Matters needing attention in culturing sea cucumbers in spring

Sea cucumber culture in northern China is mostly open-air culture in tidal streams and shrimp ponds. Many farmers have the concept that the winter temperature is low and sea cucumber is not managed, resulting in the death of many sea cucumbers. According to the situation known in recent years, the time of large-scale disease of cultured sea cucumber is basically the same. In Shandong area, it is mostly from the middle of February to the first ten days of May, concentrated in March to April.

During this period, the important change factor is that the temperature and water temperature gradually rise from the cold winter low temperature period, but the recovery speed of the temperature and water temperature is different, the temperature rises quickly, the water temperature rises slowly, and there is a lag phenomenon. When the temperature exceeds the water temperature, the middle and bottom layers of the water in such a culture pond form a water temperature difference, forming a water temperature stratification. After measurement, the temperature difference between 1 meter and 3 meters of water depth is 1 degree to 2 degrees. The density of water with high water temperature is small and its specific gravity is small, which leads to the upper water always in the upper layer and cannot be exchanged with the bottom water through up and down convection. As a result, the bottom water on which sea cucumbers live becomes "stagnant water", resulting in sufficient dissolved oxygen in the upper water not being transported to the bottom layer through up and down convection of water.

In addition, the activities, metabolism and decomposition of organic matter of sea cucumbers consume a large amount of oxygen at the bottom, and lack of timely supplement, resulting in the bottom zone becoming a hypoxic zone or even an oxygen-free zone. After detection, the dissolved oxygen in the bottom water during this period was mostly below 3 mg/L. Under the condition of hypoxia or anoxia, the metabolic level of sea cucumber decreases, the functions of circulation, nerve, digestion, respiration and other systems are blocked, and the resistance to stress and disease resistance are greatly weakened. At the same time, anaerobic bacteria multiply in large numbers and become anaerobic decomposition of organic matter, producing harmful substances such as ammonia nitrogen and hydrogen sulfide, which further aggravate the adverse effects on sea cucumber. Due to the deterioration of water quality, sea cucumber constitution weak, various bacteria and other pathogens will take advantage of the opportunity to cause sea cucumber disease.

In order to prevent the occurrence of the above situation, it is necessary to maximize the actual exchange volume of water in the ginseng culture pool, inject as much new water as possible into the ginseng culture pool at high tide level, minimize the temperature difference between day and night, and prolong the running time when the water temperature rises; patrol the pool frequently, and send divers to the bottom of the pool to check the activity status of Stichopus japonicus when necessary. If individual sea cucumber is found to have skin melting phenomenon, it should be removed in time and soaked in disinfectant to prevent infection of other healthy sea cucumber.