Physiological and behavioural consequences of catch-and-release angling on northern pike (Esox lucius L.)

We examined the physiological and behavioural consequences of, and recovery from, catch-and-release related stressors using a combined laboratory and field study in northern pike (Esox lucius L.). A laboratory experiment was conducted to investigate the recovery dynamics of physiological indicators of stress resulting from a simulated angling event resulting in exhaustion, with and without additional air exposureof 300 s. In addition, a field study using a combination of physiological and behavioural assessment was conducted to assess the long-term consequences of exhaustive exercise and various air exposure durations. Exhaustive exercise for 60 s led to increased muscle lactate, decreased tissue energy stores,and alterations in plasma ionic status. Recovery from physiological disturbance was rapid with all physiological variables except plasma glucose returning to baseline levels after 6 h. The recovery profile was largely unaffected by air exposure of 300 s that simulated extended de-hooking time. The field component of our study verified the impact of exhaustive exercise on blood lactate values, but did not detect any impact of air exposure varying between 0 s and 300 s on physiological stress indicators. However, pike exposed to air for 300 s were behaviourally impaired in the first hour post-release indicating that despite limited effects on physiological status air exposure resulted in significant impairment of organismal performance. Behavioural patterns returned to normal within several hours. In a three-week post-release monitoring period no mortality occurred. Our results emphasize that angling-induced stressors result in physiological and behavioural disturbances, but that recovery is quick. This suggests that pike are relatively resilient to catch-and-release related stressors but air exposure durations should be kept < 300 s to minimize behavioural impairment.