinity 2 and 6 had no differences, but was significantly different from salinity 10 and 14.(3) The effect of salinity on oxytocin-induced serum GTH, VTG and sex hormones of juvenile carp. At 0 h, juvenile carp had low GTH levels. After injection the hormone oxytocin 6, 12, 24 and 48 h, serum GTH content was first increased then decreased among all groups. At 0 h, except the water group, serum VTG contents in the other groups were high. With time flying, the serum VTG contents drastically reduced and remained almost unchanged. The effect of salinity on E2. Before injection, the content showed a downward trend with increasing salinity. With time flying, the 2, 6 and 14 salinity content showed down then up, but salinity 10 showed first up then down. Effects of salinity on T.Before injection salinity 2 and 6 had high content, and salinity 10 and 14 had low sontent. With time flying, the content of salinity 2 and 6 decreased and salinity 10 and 14 increased.