A study of limnological conditions of Skeena lakes as they affect the distribution and abundance of whitefishes Coregonus and Prosopium

Limnological conditions in lakes of the Skeena drainage, British Columbia, have been examined to ascertain what factors may be restricting the distribution and/or abundance of the Eastern and Rooky Mountain whitefishes. The Eastern whitefish is known to be in only four Skeena lakes, and the Rocky Mountain whitefish in all Skeena lakes which have been investigated. It is probable that the Eastern whitefish has not entered other Skeena lakes because the lake conditions are not suitable for its establishment. Such conditions are mainly warm waters, shallow depths, and small area; and are sometimes the heavy silting of the water, and the resultant poor food supply. It is not numerous in any of the four lakes, probably because of the relative poor abundance of bottom food organisms, particularly in the absence of such organisms as the amphipod Pontoporeia. Conditions are apparently most favourable for Eastern whitefish in oligotrophia lakes. Rocky Mountain whitefish appear to favour eutrophic lakes, and are most abundant in lakes where a good supply of bottom food is assured by the absence of such potential competitors as the Peamouth chub and Squawfish. There is no evidence of any heavy predation on either of the two whitefish. It is improbable that any physical barrier has limited the distribution of these fish.Science, Faculty ofZoology, Department ofGraduat