The post-spawning movement and diel activity of rainbow trout, Salmo gairdneri, as determined by ultrasonic tracking in Batchawana Bay, Lake Superior, Ontario.

Abstract

Diel activity changes dramatically from a peak between 0600-0900 h to an irregular low level between 1600-0400 h. Overall diel swimming speed was 0.22 body lengths per second (BL s-1). Swimming speeds measured between consecutive position fixes were largely (73-76% of observations) <1 BLs-1 but swimming speeds of up to 8 BL s-1 occurred during the dawn period of peak activity. Males re-entered the spawning stream almost 3 times more frequently than did females. All fish not re-entering the spawning stream oriented to the shoreline were usually within 150 m of shore and remained in shallow water (<5m) until at least mid-June. Most fish, c90%, travelled north along the shoreline. The choice of direction may have been influenced by wind-generated currents in the bay. -from Sport Fishery Abstracts