Status of the Lake Simcoe Whitefish, Coregonus clupeaformis, in Canada

The Lake Simcoe Whitefish (Coregonus clupeaformis ) stock is spatially isolated and separated from adjacent Great Lakes whitefish stocks by geographic and man-made barriers, and has been reported to be genetically distinct from adjacent allopatric stocks. The population was estimated to number 250 000 in 1979, a decline of 85% since 1963 to 1965. Recruitment has been very low since 1970 even though spawning occurs and larvae are present in the surface waters during early spring (May). The spawning substrate utilized by the Lake Simcoe Whitefish consists of cobble-boulder limestone over a sand, clay or bedrock base extending from the shoreline to a depth of several metres. Deterioration of habitat quality has occurred, but the effect on reproductive success is unknown.