Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print.
Juvenile fish winter mortality, whether through starvation, predation, or disease, depends in part on feeding history. Assessing mortality risk thus requires metrics that can distinguish well-fed from poorly fed individuals. To investigate the effects of winter feeding and spring re-feeding after winter fasting on young-of-the-year Pacific herring (Clupea pallasii), captive herring were maintained on different feeding rations for 20 weeks under ambient winter and spring conditions and evaluated for differences in size, gut mass, RNA/DNA ratio, body composition, and swimming performance. Lipid and moisture levels were inversely related indicators of feeding history, differing most between full-ration and fasted herring. Fasted herring that were re-fed in spring had evidence of compensatory growth without impacting swimming performance. Minimal growth and reduced gut mass observed even among fully fed herring suggest limits to winter feeding benefits. Metabolically processing stored fat rather than foraging and incurring greater predation risk may thus be an advantageous strategy regardless of winter food availability. Mortalities due to starvation and possibly disease were highest among small herring across rations, supporting the importance of size-dependent winter mortality.

中文翻译：

---

冬季饲喂条件下太平洋鲱鱼幼鱼的生长、状况和游泳性能

加拿大渔业和水产科学杂志，提前印刷。
幼鱼冬季死亡率，无论是由于饥饿、捕食还是疾病，部分取决于饲养历史。因此，评估死亡风险需要能够区分营养充足和营养不良的个体的指标。为了研究冬季禁食和冬季禁食后春季再喂养对太平洋鲱鱼（Clupea pallasii）的影响，在冬季和春季环境条件下，将圈养鲱鱼以不同的饲料量饲养 20 周，并评估了大小、肠道质量、RNA/DNA 比率、身体成分和游泳表现的差异。脂质和水分水平是喂养历史的负相关指标，全日粮和禁食鲱鱼之间差异最大。在春季重新喂食的禁食鲱鱼有补偿性生长的证据，而不会影响游泳表现。即使在完全喂养的鲱鱼中观察到的最小生长和肠道质量减少表明冬季喂养益处有限。因此，无论冬季食物供应情况如何，代谢处理储存的脂肪而不是觅食和招致更大的捕食风险可能是一种有利的策略。由于饥饿和可能的疾病导致的死亡率在不同口粮的小鲱鱼中最高，支持了与体型相关的冬季死亡率的重要性。