Meeting Abstract

P1.67  Jan. 4  SWIMMING PERFORMANCE AND KINEMATICS OF WILD JUVENILE COHO SALMON: ARE THERE SEX DIFFERENCES? DURFEE, BD*; ANDERSON, CW; RODNICK, KJ; Idaho State University; Idaho State University; Idaho State University andecurt@isu.edu

Swimming performance is a key determinant of behavior and fitness in aquatic animals. For young Pacific salmon, principle locomotory activities relate to feeding, avoidance of predation, and in stream migration to favorable habitats. We initially conducted streamside studies of sustained (critical) swimming speed (Ucrit) using swim tunnel respirometers and fish from the West Fork Smith River, Oregon. This type of swimming is supported by aerobic metabolism and female fish surprisingly performed better than males (Ucrit = 60.2 � 4.8 vs 39.9 � 5.3, n = 15-16). In contrast, sprinting and intermittent movements may be of particular importance to young salmon for predator avoidance. Consequently, the objective of the current study was to measure performance and kinematics of male and female juvenile coho salmon as they swim at increasing velocities, and to identify gait transition from sustained to periodic bursting and coasting. Fish were acclimated in swim tunnels for 30 min at 15�C and 10 cm/sec, and the speed was increased 5 cm/sec every 5 min until we observed the gait transition. Digital videography was used to measure tail-beat duration and frequency, as well as actual velocity and stride length for each speed increment. At the midpoint of each tail-beat, individual frames of the video were extracted to measure overall area of the fish and functional area of the caudal fin. Preliminary data suggest that with varying swimming speeds, juvenile coho salmon increase either tail-beat frequency and or stride length to increase speed. Functional area of the caudal fin can also be modified as swimming speed increases and during gait transitions. These locomotory variables may ultimately affect muscle energetics, feeding ecology, and behavior of juvenile coho salmon. Supported by the Western Ecology Division of EPA.