Causes and countermeasures of low lobster yield in ponds. The average lobster yield per mu is normal.

First, the survival rate of fry stocking is low.

When the seedlings were put in, they

Causes and countermeasures of low lobster yield in ponds. The average lobster yield per mu is normal.

First, the survival rate of fry stocking is low.

When the seedlings were put in, they were short of water for a long time due to long-distance transportation. The gill filaments of shrimp shrink and are not fully absorbed when stocked. After the shrimp species enter the pond, they swell to death due to excessive water absorption. Some seedlings are trapped by drugs and have a high mortality rate after stocking. Some seedlings are released in the cold winter, and they freeze to death directly when they are stocked.

Fish fry should be purchased locally and stocked locally, and shrimp fry should be evenly stocked around the pond and evenly distributed. When the cultured shrimp seedlings are transported for a long distance, they are first soaked in water for 3-5 minutes, then placed by the pond for 2-3 minutes, and repeated for 2-3 times. After the shrimps have absorbed enough water, they can be slowly put into the pond, which can improve the survival rate of stocking. It is forbidden to put them in the pond for drug trapping.

Second, the stocking density is high.

The stocking density in Tangkou is high, and the same batch is stocked in Tangkou, with different specifications, resulting in asynchronous growth speed, strong feeding ability and low breeding yield. To raise lobsters in ponds, 20 ~ 40 kg of shrimp fry should be put per mu, and the specification is 60 ~ 80 kg. Shrimp seedlings should have uniform specifications, strong physique, no disease or injury, and be put enough at one time to avoid stocking in batches. When stocking, shrimp seedlings should be soaked in 3% ~ 5% salt solution for disinfection before being put into the pool.

Third, there are many enemies.

Due to the incomplete cleaning of the pool, the water injection has not been strictly filtered. There are frogs, water snakes, snake heads and other pests in the shrimp pond. Eating young shrimps and tapping soft-shelled shrimps during molting directly affects the output of lobster culture. Therefore, the pond where lobsters are cultured should be thoroughly cleaned with drugs before the seedlings are released to kill pests. Commonly used drugs are quicklime, strong chlorine essence and croton.

Fourth, the light is insufficient.

In many low-yield shrimp ponds, there are too many aquatic plants, too high coverage, less light-receiving surface, small water flow and insufficient illumination. As a result, the aquaculture yield is low and the market specification is small. The coverage rate of normal aquatic plants is generally about 1/3 of the pond water surface, which is beneficial to lobster shading and breeding plankton that lobsters like to eat. If the aquatic plants are too dense, a ditch with a width of 3-5 meters can be cut with a knife every l0-l5 meters to ensure that the fish pond has enough light receiving surface. Aquatic plants should be replenished in time after rotting in July and August to meet the needs of lobster growth and molting.

Fifth, the amount of bait is insufficient. Fifth, the amount of bait is insufficient

Due to the high stocking density, insufficient feeding quantity, improper feeding method, incomplete nutrition and bad size, some lobsters can't eat bait. One is that lobsters kill each other. Second, due to malnutrition, some lobsters can't shell. The third is to cause some lobsters to escape due to bait. The daily feeding amount is based on satiety, eating and leaving no residual bait. Generally, crayfish and adult shrimps are fed at L5% ~ 20% of their body weight, which can be adjusted according to their eating conditions.

6. Poor water quality conditions

First, the pond water quality is too fat, the ph value is too low, or the water quality is thin and the water transparency is too large, which is not conducive to the growth of lobster molting. Second, the water level is too shallow in summer and the water temperature is higher than the limit temperature, which will inhibit the growth of lobsters and promote their precocious puberty. In winter, lobsters are prone to hypoxia and suffocation. Third, the fluctuation of water level caused some lobsters to make holes near the water level line, mainly burrowing. After a long time, I adapt to the cave life, don't shed my skin, and don't feed. Lobsters are divided into male and female, small in size, lazy in activity and low in breeding yield. In the process of breeding, the water level should be kept stable and the water quality should be kept fresh for a long time to prevent the water quality from being polluted by industry, pesticides and chemicals. In the process of culture, if the lobster is found to be unresponsive, it swims to the shore and climbs to the shore with its head floating, which indicates that the lack of oxygen is serious, and it is necessary to inject water in time or turn on the aerator to increase oxygen.

Seven, poor management

First, the pool mouth area is too large or too small, the slope ratio is small, and there is no shallow water layer, which is not conducive to the growth of lobster shelling. Second, the anti-escape facilities are poor, which is easy to cause lobsters to escape. Third, the fishing was not timely, which caused some lobsters to make holes in the pond and could not be caught. The pond mouth area suitable for crayfish culture is 10 ~ 30 mu, and the slope ratio is L ∶ 2 ~ L ∶ 3. Lobsters love construction, so it is necessary to strengthen escape prevention facilities to prevent lobsters from escaping. Lobsters mature sexually every other year, and young shrimps that leave their mothers in September reach sexual maturity in July-August of the following year. Young shrimps that leave their mothers in June will be sexually mature in April-May of the following year. When lobsters are sexually mature, males tend to die. Generally, crayfish will be kept for about 2 months. When the individual weight exceeds 40 grams, it can be caught and put on the market, which will increase the aquaculture yield.