Matters needing attention in sea cucumber culture in spring

The cultivation of sea cucumbers in northern China is mostly open-air culture of reefs in tidal streams and shrimp ponds. Many farmers have the idea that the temperature is low in winter and sea cucumbers do not need to be managed, which leads to the death of many sea cucumbers. From the understanding of the situation in recent years, the incidence of large areas of cultured sea cucumbers is basically the same, Shandong area is mostly from mid-February to early May, concentrated in March to April.

The important change factor during this period is that the air temperature and water temperature gradually rise from the cold winter low temperature period, but the rising speed of air temperature and water temperature is different, the air temperature rises quickly, the water temperature rises slowly, and there is a lag phenomenon. When the air temperature exceeds the water temperature, the water temperature difference is formed between the upper and lower layers of the water in the culture pond, and the water temperature is stratified. According to the measurement, the temperature difference at the depth of 1 to 3 meters is 1 ~ 2 degrees. The density and specific gravity of the water with high water temperature is small, so that the upper water is always in the upper layer and cannot be exchanged with the bottom water through upper and lower convection. as a result, the bottom water on which sea cucumbers depend for survival becomes "stagnant water". As a result, sufficient dissolved oxygen in the upper layer cannot be transported to the bottom through the upper and lower convection of the water.

In addition, sea cucumbers consume a lot of oxygen in the bottom activity, metabolism and organic decomposition, but lack of timely replenishment, resulting in the bottom area into a hypoxic zone, or even an anaerobic zone. After testing, the dissolved oxygen in the bottom water is less than 3 mg / L in most places during this period. Under hypoxia or anaerobic condition, the metabolic level of sea cucumbers decreased, the functions of circulation, nerve, digestion and respiration were blocked, and the ability of stress resistance and disease resistance were greatly weakened. At the same time, anaerobic bacteria multiply in large numbers, turn into anaerobic decomposition of organic matter, and produce toxic ammonia nitrogen, hydrogen sulfide and other harmful substances, which further aggravate the adverse effects on sea cucumbers. Due to the deterioration of water quality, the physical weakness of sea cucumbers, a variety of bacteria and other pathogens will take advantage of the deficiency, leading to the incidence of sea cucumbers.

In order to prevent the occurrence of the above situation, it is necessary to maximize the actual exchange capacity of the water body of the ginseng pond, seize the high tide as much as possible to inject new water into the ginseng pond, minimize the temperature difference between day and night, and prolong the running time when the water temperature rises; always patrol the pool and send divers to the bottom to check the activity of sea cucumbers if necessary. If individual sea cucumbers are found to have peeling phenomenon, they should be fished out in time and soaked in disinfectant to prevent infection of other healthy sea cucumbers.