Tagging . Tags have been placed in 274 adult northerns since 1973 (table 

 30). Angler returns have been consistent, with an average return of 13.9 per- 

 cent (range 12.5 - 16.4 percent). The highest return rate occurred the same 

 year the fish were tagged. An overall return rate of about 14 percent is simi- 

 lar to catch rates reported for other marginal northern pike waters. 



TABLE 30. Summary of northern pike tag returns by year for Tongue River Reser- 

 voir, 1973-76. (Number in parentheses is the percentage of total tagging) 



Walleye and Sauger 



Habitat Preference. 



Sauger (Stizostedion eanadense) and walleye (Stizo- 



stedion vitreum) are tolerant of a great range of environmental situations, 

 with both preferring large, shallow lakes. Sauger are also found in tur- 

 bid, slow-flowing rivers. Sauger generally succeed over walleyes in very tur- 

 bid waters. Both species are generally absent from vegetated waters. Spawning 

 occurs in the spring, with both species moving either upstream or to suitable 

 rocky areas. Eggs are deposited at random among the rocks to incubate. 



The Tongue River Reservoir provides good walleye and sauger habitat, and 

 both populations are doing well. Walleyes were introduced from 1965-1969 and 

 are now successfully reproducing. Sauger were not taken in the reservoir until 

 1973. Personal communication with Wyoming Game and Fish personnel revealed that 

 sauger were transplanted into the Tongue River near the Wyoming-Montana state 

 line in about 1967. The fish apparently moved into the reservoir and have become 

 an established population. 



Catch Rates and Distribution. In 1975, the trap-net catch of walleyes was 



distributed about equa 

 percent, respectively; 

 A, and 29.6 percent in 

 best walleye habitat 

 1976 precluded equal s 

 species distribution i 

 in April; in 1976 the 

 Catch rates were consi 



lly between zones A and B, which contribute 40.7 and 41.7 

 in 1976, 63.0 percent of the walleyes were taken in zone 

 zone B (tables 23 and 24). These zones represent the 

 Hov/ever, the effort to obtain mature northern pike in 

 ampling effort, and the results may not represent the true 

 n the reservoir. In 1975, the walleye catch was largest 

 catch was about equally distributed between April and May. 

 stent in 1975 and 1976 (table 25). 



Sauger were absent from trap-net catches until 1973, when they contributed 

 0.02 fish per net night (table 25). Catch rates in 1974 and 1975 were 0.09, in- 

 creasing to 0.90 in 1976. In 1975 and 1976, sauger were taken primarily in zone 

 A (72.7 to 79.6 percent of sauger catch, respectively). This zone is generally 

 turbid during the spring season and probably represents preferred sauger habitat. 



97 



