Population-specific ranges of oceanic migration for adult Atlantic salmon (Salmo salar) documented using pop-up satellite archival tags

Abstract

Pop-up satellite archival tags identified differences in oceanic migration of Atlantic salmon (Salmo salar) kelts from three distinct Canadian populations. Kelts from two endangered populations were restricted to coastal areas near home rivers, whereas kelts from a persisting nearby population migrated to the Labrador Sea and towards the Flemish Cap. Kelts spent most time near the surface (0–5 m), but coastal migrants undertook repeated daytime dives (10–40 m), associated with feeding, upon marine entry and progress was slow (8–23 km·day−1). Distant migrants moved rapidly along the continental shelf (10–50 km·day−1) against prevailing ocean currents, remaining near the surface, except for deep dives (100–1000 m) when crossing ocean channels and at the shelf edge. Home range water temperatures (0–15 °C) indicated that kelts avoided warmer adjacent areas in summer. Kelts did not avoid cold coastal habitat (0–5 °C) in winter, but avoided the surface layers. Kelt migration mimicked that of postsmolts of similar origins, with water temperature acting as a directive or controlling factor. Containment of kelts from endangered populations in coastal habitat was probably responsible for the disappearance of repeat spawners.