Measurement of burst swimming performance in wild Atlantic salmon (Salmo salar L.) using digital telemetry

Swimming performance of wild Atlantic salmon (Salmo salar L.) was investigated in an experimental flume using coded radio signals. To calculate swimming speed, distance moved and time elapsed were measured with a digital spectrum processor using near real-time spectrum analysis. This device was designed to be used in a coprocessing arrangement with a receiver, thereby providing pulse position code discrimination, verification and continuous data storage. Radio-tagged adults (48.3 to 54.8 cm long) voluntarily swam against water velocities, ranging from 1.32 to 2.85 m s(-1), in an 18 m long flume at a mean water temperature of 10.1 +/- 1.6 degrees C. At water velocities of 1.32-1.55 m s(-1), individuals successfully ascended the flume at swimming speeds of 1.61-2.55 m s(-1), or 3.30-4.79 body lengths per second (l s(-1)), respectively. At high water velocities ranging from 1.92 to 2.85 m s(-1), individual swimming speeds increased from 2.55 to 3.60 m s(-1), or 4.94-7.27 l s(-1), respectively. However, above a threshold value of 1.92 m s(-1), individuals traversed shorter distances and were unable to ascend the flume. The highest swimming speed observed was 4.13 m s(-1) or 8.35 l s(-1). The results of this study indicate that in addition to its applicability in the determination of burst swimming speeds, digital telemetry could prove a useful tool in the design and evaluation of future fishways and culvert installations. (C) 1998 John Wiley & Sons, Ltd.