Angler experience and seasonal effects on the response of lake sturgeon (Acipenser fulvescens) to catch and release angling

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Date
2020
Authors
Mullen, Eric
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Abstract
Lake sturgeon (Acipenser fulvescens), once widespread throughout North America, are now considered endangered in much of their natural range. However, there are areas where a presumably strong population has resulted in recreational fisheries, with catch and release (C&R) being common practice. Here, we evaluate physiological and behavioural impairment of lake sturgeon following C&R angling. Fish were captured by volunteer anglers and transferred to a holding pen in the Winnipeg River to recover and facilitate sampling post-angling. Measured physiological traits included blood osmolality, haematocrit, pH, glucose, cortisol, estradiol, and testosterone. Behavioural impairment was measured as a binary score using Reflex Action Mortality Predictors (RAMP) in addition to ventilation rate. The effect of season and angler experience on these measured variables were assessed. C&R angling resulted in an immediate physiological stress response and behavioural impairment in all lake sturgeon, regardless of treatment. Though generally we observed a recovery of changes in the acid-base balance, ion balance and reflex impairment by 24 h. Cortisol and glucose were elevated throughout the recovery period, possibly indicating interactive stressors of holding and repeat sampling. Sex steroid concentrations were highly variable, and indicated no clear response to C&R. Angling in the summer period caused increased ventilation rate and decreased osmolality at all timepoints, compared to spring angling. Novice anglers caused higher reflex impairment in sturgeon immediately post-capture compared to experienced anglers. This is the first study to examine the response of wild lake sturgeon to C&R. The data show an apparent resilience of lake sturgeon to C&R, and can be used to assess the validity of C&R as a management strategy in the conservation of lake sturgeon.
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Keywords
Lake Sturgeon, Catch and release, Reflex impairment, Stress, Angler experience
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