Research On Reproductive Biology And Artificial Breeding Technology Of Atrina Pectinata Linnaeus

The shellfish breeding is a mainstay mariculture industry with a long history in china, which still possessed significant contribution to the development of national economy. Due to the immature artificial rearing technique, the breeding industrialization of Atrina pectinata Linnaeus has not formed as oyster. The study included fattening and induced spawning methods and key technology for artificial larvae cultivation based on observation of embryonic and larvae development after the reproductive biology investigation of Atrina pectinata Linnaeus, Dongshan Bay.The monthly development of gonad, determination result of gonad index indicated that the gonad matures once a year and the development of gonad could be approximately divided into proliferating period, growing period, maturing period, spawning period, and resting period. The idophase is from May to October. The peak of idophase respectively are the first ten days of June and middle of September. The peak of spawning period are from the first ten days of June to October. Growing period, maturing period and spawning period appeared simultaneously during the peak of spawning period. Therefore, it is feasible for fattening parent shellfish of low maturity by rising temperature of seawater indoor and strengthening nutrition from March to April every year, preparing for induced spawning and artificial cultivation of larvae. Furthermore, artificial breeding could be carried out after fattening parent shellfish of relatively higher maturity by strengthening nutrition for short period from middle of May to the first ten days of June, or from August to September.It could obviously shorten dry exposure time and increase spawning rate of parent shellfish by using the multigrid shelf of simulated ecological culturing and induced spawning for shellfish as a assistive devices of inducing spawn, which was devised and applied for the first time. The gonad development results of parent shellfish reared under constant temperature, different microalgae and water temperature showed that gonad matured reared with feeding of Isochrysis zhanjiangensis and mixed algae under 24℃approximatly for 1 month approximately. Among the five methods of inducing spawning, dissection was not suitable for artificial breeding. Using method of natural discharge could acquired spermatozoa and ova of best quality but lowest release rate. Back to water after dry exposure, ultraviolet irradiation and variable temperature irritation obtained the highest release rate of 50-80﹪. However, ultraviolet irradiation was not applicable to induced spawning considering the harmful effects to development of embryonic and larvae.The growth and development of larvae in the preliminary experiment showed that the larvae trend to move toward light sources under subdued light conditions. As the shell length and height grow rapidly by turns in the different developmental periods, it exhibits apparent difference among d-larvae, umbo larvae and juvenile shellfish. Shell, especially the neonatal shell of juvenile shellfish would break even if under slightly press. It frequently occur problem of larvae conglutination and difficult of metamorphosis etc in artificial larvae culture. All as problem of larvae conglutination, highlight, and harmful organisms etc are the reason of low survival. The result of artificial cultivation of larvae indicated that cement pool of large surface, suitable intensity of illumination, seawater of ultraviolet sterilization-treated and high oxygen dissolution, larvae of low density, filtered mixed algae of fresh and high concentration, changing the water and cleaning the bottom often, separate larvae of different size in time, monitoring physical and chemical index of seawater, and reinforcing routine management could effectively solve the problem of larvae conglutination. Pulvinus of dacron was first ever used as cultch in spatfall study, the result indicated that the method of paving thin sand on the Pulvinus of dacronthe obtained the highest adhesive rate and survival of metamorphosis period of young shellfish. Nevertheless the Pulvinus of dacronthe is easily polluted, and resulting in low survival of young shellfish. Furthermore, the young shellfish survival of other two methods are merely 27.54﹪and 34.37﹪. Consequently, there still need to study further how to overcome the disadvantage of spatfall using Pulvinus of dacronthe and raise the survival of metamorphosis period of young shellfish.