Diel Movement of Walleye, Stizostedion vitreum vitreum, in West Blue Lake, Manitoba, as Determined by Ultrasonic Tracking

Abstract

Eight walleye (Stizostedion vitreum vitreum) between 2 and 5 yr of age were equipped with ultrasonic transmitters, released, and followed for periods up to 24 h. During the study period, September 24–October 2, 1975, West Blue Lake was thermally stratified. Movement was limited to the homothermous epilimnion, above 10 m, and to the region of steeply sloping bottom of about 5–10 m which was usually within 100 m of shore. Midbasin crossings of the lake were infrequent. Transmitter attachment caused temporary high activity after which a more normal rhythm was apparent with peaks of activity at dusk and dawn. The majority, 86%, of observed swimming speeds were under 1 body length s−1. Since much localized activity, too restricted to measure, was apparent, these observations must be regarded as only approximations of natural activity.