Influence of water level drawdown on the fish populations of Cross Lake, Manitoba /
Regulated discharges into Cross Lake, Manitoba, resulted in average summer water volumes in 1980 and 1981 that were 49% lower than preregulated volumes. Water level drawdown in the summer reduces the amount of available habitat. Consequently, the standing crops of lake whitefish (Coregonus clupeafor...
|Additional Author(s):||Patalas, J. W.|
|Report Numbers:||SUS 274|
Fishes -- Manitoba -- Cross Lake -- Reproduction.
Fisheries -- Catch effort -- Manitoba -- Cross Lake.
|Online Access:||Link to Full Text|
Link to Full Text
|Library Holdings:||Print Versions|
|Summary:||Regulated discharges into Cross Lake, Manitoba, resulted in average summer water volumes in 1980 and 1981 that were 49% lower than preregulated volumes. Water level drawdown in the summer reduces the amount of available habitat. Consequently, the standing crops of lake whitefish (Coregonus clupeaformis), walleye (Stizostedion vitreum vitreum), northern pike (Esox lucius), and cisco (Coregonus artedii) are lower now than in preregulation and early postregulation years. Unusually early and rapid drawdown in March 1981 resulted in a severe winterkill, causing a substantial decrease in catches per unit of effort (CPUE) for most species from 1980 to 1981. The most affected species were whitefish and cisco, which showed a 50% reduction in CPUE from 1980 to 1981. The amount of fall to late spring drawdown and the year-class strengths of coregonid fishes were inversely related. A marked overwinter drawdown reduces whitefish and cisco hatching success apparently by dewatering their spawning areas and desiccating the eggs. Low water levels in spring prevented pike and walleye access to spawning areas.|
|Physical Description:||p. 118-125 : ill., 1 map ; 28 cm.|
|Related Titles:||Originally published in: Canadian journal of fisheries and aquatic sciences 1984 Vol. 41, p. 118-125|
|Bibliography:||Includes bibliographical references (p. 124-125).|