Abundance of Arctic Grayling in a 30-km Reach of the Wapiti River, Alberta
John Tchir, Tyler Johns and Greg Fortier
Arctic grayling (Thymallus arcticus) is an important sport fish species in several lakes and rivers in Alberta, including the Wapiti River. However, abundance and distribution of this species have declined throughout the province as a result of increased angling pressure and habitat destruction. In the present study, we conducted a mark-recapture survey to generate data on distribution and abundance of Arctic grayling within a 30-km reach of the Wapiti River that should aid in formulating management guidelines for this species in Wapiti River system.
A total of 147 Arctic grayling were captured over the 30-km stretch during our study. Mean (±SD) fish size (fork length) was 304 ± 38.1 mm and size composition was uniform throughout the study area.
Using the bias corrected Lincoln-Peterson method, estimated total abundance of Arctic grayling in the 30-km reach of the Wapiti River was 612 (95% CI = 281 - 943). Estimated abundance of harvestable fish (≥ 350 mm total length (TL)) was 291 fish (95% CI = 34 - 547). With the maximum likelihood estimate method, estimated total abundance was 670 fish (95% CI = 430 - 1748) while that of harvestable fish was 408 (95% CI = 281 - 2366).