Large-scale lake breeding crabs can not set up anti-escape facilities. The escape of crabs causes great economic losses. There are certain reasons for the escape of crabs. If they can be properly mastered and take appropriate measures, they can greatly reduce losses.
First, timely fishing, anti-maturity mature escape. The crabs have the habit of breeding in fresh water, growing up, and estuaries in the estuaries or in the shallow sea. Every autumn when the westerly winds, sexually mature crabs leave the freshwater waters that live in their daily life and copulate in brackish water, spawning into the sea to lay eggs. . Even if it does not have large water surface that meets the conditions of the sea, it will blindly go ashore because of the need for the "physical maturity" of crabs. Therefore, timely fishing should be done.
Second, provide enough food, anti-feed less than enough to escape. Crabs have a mixed diet, but they prefer to eat animal foods, and eat plant foods such as aquatic plants. If there are too many seeds in the water body and the supply of natural food is in short supply, crabs will escape due to foraging. Therefore, when investigating seedlings, it is necessary to analyze the bait resources in the water area so that reasonable stocking densities can be achieved.
Third, provide a good environment to prevent the escape of bad environment. In general, crabs are very adaptable to the water environment, but they will escape if they exceed the tolerance range. First, water pollution, low dissolved oxygen, high concentrations of harmful substances, forced migration of crabs; second, there is no too little water plants or plants. The fisherman said "crab size, look at plants." The importance of aquatic plants to crabs is as follows: 1 Directly as bait; 2 Indirectly providing bait: Rich in aquatic plants, small fish, shrimps and benthic animals, easy to be eaten by crabs; 3 can provide concealment for crabs, rich in dissolved oxygen, and cool when it is hot A good living environment. Anti-escape measures: First, when the seedlings are placed, they should be put into cages or nets for a few days in order to adapt to the new water environment. Then open the cage and remove the nets to allow the crabs to move freely into the lake. Second, if there is no or very There are few aquatic plants. Artificial transplants such as Vallisneria, water peanuts, etc. can be used. Straw, branches and leaves can also be used to make artificial "crab nests" for hidden crabs.
Fourth, set the light source, prevent light induced escape. The crab has a strong phototaxis and can even reach the lights without regard to the danger of being caught. Therefore, the phenomenon that river crabs in big water surface flees to the surrounding villages, factories, mines, and farm buildings is universal. About 1 meter above the water surface in the center of the water, several strong lights can be set to offset the lure of outside lights. If the light is strong, not only can it prevent flight, but it can also attract crabs that have climbed ashore.
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