1976 

 1975 

 1974 



400 



500 



600 



700 

 Length 



900 



1000 



100 



Figure 31. Length-frequency of northern pike captured in trap nets. 

 Tongue River Reservoir, 1974-76, expressed as each size interval's percentage 

 of the total sample. 



significant decrease from 1975 to 1976. This reduction appeared to be in larg- 

 er fish, as shown in figure 31. Based on the average weight of trap-netted 

 fish, the northern pike standing crop was estimated at 0.564 kg/ha (.503 lb/ 

 acre) in 1974, 0.496 kg/ha (.442 lb/acre) in 1975, and 0.315 kg/ha (.281 lb/ 

 acre) in 1976. The standing crop of northerns in the Tongue River Reservoir 

 Is considerably lower than most others reported. For example, estimates of 

 standing crops of northern pike in Wisconsin lakes ranged upward from 0.673 kg/ha 

 (Snow and Beard 1972); in a southern Michigan lake, crops ranged from 3.5 to 

 5.3 kg/ha (Schneider 1971). Scott and Grossman (1973) reported standing crops 



95 



