|•Parry Sound one of the largest and deepest Bays
|• 9207 ha, 112 m maximum depth, 41 m mean depth
|• Shallow channel joining to GB (12 m)
|• No commercial fishing
|•The isolation of Parry Sound from Georgian Bay,
combined with few local streams being suitable for sea lamprey reproduction,
likely reduced the effect of sea lamprey predation on these lake trout and
saved them from extirpation.
|•But by 1958 lamprey parasitism was 45 time
higher than that observed in 1988 to 1998.
|•Large lake trout are able to survive lamprey
attacks better than small fish.
|• The absence of a commercial fishery prevented
the combined effects of sea lamprey parasitism on smaller lake trout and
exploitation of larger/older fish which led to the extirpation of other
stocks in the Great Lakes.
|• This lack of commercial fishing allowed the
larger Parry Sound lake trout to survive until sea lamprey control was
initiated in the early 1960s.
|• Residual sea lamprey and a continuing sport
fishery appears to have prevented rehabilitation, however, and kept the
population numbers depressed.