OBSERVATIONS OF SWIMMING ABILITY IN SHOVELNOSE STURGEON (SCAPHIRHYNCHUS-PLATORYNCHUS)

Swimming performance and behavior of five adult (57-69 cm fork length) shovelnose sturgeon, Scaphirhynchus platorynchus, were studied in a 9 45-L swim tunnel at 16 degrees C. Fifteen-minute critical swimming spe eds ranged from 65 to 116 cm s(-1). Sturgeon swam volitionally at low speeds (5-30 cm s(-1)), but at higher speeds (40-120 cm s(-1)) sturgeo n alternated between active swimming and appressing themselves to the bottom of the tunnel. This second behavior is enhanced by sturgeon mor phology - streamlined body shape, flat rostrum, and large pectoral fin s. It allows shovelnose sturgeon to exploit river bottoms as a refugia from current and maintain position in high velocities.