The cause of death of river crab in autumn

Autumn is a very important stage in the year-round breeding and production of river crab, which is not only the season of maturity and harvest, but also a period of easy death of river crab. If farmers relax slightly at this stage and do not pay attention to strengthening management, it will often cause a large number of deaths of river crabs, bring unnecessary losses to aquaculture production, and make the whole year's aquaculture production fall short of success and all previous efforts will be wasted. Therefore, how to strengthen the management of river crab culture in autumn and prevent accidental death is a key to ensure the benefit of river crab culture throughout the year.

The large temperature difference between day and night causes the river crab to catch a cold and cause death.

Due to the large temperature difference between day and night after autumn, the water temperature difference also changes greatly, especially in autumn when there is a lot of Rain Water weather, and the water temperature difference sometimes even reaches about 9 ℃ or so after rain. Some river crabs with poor physique are often difficult to adapt to this large temperature difference and are extremely prone to "cold", resulting in loss of appetite, difficulty in breathing and death. For this phenomenon, we should pay attention to timely control the water level in daily production, control drastic changes in water temperature, and properly deepen the water level when the weather changes greatly. in addition, there are more floating plants on the water surface, such as water hyacinth, water peanuts and so on. it can also play a certain role in heat preservation and temperature control.

Death caused by improper baiting

After entering autumn, the temperature difference between day and night is large, the changes of air pressure and water temperature will increase, and the appetite of river crabs will also change. Excessive feeding of plant feed can easily cause indigestion and death, resulting in the so-called "bloating to death" phenomenon. At this time, we should increase the feeding of small fish, snails and other baits with high protein content and easy digestion, supplemented by a small amount of plant feed, which is not only beneficial to the digestion and absorption of river crabs, but also beneficial to the fattening and fattening of river crabs; at the same time, we should pay attention not to cast unclean bait so as not to cause gastrointestinal diseases of river crabs.

Timely fishing to prevent and reduce natural deaths

In the process of growth and development, with the molting time and time again, the size becomes larger and the weight increases. From September to November in autumn, especially before and after "Frosts Descent" (October-November), there will be a number of biennial river crabs whose gonads mature from "yellow crab" to "green crab". Due to the increase of osmotic pressure in the body, mature river crabs stimulate adult crabs to migrate down the river and breed in shallow waters. As the saying goes, "crab feet are itchy from the west wind". If they are not caught and listed in time and kept in a fresh water environment, it will easily lead to river crabs escaping and unable to adapt to fresh water low osmotic pressure, physiological disorders and death. At present, in order to pursue benefits unilaterally, some farmers often hoard and raise river crabs that have reached market specifications, and sell them when the market volume is small and the price is high. At this time, more attention should be paid to the timely sorting, catching and sale of sexually mature "green crabs" to avoid unnecessary economic losses caused by natural death.