Safer at night

Posted on May 26, 2009

Stocks of Atlantic salmon are declining in the face of a variety of threats, including competition with exotic fish species.   Invasive rainbow trout are aggressive toward Atlantic salmon and force them to leave their refuges, making them more vulnerable to day-active predators.  However, at twilight and at night, trout have no significant effect on salmon behaviour, apparently because aggression is reduced at low light levels.

Reference: Blanchet, S., Loot, G., Bernatchez, L. & Dodson, J.J.  2008. The effects of abiotic factors and intraspecific versus interspecific competition on the diel activity patterns of Atlantic salmon (Salmo salar) fry.  Canadian Journal of Fisheries & Aquatic Sciences 65, 545-1553.

Posted in: behaviour, fish, predation