Effect of 3-h copper exposure on the response of juvenile coho to an alarm pheromone Behavioral responses of two juvenile coho salmon to a chemical alarm stimulus. Prior to placement in the observation tank, the fish were exposed for 3 hours to either normal hatchery water (TOP) or 10 µg/L dissolved copper (BOTTOM). Movement of the fish within the observation tank was recorded with two cameras (left and front views). This allows a computer to triangulate the location of the fish in three dimensions. Notice the similarity in spontaneous swimming rate prior to the addition of alarm pheromone (GREEN LIGHT). After the addition of the alarm pheromone (RED LIGHT), the control fish displays a stereotypical predator avoidance response (freezing). The copper-exposed fish, however, fails to react to the chemical cue, indicative of a loss of olfactory sensitivity. Under natural conditions, copper-exposed fish may be more vulnerable to predation.

last modified 02/16/2007
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