Abstract Lake Michigan salmon and trout populations are important species for recreational fisheries and food web management, and are largely supported through stocking efforts, with varying degrees of natural recruitment. Ongoing fisheries management of these salmonine populations is dictated by relationships between predator and prey abundance as well as community structure within the lake. However, while prey fish biomass has declined, and species composition has changed in recent decades, knowledge of prey consumption by the salmonine community has lagged. Herein, we explore trophic relationships using fatty acids profiles, which offer insights into the foraging habits and energy pathways relied on over weeks to months prior to collection. Fatty acids of the prey base for salmonines in Lake Michigan indicate a gradient of foraging habits that range from pelagic (typified by alewife and rainbow smelt) versus benthic (i.e., slimy sculpin and round goby) resource use. Fatty acids implied that there was more variation in foraging habits among individual lake trout and brown trout compared to Chinook salmon, coho salmon and rainbow trout, which appeared to all rely almost exclusively on pelagic prey. Fatty acid profiles also indicated size-based shifts in foraging habits; for example, larger lake trout consuming a greater proportion of benthic prey than smaller individuals. Data herein suggest that Chinook and coho salmon, as well as rainbow trout, are more likely to experience competitive interactions during times of low pelagic prey-fish abundance in Lake Michigan, whereas brown and lake trout are able to utilize benthic resources to a greater degree.

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脂肪酸揭示鲑鱼碱——密歇根湖的猎物关系

摘要 密歇根湖鲑鱼和鳟鱼种群是休闲渔业和食物网管理的重要物种，主要通过放养努力得到支持，自然补充程度不同。这些鲑鱼种群的持续渔业管理取决于捕食者和猎物丰度以及湖内群落结构之间的关系。然而，虽然猎物鱼类生物量下降，物种组成在近几十年来发生了变化，但鲑鱼群落对猎物消费的了解却滞后。在这里，我们使用脂肪酸谱探索营养关系，这提供了对采集前数周到数月所依赖的觅食习惯和能量途径的见解。密歇根湖鲑鱼的猎物基础的脂肪酸表明觅食习惯的梯度范围从远洋（以白鲆和虹鲱为代表）与底栖（即粘稠的杜鹃和圆虾虎鱼）资源利用不等。脂肪酸表明，与奇努克鲑鱼、银鲑鱼和虹鳟鱼相比，个体湖鳟鱼和褐鳟鱼的觅食习惯差异更大，它们似乎都几乎完全依赖远洋猎物。脂肪酸分布也表明觅食习惯的大小变化；例如，较大的湖鳟比较小的个体消耗更大比例的底栖猎物。这里的数据表明奇努克鲑鱼和银鲑鱼以及虹鳟鱼在密歇根湖中上层猎物鱼丰度低的时期更有可能经历竞争性相互作用，