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 6 h 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 0.5 h post-angling. Loss of orientation was the most common reflex impairment (84% of fish) 4 h 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 420 s before assessment (3.4% mortality). For fish air-exposed for 300 s or more, 14% lost orientation during immediate assessment. Bloating occurred in 20% of fish air-exposed for 60 s. An air exposure duration of 420 s significantly impaired reflexes. Recreationally caught lake trout show behavioural and physiological impairment with such impairments magnified by extended air exposure.