Yield is related to benefit causes and countermeasures of low yield of crayfish

Crayfish culture

First, the survival rate of seedlings is low:

When the seedlings were released, due to long-distance transportation and long time away from the water, the Gill filaments of crayfish shrunk, did not fully absorb water during stocking, and "swelled to death" due to excessive water absorption after entering the pond. Some shrimp species are trapped by drugs and have a high mortality rate after stocking. Some are released in winter, directly frostbite and frostbite to death in the process of stocking.

The seedlings should be purchased and released on the spot, and the shrimp seedlings should be evenly stocked and evenly distributed along the pond. For the shrimp seedlings transported over a long distance, soak the shrimp seedlings in water for 3 minutes for 5 minutes, then put them on the edge of the pond for 2 minutes and repeat for 3 times. After letting the shrimp seedlings absorb enough water, and then slowly put the shrimp into the pond, the survival rate can be improved and the seedlings trapped by drugs are strictly prohibited.

Second, high stocking density:

The stocking density in Tangkou is high, and there are many batches of stocking in the same Tangkou with different specifications, resulting in non-synchronous growth rate, strong and weak feeding ability, killing each other of crayfish in the process of culture and low yield. Lobster culture in the pond, 20-40 kg per mu of shrimp seedlings, 60-80 per kilogram, shrimp seedlings require uniform specifications, strong physique, disease-free and injury-free, and full at one time to avoid batch stocking. When stocking, the shrimp seedlings should be washed and sterilized with 3%-5% salt water and put into the pond.

Third, there are many harmful creatures:

Because the pond is not cleaned thoroughly, the water injection is not strictly filtered. In the shrimp pond, there are enemy pests such as frog, water snake, snakehead and so on, which feed on young shrimp and invade the soft shell shrimp in the molting process, which directly affects the yield of lobster culture. Therefore, in the ponds where lobsters are farmed, drugs should be used to thoroughly clear the ponds before releasing seedlings to kill enemy organisms, such as quicklime, strong chlorine, Croton and so on.

Fourth, lack of light:

In many low-yield shrimp ponds, there are too many aquatic plants, the coverage rate is too high, the light surface of the water body is less, the water flow is small, and the light is insufficient. As a result, the aquaculture yield is low and the listing specification is small. The normal coverage rate of aquatic plants is generally about 1 stroke 3 of the surface of the pond to facilitate lobster shade and breed lobster's favorite plankton. The water and grass are too dense, you can cut a 3-5-meter-wide passage with a knife every 10 to 15 meters to ensure that the fish pond has an adequate light surface. From July to August, aquatic plants should be replenished in time to meet the needs of lobster growth and molting.

(5) insufficient amount of bait:

Due to the high stocking density, insufficient feeding quantity, improper feeding method, incomplete nutrition of bait and unpalatable size, some lobsters can not get food. First, it caused lobsters to kill each other; second, due to malnutrition, some lobsters failed to molt; third, some lobsters escaped because of bait. The daily feeding amount is to be full, finished, and no residual bait is left. Generally, crayfish and crayfish are fed at 15% to 20% of body weight and adult shrimp at 5% to 10% of body weight, which can be adjusted according to the eating condition of shrimp.

6. Poor water quality conditions:

First, the water quality of the pond is too fat, the pH value is too low, or the water quality is thin, and the transparency of the water body is too large, which is not conducive to lobster molting growth. Second, the water level in summer is too shallow and the water temperature is higher than the limit temperature, which will inhibit the growth of lobster and promote the precocious maturity of lobster. Frozen in winter, it is easy to cause lobster asphyxiation due to hypoxia. Third, the water level is suddenly high and low, causing some lobsters to make holes along the water level, mainly living in caves. A long time, adapted to the cave life, neither molting, nor feeding growth, lobster male and female, small size, lazy activities, low production. In the process of culture, the water level should be kept stable for a long time, the water quality should be fresh, and the water quality should be strictly prevented from industrial pollution, pesticide pollution and chemical pollution. If the lobster is found to be slow in response, gather on the shore, float its head and climb to the shore, it shows that the hypoxia is serious, and it is necessary to inject water or turn on the aerator to increase oxygen in time.

7. Poor management:

First, the area of the pond mouth is too large or too small, the slope ratio is small, and there is no shallow water layer, which is not conducive to the shelling and growth of crayfish; second, the anti-escape facilities are poor, which is easy to cause the lobster to escape; third, the fishing is not timely, resulting in some lobsters living in the pond and can not be caught. The suitable entrance area of crayfish pond is 10-30 mu, and the slope ratio is 1 ∶ 2-1 ∶ 3. Lobsters love burrowing, so anti-escape facilities should be strengthened to prevent lobsters from escaping. The lobster matured sexually every other year, and the young shrimp left the mother in September to mature sexually in July-August of the following year. The young shrimp that left the mother in June matured sexually in April-May of the following year. After the lobster is sexually mature and mated, the male is easy to die. It is generally raised for about 2 months, and when the individual weight of crayfish reaches more than 40 grams, it can be caught and listed on the market to increase the production of culture.