mined by sampling the commercial catches. Efiforts are constantly applied to find 

 which environmental factor or combination of factors produces the failures and 

 the strong year classes. It is believed that the answer will be achieved earlier if 

 several populations are studied at the same time. It is hoped that we are taking 

 measurements of the responsible factors. 



Projects dealing with splake introductions at South Bay, with the smelt spawn- 

 ing runs, gill net selectivity and others, were continued successfully in 1962. The 

 sudden death in September of John Budd, scientist-in-charge of the Lake Huron 

 program, was a severe loss to fisheries research in Ontario. 



LAKE ERIE 



Smelt, perch and walleye (yellow pickerel) were the species on which the 

 attention of the Wheatley Station staff was concentrated during 1962. Smelt and 

 perch received their attention because they were the most important species to the 

 fishery, and also because regulations restrictive to the harvest of the very abundant 

 perch were removed in response to demands by the industry. The walleye received 

 attention through requests by the Great Lakes Fishery Commission reflecting 

 concern over the current scarcity of this valuable and formerly abundant species. 



In the smelt studies, effort was directed to determining where smelt were 

 concentrated at various times of the year, and why these concentrations occurred. 

 This study required experimental trawling at grid locations adequate to cover the 

 entire central and eastern basins (few smelt occur in the shallow western basin). 

 In carrying out this program it was difficult for experienced fishermen to under- 

 stand why the research staff fished and measured environmental conditions in areas 

 which both fishermen and researchers were quite sure contained no smelt. It is felt 

 however that both negative and positive measurements will reveal the "why" of 

 smelt concentrations more quickly than will measurements only in areas of smelt 

 schools. 



Preliminary data show that in late summer smelt in the central basin may be 

 forced down from the surface by warm water, and forced up from the bottom by 

 oxygen deficient water, and are therefore confined to a very thin layer in 

 the thermocline. They may then move out to the eastern basin where water con- 

 ditions are more favourable. Those which do not find their way to better water 

 conditions are nicely concentrated for trawlers, but the stress of environmental 

 conditions may contribute to their gradual emaciation. Further work, to clarify 

 these preliminary suggestions, is planned for 1963. 



In the case of yellow perch, there was no apparent biological reason to dis- 

 courage further exploitation. The research in the past had shown great abundance, 

 high natural mortality and a suggestion of over-population. The program of study 

 was geared to assess the impact of increased exploitation on this population. Such 

 increased exploitation did not, in fact, develop because of economic conditions 

 which led the fishermen to voluntarily restrict their catches. Studies did show, 

 however, that the 1962 catch was supported largely by the 1959 year class (perch 

 at three years of age); that catches were much larger in the western end than in 

 the eastern end of the lake; and that growth of perch in the western end was 

 noticeably slower than that of perch in the eastern end of the lake. 



All walleye data accumulated through routine sampling of the commercial 

 catches were summarized and presented at a Great Lakes Fishery Commission 

 meeting held in Ottawa in 1962. Although these data were limited, they were 

 highly significant when combined with information submitted by other agencies 

 from the U.S. side of the lake. Our data suggested that increases in fishing pressure 



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