Detailed Explanation of Key Technical Points for Sea Cucumber Pond Aquaculture

With the vigorous development of China's sea cucumber aquaculture industry, pond-based sea cucumber farming in the north has achieved many successful examples. In order to improve the technical level and economic benefits of sea cucumber aquaculture, the high-yield techniques for sea cucumber pond aquaculture are hereby recommended for everyone's reference.

I. Building Sea Cucumber Ponds

In the mid-tidal zone or low-tidal zone, taking advantage of local geographical advantages, preferably with a rocky reef substrate, use concrete and stones to enclose ponds of varying shapes and sizes. In sea areas with strong winds, the enclosure walls should be thickened and reinforced; during neap tides, the water storage must be guaranteed to be no less than 1.5 m, and there must be no leakage; the selected sea area must not have pollution, especially oil pollution; salinity must not be lower than 28 parts per thousand, with no river inflow; the disadvantage of this type of pond is its excessively high construction cost. A shrimp aquaculture pond, preferably with a mud-sand substrate, can also be converted into a sea cucumber aquaculture pond. The aquaculture pond should have one inlet and one drainage gate each. Water exchange in the pond should preferably rely on natural tidal flushing, with a daily water exchange rate of no less than about 30 percent, and an average water depth in the pond of over 1.5 m. The advantages of this type of pond are that it is convenient for observation and management and has low construction cost, but note that ponds where the bottom water temperature exceeds 20 degrees Celsius for more than 3 months in summer are not suitable for sea cucumber aquaculture.

II. Placing Artificial Sea Cucumber Reefs

The purpose of building artificial sea cucumber reefs is to provide hiding places for sea cucumbers and to cultivate large amounts of seaweed and aquatic plants for sea cucumbers to inhabit, feed on, and aestivate in. Therefore, artificial sea cucumber reefs must be placed in ponds converted from shrimp ponds. The materials for artificial sea cucumber reefs can be tiles, bricks, discarded scallop cages, concrete blocks, or even slightly larger stones of varying shapes, which also make very good reefs; the placement of reefs should follow the principle of maximizing the hiding space for sea cucumbers as much as possible, and they can be arranged in rows or piles; the number of reefs placed should be as many as actual conditions allow; tiles, stones, fruit crates, or hollow bricks can be used to build reefs, as follows:

1. Tile reefs: Use red tiles used for roofing houses, with every three tiles as a group, the long sides of the three tiles joined in sequence to form a triangular prism, and tie the prism tightly with thin rope. Use these prisms to pile up several reef piles on the pond bottom, with a spacing of 35 m between reef piles, generally using about 2,500 tiles per mu. Each reef pile consists of an upper and a lower layer of prisms, with each layer further divided into 2 rows running north-south, with 59 prisms per row in the lower layer and 48 prisms in the upper layer (stacked in a staggered manner), and the upper layer of prisms is then covered with tiles. In this way, viewed from the south to the north direction, the entire prism pile is composed of several triangular spaces.

2. Stone reefs: Each reef pile uses 0.8—1.0 cubic meters of stones. When piling, leave as many gaps between the stones as possible, with a spacing of 4—5 m between reef piles.

3. Fruit crate reefs: Each reef pile consists of three fruit crates, with 2 on the bottom and 1 on top, tied firmly with thin rope. The crate openings face north, and stones are pressed inside the crates to prevent the fruit crates from moving.

4. Hollow brick reefs: The method is the same as for tiles.

For ponds where reefs have already been placed, before releasing seedlings it is best to first clear the pond to kill predators and pathogenic bacteria. Usually, 10 ppm tea seed cake and 20 ppm bleaching powder are splashed over the entire pond, and after one day, the pond is continuously rinsed 2-3 times before use. After disinfection is completed, fill the sea cucumber pond with water, and use 10 days—15 days to fertilize the water and cultivate basic biological feed.     

III. Transportation of Sea Cucumber Seedlings

Two methods, the wet method and the dry method, are usually used to transport sea cucumber seedlings. The so-called wet method transportation means that when transporting sea cucumber seedlings, the seedlings are placed in canvas buckets, with about 300 seedlings per bucket, and about 0.2 cubic meters of water added. The so-called dry method transportation means placing the sea cucumber seedlings in plastic turnover boxes, with a 2 cm thick layer of absorbent cotton laid at the bottom of the box, two layers of gauze laid on top, soaked through with seawater, the seedlings spread evenly and flat, then 4 more layers of wet gauze covering them, after which the plastic turnover boxes are stacked one by one, with plastic sheeting on the outside to block wind. When the weather is cold, add foamed plastic on the outer layer for insulation. If the weather is dry and hot, seawater should also be appropriately sprayed during transport.