Crayfish breeding and breeding techniques
Red-claw crayfish, known as Australia's lobster after its introduction in China, was originally a wild species in Australia. In 1971, it was only cultivated in Australia. It resembles lobster in appearance and is one of the finest freshwater cultured shrimps in the world. In June 1990, Niuwan Town, Xinhui City, Guangdong Province introduced breeding and aquaculture from Australia. On April 27th, 1995, we introduced 150-200 g/kin of broodstock from Shuikou Town, Pingshan City, Guangdong Province, and 86 species of 7-10 cm shrimp (10 dead). On May 25, we introduced 7 to 10 cm. There are 1850 shrimp species (of which 200 are dead), and the male to female ratio is 1:1. The experimental observations are now reported as follows:
First, the biological characteristics Red ancesal crayfish belonging to Decapoda, quasi crayfish, light shell shrimp, the general individual 100-2O0 grams, the largest individual up to 500 grams. The body color is mosaic brown green, the head and chest are evenly connected with the abdomen, and the outside is covered with a hard shell. There are five pairs of thoracodorsa. The first pair of thoracic feet is particularly developed and specializes as a powerful chelator. Male chelators are more developed than females. There is a membranous red chelonian belt on the outer side of the chelate. It is the second sexual distinction between male and female.
Two male external genitalia, born in the base of the fifth pair of feet, one left and right, showing a transparent protrusion of 0.5 cm long; the female's genitals are at the base of the third pair of feet, one on the left and one on the other, round Shaped, there is a film covering the mouth. The Australian lobster tail has five powerful tail fans and three outer rims. The middle tablet is small. In the egg-bearing period and hatching period, the tail fan is curved inwards, and the eggs adhering to the abdomen are held in the abdomen. The female shrimps do not damage the fertilized eggs and juvenile shrimps when crawling or receiving the enemy eggs. This is the distinction between holding eggs and not holding eggs.
The shrimp is dark and afraid of light, crawling life. Under normal conditions, it hides in deep water perches during the day. There is little activity for food; in the evening, activities begin, and most gather in shallow water to crawl and feed. If you are frightened during your spouse-hunting, you quickly flee back into the deep water; when you grapple and move, you will crawl forward. When you are frightened or when you encounter an enemy, you will quickly bounce back and avoid. Happy living water new water, when the environment is not suitable, it will be inhabited on the edge of the pond. It has wide adaptability and can endure bad environment. The water temperature can survive at 5-35°C. Omnivorous, wide source of feed.
Juvenile shrimp leave shells every 1.5 to 2 days within two weeks of the mother’s body. Afterwards, shrimps are shelled once every 4–6 days in 3-4 weeks. The speed and slowness of shelling increase with shrimp growth. Accumulation, physiological conditions, environmental adaptation, and water quality are factors that determine. It was observed that the shrimp shelled 25 times in a lifetime. The shrimp, 15 cm in length, can escape from the scene from the beginning of shelling to the hardening of the shell, a total of 15 minutes. Shelling takes place at night in the shallow water.
The development of the egg: Oval, the female shrimps are discharged to the abdomen immediately after sexual maturity and adhere to the abdominal foot. Begin the egg into pale yellow, turn to brownish red, juvenile shrimp shell out, cycle 15-40 days. The hatching time of juvenile shrimp is closely related to temperature and water temperature. Water temperature and high temperature have short incubation time and vice versa. Under the same conditions, the amount of eggs held by the broodstock is closely proportional to the length of the breastplate. The relationship is Y=7.5X2 +20X-40 [Y is the amount of eggs (grain), and X is the length of the cephalothorax (cm)] . The newly hatched juvenile shrimp began to adhere to the mother and was protected by the broodstock and left the mother body completely for about one week.
The shrimp has six tentacles on its head and grows with its length. The tentacles are composed of countless knots. The near head is thick, the tip is small and sharp, and the sensitivity is very high. The two tentacles at the outer edge of the head are particularly thick and long, generally one third longer than the body length, and four short beards perched in the middle. At the time of normal crawling, six tentacles are in front. If frightened or attacked, two long touches must be bent towards the tail to prevent the tail from being attacked by the enemy.
Second, artificial propagation from shrimp seedlings to sexual maturation takes about a year (l winter), under conditions to adapt, breeding twice a year. In April-January each year, the water temperature is above 20°C. After the overwintering broodstock, when the water temperature rises, the gonadal development is very rapid. After the water temperature rises to 20°C, the female shrimp starts to hold eggs. If the water temperature continues to rise to 25-27°C, it will develop into shrimp after 25-45 days. , Incubate for 20 days and grow to 2cm body length (in Niuwan Town, Xinhui, Guangdong Province, lay eggs in mid-May, lay eggs in June, and produce once in August). One month prior to spawning, the male and female co-feeders should be reared separately. If the egg-bearing shrimp is in an uncomfortable water temperature, or is suddenly frightened, the egg will be separated from the mother and will not continue to develop and die, even jeopardizing the life of the female shrimp. According to the test, the male and female ratio is better than 1:4. The body length of 9 cm females spawns 600 eggs, 8 cm spawns 500, 7 cm spawns 400, 6 cm spawns 300, 4 cm spawns 100 grain.
The egg-holding shrimps gather in dark holes in shallow water, and they have strong water repellency. This feature can be used to catch egg-holding shrimps in the evening for artificial hatching.
The breeding of broodstock is the key to artificial reproduction. The broodstock has less activity and the food intake is less than 15°C in the winter, and it can only be normal when the water temperature is above 15°C. It is advisable to feed high-protein feeds at this time, and fresh fish or small shellfish should be preferred. Usually broodstock individuals hold about 300-500 capsules at 100-150 grams. However, in the case of undernutrition, each broodstock holds only about 100 eggs.
Artificial breeding method of shrimp seedlings, the general use of pond natural breeding and cement pond breeding two. (A) pond natural breeding method pond area to l - 5 acres is appropriate, the choice of irrigation and drainage convenient, depth of about l meters, the pond slope of 25 degrees in the pond, after clear pond disinfection, adjust the water quality, pH value in 7.5-8. Add some organic fertilizer to the pond to cultivate plankton. After putting in appropriate quantities of water-lily masks, etc., put the broodstock when the temperature is appropriate. The proportion of males to females is 4:1, and about 100 tails per acre are placed. After mating, the hatching hatches. After the shrimp completely leaves the mother (about 30-35 days), the male and female broodstock are captured, and the other pool is cultivated. The pond has become a naturally hatched shrimp pond. Shrimp mainly rely on organic debris and plankton in the pond for food. At the same time, put an appropriate amount of egg yolk every day to ensure that shrimp has enough food. It takes 30-35 days for shrimp to grow to 1.5-2 cm. This method of hatching from shrimp to grow to 1.5-2 cm in length, takes 60-70 days, under normal circumstances, each female shrimp can get about 2 cm body length 150-200 tail shrimp. This method is relatively simple and convenient, the water surface is large, the group is small, and the cultivated shrimp seedlings are more robust; however, there are disadvantages such as the large number of flower cultivars and the low seedling rate for catching small ponds.
(b) Cement pond breeding Each hatching pond is 6-10 square meters, the water depth is kept at 40-70 centimeters, and 6-8 tails can be placed per cubic meter. The temperature of the water is controlled at about 30 degrees Celsius, and each tank enters the water surface. Appropriate amount of water-living lotus as cover (in order not to exceed 1/3 of the surface of the pool is appropriate), air and oxygen aeration or micro-flowing water. After the shrimp hatches and leaves the mother, the mother shrimp is taken away and it becomes a small cultivation pond. Feed plankton and protein particles every morning, morning, and evening, and keep them in the pool for 4-5 weeks. Individual shrimps reach 1-1.2 cm in size, and then they are stocked again.
The advantages of this method are: no natural enemies harm, high survival rate. It is easy to manage, easy to observe and find problems; the shrimp is fast in the early stage, it is easy to isolate the shrimp, and the shrimp is easy to recycle. Disadvantages: high equipment requirements, high costs, sophisticated management requirements, and high risk
30% shrimp breeding
1. Pond requirements: generally 3-7 acres is appropriate, sediment ratio is 1:1, the bottom of the pond should be flat, the slope of the pond is 25-30 °C as well, the water depth requires more than 1.5 meters, PH value of 6-8 are Yes, but 7-7.5 is better. Water quality requires a transparency of 30 cm, preferably greenish green. Irrigation and drainage should be convenient, and facilities must be set up around the pond.
2. Reasonably put in shelters, put appropriate amount of water-lilies on the surface of the water, use stones or tiles at the bottom of the pond, place 300-500 waste tires per acre around the bottom, or use Lucha, Luzhu Bundles, placed in ponds for their shelter.
3. Stocking density: shrimp body length l-1.5 centimeters, 15 fishes per square meter of water; body length 3-5 centimeters, 8 to 10 tails per square meter of water; body length of 10 centimeters, stocking water per square meter 4-6 tails,
4. Feed requirements: Both shrimp feed and small trash fish are available. Crude protein content is 40%; it is preferred to feed two times a day in the morning and in the evening, and 70% in the evening.
5. Feeding amount: the feed coefficient is about 2. l, the juvenile shrimp is 20%-25% of the body weight, the middle shrimp is 15%-20%, and the adult shrimp is 5%-10%.
6. Water quality management: Change water according to water quality and shrimp period. The number of water changes in general should not be too busy, and there is no need to change the water every day. The depth of water is generally more than 1.5 meters. When the temperature is high, it is properly deepened. When the temperature is low, it can be shallower. When the water temperature is 27-28°C, the shell should be removed. When the shell is removed, the water should be shallow, and the water should be deeper when living.
7. Fishing: Trawling can be used to fish; catch traps can also be used (that is, the decoy is placed in the cage and the shrimp can not be returned). Crawfish do not tolerate low water temperatures below 5°C and must be captured at temperatures above 5°C. Shrimp time is better in the early morning or evening.
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