elevation and mean velocity were found to be not significantly different 

 from actual values. Although hydraulic characteristics predicted by WSP 

 are mean values, they are adequate for use with current knowledge of fish 

 requirements. 



SAMPLING AND TAGGING 



Six primary sampling stations were sampled six times in the fall of 1974. 

 Two sections (lib and Vb) were not sampled in the fall of 1975; the remaining 

 four sections were sampled three times each. Only section IVb was sampled 

 in the fall of 1976 to check on the reproduction of the smallmouth bass 

 population. Four secondary sections (la, Ila, IVa, and Va) were sampled in 

 the fall of 1974 for further definition of fish population distribution. 



River fish populations were sampled by several methods. Electrof ishing 

 gear with an output of 0-500 volts variable direct current, fished either 

 from a fiberglass boat as described by Vincent (1971) or from the banks of 

 smaller streams, was utilized to sample fish populations in the river and 

 tributaries. Baited trap nets (wire-frame, 3-ft hoop traps with 1-inch mesh 

 webbing) were used for channel catfish. A 4-inch bar-mesh gill net was also 

 utilized to sample fish. 



Spring sampling concentrated on the migrant fish which utilize zone I, 

 the lower 32.8 km (20.4 mi) of the river, for spawning. A portion (10.9 km; 

 6.8 mi) of this section was sampled extensively by use of traps, gill nets, 

 and electrofishing techniques. 



Each of three major tributaries to the Tongue River, Pumpkin, Otter, 

 and Hanging Woman creeks, was spot sampled at 16-to-24-km (lO-to-15-mi ) 

 intervals in 1974 to determine species composition and distribution. 



SHOVELNOSE STURGEON 



Shovel nose sturgeon ( SaapHrhynchus platorynchus ) were sampled by two 

 means: (1) by drifting the 4-inch bar-mesh gill net through an area free 

 of snags and (2) by electrofishing. The gill net was divided into ten 3 m 

 segments to determine sturgeon distribution across the channel. The number 

 of fish captured in each segment was recorded for each drift. Samples were 

 taken at least three days each week of the run. 



Several methods were used to tag sturgeon. In 1974, Floy anchor tags 

 were inserted immediately posterior to the dorsal fin. Observed tag losses 

 led to the use of No. 3 monel wing band tags placed over the anterior fin 

 rays of the pectoral fin as described by Schmulbach (1974). Irritation to the 

 pectoral fin caused by the monel tag resulted in the cessation of use of this 

 tagging method. Tagging in 1975 was accomplished by inserting the Floy 

 anchor tag in the pectoral girdle (Helms 1974), but tag loss associated with 

 this method was also high. A numbered aluminum strap tag encircling the 

 caudal peduncle at the base of the caudal fin as described by Christenson 

 (1975) was used in 1976. Several sturgeon thus tagged were held at the 

 Miles City National Fish Hatchery for observation. Severe irritation occurred 



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