Data for: Dynamic coastal pelagic habitat drives rapid changes in growth and condition of juvenile sockeye salmon (Oncorhynchus nerka) during early marine migration

<b>Abstract</b><br/><p>Migrating marine taxa encounter diverse habitats that differ environmentally and in foraging conditions over a range of spatial scales. We examined body (RNA/DNA, length-weight residuals) and nutritional (fatty acid composition) condition of juvenile sockeye salmon (<em>Oncorhynchus</em> nerka) in British Columbia while migrating through oceanographically variable waters. Fish were sampled in the stratified northern Strait of Georgia (NSoG); the highly mixed Johnstone Strait (JS); and the transitional zone of Queen Charlotte Strait (QCS). In 2015, body and nutritional condition were high in the NSoG but rapidly declined to reach the lowest levels in JS where prey availability was low, before showing signs of compensatory growth in QCS. In 2016, juvenile salmon had a significantly lower condition in the NSoG than in 2015, although zooplankton biomass was similar, condition remained low in JS, and no compensatory growth was observed in QCS. We provide evidence that differences in juvenile salmon condition between the two years were due to changes in the food quality available to juvenile fish. We propose that existing hypotheses about fish survival need to be extended to incorporate food quality in addition to quantity to understand changes in fish condition and survival between years.</p>

<b>摘要</b><br/><p>洄游性海洋类群会在不同空间尺度下遭遇环境特征与觅食条件均存在显著差异的多样生境。本研究针对不列颠哥伦比亚省洄游经过海洋环境多变水域的幼年红大马哈鱼（*Oncorhynchus nerka*），对其身体状况指标（RNA/DNA比值、体长体重残差）与营养状况指标（脂肪酸组成）展开了调查。研究采样区域包括分层的乔治亚海峡北部（Northern Strait of Georgia，以下简称NSoG）、强混合的约翰斯通海峡（Johnstone Strait，以下简称JS）以及夏洛特皇后海峡（Queen Charlotte Strait，以下简称QCS）的过渡带。2015年，乔治亚海峡北部的幼鱼身体与营养状况良好，但在猎物可获得性较低的约翰斯通海峡，幼鱼状况迅速下降至最低水平，随后在夏洛特皇后海峡出现补偿性生长的迹象。2016年，乔治亚海峡北部的幼年红大马哈鱼状况显著低于2015年，尽管该区域浮游动物生物量与2015年相近，但约翰斯通海峡的幼鱼状况仍处于低位，且夏洛特皇后海峡未观察到补偿性生长。本研究证实，两年间幼鱼状况的差异源于幼鱼可获取食物的质量变化。我们提出，现有关于鱼类存活率的假说需进一步拓展，除考量食物数量外，还应纳入食物质量因素，以此阐释年际间鱼类状况与存活率的变化规律。</p>