BIOCHEMICAL CHANGES DURING DEVELOPMENT OF EGGS AND YOLK-SAC LARVAE OF HERRING AND PLAICE

Changes in quantities of water, sodium, potassium, lipid and protein were compared in developing eggs and yolk-sac larvae of herring dupes harengus L., a species with demersal eggs, and plaice Pleuroncctcs platessa L., a species with pelagic eggs. The principal difference between the two species was the occurrence in herring, but not in plaice of considerable increases in water content and in one or both of the above ions at three distinct stages: at fertilization,during the middle stage of egg development, and in the days immediately after hatching. Newly hatched larvae of the two species differed greatly in water content because of the difference in mass and water content of the yolk, not in the water content of the rest of the body. In herring, there were increases in sodium and potassium which coincided broadly with the increase in water content. These differences are related to the gradual acquisition of buoyancy by herring during this period, comparable with the buoyancy conferred on plaice eggs a     

真鲷仔鱼早期阶段的摄食能力──发育反应和功能反应

于１９９５年４月￣１９９６年５月在中国水产科学研究院黄海水产研究所小麦岛苗种基地,采用梯度试验方法在不同褶皱臂尾轮虫饵料密度下２￣１２日龄真鲷仔鱼的摄食率和摄食强度,通过拟合发育反应和功能反应模型模型的数据来评价真鲷仔鱼早期阶段的摄食能力。结果表明,从仔鱼开口２日龄至１２日龄,摄食强度从０．３１６μｇ／ｈ提高到１．３７４μｇ／ｈ;摄食成功率从５９％提高到７０％,平均摄食发生率从０．４６９μ ｇ／ｈ     

海洋鱼类仔鱼在早期发育和饥饿期的巡游速度

本文运用红外光源和录象系统首次对大西洋鲱(Clupea harengus L.)的两个地理种群:苏格兰西海岸和波罗的海鲱、大西洋鳕(Gadus morhua L.)和欧洲江鲽(Platichthyslesus L.)由人工授精来源的卵黄囊期仔鱼以及苏格兰西海岸鲱的较大仔鱼(36和60日龄)在早期发育和饥饿期的巡游速度作了测定。仔鱼巡游模式的发育和完善符合种的发育和生长过程。卵黄囊期仔鱼在卵黄囊耗尽前后仍不能建立外源性摄食,或较大仔鱼在停食后,其巡游速度都有增快的倾向,一般均在抵达“不可逆点”(PNR,即the point-of-no-return)前两天左右达到高峰值。所记录到的平均[一次游泳过程或1000毫秒(ms)间期]和最大(20 ms间期)巡游速度的高峰值分别为1.1—1.2和2.3—3.4BL/s(体长/秒,鲱),1.7和5.7BL/s(鳕)以及1.6和4.1BL/s(江鲽)。此外,本文还对饥饿仔鱼的巡游速度和摄食生态的相互关系作了初步探讨。