Risk of bare grass: Due to the increase of crab density and seedling survival rate, as well as the increase of seedling specifications, the maintenance and management of water-fed leeks have brought pressure, and if they are not careful, they will be caught bare, resulting in the dilemma that the last 1 shell or the second shell of the crab pond has no grass.
Polyculture risk: the disease risk caused by polyculture of freshwater shrimp or crayfish. Mixed culture of crayfish is easy to destroy the ecology of aquatic plants and infect snails; Mixed culture of freshwater shrimp is easy to lead to hypoxia, hydrogen sulfide poisoning and snail-carrying bacteria at the bottom of crab ponds at high temperature. Eventually, crab breeding diseases broke out, with no yield and specifications.
How do crab farmers overcome the risks to achieve high yield and high efficiency?
The cultivation techniques of water leek in high-density mode mainly include: improving the basic fertility of pond bottom through ploughing and fertilization, so that water leek can take root deeply and grow vigorously. Increase the amount of grass seeds and increase the planting density of water leek. By controlling the water level in the early stage, the underground roots of water leek can grow horizontally. By killing insects, the germination rate is ensured. By feeding high-quality feed with good palatability, the grass is reduced. Regularly change the bottom to transfer water, increase dissolved oxygen and reduce grass. Through frequent mowing, space is given to improve the growth performance of Chinese chives.
In northern Jiangsu, it is suggested not to engage in mixed culture of shrimp and crab, which is not worth the loss and has a high risk of disease. If you really want to increase benefits through polyculture, it is suggested to increase microporous bottom aeration equipment for polyculture of freshwater shrimp. Mixed culture of crayfish, it is recommended to engage in segmented culture.
The ethical awareness of ecological environment needs to be strengthened urgently.
To determine the principles of ecological aquaculture and responsible fishery action, the three guiding principles are as follows: first, aquaculture should be developed under the background of ecosystem functions and services, and its bearing capacity should not be destroyed; Secondly, aquaculture should improve the equal rights and interests of human welfare and related stakeholders; Third, aquaculture needs to consider or integrate the progress and development of other related fields. The traditional breeding methods of Eriocheir sinensis do not meet the ecological breeding standards. Therefore, it is necessary to further upgrade the existing farming methods, establish an eco-environmental ethics system, and improve farmers' eco-environmental awareness.