Passage performance and physiological stress response of adult white sturgeon ascending a laboratory fishway

Our study objective was to test passage performance of adult wild-caught white sturgeon Acipenser transmontanus (123–225 cm TL) in a simulated mid-section of a 24.4-m-long experimental fishway incorporating vertical barriers, a 4% bed slope, and a series of five, paired vertical baffles (with 0.61-m slot widths) to dissipate flowing-water kinetic energy as well as to provide guidance for upstream migration. Fish, in good physical condition, reaching the upstream end of our flume in both the low (50% of the fish) and high (48%) tailwater treatments exceeded that of fish in poor condition (5%). To assist in evaluating performance we examined the physiological stress responses of a small sample of these sturgeon. Blood samples from four, cannulated fish showed post-swimming peaks in hematocrit and plasma cortisol concentrations, compared with pre-swimming and (24-h) post-experiment levels. In addition, plasma pH showed decreases and mean plasma lactate showed increases post-swimming, indicating white-muscle recruitment. Overall, a relatively high percentage of adult white sturgeon in good physical condition, successfully ascended the sturgeon-compatible fishway and displayed burst-swimming-associated stress responses typical of many teleostean fishes, followed by complete recovery after 24 h.