TABLE 33. 



Average lengths and weights of black and white crappie. Tongue 

 River Reservoir, April-May 1975. 



Conversions : 



1 mm = .0394 in 

 1 g = .0022 lb 



(90.8 percent whites). Estimates of standing crop for white crappie in 1975 

 and 1976 were 6.2 kg/ha (5.5 lb/acre) and 12.3 kg/ha (11.0 lb/acre), respec- 

 tively, and 0.535 kg/ha (.478 lb/acre) and 1.9 kg/ha (1.7 lb/acre), respective- 

 ly, for black crappie. The estimated crappie population doubled from 1975 to 

 1976. Bennett (1954) reported that a late summer drawdown similar to the lowering 

 of the reservoir in 1975 may benefit piscivorous fishes. Small fishes and aquatic 

 invertebrates are forced out of vegetation. The dislocation of these animals makes 

 them more easily hunted by the larger fishes. Since crappie do feed heavily on 

 other fishes, it is possible that their overwinter survival was enhanced by the 

 fall drawdown. 



TABLE 34. 



Population estimates of black and white crappie determined from trap 

 net catches. Tongue River Reservoir, 1974-76. 



CONVERSIONS: number/ha = 2.47 number/acre 



^Confidence interval not computed for white crappie in 1976 due to varia- 

 tion in recapture distribution. 



Tagging . Large black and white crappie (91 blacks and 9 whites) taken 

 during the trap-net season have been tagged to evaluate movements and fisher- 

 man harvest. Angler returns of blacks averaged only 3.3 percent (3 of 91) over 

 the three-year period, and none of the tagged whites were returned by fishermen. 

 In 1975 and 1976, of 36 blacks and 3 whites of taggable size taken in trap nets, 

 41.7 percent(l5) of the blacks and 66.7 percent (2) of the whites were recaptures 



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