Effectiveness of barotrauma mitigation methods in ice‐angled bluegill and black crappie

Abstract

Barotrauma can lead to physical injury and physiological disturbance (elevated stress hormones, and depleted energy stores during post-release struggling) in angled fish.Effectiveness of methods for reducing effects of barotrauma on fish has not been tested on fish subjected to ice-angling. We examined post-release behavior and redescension of bluegill Lepomis macrochirus and black crappie Pomoxis nigromaculatus.Barotrauma was mitigated for fish either during capture by slow retrieval or following capture by venting or re-descension with weights, before observation in a behavioral arena or using small acceleration and depth biologgers. Black crappie spent less time in the center of the behavioral arena and were less likely to successfully re-descend than bluegill. Depth increased over time during the post-release monitoring period, with control fish less likely to descend to depth as fish for which barotrauma was mitigated. Our results demonstrate species-specific effects of ice-angling to inform anglers on the effectiveness of barotrauma mitigation strategies to improve welfare of fish after release.

hysiological and Behavioural Responses of Lake Trout to Catch-And-Release Angling

“…Reflex indicator scores showed signs of behavioural recovery within 6 h. Loss of orientation was the most observed reflex impairment with 84% of fish displaying it 4 h post-angling during extended recovery and 14% of fish displaying it 300 s post-angling during immediate recovery. Impaired orientation has been shown to be a crucial predictor of mortality in other species (Gingerich et al 2007;Raby et al 2012) and is necessary for fish to return to desired depths upon release (Louison et al 2023). Fish experiencing an orientation impairment are likely forced to float just under the ice surface after release and therefore experience low temperatures and potential tissue freezing (Card et al 2022).…”

“…General best practices must continue to be promoted for this fishery such as preventing air exposure, limiting fight times, and careful handling upon capture (Brownscombe et al 2017;Danylchuk et al 2018;Brownscombe et al 2022;Chhor et al 2022a). Wider implementation of commercially available descending devices may combat fish mortality by returning fish to a depth that allows them to relieve barotrauma pressure (Curtis et al 2015;Bellquist et al 2019;Davies et al 2022;Louison et al 2023). These devices are an alternative to more invasive methods such as fizzing which has the potential to harm vital organs if done improperly (Kerr 2001;Nguyen et al 2009;Drumhiller et al 2014).…”

“…Barotrauma is also relatively understudied (Lawrence et al 2022;Louison et al 2023), especially for physostomous species in winter conditions. In my immediate recovery experiment, I quantified the first barotrauma signs to be reported in lake trout during the winter.…”