When and at what water temperature can high yield be achieved by releasing shrimp seedlings?

No matter what kind of aquaculture, breeders hope to get the maximum profit space through the least investment cost, so getting high yield is what they are most concerned about. So it is very necessary to reasonably master their living environment and living water temperature, so let's learn about it with Xiaobian.

When and at what water temperature can high yield be achieved by releasing shrimp seedlings?

According to the law of climate change, the requirements of water temperature for the growth of Penaeus vannamei and Penaeus Monodon, and the requirements for bait biological reproduction on water temperature, it is generally believed that the cultivation of these two kinds of shrimp should be safe and stable, and the early spring release along the coast of Zhanjiang, Guangdong Province should be released before the Qingming Festival, that is, the water temperature should be stable above 18 ℃, even in the warm winter should be released after mid-March; late cultivation should be finished before the Mid-Autumn Festival. Shrimp farmers generally believe that early release of seedlings in spring, early emergence of shrimp, the hope of making a lot of money is greater. However, early release of shrimp seedlings, the water temperature is not suitable for shrimp growth, more diseases, less success, more losers, contrary to one's wishes.

Requirements for water temperature of prawns

According to the physiological requirements of Penaeus vannamei and Penaeus Monodon, these two kinds of shrimp have a certain range of optimum water temperature, and the optimum water temperature is above 23 ℃. Only in the range of optimal water temperature can they grow healthily and rapidly, otherwise they will grow badly and diseases will continue to occur.

According to the statistics of the measured data of water temperature in Zhanjiang Luozhou Ocean Station in the past 32 years (1960 ~ 1991), it can be seen that the change of water temperature in Zhanjiang offshore is relatively slow, the annual water temperature difference is small, and the lowest water temperature mostly occurs in February. The warming period is from February to June, and the cooling rate is 3 ℃ ~ 4 ℃ / month from October to December. The annual highest water temperature was from July to August, with a monthly average of 29 ℃. Except for the high shrimp ponds, the water in other shrimp ponds in Zhanjiang area is relatively shallow, mostly 1.0 ~ 1.3 meters. The water temperature of shallow shrimp ponds varies greatly, and the water temperature will exceed the air temperature in summer. in the stifling weather with no wind and low pressure, the water temperature of shrimp ponds dissipates heat slowly, and the water temperature of shrimp ponds is higher than that of air temperature. It is common that the water temperature of shrimp ponds is above 36 ℃. In some weather, the water temperature of shrimp ponds is 37 ℃ ~ 38 ℃, which exceeds the suitable temperature range of prawns, causing long-term water temperature discomfort. During the period of low temperature in winter, the water in the shrimp pond is shallow, and the water temperature in the pond is much lower than that in the offshore area, almost close to the air temperature.

Why it is not suitable to release seedlings prematurely

The most cultured Penaeus vannamei and Penaeus Monodon in the South China Sea require a water temperature of more than 18 ℃ to feed and grow normally, and a water temperature of 24 ℃ ~ 33 ℃ to achieve an ideal state of growth. It can be seen from Table 2 that the water temperature in the coastal area of Zhanjiang from January to February is about 15 ℃, which is higher than that in shrimp ponds. Therefore, the water temperature in the sea area from January to February is not suitable for the growth of these two kinds of shrimp. Moreover, under the influence of cold air, the water temperature decreases rapidly, the light intensity is poor, the water temperature is low and the salinity is high, which is disadvantageous to the growth of algae and directly affects the growth of animal and plant bait in shrimp ponds, and the water color of shrimp ponds is difficult to stable. food organisms are difficult to meet the requirements of early feeding of prawns. Due to the growth of food organisms, the ecological conditions of the pond water are also unstable. Therefore, the risk of early release is high, even if the shrimp seedlings are not cold to death, the growth is also greatly restricted, the physique of shrimp is weak, can not withstand the drastic changes of environmental factors in the future, and is prone to disease.

When is the right time to release seedlings

According to the law of climate change, the requirements of water temperature for the growth of Penaeus vannamei and Penaeus Monodon, and the requirements of bait biological reproduction for water temperature, it is widely believed that the cultivation of these two kinds of shrimp should be relatively safe and stable, and the release of shrimp seedlings in early spring along the coast of Zhanjiang should be before and after the Qingming Festival, that is, the water temperature should be more than 18 ℃. Even in a warm winter, seedlings should be released after mid-March. Releasing shrimp seedlings before and after the Spring Festival is a gambling production. Because tropical shrimp grows within the range of suitable water temperature, the water temperature rises gradually (parabola), and the successful control is large; if the change of water temperature is wavy, it is easy to cause weak resistance and disease. Even if there is no disease and death, slow growth, high feed consumption and high cost will inevitably affect the economic benefits. According to the change law of annual water temperature along the coast of Zhanjiang, the water temperature began to decrease in September and dropped rapidly from October to November. therefore, shrimp seedlings should be released before the Mid-Autumn Festival. A simple and effective way to keep the water temperature in winter is to deepen the pool water. If the water depth can be maintained at more than 2 meters, the water temperature is more than 2 ℃ higher than that of shallow shrimp ponds.

In the same period, the coastal water temperature of Beihai in Guangxi is 1 ℃ ~ 2 ℃ lower than that of Zhanjiang, and the coastal water temperature of Fangcheng is about 1 ℃ lower than that of Beihai. Therefore, to the north of Beibu Gulf, it is appropriate to release seedlings in early spring after the Qingming Festival. The southern coast of Hainan Island is less affected by cold air, and shrimp can be raised all year round except to avoid hot days from June to July, while the north will be affected by cold air, so shrimp seedlings should be released from late February (that is, after Rain Water). The temperature in the Pearl River Estuary is about 2 ℃ lower than that in Zhanjiang, and the normal release of shrimp fry in shrimp ponds without greenhouse facilities should be 10 ~ 15 days later than that in Zhanjiang. If there is a greenhouse shrimp pond, the water temperature can be kept above 18 ℃ in winter, there is no big problem when to release shrimp fry. If the heat preservation capacity is poor, it is also necessary to control the most appropriate time for seedling release according to the local climate change. In early spring, the coastal water temperature in Shantou is more than 2 ℃ lower than that in Zhanjiang.

Therefore, it is more appropriate to release shrimp fry in the middle of April. In autumn, the temperature in other coastal areas of Guangdong will come earlier than that of Zhanjiang, and the late production of shrimp fry should be earlier than that of Zhanjiang. To master the above-mentioned release time, it is also enough to breed shrimp twice a year, and there is no need to release seedlings too early in early spring, resulting in unnecessary economic losses. The death of shrimp leads to the pollution of water sources in shrimp ponds or sea areas, which makes shrimp diseases occur frequently, which is extremely disadvantageous to the development of shrimp culture. Therefore, all operators must act in accordance with scientific standards before the shrimp farming industry can continue to develop.

Reasonable control of the release time of shrimp seedlings, the growth of shrimp is very important, and the survival of shrimp also has requirements on the water temperature, a reasonable grasp of shrimp release time and its water temperature can effectively reduce unnecessary economic losses, effectively save investment costs, and obtain more profits.