SumatO/Uf 



A study was conducted on the Tongue River from 1974 to 1976 to determine 

 fish species composition, distribution, and diversity and to evalute impacts 

 of water withdrawals on the river system. Distribution of the 31 fish species 

 taken in the Tongue River was found to be influenced by irrigation structures. 

 Species migratory from the Yellowstone were restricted by the T&Y Diversion, 

 22.7 km upstream from the mouth. Small mouth bass were the dominant resident 

 game fish. Discharge patterns from the Tongue River Dam affected the 

 reproductive success of the smallmouth bass population. Species diversity 

 indices generally increased with progression downstream and appear to be a 

 useful tool in describing the fishery of a prairie stream. 



Migrant fish populations using the lov/er Tongue River were monitored. 

 Shovelnose sturgeon moved into the Tongue River from the Yellowstone River 

 during April, May, and June in 1975 and 1976. The majority of the sturgeon 

 sampled were between 710-785 mm in length in 1975 and 725-800 mm in 1976. 

 Compared with a spring sample taken on the Yellowstone River at Intake, the 

 Tongue River fish were considerably larger. Weights to 6 kg, larger than 

 shovelnose reported in other areas, were not uncommon. Schnable-type 

 population estimates showed 400-500 sturgeon/km present during the spring 

 runs both years. Quadratic equations comparing number of fish with dis- 

 charge and temperature documented passage preferences. It appears from those 

 regressions that a minimum discharge of 8.50 m^/sec is necessary for shovel- 

 nose sturgeon passage and that the optimum temperature range for sturgeon 

 spawning is from 16.90C to 21.5°C. Fish tagged with monel bands on the 

 pectoral fin lost weight between the times of tagging and recapture; those 

 tagged with Floy anchor tags gained weight. Angler harvest of sturgeon in 

 1974-76 was light. 



Sauger were sampled during April and May of 1976; 1,004 fish averaged 

 377 mm in length and 441 g in weight. A preferred passage flow for sauger 

 was estimated at 13.6 m^/sec using a quadratic regression of catch rate 

 against discharge. Population estimates showed around 3,700 sauger moved into 

 the lower river in 1976. The optimum temperature range for sauger spawning 

 migration was from 9.3°C to 12.40C. Tagging studies indicated that the 

 Yellowstone River sauger population is mobile and underutilized by fishermen. 



Channel catfish were sampled with baited traps both years. In 1975, 

 average lengths of catfish from the three river study sections sampled ranged 

 from 401 to 493 mm, and average weights from 690 to 1270 g. In 1976, fish 

 were smaller; average lengths ranged from 375 to 379 mm and average weights 

 from 596 to 644 g. Pectoral spines were taken, sectioned, and analyzed for 

 age and growth. Tag returns by anglers of sturgeon, sauger, and catfish 

 were low and suggested an underutilized resource. 



Recommended flows for passage and spawning of three indicator species-- 

 sauger, shovelnose sturgeon, and channel catfish--were determined in order 



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