Stress Response and Habituation to Motorboat Noise in Two Coastal Fish Species in the Bothnian Sea.

ABSTRACT

The effect of motorboat noise on stress responsiveness in Eurasian perch and roach was tested in field enclosure experiments. Perch showed elevated cortisol levels after one 30-min noise exposure but not when exposed to noise repeatedly for 11 days. Roach had higher cortisol levels when exposed to noise than without noise when short- and long-term experiments were pooled. Both species had more cortisol in enclosures with mixed species compared with single-species enclosures. Both species also had higher cortisol levels in the short-term compared with the long-term experiment. Thus, a stress effect of motorboat noise may decrease with time due to habituation.