Experience of raft culture of abalone in shallow sea

I. the choice of sea area

The selection of sea area for abalone culture is as follows: smooth water depth, fresh water quality, no pollution, no rivers nearby, rich in seaweed resources, relatively stable and medium salinity. The specific requirements are:

1. Water depth: in the abalone culture area, the sea water is not easy to be shallow, and the best water depth can reach 15m / 20m.

two。 Water temperature: the range of water temperature for abalone is 1-28 ℃, and the optimum water temperature for growth is 14-22 ℃. Therefore, the water temperature in abalone culture area is not less than 1 ℃ in winter and not more than 28 ℃ in high temperature season.

3. Salinity: abalone belongs to marine organisms with medium salinity. It is appropriate for abalone to be stable in the range of 29 ‰ ~ 31 ‰, with a minimum of 27 ‰ and a maximum of 36 ‰.

4. Current: because abalone likes to flow smoothly, we should choose the normal sea area of back-and-forth flow, and the flow rate should be divided into 50~60m/.

5. The physical and chemical factors of water quality: the pH value of abalone is 8.08.4, dissolved oxygen is not lower than 4mg/L, ammonia nitrogen is not more than 100mg/L, and organic oxygen consumption is below 0.5-1mg/L.

Material preparation for abalone culture

1. The key to the wind and wave resistance of wood and raft culture lies in wood, so the wood of abalone culture should be large and strong, with a diameter of 20-25cm and a length of not less than 80-100cm.

two。 Rack rope and root rope: both the rack rope and the root rope are made of polyethylene rope of  25-30mm. The length of the rope is 60-70m, and the length of the root rope is 30-40m. It can also be determined according to the water depth.

3. Hanging rope: use φ 10-15mm polyethylene rope, the length is generally 8mi 10m, one for each crane.

4. Falling stone: one of the falling stones needed to raise abalone is a stone and the other is made of cement, each 2-2.5kg.

5. Buoyancy: use the plastic buoyancy of φ 30cm, 25 per shelf, or increase buoyancy according to the growth of abalone.

6. Rubber rods: made of rubber, φ 8cm, long 40cm, rubber rods are mainly used to remove algae and some shellfish from net cages during management.

7. Small shovel: a small iron shovel with long 20cm and wide 5cm made of iron. It is mainly used to remove some shellfish such as oysters and barnacles attached to abalone shells.

Third, the choice of equipment for abalone culture:

Whether the cultivation equipment of abalone is reasonable or not directly affects the cultivation effect of abalone. According to many years of production practice, after screening, there are three kinds of abalone cage have the best effect, the main forms of cultivation are:

1. New style abalone cage:

Rongcheng plastic plate specifications for 52cm × 52cm, fillet four-layer composite square plate cage, fixed steel bolts in the middle, long 64.5cm φ 12mm, cage wall with specifications 2-2.5cm polyethylene mesh stitching, this kind of equipment water permeability, dimming, firmness, economy and practicality is good, is currently an ideal equipment for abalone culture.

two。 To refit the cage, the cage originally used for raising scallops was converted into 8 layers, in which the plastic plate of  40cm was used, which was covered with round holes of 0.8-1cm, and the cage wall was stitched with polyethylene mesh of 1.5-2cm. The disadvantage of this kind of equipment is that it is not convenient to feed.

3. The introduction of Japanese-style zipper multi-layer cage: φ 60cm, a total of 5 layers, each layer high 40cm, cage wall sewn with 2-2.5cm polyethylene mesh, feeding mouth with zipper combination, the disadvantage of this kind of abalone cage is high cost, zipper easy to damage.

IV. Transportation of seedlings

The transportation methods of abalone fry are dry transportation and water transportation, and the short-distance transportation time is not more than 15 hours. Long-distance transportation should be carried by water. When transporting seedlings, abalone should be transported together with polyethylene corrugated plates to prevent abalone seedlings from squeezing each other, injury and death. Abalone fry can also be stripped and transported in polyethylene mesh bags together with kelp.

1. Dry transportation: transport containers can be made of plastic foam boxes or wooden buckets, which must be fully soaked in clean sea water before they can be used. Put a layer of soaked large leaf grass or fresh kelp at the bottom of the container, then put the abalone fry, together with the attachment plate, or put in a small net bag after peeling, abalone fry on big leaf grass, one layer of abalone fry, one layer of big leaf grass or fresh small kelp, no more than three layers. This method of transportation, abalone seedlings evenly distributed, not squeezed, not injured, but also can maintain humidity, transport survival rate of 98%, is currently the best transportation method.

two。 Water transportation: for long-distance transportation, abalone fry is first stripped off and then packed into a polyethylene mesh bag. The net bag with a specification of 40 × 30cm can hold about 1000mur1500 abalone fry. When transporting, the net bag can be put into the ship's canvas bucket. 3000 abalone fry can be released in a canvas bucket per cubic meter. On the way, a pump is used to pump water and replace fresh sea water every hour. Under the condition of running water, the survival rate of abalone fry can reach 96% after more than 100 hours of waterway transportation. When transporting seedlings, you must choose a sunny day, the temperature should be above 5 ℃, and prevent direct sunlight. After the seedlings are transported to their destination, they should be caged and released to the sea immediately. Do not pack the cages overnight.

V. Marine nurturance management:

1. Nurturance density: new abalone cage specifications φ 52 × 52cm, fillet four-layer combined square plate cage, each layer can store abalone with shell length 3cm or more, one cage with four layers, can store 600pieces; specification φ 40cm8 layer modified cage, each layer can put 80 abalone seedlings with shell length 3cm or more, and a cage with 8 layers modified cage can store 640 abalone seedlings; Japanese zipper multi-layer cage specification φ 60cm, each layer can store abalone seedlings with shell length 3cm or above, and a cage with five layers can release 1000 abalone seedlings.

two。 Feed: the main food varieties of abalone are kelp, undaria, Ulva Lactuca, followed by sargassum, sargassum and so on. The feeding amount depends on the feeding condition of abalone, generally 15-20% of abalone body weight, feeding every 8 days from March to April, every 5 days from April to June, every 7 days from June to July, every 10 days from July to September, every 7 days from September to December, and every 15 days from December to March. The residual bait should be removed first and the floating mud and attachments in the cage should be washed. Create a good environment for the growth of abalone.

3. Timely seedling thinning: when abalone grows to 4.5-5cm by the middle of April next year, it is necessary to measure the seedlings in separate cages in time. The new abalone cages are 150 grains per layer, 80 for each layer, 80 for each layer of modified cages, and 50 for each layer of Japanese-style zipper multi-layer cages.

4. Water layer of abalone culture: the water layer of abalone culture is generally 4mur5m, which can avoid the attachment layer such as oysters and mussels, and the water temperature drops gradually in winter. The water layer is adjusted to 7mur8m, and the cage distance is about 3m.

5. Removal of enemies: in daily management, shellfish and algae mud should be removed from the cage wall or cage at any time, especially oysters, mussels, barnacles, sea squirts, bryozoans and sea anemones fixed on abalone shells. Most of these enemy organisms can be fixed on the net cage and abalone shell, resulting in the decrease of water permeability of abalone cage, affecting the action and growth of abalone, making it difficult to eat, thin and dead. At present, prevention and manual removal are mainly adopted for these enemy organisms. Prevention is to avoid the peak period of their attachment on the basis of mastering the law of reproduction, and pharmaceutical coatings can also be used to prevent it. Manual removal is to gently hit the algae and shellfish on the abalone cage with rubber rods. If the rubber rods do not damage the net cage, the remaining shellfish can not be knocked out. Fix the shellfish on the abalone shell and clean them with a small shovel. In addition, every time after sending to the sea, you should suddenly clean the floating mud in the cage to prevent death caused by mud blockage.

6. In safe production, cage racks, wooden bars, root ropes, hanging ropes, floating floats and falling stones should be inspected frequently. If the phenomenon of rope entanglement is found, it should be solved in time, especially before the typhoon, check in detail whether various abalone culture facilities are firm, enter the winter water temperature gradually drop, try not to leave the water dry dew, the temperature below 5 ℃ do not come out of the water.