Svmpatric presence of dwarf and normal forms of the Lake Whitefish, Coregonus ciupeaformis, in Como Lake, Ontario

Abstract

The presence of a dwarf form of the Lake Whitefish, living sympatrically with a normal sized Lake Whitefish form, is documented for Como Lake, northern Ontario. Gillnet catches on a shoal revealed two distinct size classes of spawning fish, with modal sizes of 170-179 mm and 280-289 mm fork length. Dwarfs grew more slowly and had shorter life spans as compared to normals. Gillraker numbers for the two forms were slightly different (p = 0.025) with a mean of 24.4 for dwarfs and a mean of 25.0 for normals. Both forms had modal gill raker counts of 24. The dwarf whitefish of Como Lake are the only sympatric dwarf whitefish known in the central part of the range of the species, outside of Algonquin Park, Ontario.