Artificial breeding of bay scallop

The indoor artificial breeding of bay scallop includes the following procedures: parent shell selection and fattening bay scallop The selected parent shell height is generally above 5 cm, and the gonads are required to be fully developed. If they are not mature and full, they will be temporarily raised and fattened. Parent shellfish fattening bait species are generally flat algae, Nitzschia closterium, Chaetoceros, algae, etc., can also be used with compound feed. In the 1980s, China has been able to artificially control the temperature of bay scallop breeding. The parent shellfish were bred and fattened in advance under temperature control, so as to obtain juvenile shellfish earlier and prolong the growth cycle of culture. Bay scallops are generally temperature controlled at 20-24 degrees Celsius. The daily rise in water temperature is 1-2 degrees Celsius. The daily feeding amount of bait is: 60,000 - 100,000 cells/ml of Platyphyta; 150,000 - 400,000 cells/ml of diatom and chrysophyta. When fattening, other suitable physical and chemical factors are: pH value 7.9-8.2; salinity 25‰-28‰; total ammonia oxygen content not exceeding 300 mg/m3; illumination not exceeding 500 lux; chemical oxygen consumption not exceeding 2.3 ml/l. After 20-25 days of incubation, mature sperm and eggs can be obtained.

Fertilization and incubation The sperm and eggs of scallops are agitated in purified seawater for fertilization and incubation. The developmental process of fertilized eggs and larvae of all kinds of scallops is basically similar, but the developmental time is slightly different. The fertilized egg goes through multicellular stage, morula stage, blastula stage and gastrula stage; larva development shares rotifer, linear hinge larva, early shell top larva, late shell top larva, eye-point larva stage after appearing eye-point, enough to crawl, face plate begins to degenerate and disappear, enters creeping stage, attaches and metamorphoses into juvenile shell after appearing secondary shell.

After larva cultivation and hatching, the linear hinge larvae are selected and cultured in separate ponds according to the density of 8-12 larvae per milliliter of water. The suitable environmental factors for cultivation should be controlled: water temperature is 22-24 degrees Celsius, ammonia state is not more than 200 grams/m3; illumination is below 500 Le; continuous or intermittent aeration, dissolved oxygen is not less than 5 mg/L;pH value is 7.9-8.2;COD is not higher than 2 mg/L. The opening bait is Phaeodactylum tricornutum, Chrysosphaera, Ceratoceras. After 3 days, the mixed diet mainly composed of Platymonas was fed. The amount of feed depends on the contents of the larvae stomach. Change the water twice a day, and the temperature difference should not exceed 2 degrees Celsius when changing the water. In order to prevent water pollution and microbial and bacterial infection, 2-3 times of pond replacement and bottom sewage management should be carried out during larva cultivation. Antibiotics or chelators are added when necessary to purify water.

After the eyepoint appears, the adhesion base should be put in time. intermediate cultivation. Before leaving the pool, it should be gradually cooled down, about 2 degrees Celsius every day, and when it drops to close to the natural seawater temperature, it will be temporarily raised in the sea. Using double net bag, plastic tube or net cage to protect seedlings, can also be temporarily raised in large prawn culture pond to protect seedlings. After 25-30 days of intermediate cultivation, the shell can be sold as commercial seedlings when the shell is 0.5 cm high. By the end of 1980s, the technology of artificial scallop breeding in China had reached the industrial level, and 100,000 - 500,000 commercial seedlings could be produced per cubic meter of water, with the highest number reaching 988,000.