Foods and Feeding of Sauger 125 



In order to overcome bias due to differences in stages of digestion 

 of food items, the original weight of individuals can be estimated 

 (Lagler 1956). This is done by averaging weight of 30 undigested indi- 

 viduals of the species. The figure obtained is an approximate "weight 

 when alive" value. 



To determine if seasonal variations occur in the diet of the sauger, 

 151 specimens were arbitrarily grouped according to season: spring 

 (March, April, May), summer (June, July, August), and fall (Sep- 

 tember). The number of empty stomachs from each season also was 

 recorded, to determine if there was any seasonality in the percentage 

 frequency of their occurrence. 



Specimens were divided into two total-length classes — 150 mm 

 and less, and 151 mm-400 mm — to determine if food varied with 

 length. 



Our study was concurrent with a WVDNR creel survey, conducted 

 from 1 April through 31 November 1981. 



The relationship between water temperature and sauger catch (from 

 the WVDNR creel survey) was determined by regression analysis and 

 tested with a coefficient of correlation. Temperatures used for the 

 regression analysis consisted of means calculated from monthly average 

 values from the Gallipolis Locks and Dam, and single day values from 

 other dams included in the investigation. Temperature data were 

 obtained from an electronic water quality monitoring system and a 

 manual sampling system, both maintained by ORSANCO. 



RESULTS AND DISCUSSION 



Of the 151 sauger stomachs examined, 105 (69.5%) contained food. 

 The number with food was highest in September (89.7%) and lowest in 

 July (50%) (Fig. 1). Thus, sauger appeared to feed most intensively in 

 the fall. 



Food Items 



Fishes were the primary food of sauger, both by weight (99.7%) 

 and by frequency of occurrence (100%) (Table 1). Emerald shiners, 

 Notropis atherinoides Rafinesque, and gizzard shad, Dorosoma cepedi- 

 anum (Lesueur), accounted for 56.6% of the total volume of food con- 

 sumed (Table 1). Together these two forage fish comprised 96% of all 

 identifiable food items (Table 1). 



Emerald shiners were the most important food item by number, 

 occurring in 49% of stomachs that contained food, and by weight mak- 

 ing up 32% of food biomass (Table 1). Gizzard shad were second in 

 importance appearing in 11% of stomachs that contained food and 

 comprising 25% of the total volume of food consumed (Table 1). Other 

 identifiable food fishes were striped shiners, A^. chrysocephalus (Rafi- 



