抄録
We evaluated the age structure and the maturity condition of the Japanese sardine spawning in Tosa Bay during the period of small stock size to confirm the year class strength and to maintain the spawning stock. Samples were collected in Tosa Bay, southwestern Japan, which is one of the main spawning grounds of the Japanese sardine in the Pacific coast of Japan, in the spawning seasons of 1999-2000 and 2000-2001. The year class composition and the gonad maturity of the spawning stock were analyzed. The spawners in Tosa Bay were composed of the 1998-year-class in 1999-2000 and of the 1998 and 2000-year-classes in 2000-2001. The estimated age at first maturity of spawners in Tosa Bay was about 1-year-old.
