Gut contents from multiple morphs of lake trout (Salvelinus namaycush) at two offshore shoals in Lake Superior

Journal of Great Lakes Research
By: , and 



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 (<50 m), mid (50–100 m), and deep (>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.

    Study Area

    Publication type Article
    Publication Subtype Journal Article
    Title Gut contents from multiple morphs of lake trout (Salvelinus namaycush) at two offshore shoals in Lake Superior
    Series title Journal of Great Lakes Research
    DOI 10.1016/j.jglr.2020.06.020
    Volume 46
    Issue 5
    Year Published 2020
    Language English
    Publisher Elsevier
    Contributing office(s) Great Lakes Science Center
    Description 9 p.
    First page 1382
    Last page 1390
    Country Canada, United States
    Other Geospatial Lake Superior
    Google Analytic Metrics Metrics page
    Additional publication details