Vessel noise cuts down communication space for vocalising fish and marine mammals

TitleVessel noise cuts down communication space for vocalising fish and marine mammals
Publication TypeJournal Article
Year of PublicationSubmitted
AuthorsPutland, R. L., Merchant N. D., Farcas A., and Radford C. A.
JournalGlobal Change Biology
ISBN Number1365-2486
EndNote Rec Number11737
Keywordsacoustics, anthropogenic noise, Automatic Identification System, Balaenoptera edeni, bigeye, bryde's whale, communication space, Pempheris adspersa

Anthropogenic noise across the world's oceans threatens the ability of vocalising marine species to communicate. Some species vocalise at key life stages or whilst foraging, and disruption to the acoustic habitat at these times could lead to adverse consequences at the population level. To investigate the risk of these impacts, we investigated the effect of vessel noise on the communication space of the Bryde's whale Balaenoptera edeni, an endangered species which vocalises at low frequencies, and bigeye Pempheris adspersa, a nocturnal fish species which uses contact calls to maintain group cohesion while foraging. By combining long-term acoustic monitoring data with AIS vessel-tracking data and acoustic propagation modelling, the impact of vessel noise on their communication space was determined. Routine vessel passages cut down communication space by up to 61.5% for bigeyes and 87.4% for Bryde's whales. This influence of vessel noise on communication space exceeded natural variability for between 3.9 - 18.9% of the monitoring period. Additionally, during the closest point of approach of a large commercial vessel, less than 10 km from the listening station, the communication space of both species was reduced by a maximum of 99% compared to the ambient soundscape. These results suggest that vessel noise reduces communication space beyond the evolutionary context of these species and may have chronic effects on these populations. To combat this risk, we propose the application or extension of ship speed restrictions in ecologically significant areas, since our results indicate a reduction in sound source levels for vessels transiting at lower speeds. This article is protected by copyright. All rights reserved.