Retention of T‐Bar Anchor Tags for Channel Catfish in the Red River of the North

Tagging fish for mark–recapture studies is a common practice in fisheries science that is used to estimate population parameters. However, biased estimates may result from an incomplete understanding of tag retention. The objective of this study was to assess tag retention for a large-river population of Channel Catfish Ictalurus punctatus over a 2,196-d period by using both discrete and instantaneous tag-retention models. A total of 3,827 Channel Catfish were double tagged with T-bar anchor tags in the Red River of the North from 2013 to 2016. The number of tagged Channel Catfish that were recaptured from 2013 to 2019 was 227, with 177 individuals retaining both tags and 50 individuals retaining one tag. Tag retention was estimated at 88% over the study interval by using a discrete tag-retention estimator. An instantaneous tag-retention model suggested that initial tag retention was high, while instantaneous tag shedding was 0.00028 (95% CI= 0.00021 to 0.00038). Based on the instantaneous model, tag retention was predicted as 90% (95% CI= 87% to 93%) at the end of the first year and 54% (95% CI= 44% to 64%) at the end of the study interval. When instantaneous estimates of tag retention are obtained, T-bar anchor tags may be appropriate for studies that evaluate population parameters for Channel Catfish over extended periods. Understanding the tag-retention process is fundamental to ensure that mark–recapture studies enable accurate estimates of population abundance, survival, growth, and movement (Guy et al. 1996; Pine et al. 2012). If tag retention is low, for instance, negatively biased estimates of population survival may result and lead to unnecessary management actions (Fabrizio et al. 1999). Furthermore, low tag retention can impede analyses by causing low accuracy and precision in the population parameter estimates (i.e., survival and movement) that are generated simultaneously by using advanced statistical methods (Pine et al. 2012). The tag type, location of the tag on a fish, species of fish, environment (e.g., lake or river), and the skill of the tagger are all possible factors that can influence tag retention (Timmons and Howell 1995; Buzby and Deegan 1999; Daugherty and Buckmeier 2009; Pine et al. 2012). Therefore, the estimation of tag retention through field-based or literature-based evaluation is a critical step toward ensuring reliable estimates for population parameters from mark–recapture studies (Pine et al. 2012). Assessments of Channel Catfish Ictalurus punctatus populations in river environments are increasingly needed, as the species has become a popular sport and sustenance fish in many river systems throughout its distribution (Michaletz and Dillard 1999; Bodine et al. 2013). Implementating mark–recapture studies in large-river systems may facilitate the assessment of Channel Catfish populations by providing data that can be used for estimates of the population parameters for this species (Siddons et al. 2017). Tagging Channel Catfish as part of mark–recapture *Corresponding author: spurgeonj@uapb.edu Received October 28, 2019; accepted December 18, 2019 North American Journal of Fisheries Management 40:330–334, 2020 © 2020 American Fisheries Society ISSN: 0275-5947 print / 1548-8675 online DOI: 10.1002/nafm.10410