Culture techniques of Australian freshwater lobster

Australian freshwater lobster belongs to crustacea, decapoda, crayfish family, smooth shell shrimp genus, its origin is in the tropics of the northeast coast of Australia. Near a bay river in a subtropical climate. Trial culture was introduced into China in the early 1990s, which confirmed that Australian freshwater lobster has the characteristics of large individual, fast growth, miscellaneous eating habits, high culture yield, delicate meat quality and high meat yield (the edible part accounts for about 40% of the body weight). It is a new superior freshwater crayfish species worth popularizing. Some biological characteristics and artificial culture techniques of freshwater lobster are introduced below.

Reproductive habit

Australian freshwater lobster is native to the tropics of Australia and has a rapid growth rate, reaching 50ml 80g in 6 months. Australian freshwater lobsters generally reach sexual maturity at the age of 6-12 months. The large claw extension of sexually mature male shrimp has a distinct red or orange stripe, and there are a pair of papillary reproductive spines at the base of the fifth pair of footsteps. The female shrimp has a pair of reproductive pores at the base of the third pair of feet, and the claw of the male shrimp is blue and the length is less than the body length. Sexually mature Australian freshwater lobsters reproduce naturally in ponds when the water temperature is above 21 ℃.

Australian freshwater lobster breeds for a long time, starting in April and ending in October. The optimum temperature for reproduction is 22 ℃, and the optimum water temperature is 28 ℃. Mature female shrimp must be shelled before mating. Generally, the female shrimp ovulates within 24 hours after mating, then combines with sperm and fertilizes, and the fertilized egg is orange. After spawning and fertilization, the eggs are hatched by the mother with eggs, and the incubation period is 30 / 32 days when the water temperature is 28 / 29 / ℃. Australian freshwater lobsters can lay eggs 2mur3 times a year.

Growing environment

1. Water temperature: Australian freshwater lobster has the habit of adapting to the tropics and can withstand high temperature. the suitable temperature range for growth is 24 ℃ 42 ℃, which is lower than 21 mol. Below 10 ℃, the adult shrimp stopped growing. Adult shrimps will also die if they grow up below 9 ℃, so overwintering management should be carried out in areas with lower winter temperatures.

2. Dissolved oxygen: Australian freshwater lobster can withstand not only high temperature but also low oxygen. Under normal circumstances, the dissolved oxygen in the pool is kept between 4-5mg/L and grows normally. Adult shrimp can even tolerate the dissolved oxygen content of 1mg/L and can climb out of the water for a short time to breathe in the air. Young shrimp are relatively sensitive to low dissolved oxygen, and shrimp seedlings can not survive in 1.2mg/L water.

3. Ph value: the suitable pH value is 6.5 Mel 9. The incubation period should be more than 7, because the acidic water quality is not conducive to shelling growth, which will increase shelling death or prolong shelling time.

4. Salinity: Australian freshwater lobster does not require high salinity, so it can grow smoothly in freshwater ponds. At the same time, the larvae can adapt to the salinity 3g/L, and the adult shrimp can still adapt to the 5g/L concentration. Therefore, 1% of juvenile shrimp and 3% of adult shrimp can be soaked in salt water for a short time to kill the body surface parasite.

Culture technology

1. Shrimp seedling cultivation

① cultivation pond conditions: in order to facilitate management, the cultivation pond is generally a cement pond of 50ml / 300m2, with a water storage depth of 1m, which requires convenient entry and drainage. At the same time, concealment was placed at the bottom of the pond and on the water surface, accounting for 1 hand, 4 meters, 1 hand, 3, in order to increase the effective habitat area of shrimp fry.

② stocking density: in the first four weeks of larval cultivation, the stocking density in the breeding pond should not exceed 1000 tails / square meter. Proper sparse culture and timely separate cultivation are beneficial to improve the survival rate, and the general survival rate can reach 50%. 70%.

③ feeding: in the first three days of breeding, the young shrimp can be fed with steamed eggs and fish paste, and the shrimp with 44% 46% crude protein content can be gradually replaced with open bait and Artemia. The daily feeding rate of shrimp fry was 3ml / d for 5 times. When the larvae grow to more than 2cm, they can be fed pellet bait, which is 15% of the body weight of shrimp in the pond, and should be increased or decreased appropriately according to water temperature, feeding and growth.

④ water quality control: water quality is required to be fresh and transparent, preferably with a little bit of running water. Avoid excessive bait. There should be no residual bait and waste deposits in the water. Clean up in time. When the larva grows to 3cm and weighs about 1 gram, it can be put into the pond to cultivate adult shrimp. In order to ensure the survival rate, shrimp seedlings can continue to be sparsely cultured in the pond, so that the shrimp seedlings can reach more than 2 grams, and then put into the shrimp pond.

2. Adult shrimp culture in ponds

① pond conditions: the pond used for Australian freshwater lobster culture covers an area of 1.5mu, the depth of the pond is 1-1.5m, the bottom of the pond has a slight slope, has a good intake and drainage system and oxygen enrichment system, no leakage, and should build anti-escape facilities. The pond must be cleared before stocking to prevent enemies and pathogens from staying in the pond. the method is the same as the general fish pond, dry cleaning pond with 150-300kg per mu of raw lime. Australian freshwater lobsters like shade and fear light, and are good at climbing and escaping, requiring aquatic plants on the water body (about 1 / 3 of the water surface), planting aquatic plants (verticillium verticillata, etc.) at the bottom of the pond, and bamboo tubes or other similar objects can be set up at the bottom for their burrowing.

Release of ② shrimp seedlings: the toxicity of lime water disappears in 10 days and the water quality is normal, then the seedlings can be released. The general stocking density is 7000m / mu, about one month, and the silver carp with 50-250g/ tail can be mixed with 60mu / mu in time. Freshwater lobster is a benthic crustacean. Proper mixed culture of pelagic filter-feeding fish can improve the growth environment of lobster. On the other hand, this kind of fish is sensitive to dissolved oxygen in water and can be used as an indicator of anoxia in ponds. However, be careful not to culture carnivorous fish and other eating fish, so as not to affect the growth of crayfish.

③ water quality management: under normal circumstances, the main purpose of water quality management is to ensure sufficient dissolved oxygen in shrimp ponds and to ensure fresh and good water quality. it is best to inject fresh water into the pond water every day. Regularly sprinkle lime water to improve water quality, increase calcium, facilitate shrimp shelling and improve the survival rate.

④ feeding management: mainly feed fish and shrimp with a daily feed of 3% of shrimp body weight. Feeding is divided into two times in the morning and evening, because its feeding habit usually forages by the pool in the evening and at night, so feeding in the evening should account for about 2x3 of the total. The fixed-point feeding is combined with pool-side sprinkling. Because Australian freshwater lobster is an omnivorous and saprophytic diet, it is necessary to increase the feeding of plant feed. In the early stage of culture, some hay can be put on the edge of the pond, 40kg per month, while in the later stage, soybeans and barley can be fed. The feeding amount during the whole breeding period was appropriately adjusted according to the water temperature. At first, because the water temperature was low, the feeding rate was low, and the feeding rate was about 6% of the body weight. In the middle period, the water temperature was high, and the feeding rate was about 10% of the body weight. Later, as the water temperature decreased, the feeding rate decreased to about 3%.

Prevention and treatment of ⑤ shrimp disease: Australian freshwater lobster is susceptible to a crayfish plague, which is caused by a fungal infection. The suitable temperature for the growth of this fungus is not higher than 18 ℃. When the water temperature is higher than 21 ℃, the growth of the fungus will be inhibited. Therefore, crayfish will not get sick as long as the water temperature during stocking and fishing is controlled above 21 ℃.

⑥ fishing: crayfish fishing methods include shrimp cage trapping and dry pond fishing. When the water temperature drops below 18 ℃, adult shrimp ponds that are not ready to overwintering can be collected in dry ponds, as long as the pond water is drained, and then shrimp are collected in the ponds. In the process of dry ponds, a net should be set up at the outlet to collect shrimp flocks. Usually a small amount of fishing, can be used to trap shrimp cage, shrimp cage woven with net thread, mesh size for 2cm or so, the shape of upright and cone-shaped two. When trapping, put the bait into the shrimp cage, then sink into the pond and harvest the shrimp immediately. After 6 months of cultivation, the yield of shrimp can generally reach 70-110kg/ mu, with an individual specification of 70ml 180g, with a maximum of about 450g.