No Slide Title

• Largest and deepest bay in Georgian Bay

• Isolated, with few lamprey streams delayed lamprey effects

• By 1958 high lamprey predation

• Large fish survive better than small

• No commercial fishing on top of sea lamprey

• Old fish survived until lamprey treatment in 1960s

• Residual sea lamprey and sport fishing kept population size

depressed through the 1960s and 1970s

Sea Lamprey



	•Parry Sound one of the largest and deepest Bays in GB
	• 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.