Effect of acoustic environment on gilthead sea bream (Sparus aurata): Sea and onshore aquaculture background noise

The present study evaluated the impact of sea background noise (the acoustic environment of the offshore aquaculture system) and onshore aquaculture system's ambient noise on the welfare of gilthead sea bream juveniles (Sparus aurata) through primary, secondary (biochemical and haematological indexes) and tertiary (growth performances) stress responses. The experiment lasted 120 days during which two different playlists of acoustic stimuli were projected inside six experimental tanks (each condition was replicated in three tanks). Offshore aquaculture noise conditions were recreated as the typical acoustic field in proximity of an offshore sea cage for fish farming using a random sequence of quiet sea background and boat noises. The acoustic field inside an onshore open concrete tank for fish farming represented the onshore aquaculture noise conditions. The other three tanks were used as a control condition without acoustic projection. The weights and lengths of fish exposed to offshore aquaculture noise were higher than the specimens in the control and onshore aquaculture groups. Moreover, higher levels of serum cortisol, glucose, red blood cell count, haematocrit value and haemoglobin content and lower levels of white blood cells were recorded in fish groups from the control and onshore treatments. These results allow us to hypothesise that offshore aquaculture noise and the sea soundscape in particular positively influence growth performance and could reduce stress and improve the welfare of the sea bream. (C) 2013 Elsevier B.V. All rights reserved.