Angler Survey in the Upper Oldman River Watershed, 2018
Brad Hurkett and Kevin Fitzsimmons
We completed an aerial-access-type angler survey in the Upper Oldman (UOM) River hydrological unit code (HUC) 8 watershed to determine the level of fishing pressure on the sportfish population. The main objective of this angler survey was to provide current information on westslope cutthroat trout (WSCT) and other sportfish populations in the UOM River watershed to aid in the recovery and managing of these important sportfish fisheries.
We estimated fishing effort from aerial angler counts, while fish catch, trip length, and other pertinent demographic information were collected from angler interviews during roving surveys. We used bootstrapping techniques to derive estimates and confidence intervals for angler survey metrics in six stream reaches: i.) UOM River, ii.) Middle Oldman River, ii.) Lower Oldman River, iv.) Livingstone River, v.) Dutch Creek, and vi.) Racehorse Creek.
We completed 88 interview shifts and 25 instantaneous flights in the study area between June 16 and October 31, 2018. We interviewed 958 anglers who reported fishing 2,385.25 hours and we counted 1,052 anglers during flights. The highest number of anglers interviewed, and the highest angler counts during flights was in the Livingstone River, followed respectively by the Middle Oldman River, UOM River, Lower Oldman River, Racehorse Creek, and Dutch Creek. Estimated angling effort for the entire study area (119 river-kilometers study area) was 91,679 (95% CI = 80,506–103,311) angler hours and over half of the total effort was estimated from the Livingstone River at 25,964 (95% CI = 18,793–33,540) hours and the Middle Oldman River at 23,443 (95% CI = 17,663–29,842) hours. Angling effort estimates in the UOM River (17,366 [95% CI = 12-972–22,304] hours), and Lower Oldman River (14,758 [95% CI = 11,301–18,435] hours) totaled just over one-third the overall effort; angling effort in Racehorse and Dutch creeks were minimal compared to the rest of the streams. Estimated angling trip total for the entire study area was 21,651 (95% CI = 17,859–25,462) trips.
Estimated total fish catch over the study period was 91,228 (95% CI = 81,235–101,224) and 88% (n = 80,180) of those fish were WSCT. Westslope cutthroat trout was the most common species captured in the study, comprising 93% (n = 2,776) of the total 2,980 fish reported caught. Estimated average catch rates for WSCT ranged between 0.78–1.30 fish/hour with the highest rate being in the UOM River; catch rates for all other species were considerably lower (<0.15 fish/hour). The highest estimated WSCT catches occurred in the Livingstone River (20,929 [95% CI = 15,071–27,127]), the UOM River (20,609 [95% CI = 14,708–27,381]), and the Middle Oldman iii River (20,419 [95% CI = 15,219–26,161); the Lower Oldman River, Racehorse Creek, and Dutch Creek WSCT combined catch estimates were less than 20% of the overall estimate.
Data collected from this study have enabled us to estimate the degree of angling pressure in the UOM River watershed. Angling effort and catch estimates can be used to compare data from previous surveys and assist in managing the sportfish population and aid in the recovery of WSCT populations in the UOM River watershed.