In order to know the process of the maturation of a shad, Konosirus punctatus, observations and measurements of the ovaries and ovarian eggs were done, and the following results were obtained. Eggs of the yolk globule stage and younger stages were observed together in an ovary during the spawning season. In some of such ovaries there were eggs older than yolk globule stage. In egg-diameter composition of an ovary taken in the spawning season, 1～4 modes were recognized, showing the existence of some batches in an ovary. The largest mode (the largest batch) in ovarian egg diameter composition is formed in more than 0.4mm. The largest batch passes the stage where the mode is in 0.41～0.70mm in 2 days of more. This batch passes the stage of 0.71～4.00mm in about half a day from 3 a.m. to 3 p.m., and becomes ripe. The spawning is carried out in the time from 3 p.m. to midnight. Individual shad spawns twice or more in a spawning season of one month or one month and half. Spawning interval of the individual is estimated to be 3 days or more.有明海産コノシロKonosirus punctatusの増殖生態を明らかにする目的で,漁獲統計によって魚群の移動を調べ,魚体測定によって成長と肥満度,成熟度などの魚体の状態を明らかにした。本種は,冬は有明海湾口部に近い,比較的外洋的な水域に分布し,春から秋は主に湾奥部浅海に分布する。1974年の調査結果から,平均体長は生後満1年で148mm,2年で189mm,3年で約210mmと推定した。1,2年魚が漁獲の大多数を占め,4年以上のものは認められなかった。全ての年令群が産卵に加わる。生殖腺重量指数の時期的な変化から,1974年の産卵盛期は4,5月と推定した。1年魚は2・3年魚より産卵期がわずかにおそい。肥満度に,生殖腺重量指数の変化に対応した変化が認められた
