Lake Erie 



The continued scarcity of blue pickerel in Lake Erie made efforts to obtain 

 information on this species unecomonical, and having determined, by a survey 

 of spawning grounds, early in 1961, that there would be no immediate improve- 

 ment in the population, the project was terminated. Subsequently our research 

 program has been directed to studies of smelt and of yellow perch, the two 

 species which are currently of major economic importance in this lake. 



A sound basis for regulating the newly developed smelt trawling industry 

 is of considerable importance to management. It is important to know where 

 in the lake smelt are concentrated at different seasons of the year so that they 

 may be exploited without danger to other species. Studies have therefore been 

 started to assess local concentrations and also to assess those factors such as 

 temperature and oxygen content of the water which may dictate the movements 

 and concentrations of smelt. Such knowledge, together with hydrographic survey 

 data provided by other research agencies, will allow us to reliably predict where 

 smelt will be found in any particular season or year. It will also eliminate the 

 need for the costly and long term exploratory fishing which would otherwise 

 be necessary to provide the same information on a less reliable basis. 



Other studies of smelt, facilitated by sampling the commercial catches of gill 

 netters, trawlers and pound netters, as well as our own experimental fishing, have 

 revealed a peculiar alternation of strong and weak year classes. It has been found 

 that the 1952, 1954, 1956 and 1958 year classes were all strong, compared to 

 those of the odd numbered years. Since the trawling industry as well as the 

 fishery using other types of gear tend to crop each year class of smelt as it 

 grows into the size suitable for marketing, and since natural mortality in smelt 

 is extremely high after age three, the industry is largely dependent upon a single 

 year class each year. A good year class, followed by a poor one on a continuing 

 basis is conducive neither to a stable fishery nor a stable market situation. Our 

 research therefore has been directed towards confirming that this situation really 

 does exist, and in attempting to find its causes. The obvious postulation is that 

 one generation in some way affects that which follows next year. We have 

 therefore begun a study of the food of smelt to determine whether adults are 

 cannibalistic on young of the year. 



Studies of yellow perch have strongly suggested a very high rate of natural 

 mortality in older fish (beyond age three) and a high population density. The 

 high population density appeared related to the high mortality and may also have 

 contributed to a depressed growth rate. When the legal gill net mesh size was 

 274", it appeared that fishing was accounting for about 15 per cent of the total 

 mortality and "old age" and other natural mortality factors accounted for over 

 60 per cent of the total mortality each year. In addition that mesh size was 

 inefficient in catching perch of the size achieved by this species in Lake Erie at 

 age three. Thus, to avoid waste of perch, it appeared judicious to allow gear to 

 be used which would more efficiently harvest the perch at a smaller size. 



Yellow pickerel studies demonstrated that no immediate improvement in this 

 population was imminent. Our small effort concerned with this soecies was 

 thoroughly co-ordinated with a more substantial undertaking by the U.S. Bureau 

 of Commercial Fisheries. 



Co-operative studies with the Industrial Development Branch of the Federal 

 Department of Fisheries in the field of gear development continued. The success 

 of efforts to develop a trawl to harvest perch have been somewhat less spectacular 

 than was the smelt work. 



During late August and September of 1961 another survey by our research 



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