I’d like to clarify some misinformation about lake trout species that I and others have believed, namely about the number of “species” of Lake Superior lake trout. Tom Rozich, in his DMG Outdoor Page column, August 2014 addresses this question very well and here is his article:
An Age Old question and frequent topic of discussion among Lake Superior lake trout anglers is, “How many kinds of lake trout are there in Lake Superior?” Many feel there are up to a dozen different kinds, but most only two types. What are the facts?
Sport fishers and commercial fisherman have names for what they believe are different kinds of lake trout. They are, in no particular order, nor is the list comprehensive, Mackinaw, lean, fat, siscowet, paper bellies, Isle Royale redfin, half-breeds, lake char, humpers, grey trout, Klondike Reef, togue, laker, reef creatures, namaycush, greasers, lunge, tyrant of the lake, red trout, and land-locked salmon. Confused? Most of these are common names and come from different geographic regions of the lake trout range.
The fact is, there is only one species of lake trout, that being good old Salvelinus namaycush. That being said, there are currently at least four recognized morphs or forms of lake trout in Lake Superior. What is a morph or form you ask? The best analogy or comparison is the human species. There is only one species of humans, that being Homo sapiens, but there are four recognized races, with each having distinct body shape and color. They are, in alphabetical order, Australoid, Caucasian, Mongolian, and Negroid.
As early as 1884 scientists recognized two forms of lake trout. George Goode, who was documenting the Fishery Industries of the United States for the US National Museum, described two forms. He called them namaycush (leans) and siscowet (fats.) Siscowet comes from the Ojibwa and means “cooks itself.” He also said one was a shallow water inhabitant, while the latter lived in deep water. He described siscowet as having a shorter and broader head, larger teeth and fins, stouter body, fatter/oily, and lived in 40 fathoms or more. His claim was that siscowet was very good eating if salted for 48 hours, then washed and broiled. (Must try!)
Modern day research by fisheries biologists and scientists has shown four different morphs or forms. They are lean, humper, siscowet, and redfin. They indicated the four forms have different shapes, traits in feeding and swimming, buoyancy, and habitats. The collections were from Isle Royale National Park waters, with almost 600 fish being analyzed.
How did they arrive at these conclusions? Through analysis of head shape, body shape, and visual identification. Actual measurements of all aspects of the head and body were taken. Some of them were width and length of head, distance between eyes, jaw length, etc. Distance between fins, depth of body, length of fins, etc. A mathematical analysis was then done, which showed four distinct groupings, hence four morphs or forms.
A brief description of each form follows: Lean– longer head and streamlined body, shallow body, less fat, typically lives in water less than 50 meters deep. Humper– shortest head of all four, smallest body of the four, intermediate in fat content, lives on isolated reefs or humps. Siscowet– Very short head, eyes close to the top of head, deep body, high fat content, typically lives in waters 100 meters deep or more. Redfin– red or red/yellow fins, very big eyes, overbite jaw, very large pectoral fins, very deep body, typically lives in depth of 80 meters.
All that said and done does not mean there aren’t varieties of each form. Remember that all belong to the same species and are capable of interbreeding, as are humans. Also, my feeling is there may be “other” forms in Lake Superior, as there are many very isolated shoals and reefs that have not been explored in this gigantic lake. A couple of years ago, three of us made a fishing trip to Lake Superior shoal, which is in Canadian waters, mid-way between Isle Royale and Michipicoten Island in the middle of Lake Superior. These lake trout were like no others this author had ever observed……..being short and deep. A DNA analysis of these fish is being conducted at Michigan State University, so this story may have a sequel!