Abstract
In order to obtain the basic information for seedling production of venus clam, Protothaca jedoensis, the annual reproductive cycle was investigated mainly by histological observation from September 1998 to August 1999. P. jedoensis was dioecious. The gonads are located between the digestive diverticula and muscle tissue of the foot. The ovary was composed of a number of ovarian sacs, and the testis was composed of several testicular tubules. The condition index was reached its maximum (20.0) in February, and then decreased to 11.5 in June. In August, the value was the lowest (9.0) and then increased slowly. Minimum size for the sexual maturation of individuals were 38.4 mm in shell length. One the other hand, the size of mature oocytes was ranged to $50-60\mu{m}$ in diameter and testis-ova was observed in testis of the mature stage. The reproductive cycle of P. jedoensis could be classified into five successive stages: early active (December to February), late active (January to April), ripe (March to July), partially spawned (June to August) and spent/inactive (July to January) stages.
한국산 살조개 (Protothaca jedoensis)의 새로운 산업화 양식품종으로 개발하기 위한 기초자료를 얻기 위하여 1998년 9월부터 1999년 8월까지 주로 조직학적 방법에 의해 생식소의 발달과정과 생식주기를 조사하였다. 살조개는 자웅이체로서, 생식소는 해부학적으로 소화맹낭과 족부근육 사이에 위치하였다. 난소와 정소는 각각 난자형성소낭과 정자형성소낭으로 구성되어 있었다. 비만도는 2월에 20.6로 가장 높았으며 8월에 최소값 (9.6)을 보였다. 군성숙도의 경우, 생물학적 최소형은 각 장 38.4 mm로 나타났다. 성숙한 난모세포의 크기는 $50-60\mu{m}$였으며, 성숙기의 정소에서 정소란이 관찰되었다. 살조개의 생식주기는 초기 활성기(12-2월), 후기 활성기 (1-4월), 완숙기 (3-7월), 부분 산란기 (6-8월), 퇴화 및 비활성기(7-l월)의 연속적인 5단계로 구분되었다.
