Physiological stress response, reflex impairment and delayed mortality of white sturgeon Acipenser transmontanus exposed to simulated fisheries stressors

Montana F McLean; Kyle C Hanson; Steven J Cooke; Scott G Hinch; David A Patterson; Taylor L Nettles; Matt K Litvak; Glenn T Crossin

doi:10.1093/conphys/cow031

Physiological stress response, reflex impairment and delayed mortality of white sturgeon Acipenser transmontanus exposed to simulated fisheries stressors

Conserv Physiol. 2016 Aug 26;4(1):cow031. doi: 10.1093/conphys/cow031. eCollection 2016.

Authors

Montana F McLean¹, Kyle C Hanson¹, Steven J Cooke², Scott G Hinch³, David A Patterson⁴, Taylor L Nettles⁴, Matt K Litvak⁵, Glenn T Crossin¹

Affiliations

¹ Department of Biology , Dalhousie University , Halifax, Nova Scotia , Canada B3H 4R2.
² US Fish and Wildlife Service , Abernathy Fish Technology Center , Longview , Washington, USA 98632.
³ Department of Biology , Carleton University , Ottawa, Ontario , Canada K1S 5B6.
⁴ Department of Forest and Conservation Sciences , University of British Columbia , Vancouver , British Columbia , Canada V6T 1Z4.
⁵ Fisheries and Oceans Canada , Cooperative Resource Management Institute , School of Resource and Environmental Management , Simon Fraser University , Vancouver , British Columbia , Canada V5A 1S6.

Abstract

White sturgeon (Acipenser transmontanus) are the largest freshwater fish in North America and a species exposed to widespread fishing pressure. Despite the growing interest in recreational fishing for white sturgeon, little is known about the sublethal and lethal impacts of angling on released sturgeon. In summer (July 2014, mean water temperature 15.3°C) and winter (February 2015, mean water temperature 6.6°C), captive white sturgeon (n = 48) were exposed to a combination of exercise and air exposure as a method of simulating an angling event. After the stressor, sturgeon were assessed for a physiological stress response, and reflex impairments were quantified to determine overall fish vitality (i.e. capacity for survival). A physiological stress response occurred in all sturgeon exposed to a fishing-related stressor, with the magnitude of the response correlated with the duration of the stressor. Moreover, the stress from exercise was more pronounced in summer, leading to higher reflex impairment scores (mean ± SEM, 0.44 ± 0.07 and 0.25 ± 0.05 in summer and winter, respectively). Reflex impairment was also correlated with lactate concentrations (e.g. physiological stress measures related to exhaustive exercise; r = 0.53) and recovery time (r = 0.76). Two mortalities occurred >24 h after the cessation of treatment in the summer. Given that natural habitats for white sturgeon can reach much higher temperatures than those presented in our study, we caution the use of this mortality estimate for a summer season, because latent mortality could be much higher when temperatures exceed 16°C. This is the first experiment investigating the physiological disturbance and reflex impairment of capture and release at two temperatures on subadult/adult white sturgeon, and the results suggest that future research needs to examine the longer term and fitness consequences of extended play and air exposure times, because these are largely unknown for wild populations.

Keywords: Catch-and-release angling; reflex impairment; stress physiology; temperature; white sturgeon.