The fry production of bay scallop is the leading industry in the northern coastal areas. After years of improvement, the seedling raising technology has been greatly improved. However, due to the low hatching rate, many enterprises still can't get enough scallop seedlings every year, which directly leads to the failure of seedling raising. Therefore, improving the hatching rate of bay scallop is one of the key technologies in seedling production. The technicians of Laizhou Fisheries Research Institute in Shandong Province summarized the following technical measures to improve the hatching rate of bay scallop through production practice: 1. Parent selection and overwintering 1. Parents with full gonads, large individuals and complete appearance are required. The parents were stable for 2 days after entering the workshop, the water temperature was natural water temperature (3℃), and the temporary breeding density was 90 ~ 100 /m3. 2. It is suggested to overwinter indoors, replace the natural seawater of 1/3 or 1/2 every day, and suck sewage every 5 ~ 6 days. Second, the cultivation of parent shellfish is the foundation, and the maturity of gonad development of parent shellfish directly affects the quality of eggs obtained. 1. Pay attention to the increase of effective temperature and control the speed of water temperature increase. At the initial stage of shellfish rearing, the water temperature increased by 65438 0℃ every day, and it remained stable for 3 days when it rose to 65438 05℃, then increased by 0.5℃ every day, and it was ready to give birth when it rose to 65438 09℃. 2. Pay attention to improve the ammonia nitrogen content and dissolved oxygen in water. In the early stage of shellfish culture, the pond should be inverted 1 time every day. After the water temperature reaches 16℃, the water quality can be improved by running water for a long time and frequently sucking sewage, and the exchange water can reach 1 unit/day. At the same time, the water body should be slightly aerated every day. 3. Pay attention to the nutrition collocation of the bait, so that the hatching yellow can accumulate to a certain amount. The bait is mainly fresh diatoms, supplemented by golden algae and alternative bait (such as starch, egg yolk and spirulina powder). In the early stage, the daily feeding amount was 50,000 cells/ml water to 200,000 cells/ml water. The villages and towns enjoyed water, and after 14℃, the food intake increased, and the daily feeding amount was 200,000 cells/ml water to 400,000 cells/ml water, with a total of 8 times to 12 times. Third, control the abortion of parent shellfish through 1 After the water temperature rises to 18℃, it should be handled carefully, and the fluctuation range of water temperature should not exceed 0.2℃. When changing water, it is required to add water slowly, and the fine water should always flow. 2. Suck pollution frequently to prevent the ammonia nitrogen content in the water from rising, leading to abortion of the parent shellfish. 3. Feed less and be diligent, don't feed the parent shellfish directly, and reduce the stimulation to the parent shellfish. Fourthly, the process of spawning and hatching is the key, because bay scallop is hermaphrodite, and the number of sperm and eggs discharged is difficult to control. 1. The water temperature for spawning should not be too low. Generally, the water temperature should be 2 1℃ ~ 22℃, and the lowest temperature should not be lower than 20℃, otherwise it will affect the fertilization speed. 2. Too much semen seriously affects the fertilization rate. It is necessary to take the method of egg washing to salvage the excess semen. Generally, it is advisable to have 2 ~ 3 sperm around an egg under a microscope. It is required to stir every half hour and slightly inflate. 3. The application of 1ppm ~ 2ppm penicillin and 2ppm EDTA can also improve the hatching effect.