A Stock Assessment of the Kakwa River Arctic Grayling Population, Fall 1997 


Travis Ripley


Arctic grayling (Thymallus arcticus) were captured using a 5.0 GPP float e!ectrofishing unit within a 32 km study section of the Kakwa River, Alberta, in 1997. In combination with electrofishing, angling as a capture method was also used to collect grayling within deeper pools, often where electrofishing was less effective. The stock assessment was accomplished using population estimates, length distribution and age composition. The . long section of river was chosen to determine the validity of all assumptions associated with population estimates and to accurately predict Arctic grayling abundance. Movement probabilities were tested and the population structure was stratified when necessary. A Peterson mark-recapture technique was used to calculate population estimates. The population abundance whithin the study area was 482 (SE = 34) for the combined ( angling and electro fishing) estimate, 603 (SE = 96) for electro fishing only and 185 (SE= 19) for angling. The length frequency distribution ranged from 149 mm to 410 mm fork length which spanned 3 to 11 years of age with age five comprising the majority of the sample. No significant differences in size distribution between each capture method was observed. The comparison of these capture methods leads to unique conclusions about the effectiveness of each method for conducting stock assessments on Arctic grayling . 

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