著者

木村 清志 有滝 真人 Kimura Seishi Aritaki Masato

出版者

三重大学水産学部

雑誌

三重大学水産学部研究報告 (ISSN:02875772)

巻号頁・発行日

no.12, pp.p181-192, 1985-10

被引用文献数

4

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1983年と1984年に三重大学水産学部附属水産実験所において,イサキの水槽内自然産卵に関する実験を行い,次のような結果を得た。1.産卵は6月上旬から7月中旬までの期間に20数回行われた。また,本種の場合は,漁獲直後の親魚から採卵することが可能であった。2.産卵行動の観察などから,本種の産卵時刻を19時から21時であると推定した。3.雌体重1g当りの産卵数は約500粒であった。4.卵径は0.76~0.87mm(平均0.815,標準偏差0.021)で,産卵終期の高水温期には小さくなる傾向がみられた。油球径は0.16~0.21mm(平均0.190,標準偏差0.008)で,卵径と正相関が認められた。5.孵化率は通常50~100%であった。孵化率と水温 卵径,産卵数との関係に有意性は認められなかった。孵化率と浮上卵率および卵径の標準偏差との関係では有意な相関が認められる場合もあった。6.胎盤性性腺刺激ホルモンは,畜養親魚を用いる限り,有効性は認められなかった。7.孵化率は卵収容容器の表面積に対する密度と逆相関するが,20粒/cm2以下の範囲では,密度の影響を受けなかった。The present report with the natural spawning in tanks of the threeline grunt, Parapristipoma trilineatum (Pisces: Perciformes: Haemulidae). The experiments were carried out at the Fisheries Reserch Laboratory,Mie University in 1983(Group A) and 1984(Group B and C). The majority of Group A and minorities of Group B and C were caught by hand line a few days before the experiments.The other parental fish were reared in a net cage for one year or more.The fish of Group A and B were injected in the epaxial musculature with gonadotropin(HCG) in order to induce their spawning.The results obtained are summarized as follows: 1) Spawning were observed twenty times or more for each group during the period from early June to mid-July. 2) It was possible to collect the fertilized eggs from non-reared fish. 3) Females spawned ca. 500 eggs per 1 g body weight during the spawning season. 4) Egg diameter ranged from 0.76 to 0.87mm (av. 0.815 and s.d. 0.021) and became smaller at the end of the spawning season.Diameter of oil globule ranged from 0.16 to 0.21mm(av.0.190 and 0.008)and correlated significantly with egg diameter. 5)Hatching rate usually ranged from 50 to 100%. There were no significant relations hatching rate to water temperature, egg diameter,nor number of eggs spawned. Relationships between hatching rate and ratio of floating eggs and standerd deviation of egg diameter were significant only in Group A. 6)Effectiveness of injection of gonadotropin was not observed for reared fish. 7) Hatching rate decreased with increment of areal density of eggs within more than 20 eggs/cm². The rate was independent of voluminal density.