MEPS 355:235-246 (2008)  -  DOI: https://doi.org/10.3354/meps07239

Active migration of wild Atlantic salmon Salmo salar smolt through a coastal embayment

Richard D. Hedger1,*, François Martin1, Daniel Hatin2, François Caron3, Fred G. Whoriskey4, Julian J. Dodson1

1Département de Biologie, Université Laval, Québec, Québec G1K 7P4, Canada
2Direction de la Recherche sur la Faune, Ministère des Ressources Naturelles et de la Faune du Québec, Longueil, Québec J4K 2T5, Canada
3Direction de la Recherche sur la Faune, Ministère des Ressources Naturelles et de la Faune du Québec, Jonquière, Québec G7X 8L6, Canada
4Atlantic Salmon Federation, PO Box 5200, St. Andrews, New Brunswick E5B 3S8, Canada

ABSTRACT: Migration patterns of wild Atlantic salmon Salmo salar smolt were examined in a coastal embayment in the Gaspé peninsula of Québec, Canada. Twenty-four smolt in 2005 and 30 in 2006 were tagged with coded ultrasonic transmitters, and their migration throughout the bay was monitored using an array of fixed VR2 hydrophone receivers. Migration patterns were complex, with some smolt taking a direct route through the coastal embayment and others repeatedly changing direction over short spatial and temporal scales. Migration was mainly an active process with an overall outward (seaward) migration in the face of an inward residual circulation. Swimming direction was mainly outward during nocturnal inflowing currents but was more dispersed during daytime and nocturnal outflowing currents; swimming speed was greater during daytime than during nighttime. This pattern was consistent with smolt migrating offshore nocturnally and using daytime for prey detection and predator avoidance. Salinity had a strong effect: exposure to more saline waters caused increased swimming speeds. These observations are consistent with the hypothesis that smolt exploit an innate compass to maintain a preferred bearing and that the speed and direction of swimming is controlled by salinity and the diurnal cycle.


KEY WORDS: Salmon smolt migration · Current flow · Salinity gradient · Orientation ·Diurnal migration


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Cite this article as: Hedger RD, Martin F, Hatin D, Caron F, Whoriskey FG, Dodson JJ (2008) Active migration of wild Atlantic salmon Salmo salar smolt through a coastal embayment. Mar Ecol Prog Ser 355:235-246. https://doi.org/10.3354/meps07239

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