A Reward-Recovery Study to Estimate Tagged-Fish Reporting Rates by Idaho Anglers

From 2006 to 2009, we tagged and released 22,202 fish with T-bar anchor tags valued at US$0 to $200 if returned. Our intent was to assess angler tag reporting rates in Idaho and to determine whether reporting rates declined over time or differed between species. A total of 4,643 tags were reported by anglers. Assuming a reporting rate of 100% for $200 tags, weighted mean reporting rates were 54.2% for $0 tags, 69.7% for $10 tags, 91.7% for $50 tags, and 98.9% for $100 tags. By combining $100 and $200 as high-reward tags to increase sample size, nonreward tag-reporting rate was 54.5%. Tag reporting rates varied between groups of species, being highest for harvest-oriented species, both coolwater and warmwater, such as walleye Sander vitreus ($0 = 68.3%), yellow perch Perca flavescens (58.5%), and crappie Pomoxis spp. (59.7%), and lowest for largemouth bass Micropterus salmoides (39.2%). There was little variation in tag-reporting rates over time, weighted means being 53, 56, 50, and 56% from 2006 to 2009, but reporting rate did appear to decline for some species (most notably crappies). There was some evidence of a slight violation of the assumption of independence in tag-reporting, indicated by nonreward tag-reporting rates being marginally higher for anglers reporting both nonreward and reward tags than for those reporting only one or the other (signifying possible batch-reporting of tags). No batch-reporting was evident from differences in reporting rates for households reporting multiple tags compared with those reporting only one tag. Our results suggest that anglers in Idaho reported over half the nonreward tags they encountered, but rates appeared to vary among species, and this knowledge is being used to estimate angler exploitation across Idaho.