Critical Swimming Speed and Behavior of Juvenile Shovelnose Sturgeon and Pallid Sturgeon

The swimming performance of hatchery-reared, juvenile shovelnose sturgeon Scaphirhynchus platorynchus and pallid sturgeon S. albus was studied in a laboratory swim tunnel at 20°C and 10°C. The mean 30-min critical swimming speed was not significantly different between species at either temperature (36.9 cm/s for shovelnose sturgeon and 35.9 cm/s for pallid sturgeon at 20°C, 19.4 cm/s for shovelnose sturgeon and 15.0 cm/s for pallid sturgeon at 10°C). Free swimming (swimming without contact with the substrate) was observed less than 18% of the time at speeds greater than 15 cm/s. As speed increased, pallid sturgeon swam significantly less in the water column at 20°C; however, speed had no effect on percent free swimming among shovelnose sturgeon at 20°C. The results of this study indicate that, over the temperature and size range tested, shovelnose sturgeon and pallid sturgeon probably do not segregate in rivers due to different swimming or station-holding abilities