Parent cultivation technique of small yellow croaker Pseudosciaena Crocea

Small yellow croaker (PseudosciaenapolyactisBleeker) belongs to Perciformes, Perciformes, Coleopteridae and Pseudosciaena Crocea, distributed in the Bohai Sea, the Yellow Sea and the northern part of the East China Sea. It is a warm near-bottom fish and was originally one of the four major marine economic fishes in China. The resources of Pseudosciaena Crocea have declined seriously since the 1950s. In this paper, the author introduced the technique of parent culture of Pseudosciaena Crocea. Through the observation of the growth process of Pseudosciaena Crocea, the growth parameters were recorded, which made a good preparation for the artificial reproduction and culture of Pseudosciaena Crocea.

I. gathering and catching of parent Pseudosciaena Crocea

There are two geographical populations of Pseudosciaena Crocea in the Yellow Sea and Bohai Sea: northern population and Lusi population. The northern population overwinters in the central and southern part of the Yellow Sea, takes bait and reproduces in the north and along the Bohai Sea, while the Lusi population is larger, has a short seasonal migration distance, and mainly moves from east to west in the south of the Yellow Sea. Pseudosciaena Crocea began its reproductive migration from the overwintering ground in March and spawned in shallow coastal waters from April to May.

The parent fish of small yellow croaker, Pseudosciaena Crocea, is located in the south of the Yellow Sea and the north of the East China Sea. In May, a small offshore fishing boat at the eastern pole of Putuo adopted a "small trawl" round-up operation in Zhongjieshan fishing ground, resulting in relatively minor scratches on the small yellow croaker, although the number was small, but there were surviving small yellow croaker. By July, a total of nearly 150 people were organized to go out to sea with the boat to collect 24 times, and more than 400 small yellow croaker were caught alive. After temporary breeding and transportation, only 16 were left.

2. Cultivation of parent Pseudosciaena Crocea

After being transported to the Zhoushan Experimental Base of Zhoushan Fisheries Research Institute, the parent Pseudosciaena Crocea was bathed with a certain concentration of antimicrobials, stabilized in the seedling pond for a period of time, and then moved into the soil pond cage for cultivation. When the water temperature in the sea area drops to 10 ℃, the parent fish will be moved indoors for the winter.

1. During the cultivation of net cage in soil pond, the physical and chemical factors of sea water in soil pond are measured regularly, and the proportion of water exchange is determined according to the water quality, so as to keep the water quality fresh. The bait organisms are mainly fresh and small miscellaneous fish, which are fed twice a day, the daily feeding amount is 5%-10% of the total body weight of parent fish, and a small amount of bait is given regularly to avoid the occurrence of fish disease. Regular replacement of the cage, in the process of turning the box for a short time of medicine bath treatment. The growth of small yellow croaker was measured every month, and the body weight, total length and body length were recorded. The average body weight, total length and body length of Pseudosciaena Crocea were 27.4 g, 15.2cm and 12.6 cm on July 19, and 53.6 g, 18.4cm and 15.3cm on December 19.

two。 Indoor overwintering cultivation of parent Pseudosciaena Crocea when the water temperature in the soil pond dropped to about 10 ℃, the parents of Pseudosciaena Crocea were reared indoors. The indoor cement pool is 4.0m × 8.0m × 1.2m, inflated slightly, the water temperature is controlled at 12 ℃ ~ 15 ℃, the salinity is controlled at 22 ‰ ~ 30 ‰, and the bait organisms are fed twice a day. In the process of overwintering, the gonads of parent fish were cultivated at the same time, and the method of adding appropriate amount of vitamin E to food organisms was adopted. As most of the small yellow croaker were one-year-old fish, the gonads could not meet the requirements, so they were placed in shallow sea cages on April 5, 2004 to continue their culture. It is found that the growth rate of fish is relatively fast during overwintering, which may be closely related to bait organisms, environment and other factors. On the 20th of January, the average body weight of Pseudosciaena Crocea was 69.4g, the average full length 18.6cm was 15.5cm, and the average body weight was 89.6g, the average full length 21.8cm and the average body length 18.6cm.

3. Shallow sea cage culture of two-year-old parent fish due to the strong swimming ability of two-year-old parent fish, and in order to better simulate the actual culture environment, the author's research group decided to carry out shallow sea culture experiment and moved small yellow croaker into shallow sea cage in April 2004. The cultivation technology of shallow sea cage is basically the same as that of soil pond cage, but it is found that the growth rate of fish is not as fast as that of soil pond cage Shaanxi. On May 5, the average body weight of Pseudosciaena Crocea was 8g.2g, the average full length 22.1cm, and the average body length 18.6 cm. Up to December 6, the average body weight, average full length 23.0cm and average body length 20.5cm were 109.3 g, 109.3 g and 20.5cm, respectively.

4. The two-year-old parent fish overwintered indoors on December 6, 2004, and the small yellow croaker was moved into the room again to promote gonadal ripening. The average body weight, total length and body length of Pseudosciaena Crocea were 117.4g, 23.6cm and 21.2 cm on January 6, and 135.6g, 25.0cm and 22.6cm on March 25th, respectively.

III. Summary

1. As the small yellow croaker is easy to be injured and the scales fall off seriously, disinfection and medicine bath must be carried out in the temporary culture process to increase the survival rate of the small yellow croaker. However, due to the limitations of high temperature and other objective conditions, the survival rate of parent fish is not high, but also summed up a lot of practical experience, laying a foundation for future work.

two。 Under the control of physical and chemical factors, Pseudosciaena Crocea can grow normally in the range of 6 ℃ ~ 32 ℃. According to the observation of the growth of Pseudosciaena Crocea in the past two years, it is found that the optimum water temperature is 15 ℃ ~ 25 ℃, and the optimum growth salinity is 20 ‰ ~ 35 ‰.

3. In the growth environment, the author compared the growth of small yellow croaker with the above three different culture methods, and found that the living environment of small yellow croaker is relatively stable, and the water flow should not be too fast. Through the comparative culture experiment of shallow sea cage and soil pond cage, it can be concluded that soil pond cage is more suitable for the culture of Pseudosciaena Crocea.

4. When overwintering management overwintering, it is best to control the water temperature above 12 ℃, so that it will not affect the growth of small yellow croaker, and will not waste too much energy. In the process of overwintering, we should pay special attention to the disease prevention of small yellow croaker, feed an appropriate amount, and clean up the excrement and residual bait at the bottom of the pool in time.

5. From the perspective of the experimental process, the disease resistance of Pseudosciaena Crocea is strong, which is suitable for artificial culture; from the experimental results, the growth rate of Pseudosciaena Crocea also meets the requirements of culture, coupled with the high economic value of Pseudosciaena Crocea and broad prospects for artificial culture.