Understanding the consequences of intermittent and repeated air exposure events on Bluegill in the context of recreational fishing

ABSTRACT Objective It is common for recreational anglers to expose fish to air during handling and admiration, leading to a variety of sublethal consequences, with potential for mortality if thresholds are exceeded. To date, however, there has been no research on the extent to which intermittent air exposure versus a single continuous air exposure period affects fish condition or survival. The objective of our study was to address that issue using Bluegill Lepomis macrochirus as a model by assessing the effect of different durations of intermittent air exposure periods on their immediate reflex impairment prior to release and their short-term survival. Methods We angled Bluegill and exposed them to nine different air exposure treatments (including relevant controls), some with even intermittent air exposure (e.g., 10 s water/air) and others with uneven intermittent air exposure (e.g., 90 s air/10 s water), until a total of 180 s of air exposure was achieved. We then tested each fish for equilibrium status, immediate and delayed (12 h later) burst reflex response, and mortality over a 12-h holding period. Results The control fish had negligible reflex impairments, whereas the fish that were exposed to air had consistent reflex impairment independent of the air exposure regime. Additionally, smaller fish were more prone to mortality, suggesting that more care needs to be given to smaller Bluegill (total length <150 mm) during a capture event. Conclusions These results suggest that accumulated air exposure of 180 s, even if intermittent, can cause reflex impairment in Bluegill. Our work also suggests that there is functionally no difference between continuous and intermittent air exposure in the context that was assessed here.