Small biased body size of salmon fry preyed upon by piscivorous fish in riverine and marine habitats
Small biased body size of salmon fry preyed upon by piscivorous fish in riverine and marine habitats
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DOI：
10.1139/cjfas-2020-0339
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发表时间：
2021-05-01
影响因子：
2.4
通讯作者：
Fukui, Sho
中科院分区：
文献类型：
--
作者：
Hasegawa, Koh;Honda, Kentaro;Fukui, Sho
当旨在通过将人工饲养的个体释放到自然环境中来增加种群数量时，必须考虑捕食者与猎物的相互作用。被释放的个体为捕食者创造了丰富的猎物，捕食者与猎物相互作用的基本假设表明，捕食者由于热量含量高而选择大型猎物。另一种假设是，小个体由于躲避捕食者的能力较差而容易受到捕食。这项研究使用日本北海道海洋和河流栖息地放养的鲑鱼 (Oncorhynchus keta) 和马苏 (Oncorhynchus masou) 鲑鱼鱼苗以及食鱼性鲑科鱼来测试这些假设。从捕食者身上采集胃内容物样本，并测量猎物鱼苗的叉长。然后，将每个栖息地的叉长度与整个放养的鱼苗进行比较（平均叉长度范围（+/- SD）：45.8 +/- 2.55 至 49.2 +/- 2.76 毫米）。因此，即使在猎物丰富的条件下（即孵化场饲养的鲑鱼鱼苗刚放养后），猎物鱼苗也比整个放养的鱼苗小 3%-6%。鱼食性鲑科鱼追逐成群的鱼苗，而小鱼苗由于躲避捕食者的速度慢而很容易被捕获。
Predator-prey interactions must be considered when aiming to enhance populations by releasing artificially reared individuals into natural environments. Released individuals create an abundance of prey for predators, and a basic hypothesis of predator-prey interactions suggests that predators select large prey due to the high caloric content. An alternative hypothesis is that small individuals are vulnerable to predation due to their poor predator avoidance. This study tested these hypotheses using stocked chum (Oncorhynchus keta) and masu (Oncorhynchus masou) salmon fry and piscivorous salmonids in marine and riverine habitats in Hokkaido, Japan. Stomach contents were sampled from predators, and fork length of prey fry was measured. Then, their fork length was compared with whole stocked fry (range of mean fork length (+/- SD): 45.8 +/- 2.55 to 49.2 +/- 2.76 mm) for each habitat. As a result, prey fry were similar to 3%-6% smaller than whole stocked fry, even under a prey-abundant condition (i.e., just after hatchery reared salmon fry were stocked). Piscivorous salmonids pursue schooling fry, and small fry may be easily caught due to their slow speed in avoiding predators.