Temps d'ajustement de la flottabilité des saumons atlantiques (Salmo salar) d'élevage et flottabilité comparée de saumons atlantiques d'élevage et sauvages

Abstract

We determined the time of adjustment of buoyancy of juvenile hatchery-reared Atlantic salmon (Salmo salar) and investigated whether if their higher position off the substratum, compared with wild fish, might better result from a higher buoyancy. In flowing water, hatchery-reared Atlantic salmon adjust their buoyancy within 24 h. No difference in buoyancy exists between juvenile hatchery-reared and wild Atlantic salmon in still water. However, juvenile hatchery-reared Atlantic salmon are more buoyant in flowing water than wild Atlantic salmon. Even after 3 mo in a stream, the buoyancy of juvenile hatchery-reared Atlantic salmon did not change. Acquired hatchery behaviour appears to be responsible for their difference in buoyancy.