Lake trout (<Emphasis Type="Italic">Salvelinus namaycush</Emphasis>) spawning behaviour: the evolution of a new female strategy

A video camera inside an underwater housing was used to record the spawning activities of lake trout, Salvelinus namaycush, in Kushog Lake, Ontario (Canada). Contrary to the commonly accepted belief describing lake trout as the only salmonine to spawn exclusively at night, the recordings were taken during the day. Lake trout spawning behaviour is described in detail and compared with other salmonine species. The loss of female “nest-building” and assumption of a novel itinerant strategy during which females travel across the breeding grounds accompanied by a group of males, is considered to be an important change in the evolution of the lake trout’s unique mode of spawning.