Lake trout reflex impairment and physiological status following ice-angling

Abstract

We examined behaviour and physiology of lake trout (Salvelinus namaycush) following ice-angling. Fish were ice-angled and placed in a water-filled tub for 0.5, 4, and 6h to recover (n=19). Reflex impairment and physiological status were assessed repeatedly for every individual. Longer fight times lead to higher lactate and glucose, and lower extracellular pH 0.5h post-angling. Loss of orientation was the most common reflex impairment (84% of fish) 4h post-angling. Mortality (36.8%) was observed during the study; however, variation in handling, barotrauma, and issues with sampling may have confounded angling effects. To determine if barotrauma impacted impairment and mortality, lake trout at a later sampling date (n=29) were exposed to air for either 60, 120, 180, 240, 300, or 420s before assessment (3.4% mortality). For fish air exposed for 300s or more, 14% lost orientation during immediate assessment. Bloating occurred in 20% of fish air exposed for 60s. An air exposure duration of 420s significantly impaired reflexes. Recreationally caught lake trout show behavioural and physiological impairment with such impairments magnified by extended air exposure.