shovelnose, but pressure is considered light. The Yellowstone River shovelnose 

 offers an opportunity to evaluate the status of a relatively unfished popula- 

 tion in an unregulated river. 



Sampling during the spring of 1974 in the lower reaches of the Tongue 

 River (downstream from the TSY Diversion) produced a large number of 

 shovelnose sturgeon. Gonadal development revealed that the fish were in 

 spawning condition. Since previous sampling efforts in this reach of the 

 river failed to produce sturgeon, it appeared that the fish were migrating 

 into the Tongue to spawn. 



In determining in 

 requirements for a sen 

 sensitive species will 

 selected as a sensitiv 

 resulting passage and 

 identifying shallow ba 

 fish and determining t 

 (Thompson 1972). The 

 opportunity to investi 

 evaluate the instream 



stream flow requirements 

 sitive species are met, 

 also be met (Bovee 1974 

 e species because of its 

 spawning flow needs. Pa 

 rs which could become ba 

 he amount of water neces 

 spawning run of shovelno 

 gate certain features of 

 flow necessary to mainta 



for fish, if the life history 

 then requirements for less- 

 ). The shovelnose sturgeon was 



migrational patterns and 

 ssage flows are evaluated by 

 rriers to the passage of adult 

 sary to allow fish to pass 

 se into the Tongue provides an 



their life history and to 

 in their run. 



The objectives of this segment of the study were to: (1) sample the 

 shovelnose sturgeon spawning run into the lower Tongue River; (2) compare 

 population strength with flow and temperature; (3) collect life history data 

 on lengths, weights and sexes; (4) tag fish to aid in future studies to 

 evaluate migrational patterns, delineate home range, and determine fisherman 

 harvest. 



FISH SIZE 



Length Frequency 



Fork lengths of sturgeon captured in the Tongue River in 1975 and 1976 

 are shown in table 5. Half of the fish sampled in 1975 fell in the range 

 710-785 im (28.0-30.9 in). The size interval 725-800 mm (28.5-31.5 in) contri- 

 buted 52.0 percent of the total sample in 1976. The average size and size 

 range of shovelnose sturgeon taken in the Tongue were larger in 1976 than in 

 1975 (figure 6). 



TABLE 5. Fork lengths of shovelnose sturgeon captured in the Tongue River in 



1975 and 1976. 



26 



