(38.8 percent, of all fish taken by trawl) . Although 

 gizzard shad and alewives made up 24.2 percent 

 of the total volume of food, they were present in 

 relatively few stomachs. Similarly, few spottail 

 shiners had been eaten (frequency of occurrence— 

 1 .4 percent) even though they were readily avail- 

 able (30.8 percent of the trawl catches). Emerald 

 shiners were not taken by the trawl but were in 

 3.3 percent of the stomachs. Tendipes pupae were 

 more prominent at this time than hi any other 

 period (frequency of occurrence — 7.1 percent). 

 Maloney and Johnson (1957) reported that dip- 

 terous larvae occurred in the stomachs of walleyes 

 taken in August in Lake Winnibigoshish, Minn. 



Yellow perch made up the bulk of the food of 

 the walleyes captured in the Island area, August 

 20-30 (total volume — 91.5 percent; frequency of 

 occurrence — 84.2 percent). Gizzard shad had 

 almost disappeared from the stomachs (total 

 volume — 0.8 percent). Again, emerald shiners 

 had been eaten but were not in the trawl catches. 

 Walleyes may have been seeking out this minnow. 

 On the other hand, trawl catches may not provide 

 an exact index of relative abundance of emerald 

 shiners because this fish occasionally frequents 

 the surface waters and hence becomes unavailable 

 to bottom trawls. 



The importance of yellow perch had begun to 

 decline by September 18-19 (total volume — 60.4 

 percent; frequency of occurrence — 65.7 percent); 

 perch were being supplanted by emerald shiners 

 (total volume — 9.3 percent; frequency of occur- 

 rence — 22.9 percent). Trawl catches indicated 

 that the availability of yellow perch had decreased 

 while that of the emerald shiners had increased 

 (table 2). 



The few walleyes caught between October 29 

 and November 1 showed a further shift from 

 yellow perch (total volume— 7.0 percent; fre- 

 quency of occurrence — 11.1 percent) to emerald 

 shiners (total volume — 93.0 percent; frequency of 

 occurrence — 88.8 percent). Doan (1941) stated 

 that emerald shiners constituted 82 percent of the 

 volume of food eaten by 62 walleyes, 10-17 inches 

 long, caught at Put-In-Bay, Ohio, in November 

 and December 1940. 



Evidence from extreme western Lake Erie (Area 

 1) suggests that the walleye prefers gizzard shad 



or alewives (luring it s early months of life, even 

 though ample numbers of young yellow perch 

 (and other species) of suitable size are available. 

 It is apparent from the fish taken in the Islands 

 region (Area 2), however, that where yellow perch 

 almost completely dominate the food supply, the 

 walleye can and does feed heavily upon them. 

 The shift to emerald shiners that occurred in the 

 late summer and autumn in both Areas 1 and 2 

 may be traceable to different causes. In Area 1 , 

 the emerald shiners became prominent in the food 

 of walleyes when the gizzard shad and alewives 

 became too large to eat. In Area 2, the change 

 probably reflects species rather than size pref- 

 erence since both the emerald shiners and the 

 yellow perch captured in October were about the 

 same size (table 5). 



East of the Island Region (Area 3) 



Forty-three O-group walleyes were collected 

 off Huron and Vermilion, Ohio, and east of Kelleys 

 Island in July, August, September, and October. 

 The 38 fish that had food in then- stomachs had 

 eaten almost exclusively smelt and yellow perch 

 (table 6). Yellow perch were the only food of 

 walleyes in the small July collection. Some smelt 

 were eaten in August, and by September this 

 species had become the only food in almost all 

 stomachs. No suitable records are available of 

 the relative numbers of O-group fish living with 

 the walleyes because most were taken in trawls 

 with large-mesh cod ends that permitted the 

 escape of most small fish. A cursory examination 

 of the catches did reveal, however, that the bulk 

 of forage available to the walleyes east of the 

 Islands consisted of smelt and yellow perch in all 

 seasons. 



ACKNOWLEDGMENTS 



The Bureau of Commercial Fisheries vessel 

 Kaho and the Ohio Division of Wildlife vessel 

 Explorer collected walleyes for stomach analysis. 

 Jarl Hiltunen assisted in the identification of the 

 immature midges, and LaRue Wells helped iden- 

 tify crustaceans. Vernon C. Applegate advised 

 in the preparation of the manuscript. 



FOOD OF YOUNG WALLEYES IN LAKE ERIE 



493 



