A three-stage aquaculture method for burrowing mollusks, carried out in a north-south relay.

Abstract

This invention relates to a three-stage, north-south relay culture method for burrowing shellfish, belonging to the field of aquaculture. The method involves large-scale indoor seedling cultivation along the coast of Fujian and Zhejiang provinces in southern China from September to November. The juveniles are then transported to Shandong province in March of the following year, where they undergo intermediate cultivation in seawater ponds from March to May. After 2-3 months of cultivation, the juveniles reach a size of 5,000-10,000 clams per kilogram. They are then transported to the coastal areas of Liaoning and Hebei provinces for intertidal culture. This invention breaks with the traditional culture model for Manila clams by selecting the intermediate cultivation area in the Shandong coastal region and using raft-type suspended ponds to improve cultivation efficiency and survival rate. After intermediate cultivation, the Manila clams are transported to northern coastal areas such as Dalian, Liaoning province for intertidal culture, resulting in a high survival rate. The entire culture process shortens the cultivation cycle of Manila clams in northern China from 2-3 years to 10-12 months.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture, specifically relating to a three-stage aquaculture method for burrowing shellfish, involving a relay system between the north and south. Background Technology

[0002] Currently, the intermediate cultivation stage of Manila clams in my country is mainly carried out in the tidal flats of southern natural sea areas. The advantages of the south lie in its higher water temperature, abundant food, and faster growth; after about three months of intermediate cultivation, the shell length can reach over 10mm. However, this type of intermediate cultivation suffers from high and unstable mortality rates among juvenile clams due to uncontrollable ecological conditions. Current reports indicate that the survival rate of Manila clams cultivated in the tidal flats of Fujian is only 30%. Furthermore, southern Manila clam larvae have poor adaptability to the low temperatures of the north, and their survival rate is low after long-distance transportation. Therefore, exploring suitable intermediate cultivation techniques for juvenile Manila clams in northern regions is a crucial issue that urgently needs to be addressed. Summary of the Invention

[0003] This invention addresses the aforementioned technical problems by providing a three-stage, north-south relay aquaculture method for burrowing shellfish. The method involves breeding the shellfish in the south, cultivating them in ponds in Shandong, and then transporting them to Liaoning and Hebei in the north for further aquaculture.

[0004] This invention is achieved through the following technical solution:

[0005] A three-stage, north-south relay culture method for burrowing shellfish is proposed. The method involves large-scale indoor seedling cultivation in the coastal areas of Fujian and Zhejiang in the south from September to November, followed by transportation to Shandong in March of the following year. From March to May, the juvenile Manila clams are cultured in seawater ponds along the Shandong coast. The size of the juvenile Manila clams cultured in the ponds is 500,000 to 1,000,000 clams per kilogram. After 2 to 3 months of cultivation, the size of the juvenile clams is reduced to 5,000 to 10,000 clams per kilogram. Then, they are transported to the sea areas of Liaoning and Hebei for tidal flat culture.

[0006] As one of the preferred embodiments, the seawater pond cultivation involves setting up raft-type culture cages and net bags to cultivate juvenile Manila clams. Specifically, the juvenile Manila clams are placed in net bags and then placed in multi-layer culture cages, with one net bag placed in each layer. The multi-layer culture cages are then suspended in the pond below the floating raft.

[0007] As one of the preferred embodiments, the mesh size of the mesh bag is 40-60.

[0008] As one of the preferred embodiments, each layer of the multi-layer aquaculture cage contains more than one sea cucumber to clean the attached algae and sediment on the net bag.

[0009] The beneficial effects of this invention compared to the prior art are as follows:

[0010] This invention breaks with the traditional farming model of Manila clams, selecting the intermediate rearing location in the coastal area of ​​Shandong, between Fujian, Liaoning, and Hebei, for intermediate cultivation. The intermediate cultivation method is changed to pond cultivation, allowing for a controlled environment and increasing the survival rate to approximately 93%. Raft-type cage culture is used in the ponds to further improve cultivation efficiency. After intermediate cultivation, the Manila clams are transported to northern sea areas such as Hebei and Liaoning for tidal flat cultivation, where the survival rate is around 30%, significantly higher than the approximately 18% survival rate of seedlings cultivated in Fujian. The entire farming process shortens the cultivation cycle of Manila clams in northern China from 2-3 years to 10-12 months. Detailed Implementation

[0011] The technical solution of the present invention will be further explained below through embodiments, but the scope of protection of the present invention is not limited in any way by the embodiments.

[0012] Example 1

[0013] A three-stage, north-south relay culture method for burrowing shellfish involves large-scale indoor seedling cultivation along the coasts of Fujian and Zhejiang provinces in southern China from September to November. The juvenile Manila clams are then transported to seawater ponds along the Shandong coast from March to May of the following year for intermediate cultivation. The intermediate cultivation yields 500,000-1,000,000 clams per kilogram. After 2-3 months of cultivation to a size of 5,000-10,000 clams per kilogram, the juveniles are then transported to the tidal flats of Liaoning and Hebei provinces for further cultivation. The specific methods are as follows:

[0014] I. Seedling cultivation: From September to November, large-scale indoor seedling cultivation of Manila clams is carried out in Fujian and other southern regions.

[0015] II. Intermediate Cultivation: Shandong, located between the North and South, served as a transitional area. In mid-to-late March of the following year, waterless, low-temperature (4-10℃) waterless cultivation of Manila clam larvae bred in the South was transported to Shandong. At this time, the larvae population was 500,000-1,000,000 clams / catties. Culture rafts, multi-layer culture cages, and net bags were prepared. The juvenile Manila clam larvae were placed into net bags (made of 40-60 mesh silk, 30cm x 40cm) and placed into each layer of the multi-layer culture cages (approximately 500,000 clams / catties), with three density levels: 1000 clams / layer, 2000 clams / layer, and 3000 clams / layer. Simultaneously, a small amount (approximately 50g) of sea cucumber was placed in each layer of the culture cages (mainly to clean the surface of the net bags). The larvae were suspended in a seawater pond below the raft at a depth of 0.3m. Juvenile Manila clam larvae sown at the bottom of a Shandong pond served as a control. Regularly collect 15-20 juvenile clams from each layer of the rearing cages to measure their growth indicators, and check the mesh of the net bags for blockages and attached organisms, cleaning or replacing the net bags with suitable mesh sizes as needed. Simultaneously measure the growth indicators of bottom-seeded juvenile clams. Juvenile clams are harvested in late May.

[0016] The results at harvest on May 29th showed that, in the multi-layer cage culture method, the wet weights of 10,000, 20,000, and 30,000 seedlings per cage were 16,000 seedlings / kg (shell length 0.8±0.1cm), 41,000 seedlings / kg (shell length 0.6±0.1cm), and 43,000 seedlings / kg (shell length 0.6±0.1cm), respectively, with survival rates of 97.5%, 95.5%, and 93.3%. In the pond bottom-seeding culture method, the wet weight of Manila clam seedlings was 29,000 seedlings / kg (shell length 0.6±0.1cm), with a survival rate of 88.9%. The survival rate of cage-cultured juvenile clams was significantly higher than that of pond bottom-seeded clams, and both pond cage-cultured and bottom-seeded juvenile clams had significantly higher survival rates than those of juvenile clams from natural southern sea areas, while also exhibiting good growth performance.

[0017] Marine cultivation: In June, the juvenile clams that had completed intermediate cultivation were transported at low temperature to the tidal flats of northern sea areas such as Hebei and Liaoning for natural marine cultivation. At the same time, the juvenile Manila clams that had been intermediately cultivated on the tidal flats of natural sea areas in Fujian were transported to the tidal flats of Hebei and Liaoning for cultivation. In October, three tidal flats of the same area were sampled to count the survival rate. The average survival rate of Manila clams intermediately cultivated in ponds in Shandong was 30%, while the average survival rate of Manila clams intermediately cultivated in Fujian was 18%.

[0018] By placing juvenile shellfish in a controlled environment as much as possible during their developmental stage, the survival rate is improved and the effective growth period is extended. The suitable temperature and abundant food in earthen ponds and sea areas accelerate the growth and fattening of shellfish. This "three-stage, north-south relay aquaculture" fully and rationally utilizes the advantages of the differences between the southern and northern sea areas, as well as the fully artificial indoor environment, the semi-artificial outdoor environment, and the natural marine conditions. This allows the juvenile shellfish in the tidal flats to avoid the high-temperature season, reducing the possibility of large-scale mortality, improving the survival and growth rate of shellfish at each developmental stage, and shortening the entire production cycle of northern Manila clams from the traditional 2-3 years to 10-12 months. This approach controls industry risks while significantly improving high-efficiency aquaculture and economic benefits.

Claims

1. A three-stage, north-south relay farming method for Manila clams, characterized in that, The method involves large-scale indoor seedling cultivation along the coast of Fujian and Zhejiang in southern China from September to November, followed by transportation to Shandong in March of the following year. From March to May, the juvenile Manila clams are cultivated in seawater ponds along the Shandong coast, with a size of 500,000 to 1,000,000 clams per kilogram. After 2 to 3 months of cultivation, the juvenile clams are reduced to a size of 5,000 to 10,000 clams per kilogram, and then transported to the sea areas of Liaoning and Hebei for tidal flat aquaculture.

2. The method for three-stage, north-south relay aquaculture of Manila clams according to claim 1, characterized in that, The aforementioned seawater pond is used for the cultivation of juvenile Manila clams, which are then raised in raft-type culture cages and net bags. Specifically, the juvenile Manila clams are placed in net bags and then placed in multi-layer culture cages, with one net bag placed in each layer. The multi-layer culture cages are then suspended in the pond below the floating raft.

3. The method for three-stage, north-south relay aquaculture of Manila clams according to claim 2, characterized in that, The mesh size of the net bag is 40-60.

4. The method for three-stage, north-south relay farming of Manila clams according to claim 2, characterized in that, Each layer of the multi-layered aquaculture cage contains more than one sea cucumber to clean the attached algae and sediment on the mesh bag.