"Residual" and kokanee salmon in Cultus lake

The sockeye salmon in Cultus lake are of three kinds: (1) the normal anadromous stock, (2) a "residual" group, not anadromous, but largely or perhaps wholly the progeny of anadromous fish, and (3) a stock of non-anadromous kokanee, which have no known connection with the anadromous or residual fish at the present time. Morphological and physiological peculiarities distinguish the three kinds of sockeye at maturity. In the segregation of the progeny of a spawning of anadromous fish into migrant and residual groups, rate of growth and sex play a determining role.