Post-release locomotor activity of ice-angled Northern Pike

The study of the stress response and subsequent recovery of angled fish can inform the development of best practices for catch-and-release (C&R) angling. While large bodies of research exist detailing the impacts of C&R during warm periods of the year (i.e., open water), relatively few studies have been conducted during the colder months when sub-freezing temperatures are prominent, and anglers are targeting fish through the ice. Most research on ice angling has focused on conventional physiological stress indicators (i.e., blood cortisol, lactate, glucose) with comparatively little known about potential post-release behavioral impairments. To that end, we evaluated the consequences that ice angling C&R has on the post-release locomotor activity of Northern Pike (Esox lucius). Over 7 days of ice-angling, 20 Northern Pike were captured, air exposed for 0, 2, or 5 min and then harnessed with a biologger (tri- axial accelerometer) prior to release. The post-release locomotor activity of the Northern Pike was then recorded for 30 min before the biologger was retrieved using a quick release system. It was determined that while overall locomotor activity decreased over time during the post-release monitoring period, there was no difference between air exposure treatment groups in locomotor activity. These data reveal that Northern Pike exhibit similar locomotor activity whether they are air exposed in winter for 0, 2, or 5 min. Nonetheless, there may still be further long-term stresses that were not measured within the time frame of this experiment. Therefore, we recommend anglers fish in a way that minimizes air exposure and as a result reduces the potential for sublethal impairments or mortality.