Studies On Artificial Breeding And Effects Of Temperature On The Growth Of Juvenile Rock Scallop(Crassadoma Gigantea)

Rock scallop is large marine shellfish with strong adaptability to environment, which naturally distributed along the Pacific coast of North America. Compared to several other scallops, the size and flavor of adult rock scallop adductor muscle have great advantages. In recent years, there has been a great decline in the growth of scallop culture, seriously hurt the enthusiasm of the production of fishermen. In view of the above situation, Dalian marine and Fishery Bureau organized the relevant experts to carry out research, it is believed that the establishment of a new breeding population is one of the effective ways to solve this problem. In this context, the research on artificial breeding and growth of the rock scallop was carried out. The results are as follows:1. A preliminary observation of the development of the embryo was carried out in February 2016. The results showed that the egg diameter of the fertilized eggs was about 70 μm. It lasted 70 h from fertilized egg to D-shaped larvae. The entire process can be divided into cleavage stage, blastula stage, archenteric stage, monotrochal larva stage and D-shaped larvae stage.2. The artificial breeding indoors of wild Crassadoma gigantea imported from Canada was conducted within manual temperature control in 2015. The parent scallops were cultivated to oviposition for 80 days. Combined stimulating method of air-dried, temperature-increased and ultraviolet irradiation was adopted and about 800 million eggs were obtained. The fertilization rate was 90% and the hatchability rate was 80% under the condition of artificial insemination. The D-shaped larvae which was obtained was 650 million. Larvae planktonic period lasted for about 30 days and the survival rate was 36.4%. The metamorphism period lasted for 7 days after artificial seeding and the metamorphism rate was below 1 %. The juvenile scallops was transferred from indoor cultivation to marine cultivation after 25 days.3. The artificial breeding indoors of C. gigantea imported from Canada was conducted within manual temperature control from January to May in 2016. It is found that the parent rock scallops ovulated naturally after 28 days during the indoor cultivation. Combined stimulating method was adopted after 37 days and about 400 million eggs were obtained. The fertilization rate was 90% and the hatchability rate was 80% under the condition of artificial insemination. The D- larvae which was obtained was 320 million. Larvae planktonic period lasted for about 30 days and the survival rate was 31.4%. The metamorphism period lasted for 5 to 10 days after artificial seeding and the metamorphism rate was 13.2%. The juvenile scallops was transferred from indoor cultivation to marine cultivation after 25 days.4. Juvenile scallops were transferred to the sea near Laotieshan area for temporary raising in 2015, and observed regularly. It is found that, compared to Patinopecten yessoensis, juvenile rock scallop growth speed was slightly slow with the average growth rate of 3.5%; the survival rate(about 10%) was slightly lower than the normal levels of P. yessoensis.5. Juvenile scallops were cultured at 10, 12.5, 15, 17.5 °C for 2 months, the growth rate increased with the increase of temperature at first and reaching the maximum at 15 °C, then decreased. Single factor of analysis of variance showed that the temperature had a significant effect on the growth rate of juvenile scallop(P < 0.05), and the change of temperature had no significant effect on the survival rate of larvae(P > 0.05).