Fats, leans, and in-betweens: a genetic comparison of Lake Trout morphotypes

Abstract

The purpose of this research is to compare genotypic and phenotypic relationships between two of the three Salvelinus namaycush morphotypes in Lake Superior (i.e., subspecies), the siscowet and lean lake trout. The major physical difference between the two lies in body fat content. Siscowet (Ojibwe translation = cooks itself) harbor up to 70% body fat while lean lake trout are at only 10%. In the past, it has been relatively easy to distinguish morphotypes by eye. This is particularly important for commercial fishers as there are different harvest regulations for each. Indeed, there is a strict quota on leans that is not imposed on siscowets. Unfortunately, over the past ten years, it has become more and more difficult to distinguish between the two. Presumably, there has been a breakdown of genetic isolation (=hybridization).