Effect of Temperature on Growth, Condition, and Survival of Juvenile Shovelnose Sturgeon

Water temperature plays a key role in determining the persistence of shovelnose sturgeon Scaphirhynchus platorynchus in the wild and is a primary factor affecting growth both in the hatchery and in natural waters. We exposed juvenile shovelnose sturgeon to temperatures from 8°C to 30°C for 87 d to determine the effect of temperature on growth, condition, feed efficiency, and survival. Growth occurred at temperatures from 12°C to 30°C; the optimal temperature predicted by regression analysis was 22.4°C, and the minimum temperature needed for growth was greater than 10.0°C. The maximum feed efficiency predicted by regression analysis was 24.5% at 21.7°C, and condition factor was highest in the 18°C treatment. Mortality was significantly higher at 28°C and 30°C than at lower temperatures but less than 10% across the thermal regimes tested and 0% at 14‐18°C. Mortality was observed at and below 12°C, suggesting that extended periods of low temperature may deplete energy reserves and lead to higher mortality. Rearing juvenile shovelnose sturgeon at temperatures above 24°C reduced the growth rate and feed efficiency and increased mortality. Temperatures in the range 18‐20°C appeared to maximize the combination of condition, growth, and feed efficiency while not increasing thermal stress. This study corroborates field studies suggesting that altered temperature regimes in the upper Missouri River reduce the growth of shovelnose sturgeon. This information may help protect the thermal habitat critical to the species and guide restoration efforts by delineating temperature regime standards for regulated rivers and those affected by hydroelectric facilities and suggesting new criteria for conservation propagation.