Experimental analyses on the effect of the larval growth rate to the predation mortality of small pelagic fishes

在这些阶段，鱼类幼体的引入生长率代表着生存潜力，在生存动态中起着关键作用。成长较快的个体更有可能存活的范例已经通过大量研究出现，并导致了各种实地研究设计，尽管也有一些相互矛盾的观察。安德森(1988)的结论是，增长率和死亡率之间的联系提供了一个合理的框架，但两者之间的关系仍有待量化。为了阐明生长率如何调节生存，通过实验分析，论证了环境和生物因素之间的关系，包括生长率和营养条件，以及游泳活动，这些因素与它们逃避捕食风险的能力高度相关。本研究主要采用了两种方法：1)测定了日本鲟鱼幼鱼的耐力速度，并测定了60分钟的…在17-27℃的温度下，水洞(长100厘米，深30厘米，宽30厘米)中的ES耐力速度更高。实验结束后，分别测量游泳开始的时间和生物学参数(体长、体重、内脏重量和胃内容物重量)。耐力时间随温度和多种生物参数的变化而变化，并随体长比速度的增加而减小。2)不同鱼群位置鱼的取样器设计了不同鱼群位置鱼的取样器。选取采样器安装在上述引水隧洞中。对日本凤尾鱼幼鱼进行了十余次抽样试验。同时对各鱼群的快、中、慢三组幼鱼进行采样。耳石分析结果表明，幼虫的生长速度与学校的位置没有明显的关系。较少

INTRODUCTION Growth rates of fish larvae represent survival potential during these stages, playing a key role in survival dynamics. The paradigm that faster-growing individuals are more likely to survive has emerged through numerous studies, and led to various field study designs, although there have been some conflicting observations. Anderson(1988) concluded that the theory linking growth rate and mortality provides a rational framework, but that the relationship remains to be quantified. To clarify how growth rates regulate survival, experimental analyses were conducted to demonstrate the relationships between environmental and biological factors, including growth rate and nutritional condition, and swimming activity which highly related to the escape ability from the predation risks. Two major approaches were adopted in our study.1) Measurement of the endurance speed of young Japanese anchovy Young fishes of Japanese anchovy, Engraulis japonicus, were used for measuring of 60 minut … More es endurance speed in a water tunnel(100 cm long x 30 cm depth x 30 cm width) at a temperature of 17-27℃. Elapsed time from start of swimming were measured individually and biological parameters(body length, body weight, visceral weight and weight of stomach content) were measured after the experiments. Endurance time changed depending on temperature and several biological parameters, and decreased according with the increase of specific speed in body length.2) Sampling instrument for selecting fishes in the different school positions A sampling instrument for selecting fishes in the different school positions was designed. The selecting sampling instrument was built and attached in the water tunnel mentioned above. More than ten times sampling trials were done on the young fishes of Japanese anchovy. Fast, middle and slow group of young fishes in each school were sampled at the same time. Results of otolith analyses indicated no clear relationships between the larval growth rate and the position in the school. Less