Breeding of different types of freshwater prawns and breeding of shrimps

Green shrimp culture has become one of the leading industries for freshwater fisheries in Jiangsu Province. With the rapid development of the shrimp aquaculture industry, the rapid increase in production scale and aquaculture production, and the continuous increase in the intensity of intensification, in particular, some farmers use annual shrimp production as the broodstock for the coming year, making the traditional excellent economy of the shrimps. The traits have been degraded, such as early sexual maturity, slow growth, and the small size of commercial shrimp. At present, most of the cultured shrimp species have not been bred. Therefore, the improvement of the germplasm quality of the shrimp is imminent. The trial used the two different river systems of Taihu Lake and the Yangtze River for mating to explore the feasibility of the improvement of the germplasm of the shrimp. The relevant experiments are summarized as follows.
1 Shrimp breeding
1.1 Collection and Cultivation of Juveniles
On April 20, 2002, Taihu Lake 250kg (approximately 4.0cm in average length) was purchased in Taihu Lake, Xishan, Suzhou, and 250kg of natural Yangtze River shrimp (about 4.0cm in average length) was purchased on May 2 in Pukou, Nanjing. Test base for testing. Green shrimp transportation using shrimp box (30cm50cm15cm polyethylene network frame) aeration and oxygenation, transport time from Taihu Lake to the base 6h, transport time from the edge of the Yangtze River to the base 1h, the transport survival rate was 98% and 100%. Mu discharge shrimp species 30kg, water clarity control 30 ~ 35cm, with a feed of 32% crude protein shrimp pellets, ponds and erection mesh portion of the water for freshwater habitats peanuts every 3 ~ 4d add new water 1, May 15 and May 30 of each pool each applied fertilizer 30 ~ 50kg. May 20 to May 25 from shrimp ponds harvesting sexually mature than 5cm in length shrimp (♀ Ⅲ of shrimp, prawns to the second ♂ pereiopod approaching or equal to or exceeds the whole length of the random sample), ♀:♂ within 4:1,6d females were selected for the Yangtze River and Taihu females each 30kg, males each 8.5kg. Two kinds of shrimps were exchanged for females and males. Intensive cultivation was continued in an area of ​​3 acres of earthen ponds. On June 14, 20 oviparous shrimps were collected and the egg size was larger. Observe the development and growth conditions. See Table 1. neat.
July 25 shrimp seedlings specifications in Table 2.
From July 30th, the catch was over. There were 6.07 million tailed larvae in the Changjiang River + Taihu Lake nursery, and 610,000 tail larvae in the Changjiang River + Taihu Lake.
1.2 Acquisition parent
On May 19th and May 20th respectively, 50kg of female shrimps with a size of 5cm or more were purchased from Taihu Lake and the Yangtze River respectively. Males and females exchanged 10kg each and exchanged between male and female. Domestication and breeding were conducted in a pond with a base area of ​​3 mu, and the mortality rate of the lower pool was 3%. The Yangtze River shrimp is 1%. Crude protein was used for intensive cultivation of 32% green shrimp pellets. By June 1st, more than 90% of the shrimps had already caught shrimp. On June 18, 20 shrimps were picked up. See Table 3 for the development of fertilized eggs.
Table 3 shows that the maturation of fertilized eggs mated with sexual maturation is basically synchronized, and that the young generation of pups have neat specifications. In the pond, 90% eggs were hatched within 7 days, shrimps were cultivated 25 days, specifications were 1.0-1.5 cm, Taihu Lake + Yangtze River Dianchi was 1.35 million, and Taihu Lake + Yangtze River Dianchi was 1.6 million.
2 shrimp farming aquaculture combined with high-yielding trials of earthen ponds, stocking time is on the 22nd of the month, 1.2 mu of aquaculture ponds in the Taihu Lake + Yangtze River larvae, stocking size 1.0-1.5cm, stocking capacity 216,000, acre 180,000 At the end of the week, Taihu Lake has a total of 1.8 acres of breeding ponds, with a total stocking of 320,000, a total of 180,000 acres, and a comparison pool of cultured shrimp, with an area of ​​1.8 acres, with a total stocking of 320,000, and a mu of 180,000.
The oxygenation method is oxygenation of the inflator (sandhead gas), 400 gas pools around the shrimp pond (1m offshore), and the experimental pool is mainly composed of black algae, a small amount of agrochemicals, and the coverage rate of aquatic weeds is about 40%. Nets are set up. When shrimp larvae appear in the shrimp ponds, the larvae of the shrimps will be discharged out of the pool through a large amount of drainage, thereby reducing the impact of the plentiful shrimps on the prawn pool culture.
Feeding and management, the ponds were fed artificial compound feed and divided into 3 stages. Before August 15th, the first stage was: the shrimps were 2.5cm in length, and the crude protein content was 36% microgranular feed; August 15th to 9th On the 10th of the month, the second stage is: the shrimp body length is 2.5-4.0cm, and the crude protein is 34% small grain feed; the third stage is the shrimp body length 4.0cm or more before being listed, and the crude protein is 32% The shrimp pellet feed is fed at regular fixed-point feeding time, and is fed at 1/3 of the morning at 8:00 am, and is given at 2/3 at 5:00 hrs. The feed is on the shallow beach near the shore, and the daily feed is taken. According to the trial of 3 to 4% of the body weight of the pond shrimp, the shrimp should be adjusted according to the food intake and weather conditions of the shrimp. Generally, the food is eaten within 2 hours after feeding. The growth of shrimp was determined monthly, as shown in Table 4.
It can be seen from Table 4 that the growth specifications of different water-based mating shrimps are significantly higher than that of cultured shrimps.
During the rearing period, the high-grade fertilizer pool flows to the shrimp ponds, and the water quality of the shrimp pond is always maintained. The transparency of the water body is controlled at about 30 cm, and the oxygen is increased by the oxygen-increasing equipment to maintain sufficient dissolved oxygen.