Spawning Induction and Egg Development of Surf Clam, Spisula sachalinensis

북방대합, Spisula sachalinensis의 산란유발 및 난발생

In order to obtain the basic information for seedling production of surf clam, Spisula sachalinensis, spawning induction and egg development were investigated. $NH_4OH$ addition and serotonin injection could induce the spawning in surf clam. Water temperature rising, sperm suspension immersion, UV-ray irradiated seawater and $H_2O_2$ addition less affected on induction of spawning than $NH_4OH$ and serotonin did. On the other hand, males were more sensitive to the treatments than females. The response time to initial spawning in the case of $NH_4OH$ addition was $3\~4$ hours. However in the case of serotonin injection, it was within 5 minutes. The number of eggs released by $NH_4OH$ addition were significantly more than those released by serotonin injection. The serotonin injection induced higher rates of germinal vesicle breakdown than the $NH_4OH$ addition. Fertilizing and hatching rates of the eggs also were the similar results. Eggs of surf clam were demersal isolated eggs and averaging $65.2{\pm}±1.8\;{\mu}m$ in diameter after spawning. Optimum range of water temperature for the development of egg was $15\~20^{\circ}C$, The required time for development of D-shaped larvae was 42 hours at $15^{\circ}C$ and 27 hours at $20^{\circ}C$, respectively.

한해성 패류인 북방대합을 대상으로 자극방법별 산란유발 및 수온별 난발생 과정을 조사하였다. 모패에 대한 산란유발 자극은 $NH_4OH$ 첨가와 serotonin 주사가 효과적이었으며, 수컷이 암컷보다 민감하게 반응하였다. 반응개시 시간에 있어서 $NH_4OH$ 첨가시 방란은 $3\~4$시간, 방정은 1시간 전후에 개시되어 암수간의 차이가 있었다. serotonin 주사는 암수 모두에서 5분 이내에 방란${\cdot}$방정을 유도하였다. 방출된 알의 수는 $NH_4OH$ 첨가에서 유의하게 많았다. 그러나 serotonin 주사에 의해 산란유발된 알의 GVBD율, 수정률 및 부화율은 $NH_4OH$ 첨가에 의한 알보다 높았다. 방출된 알은 평균 난경 $65.2{\pm}1.8\;{\mu}m$인 분리 침성란으로 GVBD 이전에도 수정이 가능하였으며, 적정 발생수온은 $15\~20^{\circ}C$였다. 초기 D상 유생까지는 $15^{\circ}C$에서 42시간, $20^{\circ}C$에서 27시간이 소요되었다.