Culture techniques of Australian crayfish

Lobsters in nature mainly inhabit the sandy and muddy sea floor, with one tail lurking in each hole, but in the mating period, male and female pairs are latent, sometimes lurking in the gaps in the rocks. Lobsters must be fed during breeding, and whether various attached organisms can be used as bait should be considered.

Pond condition

The pond is best chosen where there is plenty of water, the ground is open and the terrain is slightly inclined. There is no mountain forest or buildings around, which can ensure good ventilation and is conducive to the agitation and convection of pond water. The terrain is slightly inclined to facilitate the self-flow of water drainage and irrigation.

1. The area of shrimp ponds: there is no limit to the size, but 0.2 to 0.67 hectares is better. It should be rectangular and the ratio of length to width is 1 ∶ 3.

2. Water depth: the water depth is 0.7-1.5m, which should not be too deep, which is beneficial to the growth of aquatic plants, photosynthesis, dissolved oxygen supplement and lobster habitat and growth. Under the condition of suitable temperature, shallow water culture is better.

3. Water quality: the water quality is fresh and pollution-free, the dissolved oxygen in the water is above 4mg/l, and the ph value is 7.0-8.0.

4. Irrigation and drainage system: the separation of drainage and irrigation is beneficial to the regulation and control of water quality and the prevention and control of diseases. The water quality of other rivers is also required to be good, fresh and pollution-free.

5. The slope of the shrimp pond: the ridge of the pond should have a proper slope, and the bottom of the pond should be flat and tilted slightly to the drainage side to facilitate shrimp fishing in the dry pond.

6. Transformation of shrimp ponds: make use of the dry pond fishing season to remove too much silt in the pond, leaving at most 10~20cm, and the cleared silt is used to repair and strengthen the ridge of the pond. Before stocking, the dry pond should be exposed for 15 to 30 days to make the bottom hard and the cracks small, which is beneficial to the habitat and growth of lobster.

7. Provide hiding places: freshwater lobsters have the habit of being afraid of light. Put more shingles, old tires, pvc pipes, bamboo rafts, bricks, old baskets and other concealed objects at the bottom of the pond, and sunshades can be set up on the pool where conditions permit. Several methods are combined to create a half-yin and half-yang, quiet and comfortable habitat for lobster.

8. Escape prevention: in addition to strong dikes, shrimp ponds can also be surrounded by some simple materials, such as plastic film or plastic net, to prevent lobsters from escaping or invading by enemy organisms such as frogs, snakes and rats.

Seedling releasing method

1. Seedling release time: generally from April to early June, seedlings can be released when the spring water temperature rises to more than 16 ℃.

2. Selection and purchase of shrimp seedlings: choose seedlings with bright, clean and beautiful body surface, complete limbs and healthy physique.

3. Stocking density: it depends on the specification of shrimp fry, the requirement of cultivation, the condition of shrimp pond and the level of feeding and management. Generally speaking, for lobster seedlings with a body length of more than 1.5~2cm, the amount of lobster seedlings is 5000 to 6000 per 15 ha, and the survival rate is usually more than 70% and 80%.

4. Seedling release methods and matters needing attention: the water level of ① should be more than 0.8m and 1.0m when releasing seedlings. Due to the great change of air temperature in the seedling release season, the deeper water level is beneficial to keep the water temperature relatively stable. ② should release enough seedlings at one time for each shrimp pond. ③ should be scattered in the shallow water around the shrimp pond. If ④ is the shrimp seedling transported by oxygenation method at low temperature, the shrimp seedling should be taken out first, and the temperature difference should be adjusted slowly. When the water temperature in the bag is basically the same as that in the pool, it should be put into the pond.

5. Mixed culture of fish: Australian freshwater lobster should not be mixed with carnivorous and omnivorous fish in pond culture, but some silver carp and bighead carp can be put properly, on the one hand, the water will not be too fat, on the other hand, this kind of fish is more sensitive to dissolved oxygen in the water. it can also serve as an alarm for anoxia in the pond.

Throw and feed

1. Types of feed

① plant feed: soybeans, bean cake, wheat, corn, potato and so on. It must be noted that if legumes are selected as feed, they must be heated to remove antitrypsin, which is conducive to the absorption of plant protein. Lobster will also eat some fresh and juicy aquatic plants. An appropriate amount of local aquatic plants that can grow and benefit lobster can be planted in the shallow water area of the pond or on the edge of the pond.

② animal feed: fish meal, fresh miscellaneous fish, snail, mussel meat, earthworms and livestock and poultry viscera and so on.

③ compound feed: at present, there is no special formula feed for freshwater lobster on the market, which can be replaced by shrimp and hairy crab feed, or can be prepared by ourselves.

2. Feeding amount: the daily feeding amount of dry food is generally 8%-10% of shrimp weight, 5% of shrimp weight, and 3%-4% of prawn weight. If fresh food is added, it can be appropriately higher than this figure. Lobster feeding should be flexibly controlled and adjusted timely and reasonably according to the weather, water temperature, water quality and other conditions.

3. Feeding method: generally twice a day, in the morning and evening, preferably before sunrise and after sunset, and mainly in the evening (accounting for 80% of the whole day), but some people change the afternoon to around 10 o'clock at night. because the lobster has obvious habit of sleeping and rising at night, the bait method is "four fixed and four looks", that is, timing, fixed point, quality and quantity. Look at the season, weather, water quality and lobster intake to determine the increase or decrease of bait dosage. It is mainly fed evenly on the shore and shallow water, the bait should be farther away from the beach in the morning and closer in the evening. A bait table can also be added around the shrimp pond to observe the feeding of shrimp. Different stages of feeding, the body length of young shrimp, crushed fine food; 5~10cm shrimp, the bait should be processed into a certain size before feeding; adult shrimp stage of the bait can be a little thicker. When shrimp seedlings are first put into the pond, they should be mainly animal-based and supplemented by plant-based bait; in the middle stage, they should gradually turn to plant-based bait, supplemented by animal-based bait; in the later stage, they should be fed more animal-based bait to achieve "two-end essence, middle green".

Feeding and management

The water quality of shrimp ponds should be kept fresh, high oxygen content and free from pollution. The early stage is mainly fertilizer and water, and the transparency is about 25cm; in the middle and later stage, it is best to change water frequently and add water once every 15 days, and the transparency is 30~40cm. Do a good job of increasing oxygen and running water, maintain a good pond environment, and promote appetite and growth. If possible, it can be cultured in micro-running water.

In the middle and later period, quicklime 20g 25g (water depth 1m) was used for every 15 ha in the middle and later period, and sediment improver was occasionally sprinkled throughout the pond to regulate the water quality. If possible, 0.1% molting or pellet feed for shrimp and crab can be added to the diet.

Daily management

1. Regular pond patrol: in the morning, the main purpose is to check the presence of residual bait in order to adjust the bait of the day; at noon, it is mainly to measure the water temperature and observe the changes of the pool water; in the evening or night, it is mainly to observe the lobster activity and food intake.

2. Regular inspection: maintenance and reinforcement of escape prevention facilities, especially in case of storm.

Enemy disease and its control

1. Types of enemy damage: the main enemies are rats, frogs, waterbirds, water centipedes, chironomid larvae and so on. It is necessary to kill rats in time, remove frog eggs and tadpoles in the pond, and install purse seine 30~40cm around the shrimp pond to prevent frogs and water snakes from invading. The water centipede found in the pond can be fished by fishing.

2. Disease control: Australian freshwater lobster has strong disease resistance, and no explosive and epidemic diseases have been found since its introduction, but with the improvement of intensive culture, disease prevention and control work should not be taken lightly! Mainly for prevention, the body surface should be disinfected before the seedlings go into the pond to prevent pathogens from being brought into the shrimp pond. At present, several pathogens are mainly parasites, algae and some bacteria. The general parasite can be sprinkled or hung with the mixture of copper sulfate and ferrous sulfate (5 ∶ 2) (0.5-0.7) × 10e-6. If there are ciliates attached to the shrimp, resulting in slow movement, reduced food intake and difficulty in molting, you can be treated with Shrimp and Crab Xian Chong Jing, with a dosage of 500g per 15 ha of water depth.

3. Pesticides are strictly prohibited: Australian freshwater lobsters are sensitive to pesticides. If farmland water is used to irrigate ponds, farmland water should be strictly prohibited from flowing into shrimp ponds during the period of pesticide application.