128 Steven I. McBride and Donald Tarter 



yearling freshwater drum were also an important item in Priegel's study. 

 Vanicek (1964) examined 133 sauger collected from Lewis and Clark 

 Lake and the Missouri River. He found young gizzard shad to be the 

 most important food for both reservoir and river sauger. Although the 

 emerald shiner was abundant in Lewis and Clark Lake, it appeared in 

 only 5% of the stomachs. Swenson (1977) reported that troutperch 

 were the primary source of food for sauger in Lake of the Woods, Min- 

 nesota. 



Seasonal Food Habits 



Seasonal variation in sauger diet was minimal (Figs. 2 and 3). 

 Fishes were the dominant food item by number (100% FO) and weight 

 (99.7%) throughout the year (Table 1). Emerald shiners were most 

 important in both numerical frequency and frequency of occurrence at 

 all seasons. Gizzard shad ranked second in importance by number 

 throughout the year. 



Volumetric proportions of food items generally coincided with per- 

 cent numbers in the diet. Emerald shiners were the most important iden- 

 tifiable food item volumetrically in both spring (38%) and summer 

 (29%). Gizzard shad comprised the largest proportion of food volume 

 (36%) during the fall (Fig. 3). 



The greatest variation in seasonal feeding was an increase in the 

 number of stomachs containing food from spring (61%) and summer 

 (64%) to fall (89.7%). 



There have been relatively few food habit studies documenting sea- 

 sonal variation in diet. Dendy (1946) reported that it was not uncom- 

 mon to find as many as 30 small shad in an individual stomach. The 

 shad, tending to "hibernate," are undoubtedly easy prey for sauger in 

 winter. Priegel (1969) reported that in the winter. Lake Winnebago 

 sauger consumed equal amounts of troutperch and emerald shiners. 

 When forage fishes were scarce, however, sauger consumed more chiro- 

 nomid larvae. 



Food Habits by Length Class ' 



150 mm and less. — Our methods enabled us to collect no data 

 concerning food of sauger of this length class. Priegel (1969) found the 

 food of young sauger to vary with size, changing from zooplankton to 

 chironomid larvae, to immature and adult mayflies. He considered 

 sauger less than 50 mm to be plankton feeders; however, at 50 mm they 

 would cease consuming plankton if forage fishes were extremely abun- 

 dant. Of the invertebrates utilized by sauger in the 12-50 mm size class, 

 Daphnia sp. was the most important item consumed. The major forage 

 fishes consumed by young sauger were troutperch, freshwater drum, 

 and white bass, Morone chrysops (Rafinesque). 



