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Use of a Statewide Angler Tag Reporting System to Estimate Rates of Exploitation and Total Mortality for Idaho Sport Fisheries

Author:
Meyer, Kevin A., Schill, Daniel J.
Source:
North American journal of fisheries management 2014 v.34 no.6 pp. 1145-1158
ISSN:
1548-8675
Subject:
Micropterus dolomieu, Micropterus salmoides, Perca flavescens, Pomoxis, Sander vitreus, fish behavior, fisheries, habitat preferences, hatcheries, managers, mortality, sport fishing, trout, wild fish, Idaho
Abstract:
From 2006 to 2009, 18,712 fish were tagged and released in 45 tagging events using nonreward and high-reward T-bar anchor tags to estimate the rate of exploitation (u) by anglers in various Idaho fisheries. In total, 3,100 nonreward tags and 592 high-reward tags were reported by anglers. Annual u was adjusted for tag loss, tagging mortality, and angler tag reporting rate. Tag loss, estimated by double-tagging a subsample of fish, varied greatly among species; tag loss was lowest for Yellow Perch Perca flavescens (1.1% in year 1 and 4.5% in year 2) and crappies Pomoxis spp. (2.9% and 4.8%) and was highest for Largemouth Bass Micropterus salmoides (14.8% and 30.3%), Walleyes Sander vitreus (11.4% and 43.2%), and Smallmouth Bass M. dolomieu (10.5% and 41.6%). Short-term (7–33-d) mortality averaged about 1% for both hatchery and wild fish. The nonreward-tag reporting rate averaged 54.5% across all species and years. Adjusted u averaged 19.4% (range = 2.0–44.3%) and was generally highest for crappies (mean = 28.7%) and Smallmouth Bass (22.0%) and lowest for wild trout (9.5%). Estimates of total annual mortality (A), based on the difference in tag returns between years 1 and 2, were plausible for some species but were unusually high for other species, especially Smallmouth Bass and wild trout. The implausibility of some estimates of A probably resulted from a combination of factors, including the reduced vulnerability of larger, older fish to angling, which would have caused a reduction in tag returns in year 2, likely due to a shift in fish behavior or habitat preference as tagged fish grew in size. Our results demonstrate the utility of using the high-reward tagging method to estimate u for fisheries under a variety of circumstances, but fisheries managers should use caution in attempting to simultaneously estimate A from the tag returns. Received December 23, 2013; accepted July 21, 2014
Agid:
1234377