Quantifying behavioural impairment as a proxy for physiological stress to improve welfare of imperilled white sturgeon (Acipenser transmontanus) during routine sampling efforts

The white sturgeon (Acipenser transmontanus) is a large-bodied imperilled fish species of significant conservation interest in western North America. Since 2002, hatchery-origin fish have been released in the Upper Columbia River’s Transboundary Reach to support population recovery, and captured with baited setlines as part of routine monitoring of fish health and reproductive status. Here, we investigated whether the use of increasingly long and intensive sampling protocols was associated with differences in short-term post-release behaviour derived from biologger data. In addition to basic sampling (e.g., body measurements, fin clipping), we exposed hatchery-origin juveniles to blood sampling; blood sampling and ultrasonography for sex determination; and blood sampling, ultrasonography, and gonadal biopsy surgeries. We also quantified the stress of setline-captured fish prior to processing using whole-blood glucose and lactate and compared these values (mean ± SD glucose = 4.2 ± 1.4 mmol/l; lactate = 5.9 ± 3.0 mmol/l) to those from an angled baseline group (glucose 1.5 ± 0.2 mmol/l; most lactate < 0.3 mmol/l). Overall, sampling regime did not affect tri-axial accelerometer-derived post-release locomotor activity (overall and vectorized dynamic body acceleration) or depth preferences over the course of 10 min trials, and the stress induced by setline capture and retrieval appears to be a major contribution to the total stress experienced by these fish. We offer some recommendations to improve the routine sampling protocols used in management efforts in this system and elsewhere.