ferences in their depth distributions could explain 

 failure to demonstrate predation of smelt upon 

 alewives. Recently, smelt collected from northern 

 Lake Michigan during the fall were reported to 

 contain large numbers of young-of-the-year ale- 

 wives in their stomachs (O'Gorman 1974). Smelt 

 examined in this study consumed alewives not 

 only during the fall, but also during February, 

 May, June, and August. This study and O'Gor- 

 man's confirm the smelt's role as a predator of 

 alewives in Lake Michigan. The high frequency of 

 small alewives and Mysis in the diet of smelt 

 suggests a preference for larger food items. 



Increased piscivority with size is well known 

 among predatory fishes. Lake Erie smelt longer 

 than 126 mm consumed more fishes than smaller 

 specimens (Price 1963). In this study, smelt 180 

 mm and longer consumed about three times more 

 fish than the smaller individuals (grand averages 

 of 57 and 239c, respectively). According to O'Gor- 

 man (1974), the smallest smelt which had con- 

 sumed a fish was 143 mm total length. In the 

 present study, the smallest smelt which had con- 

 sumed an alewife was 157 mm. 



Seasonal differences in food habits reflect 

 changes in depth distribution of smelt and annual 

 changes in abundance of prey. Smelt in Gull Lake, 

 Mich., consumed primarily copepods and cladoce- 

 ran during early winter but from May to August, 

 dipterans were their principal food (Burbidge 

 1969). Similarly, smelt examined in this study 

 consumed Tendipedidae only during May, June, 

 and August, when the flies were abundant. In 

 Lake Superior, smelt longer than 125 mm con- 

 sumed mostly Mysis except during May and June, 

 when copepods ranked first (Anderson and Smith 

 1971). Likewise, smelt examined in our study 

 showed a change in food habits from winter to 

 spring but, in this case, from Mysis to yearling 

 alewives. Following littoral spawning during 

 April, smelt were captured in shallower water 

 where Mysis is not abundant. Schools of small 

 alewives occupying this zone provided an alterna- 

 tive food. 



Smelt examined during October fed after dusk 

 and ceased feeding during the night. Mysis rep- 

 resented 879c dry weight of the diet during the 

 October collection. This in conjunction with the 

 known fact that Mysis undergoes a nocturnal ver- 

 tical migration (Beeton 1960) suggests that their 

 feeding was associated with the migration, and 

 consequent availability of the smelt's principal 

 food organism. Feeding of young-of-the-year sock- 



eye salmon, Oncorhynchus nerka, has been re- 

 lated to diel vertical movements of zooplankton 

 (Narver 1970). A statistically significant feeding 

 periodicity was not demonstrated during the 

 March collection. However, this could be due to 

 reduced feeding intensity as evidenced by very 

 small amounts of food present in their stomachs 

 (e.g., 0.17c body weight). 



Literature Cited 



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BEETON, A. M. 



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GORDON, W. G. 



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