Sci*K*Ha/Uf 



The Tongue River Reservoir is a unique fishery in an area with a low 

 human population. Fish population estimates, with the exception of those for 

 northern pike, suggest a healthy, reproducing fishery. Spawning habitat for 

 northerns is lacking, and present water-level management does not favor the 

 reproduction of this species. Stocking with northern pike fingerlings has been 

 effective. Crappie, bass, walleye, and sauger are reproducing. The low annual 

 pressure estimates and catch rates indicate that this fishery's potential is 

 not being utilized to its fullest. 



Trap-net catch rates range from 45.7 fish per net night in 1975 to 108.7 

 in 1976. Crappie showed the greatest increase in number from one year to the 

 next. Game fish made up 3.3 percent of the 1975 sample and 3.5 percent of the 

 1976 sample. Population estimates computed for northern pike, black crappie, 

 and white crappie were comparable to those in other northern lakes. A partial 

 creel census conducted in 1975 and 1976 showed a catch rate of 0,259 fish per 

 man hour in 1975 andO. 508 fish per man hour in 1976. Harvest rates and yield 

 were lower than those reported for other states. 



Impacts of water withdrawals on the reservoir and its fishery are dis- 

 cussed. An evaluation of the drawdown which occurred in 1975 indicates that 

 it was not extremely harmful to the fishery. In fact, the crappie population 

 may have increased. Examination of projected reservoir levels associated with 

 three levels of proposed energy and agricultural development shows minimal im- 

 pacts on the reservoir's fishery. However, provision of instream flows for 

 fish and wildlife downstream from the dam were not considered as part of these 

 projections. With an increase in release for instream needs, storage patterns 

 could be altered. Still, as shown by the short-term drawdown in 1975, if the 

 magnitude and duration of water-level reduction are not extreme, the impacts 

 should not be severe. An extreme drawdown for long periods of time would be 

 devastating. 



As industrial development proceeds in this region, water-based recreation 

 provided by the Tongue River Reservoir will become increasingly important. 



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