participation in the programs and by membership on various committees which 

 plan and review the research. 



The sea lamprey control experiment continued to be concentrated on Lake 

 Superior. Runs of adult lampreys at the assessment barriers in the spring of 1962 

 indicated that the initial stream treatments had reduced the lamprey population by 

 80 percent. Summer and fall studies revealed low levels of sea lamprey predation 

 on lake trout, and the trout population apparently responded quickly by giving 

 evidence of modest increases in numbers, average size, and catch per unit effort. 



Although we are pleased with the extent of success achieved to date in this 

 vast experiment, it is generally thought that the lamprey population must be 

 reduced quite a bit further before the lake trout population can regain its former 

 level at which it can sustain a fishing industry. 



The second round of stream treatment was initiated during 1962. 



LAKE HURON 



Tagging and associated studies have demonstrated the existence of several 

 separate populations of whitefish in the area studied by the staff of the South Bay 

 Fisheries Research Station. These distinct populations occur in the North Channel; 

 in northern Georgian Bay; in southern Georgian Bay; in southern Lake Huron, off 

 Goderich and Bayfield; in northern Lake Huron, along the south shore of Mani- 

 toulin Island; and in South Bay. The whitefish of South Bay have, for reasons of 

 proximity to the station, received the most attention. Good numbers of these have 

 been tagged in the experimental pound net fishery operations conducted in the 

 spring, and recaptures indicate that during the summer and autmn they move out 

 of South Bay and into the northern part of Georgian Bay. We do not know yet 

 where they spawn. They return to South Bay and are recaptured in the pound 

 nets in subsequent spring seasons. Experimental gill netting operations in South 

 Bay in the autumn produces numbers of whitefish, but rarely individuals which 

 have been taken and tagged in the spring pound nets. It thus appears that there 

 may be two populations of whitefish even in a body of water as small as South 

 Bay, and the suggestion is implicit that with more intensive work the population 

 structure of greater Lake Huron might prove equally complex. 



Each separate population of whitefish, of which we are aware, is sampled 

 annually. There are growth differences and, perhaps more important, age differ- 

 ences between them. Age determinations made from scale samples tell us which 

 year classes were successful and which were failures. From this sort of work we 

 know that the excellent fishing of the late 1940's and early 1950's in northern 

 Georgian Bay and South Bay was available because the hatch of 1943 was 

 phenomenally successful. There has been no really outstanding year class in these 

 areas since. We know also that the excellent fishing in the Goderich-Bayfield areas 

 in 1960 and 1961 was the result of good year classes hatched in 1957 and 1958, 

 and we know and predicted a decline in fishing quality in 1962 and 1963 because 

 samples showed few fish of the 1959 and 1960 hatches coming along. Curiously 

 enough, we know also that the North Channel and South Bay populations are 

 usually strong or weak in the same years, and that the southern Georgian Bay 

 population remains fairly stable as compared to the violent fluctuations of all other 

 populations in the lake. 



Each year, observations are made on wind, oxygen, temperature in the fall, 

 in the spring, ice cover and all other items, including the abundance of other 

 species, that might conceivably have a bearing on the success or failure of a white- 

 fish year class. This is done in each area where a separate population occurs. 

 Three, four and five years later the strength of the year class produced is deter- 



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