White sturgeon are the largest freshwater fish in North America and are the focus
of an intense catch-and-release (C&R) fishery; the effects are largely unknown. We
assessed the effect of fight and handling time, water temperature, river discharge
rate, and fish size on physiological and reflex impairment responses of wild white
sturgeon to angling. Sixty of these fish were tagged with acoustic transmitters to
assess survival and post-release behaviour. Survival was high (100%). Water temperature
and discharge influenced post-capture blood physiology. Specifically, lactate, chloride,
and cortisol concentrations were elevated in individuals fought longer, and captured
at higher water temperatures and river discharge. Cortisol was affected by fish size,
with lower concentrations found in larger individuals. Only lactate and chloride were
positively related to reflex impairment scores. Post-release movements were correlated
with physiological state, fight characteristics and the environment. Specifically,
higher blood lactate and chloride and those with longer fight times moved shorter
distances after release. Contrastingly, higher levels of circulating glucose and potassium,
as well as larger fish captured during periods of high discharge moved longer distances.
Sturgeon tended to move shorter distances and at slower rates when reflex impairment
was high, although reflex impairment in general did not explain a significant proportion
of the variance in any movement metric. Our results show intriguing variance in the
physiological and behavioural response of individual white sturgeon to C&R angling,
with some degree of environmental dependence, and highlights the importance of understanding
drivers of such variation when managing fisheries.