Haliotis diversicolor supertexta is cultivated on land, Fujian Province has been introduced from Taiwan for many years, and Guangdong Province and Hainan Province have also introduced it. Due to high-density farming, abalone whole ponds often die during the production process, especially in the summer. There are no obvious signs of death and the deaths are very sudden, often causing huge economic losses to the operators. Therefore, according to the practice of breeding for many years, the author puts forward the following views on the cause of death, death characteristics and prevention methods of abalone hypoxia, for the reference of practitioners. I. Causes of Hypoxia Death Analysis The industrial culture of Jiukong abalone adopts a high density and intensive culture method. The water content per unit of water is large, but the dissolved oxygen in water is limited, so it is easy to cause hypoxia in abalone. . In summary, the occurrence of anaerobic death of abalone in the breeding process has the following reasons. 1, the breeding density is too large. Dissolved oxygen in the water is limited. If the density of the fish is excessively increased and the unit's water production is pursued, it is often unsatisfactory. In the early stage of raising, the abalone is small and the relative oxygen consumption is also small. The contradiction between the supply and demand of dissolved oxygen is not prominent. As the abalone grows up, the oxygen consumption also gradually increases. Once the dissolved oxygen in the water is in short supply, the shortage will occur. Oxygen dying. Therefore, the death of hypoxia in the breeding process first occurs in the larger individuals, the number of breeding ponds. 2. Poor sanitation conditions in the aquaculture pond: feed residues in the rearing tank, ablation of abalone waste and decomposition must consume oxygen. If these dirts are not promptly removed, the dissolved oxygen content in the water will be reduced, resulting in the dissolution of abalone. Oxygen deficiency occurs due to lack of oxygen supply. 3. Excessive breeding of aquatic organisms: Excessive breeding of aquatic organisms in breeding ponds can also lead to oxygen competition with abalone. In addition, the decay and decomposition of aquatic plants in the pool consumes oxygen. 4. Insufficient supply of water and gas: The density of factory farming is high. If there is not enough fresh seawater flowing in and inflated to supplement the dissolved oxygen in the water, the aquaculture pond can easily cause oxygen deficiency. Once the water is stopped and stopped, the abalone's anoxia will soon die. 5, the incidence of non-timely treatment: general water temperature rose to above 20 °C some of the abalone's conventional diseases (pulling disease, swelling disease, broken belly, etc.) increased incidence, if not timely treatment, these diseases are more susceptible to hypoxia death . 6, climatic reasons: noon is the highest time of day dissolved oxygen in water, and nine hole abalone is nocturnal activity food, oxygen consumption increased, especially in hot weather, low atmospheric pressure in its own dissolved oxygen content in the sea is low, in this Hypoxia occurs at night in the weather. Second, the characteristics of hypoxic death: Most of the abalone died of hypoxia crawled into the blue door, the foot up and died near the blue door, foot muscles soft white, no other symptoms, the lower blue mortality rate is higher than In the upper part, most of the undisclosed abalones in the uppermost layer of blue crawled on the blue cover, and the abalone escaping into the pool also climbed to the upper part along the blue wall and the pool wall due to lack of oxygen. Gives a feeling that abalone wants to escape to the blue before it dies. Hypoxia deaths occur in a large number. In large individual culture ponds, if there is a long period of hypoxia, serious deaths or total annihilation will occur. The remaining undead abalone is also damaged by oxygen deficiency and it is difficult to recover. Gradually dies later, even if it does not die, it is seriously affected and it is also susceptible to other diseases. Third, the prevention of hypoxia death: 1, the ground water, diligently clearing the pool, increase the exchange of water, increase the amount of gas supply is to prevent hypoxia death of the main preventive measures. 2. For some farms, if the supply of water and gas is not sufficient due to limited conditions, the method of controlling the density of fish farming can be used to reduce the consumption of dissolved oxygen in seawater. It is also a good way to prevent death from hypoxia. Aquaculture of abalone, each blue-loaded abalone is more than 35-40, in order to avoid the death of hypoxia can reduce the number of each blue adult to 25-30. This not only prevents the death of hypoxia but also promotes the growth of abalone. 3. During the summer and autumn seasons, especially when there is no wind and sweltering weather, the inspection of the aquaculture ponds should be intensified. If abalone caught in the breeding ponds are found to climb upwards or there are more abalones on the top of the blue lid, they should be immediately prevented. Measures. 4. The early signs of hypoxia are not obvious and difficult to observe. The only reliable method is to use instruments to monitor the oxygen content in water. Generally, the dissolved oxygen content in abalone breeding seawater should be 4ppm or more, and the minimum should not be lower than 3.5ppm. If less than 3.5ppm, the industry should pay attention to it, especially in some large abalone, a large number of growth pools should immediately increase the flow of water, increase the amount of air supply, pay close attention to change the water clearing pool. Due to the new seawater extracted from the sea, the dissolved oxygen is higher than the seawater in the culture pond. Increasing the gas supply can also increase the dissolved oxygen content in seawater. Timely cleaning of culture ponds can remove feed residue and abalone excrement to reduce the consumption of dissolved oxygen in water. 5. In the event of anoxic death, the dead abalone should be promptly removed. Not only the breeding ponds in which death occurred should be changed in time, but also other pools that are not found to be deficient in oxygen should be changed in time to prevent the occurrence of hypoxic death in large areas. 6, died of hypoxia, generally do not apply drugs. Change the water, clear the pool, increase the flow of water is a good way. However, abalone death due to hypoxia caused by disease, it must be combined with water change, clearing the pool in a timely manner to prevent the spread of disease caused greater losses.
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