Abstract Four lake trout, Salvelinus namaycush, Walbaum 1792 morphs occur in Lake Superior: lean, siscowet, humper, and redfin. Diets of lean and siscowet have been relatively well described. However, less is known about diets of humper and redfin, and overall few studies have been conducted at offshore shoals. We compared gut content data among mature (357–867 mm) sympatric lake trout morphs caught at two offshore shoals in Lake Superior, Stannard Rock and Superior Shoal, in 2013 and 2014 (total n = 416). All morphs were caught in shallow ( 100 m) strata. Invertebrates made up a greater portion of the stomach contents than did fish for all morphs by both percent occurrence and proportional biomass, and Mysis was the primary invertebrate consumed by all morphs at both sites. Coregonus spp. and deepwater sculpin, Myoxocephalus thompsonii were the most commonly consumed fish. Humper had the highest average proportional biomass of deepwater sculpin and had no other identifiable species of fish in their guts. Biomass of fish in redfin guts was highest for Coregonus spp., followed by similar amounts of deepwater sculpin and burbot, Lota lota. Diet overlap among morphs was high, and differences in prey consumption between sites are likely related to prey availability. Additional study is needed to determine if differences in trophic ecology between humper and other morphs are sufficient to support concurrent stocking of multiple morphs, particularly in light of recent declines in native prey fishes, especially Coregonus spp., in the Laurentian Great Lakes.

中文翻译：

---

苏必利尔湖两个近海浅滩的多种湖鳟鱼 (Salvelinus namaycush) 的肠道内容物

摘要 苏必利尔湖中出现了四种湖鳟，Salvelinus namaycush，Walbaum 1792 变种：瘦、西斯科、驼峰和红鳍。瘦肉和 siscowet 的饮食已经得到了比较好的描述。然而，人们对驼峰鱼和红鳍金枪鱼的饮食知之甚少，总体而言，在近海浅滩进行的研究很少。我们比较了 2013 年和 2014 年在苏必利尔湖、斯坦纳德岩和苏必利尔浅滩的两个近海浅滩捕获的成熟（357-867 毫米）同域湖鳟鱼的肠道含量数据（总共 n = 416）。所有变形都被捕获在浅（100 m）地层中。就发生率和生物量比例而言，无脊椎动物在所有变体的胃内容物中所占的比例都比鱼类更大，而糠虾是所有变体在这两个位置消耗的主要无脊椎动物。Coregonus 属 和深水杜鹃，Myoxocephalus thompsonii 是最常食用的鱼类。Humper 拥有最高的深水杜鹃的平均生物量比例，并且它们的内脏中没有其他可识别的鱼类。红鳍鱼内脏中鱼类的生物量对于 Coregonus spp. 最高，其次是类似数量的深水杜鱼和江豚，Lota lota。变形之间的饮食重叠很高，站点之间猎物消耗的差异可能与猎物的可用性有关。需要进一步研究以确定驼峰鱼和其他变种之间的营养生态差异是否足以支持多种变种的同时放养，特别是考虑到最近劳伦斯大湖中本地猎物鱼类，尤其是 Coregonus spp. 的减少。Humper 拥有最高的深水杜鹃的平均生物量比例，并且它们的内脏中没有其他可识别的鱼类。红鳍鱼内脏中鱼类的生物量对于 Coregonus spp. 最高，其次是类似数量的深水杜鱼和江豚，Lota lota。变形之间的饮食重叠很高，站点之间猎物消耗的差异可能与猎物的可用性有关。需要进一步研究以确定驼峰鱼和其他变种之间的营养生态差异是否足以支持多种变种的同时放养，特别是考虑到最近劳伦斯大湖中本地猎物鱼类，尤其是 Coregonus spp. 的减少。Humper 拥有最高的深水杜鹃的平均生物量比例，并且它们的内脏中没有其他可识别的鱼类。红鳍鱼内脏中鱼类的生物量对于 Coregonus spp. 最高，其次是类似数量的深水杜鱼和江豚，Lota lota。变形之间的饮食重叠很高，站点之间猎物消耗的差异可能与猎物的可用性有关。需要进一步研究以确定驼峰鱼和其他变种之间的营养生态差异是否足以支持多种变种的同时放养，特别是考虑到最近劳伦斯大湖中本地猎物鱼类，尤其是 Coregonus spp. 的减少。其次是类似数量的深水杜鱼和江豚，Lota lota。变种之间的饮食重叠很高，站点之间猎物消耗的差异可能与猎物的可用性有关。需要进一步研究以确定驼峰鱼和其他变种之间的营养生态差异是否足以支持多种变种的同时放养，特别是考虑到最近劳伦斯大湖中本地猎物鱼类，尤其是 Coregonus spp. 的减少。其次是类似数量的深水杜鱼和江豚，Lota lota。变形之间的饮食重叠很高，站点之间猎物消耗的差异可能与猎物的可用性有关。需要进一步研究以确定驼峰鱼和其他变种之间的营养生态差异是否足以支持多种变种的同时放养，特别是考虑到最近劳伦斯大湖中本地猎物鱼类，尤其是 Coregonus spp. 的减少。