Stress response to anthropogenic noise in Atlantic cod Gadus morhua L.

Abstract

The potential effects of anthropogenic noise on the physiology of Atlantic cod have not been well described. The aim of the present study was to investigate the impact of anthropogenic noise on Atlantic cod stress response using cortisol as a biomarker as well as on broodstock spawning performance. Results showed that artificial noise consisting of a linear sweep from 100 to 1000Hz can induce a transient and mild cortisol elevation with a clear noise intensity dose response. In all cases plasma levels returned to baseline levels <1h post sound exposure. Daily exposure to a similar intensity and frequency noise range applied habitually to a broodstock population during the spawning window resulted in a significant reduction in total egg production and fertilisation rates thus reducing the total production of viable embryos by over 50%. In addition, a significant negative correlation between egg cortisol content and fertilisation rate was observed. These results confirm that cod can perceive noise generated within a frequency range of 100-1000Hz and display a heightened cortisol plasma level. In addition, anthropogenic noise can have negative impacts on cod spawning performances.