Utilizing the Nursery Workshop Dongcun Sansui Swimming Crab Technology
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1 Preparations before winter storage
1.1 Renovation of workshops and winter storage pools Idle and nursery workshops that are convenient for winter drainage and drainage, covered with black plastic sheeting (functions to keep warm and block light); the bottom of winter storage pool is 20 to 40 square meters, and the depth of pool 120 ~ 150cm is appropriate, keep 6 to 10 bubbles per pool, evenly distributed at the bottom of the pool, spare.
The ponds are strictly sterilized and brushed. The bottom of the pool is laid with fine sand 10-12cm (the used sand should be washed to remove mud and debris, washed, and soaked with 1010E-6 potassium permanganate for 25-30 minutes, the sand area is the bottom area of ​​the pool. 3/5 to 4/5, leaving a gap of 1/5 to 2/5 near the outlet, for bait, water exchange, and removal of residual bait.The day before the shuttle crab burglary, the winter storage pool in Gaza Filter water 50cm, stand by.
1.2 Selection of winter crabs The admission time of winter crabs is determined flexibly according to actual production conditions and weather conditions. Generally, it is appropriate to use outdoor water temperatures from 8°C to 13°C between mid-October and early December.
There are two sources of winter crabs. One is the acquisition of sea crabs from fishing boats and the second is the selection of crabs. Selection criteria: robust body, strong vitality; complete appendages, no internal or external injuries; body surface clean, no attachments, good fullness. Only store female crabs.
1.3 The room will be selected good crab crabs tied (to prevent damage caused by mutual clamping), transported to the indoor holding pool (water depth of 40 to 50 cm), inflatable holding 4 ~ 8h, one to allow it to adapt to the indoor environment, two It is the dirt attached to the body surface and the ankle. Then use the 30010E-6 formaldehyde solution bath to sterilize for 20-30 minutes. Rinse clean and transfer to the winter storage pool at the planned density. Loosen it loosely to allow it to move freely. General stocking 8 to 12 crabs per square meter.
2 Day-to-day management of the winter storage period The selected swimming crabs are moved into the winter storage pool and enter daily management work.
2.1 Baits are fed once daily in the evening. The bait is dominated by high-quality live bait, such as sandworms and small junk fish; the amount of bait should be 1% to 6% of the body weight of the crabs. When the water temperature is high, it is appropriate to cast more. When the water temperature is low, it is appropriate to cast less or not. Regularly check the situation of residual bait and timely adjust the amount of bait; when bait, the bait should be washed, disinfected, and put into the bait area. It should not be placed on the sand layer.
2.2 Changing the water to clean up the winter storage The second day of winter storage starts, raise the water level in the pool to 100cm, and then keep it at 100～120cm; when the water temperature is higher than 8°C, change the water every 3 days and change the water volume to 70% of the total water. 80%, below 8 °C, change the water every 5 days, change the amount of water for the total body of 50% to 60%; change the water, thoroughly remove the residual bait and death of the crab; change the water temperature does not exceed 0.5 °C.
2.3 Temperature regulation During winter storage, the water temperature is generally controlled at 5 °C ~ 12 °C. Because the insulation performance of the nursery workshop is relatively poor, it is subject to great changes due to external influences. When the water temperature is lower than 5°C, the top of the workshop and the vents should be insulated with straw curtains. If necessary, heat the stove in the workshop to increase the temperature, and open the ventilation when the temperature is higher than 12°C. Window ventilation cooling. The daily change of water temperature in the workshop does not exceed 2°C to 3°C.
2.4 When the water temperature in the pest control tank is higher than 8°C, disinfect once a week; if it is lower than 8°C, disinfect once every 10-15 days. Disinfection, the first row of pool water, with 10010E-6 formaldehyde solution, medical bath disinfection 20 ~ 30min, disinfection can be combined with water work.
2.5 Other work In case of low-pressure weather such as rainy weather or observing floating head symptoms, intermittent inflation should be carried out to prevent hypoxia. Each morning, afternoon, and evening, the swimming pool is observed once to observe the activity of the crab and find dead crabs. Fish out in time; measure the water temperature daily at 7:00am and 14:00 in the afternoon; work records should be detailed, especially the activity of the crab and the number of deaths should be recorded in time.
3 Out of the pool should be based on the actual production of winter storage and market conditions, flexible out of the pool time, generally at the Spring Festival or the Spring Festival after the price is good, higher efficiency. If the water temperature in the pool is continuously higher than 13°C, it should be discharged within a half month as soon as possible to prevent the crab from appearing eggs.
4 winter storage test results
In 2001 and 2002, we used the 480 m2 nursery in the bottom of the pool to test the crabs in the winter.
4.1 In 2001, the admission time was from October 26 to 28, and the discharge time was divided into two batches: the first batch, February 1, 2002; the second batch, March 10, 2002. The situation is shown in Table 1.
Table 1 Samples of winter storage in 2001 The total amount of ponds entering the pond/kg total pond weight/kg total ponds/only total ponds/(only) survival rate of winter storage/%
A batch of 540 490.5 3240 2827 87.25
The second batch of 180 159.7 1080 920 85.20
Total 720 650.2 4320 3747 86.70
4.2 In 2002, the admission time was from October 18 to 22, and the discharge time was divided into two batches: the first batch, January 20, 2003; the second batch, March 7, 2003. See Table 2 for the situation.
Table 2 Results of winter storage trials in 2002 Out-of-pool batch total tank weight/kg total pond weight/kg total pond/out-pool total/(only) survival rate of winter storage/%
A batch of 718 707.3 4320 4035 93.40
The second batch of 239 233.6 1440 1335 92.71
Total 957 940.9 5760 5370 93.23
discuss
5.1 Utilizing the idle nursery workshop Dongchuang Sanji Swimming Crab not only improves the utilization rate of nursery facilities, but also makes the crabs listed off-season and increases their profit margins. After two years of market conditions, after the winter storage, the crabs are each kilogram. The prices were 1.75 times and 1.20 times higher than the winter storage prices, respectively, and the benefits were considerable. And the technology is operability, easy to promote and apply.
5.2 The results of the two-year trial showed that after winter storage, the body weight of Portunus trituberculatus increased by an average of 4.08% and 5.45%, respectively; the survival rate of winter storage in 2001 was low, which was mainly due to the fact that the first year of implementation of this project was not considered. Weeks, workshop insulation measures are not effective, resulting in part of the time due to lower than the temperature of the OC. After comprehensive analysis of the management process, we believe that as long as scientific management, effective measures, the body weight of the crab can be increased by more than 7%, and the survival rate of winter storage is not less than 95%.
5.3 In winter storage trials, the survival rates of sea crabs and crabs were compared. The results showed that there was no significant difference in the survival rate between the two under the same management measures. Therefore, the requirements for sub-pool winter storage were not used in this paper. Can pay attention to this item.
5.4 With regard to the winter storage density problem, we have compared the tests together. The results show that as long as no more than 15 crabs per square meter, the survival rate of winter storage has little effect. Under normal circumstances, there is no need for continuous aeration and oxygenation.
5.5 In 2001, we also conducted a winter storage trial of male swimming crabs, but the effect was not satisfactory and the survival rate was low. This may be due to its physiological function. The specific reasons are not yet clear.