The deep-water cage is composed of three systems: frame, net, and anchor. The frame mainly solves the aquaculture load and the form of aquaculture proposition; the netting mainly solves the space enclosed by the aquaculture water body; the anchoring mainly solves the fixation and safety of the aquaculture system. The technical points of deep-water cage culture are as follows:
1. Select the appropriate main parameters of the cage
High-density polyethylene (HDPE) deep-water cage main series HDPEC40-C80 complete sets of equipment can be designed and manufactured according to the 50-year typhoon level; the large breeding load is 60 tons/box; the breeding production load is 35 tons. The wind and wave resistance can reach 14 typhoons and 6 waves, and the current resistance can reach 1.96 knots.
2. Choose a suitable breeding sea area
It is best to choose a sea area with a deep water level, a small flow velocity, and an uncomplicated flow direction in the breeding sea area. Suitable sea area conditions for aquaculture: salinity 15‰~30‰, water temperature 22~31℃, flow velocity within 0.65m/s. Considering the setting of deep-water cages, water depth requirements: it is appropriate that the bottom of the cage is about 2 meters away from the bottom of the sea at low tide level.
3. Stocking large-sized fry seeds
The stocking specifications of fry and seed have a direct relationship with the breeding, production and benefits of commercial fish. Due to the large volume and high breeding capacity of deep-water cages, it is difficult to change the net and dump the cage. Moreover, deep-water cage culture is affected by the flow rate, wind and waves. Restrictions, should try to choose large-sized seed for stocking, which can avoid the difficulty of breeding operation, shorten the breeding cycle, and improve the breeding efficiency. Cobia is stocked with seedlings of more than 30cm and 8cm or more of oval pomfret, which is conducive to production arrangements and breeding operations, and also accelerates the conversion of benefits.
4. Stocking appropriate density
A comprehensive assessment can be made based on the specifications of the deep-water cages, the species planned to be cultured, the culture environment, culture technology and management level, etc. Generally speaking, the stocking density of seedlings in deep-water cages is 3-5kg/m3, and the final breeding density is 20-30kg/m3.
5. Scientific bait feeding
Feeding principle: Generally, feed 1 to 3 times a day. Cast more when the water flow is gentle, and cast less when the tide is fast; cast less when the water is muddy, cast more when the water is clear; cast more when the water temperature is suitable, cast less or not when the water temperature is low; cast more before the typhoon, before harvest or Do not cast bait before binning. In the feeding method, you should master the three words of "slow, fast and slow": at first, you should throw less and slowly to attract fish upstream to feed. When some fish are full and spread out, the feeding speed is slowed down to take care of the weak.
6. Change the net and wash the net in time
During the breeding process, as the fish grow, it is necessary to replace the net sac and clean the attachments of the cage to ensure the breeding environment in the cage. After the cage is placed in seawater for a period of time, it is easy to be attached by some organisms. It not only increases the weight of the cage, but also affects the exchange of water in the cage. Any organisms attached to the cages should be removed in time.
7. Timely stocking and harvesting
Deep-water cage culture (cobia, oval pomfret) is closer to the wild state than traditional small cages due to its good aquaculture water environment and fewer diseases. In addition to this, the main factors affecting the price of commercial fish are the market season and market size, which are related to the time of stocking and harvesting.
On the market, the price of cobia is generally more than 8 kg/tail, and the price of oval pomfret is 0.5 kg/tail. Early seedlings or overwintering seedlings, enlarged size seedlings can also be released, and they can be put on the market in advance by using the characteristics of fast growth in anti-wind and wave cage culture. It is listed when the price is high around the Spring Festival, which improves the utilization rate of deep-water cages and improves the breeding efficiency. Of course, there is also a certain risk of low temperature in winter.