Angler reporting and tag retention estimates for Walleye in Lake Oahe

Abstract

Tag recovery studies are commonly used to estimate survival and exploitation of fish populations. Angler nonreporting and tag loss can cause estimates from such studies to be biased. In this study high-reward tags and double-marking were used to estimate reporting and tag retention rates for Walleye Sander vitreus marked with Monel metal jaw tags. As a secondary mark, a dorsal spine was removed from fish tagged during the first year of the study. Estimates of reporting rate from 2013 to 2015 ranged from 56 % to 70 % but did not differ significantly among years. The aggregate estimate of reporting rate was 58 %. Initial tag retention rate was 100 % then declined to 96 % after 1 year, 94 % after 2 years, and 83 % after 3 years. Dorsal spine removal was clearly identifiable after as many as 3 years, indicating it is a reliable batch marking technique. Walleye growth rates were slow during the study period, which likely increased tag retention rates, so caution should be used in applying these estimates elsewhere.