Comparing Angler Effort and Catch Rate Estimates Across Creel Survey Methods at Three Alabama Reservoirs

Abstract

I compared different creel survey methods at three Alabama reservoirs (Harris, Jordan, and Mitchell) to identify approaches that could improve precision and reduce costs. I was particularly interested in whether boat trailer counts from time-lapse photos taken at boat ramp parking lots could be used as an index of fishing effort to improve the temporal coverage of sampling at relatively low cost. Angler effort was estimated independently through the use of roving creels, access point creels, aerial census counts, and compared with fixed-location digital camera images of trailers at boat ramps. Digital camera counts of trailers correlated with angler effort from aerial census (R2=0.8), access point creel surveys (R2=0.76), and roving creel surveys (R2=0.64). This finding suggests that time-lapse digital cameras as a sampling method to obtain angler effort may provide a feasible method once calibrated to a system. Best-fitting models for relationships between time-lapse trailer counts and the other methods included covariates for seasonal and day type (weekend vs. weekday) effects, but not reservoir and time-of-day effects. I also compared the influence of creel survey methods on estimates of fishery metrics such as proportion of anglers targeting bass and crappie, black bass and crappie catch rate, proportion of bass and crappie harvested, proportion of anglers tournament fishing, and proportion of anglers being residents of Alabama at these reservoirs. Differences in fishery metrics were observed among roving weekday, roving weekend, and access point creel surveys. These differences included black bass and crappie catch rate, proportion of bass and crappie harvested, and proportion of anglers tournament associated. Differences in black bass catch rate were greater in roving weekday creel surveys (0.94 fish/hr) than both roving weekend (0.71 fish/hr) and weekend access (0.68 fish/hr). Additionally, the proportion of bass harvested on roving weekday creels (0.28) was higher than roving weekend (0.14) and weekend access creels (0.06). This suggest that sampling only on weekends with the use of an access point creel surveys are not fully representative of weekday rates and proportions of angling fishery metrics.