Movements of Lake Trout in U.S. Waters of Lake Superior, 1973–2001

Abstract

We analyzed tag–recapture data for lake trout Salvelinus namaycush from the U.S. waters of Lake Superior to determine whether (1) mean movement distance varied among management units, (2) mean movement distance and recapture percentage differed between spawning and nonspawning recapture seasons, (3) percentages of movements to the east and west were similar, and (4) movement distance varied with body length, sex, origin, age, or time at liberty. Mean distance moved by lake trout varied among management units. Mean movement distance was lower for fish recaptured during the spawning season than for fish recaptured during the nonspawning season for three of four tagged populations, and the spatial distribution of recapture percentages differed between recapture seasons. On average, lake trout recaptured during the nonspawning season traveled 42 km while at liberty. Lake trout tagged in two of six management units emigrated to the east and west in equal percentages, but lake trout did not emigrate from the tagging unit to other management units at equal percentages. Movement distance varied significantly with time at liberty for lake trout tagged in one management unit, but did not vary significantly with length, age, time at liberty, sex, or origin for those tagged in other management units. Lake Superior fishery managers can use our results to account for lake trout movements between management units when calculating sustainable harvest levels with catch-at-age modeling.