Status of Bull Trout in the Kakwa River, Alberta, 2006
The bull trout, a native sport fish in Alberta, has declined in abundance and distribution across the province as a result of increased angling pressure, habitat alteration and non-native species introductions. In the present study, a mark-recapture survey was conducted to generate data on distribution and abundance of bull trout in the Kakwa River. I compared the abundance and distribution of this species in 2006 with historical data from 1997 and 2000. This information will update the current status of this species and should aid in formulating management guidelines for this species in the Kakwa River.
Overall, estimated bull trout abundance appears to have changed little between 1997 and 2006. Based on the mark-recapture survey, the estimated population size of bull trout in the 32-km reach was 421 (95% CI = 299 - 544) or 13 fish/km in 2006 compared to 278 (95% CI = 137 - 418) or 9 fish/km in 1997 and 330 (95% CI = 233 - 427) or 10 fish/km in 2000. Size of bull trout captured in 2006 ranged from 103 to 646 mm FL compared to 151 to 629 mm FL in 1997 and 155 to 584 mm FL in 2000. Overall, the mean size did not differ significantly among years (ANOVA, F = 4.02, df = 2, p = 0.02), ranging from 397 mm in 1997 to 422 in 2006.