Chromosomal Polymorphism in North American Landlocked Salmo Salar

A karyotypic study was conducted with Salmo salar from West Grand Lake in northern Maine and from Craig Brook National Fish Hatchery originally from Lake Memphremagog), Orland, Maine. Specimens from the latter population were culled abnormal females with the exception of a single normal male and female. The culls gave a mode of 56, whereas all others gave a mode of 57. The difference, as well as general variation, tended to follow a Robertsonian pattern. In addition, a large submetacentric chromosome with a constriction in the long arm was found more commonly in karyotypes from the culled fish. The variation may be a result of the mixing of isolated populations in which divergent karyotypic evolution has occurred.