Atlantic salmon, Salmo salar L., smolts were exposed to environmental levels of the pesticide atrazine in a hatchery, tagged with acoustic transmitters and released into fresh water at the peak of the smolt run. The subsequent movements of the smolts were monitored within the freshwater and immediate coastal zones using an array of acoustic receivers. In laboratory‐based studies, exposure to a 0.1 μg L −1 concentration of atra...