Lake Huron 



The experimental fishery in South Bay, a semi-isolated part of Lake Huron, 

 on which our Research Station is located, was begun in 1947 and has, each year, 

 consisted of fishing with constant effort (same kind, size and number of nets) 

 in the same locations within the bay. Since the effort has been constant, it is 

 reasonable to assume that catches made and examined each year have reflected, 

 fairly well, the changes which have occurred in the fish populations. This 

 particular project has been highly rewarding. It allowed us to document the final 

 decline of the natural lake trout population to disappearance in the early 1950's. 

 It provided the means of assessing the success of six annual stockings of lake 

 trout yearlings in the bay over the period of years involved, 1953 to 1961, It 

 has already been reported that survival and growth were good, but that sea 

 lamprey predation was such that no females reached maturity at age seven. This 

 project provided the best direct evidence of the disastrous effect of sea lampreys 

 on trout. More recently this project is allowing assessment of the survival and 

 growth of the first plantings of splake hybrids in the presence of sea lampreys. 

 One additional items which may prove significant to long term management is 

 the drastic decline of the ciscoe population. Ciscoes were a staple food item 

 for the lake trout. This decline has been coincidental with the arrival in the 

 early 1950's and rise to great current abundance of the alewife. These coincident 

 changes may or may not be cause and effect — this has yet to be determined — ^but 

 the matter may be of concern in the re-establishment of lake trout when and if 

 sea lampreys are controlled in Lake Huron. 



Whitefish commercial catch sampling was continued in the North Channel, 

 Georgian Bay, and in southern Lake Huron, This sampling, together with 

 exploratory fishing by our Research vessel should allow us to detect the arrival 

 of a strong year class of whitefish at an early age. This, in turn, will allow us to 

 relate that successful year class to the conditions of weather, water and spawning 

 stock which allowed it to occur. The recent scarcity of whitefish in Lake Huron, 

 and particularly in Georgian Bay, as compared to the huge productions of the 

 late 1940's and early 1950's have caused great hardship in the fishing industry, 

 and in a substantial portion of the economy of the Province. In order to maximize 

 yield of whitefish, stable rather than violently fluctuating populations must be 

 available. In order to work towards stability we must determine the factors 

 which cause failures and allow successful year classes to be produced. Our catch 

 sampling program has this long range objective in mind as well as that more 

 immediate advantage of year to year predictions for the fishing industry. An 

 excellent example of the latter was the recent upsurge of whitefish locally in 

 southern Lake Huron (Goderich^Bayfield area), where bumper crops were pro- 

 duced by two consecutive year classes. Unfortunately, we must also predict that 

 the good fishing will end after the spring of 1962 because no new year class is 

 present to grow into the fishery. The conditions which produced these good 

 year classes apparently prevailed only in this locality. No similar exceptional 

 year classes appeared in Georgian Bay. 



The catch sampling projects have produced many other items of interest 

 to management. Among these is a suggestion that with the disappearance of the 

 lake trout a greater portion of the fishing effort has been directed to whitefish. 

 There is a possibility that this increased effort may be related to the fact that the 

 fisheries now harvest the whitefish at ages three and four, and even some at age 

 two. Formerly the fishery relied upon older fish and on a broader range of year 

 classes. This change may contribute to the violence of fluctuations in the fishery, 

 and may, with the help of the sea lamprey, tend to reduce escapement to spawning. 



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