Anders Galatius

Acoustic tags on wild harbour porpoises reveal context-specific reactions to ship noise

Research output: Contribution to conferenceConference abstract for conferenceResearch

While cetacean auditory systems have evolved to cope with underwater noise from natural sources, there is a growing concern that anthropogenic noise may disrupt the behavior, impair the hearing or compromise the general health of cetaceans. Evaluation of the effect of anthropogenic sounds on harbour porpoises is primarily based on presence-absence studies before-during-after industrial activities. Little is known about the noise free-ranging animals are exposed to and how individuals react to specific noise sources.

We deployed archival multi-sensor DTag3 tags on six wild harbour porpoises to study noise exposure and behaviour in the highly trafficked Danish Straits. The suction-cup attached tags provided continuous recordings for up to 24 hours, while logging stereo sound (500kHz), triaxial magnetometry, acceleration and depth (625Hz).

The movement and noise exposure of the animals in relation to ships were estimated using sensors on the tag and the AIS positioning system carried by larger vessels. The porpoises were exposed to low-to-moderate vessel noise for the majority of recordings, with occasional high levels extending for >1 hour.

The highest received levels reached 138 dB re 1μPa m-weighted rms sound pressure level. At 125 kHz, received third-octave rms levels reached 121 dB re 1μPa, which suggests potential for masking porpoise echolocation and communication. The animals showed context-dependent reactions to noise including cessation of foraging and echolocation, logging at the surface, or sustained energetic fluking.The avoidance responses to the ship noise exposure, suggests strong implications for foraging efficiency,energy expenditure and stress impacts. Finally, it may increase susceptibility to by-catch bydistraction, masking and reduced detection of fishermen’s nets.

Original languageEnglish
Publication year2015
Publication statusPublished - 2015
Event18. Danske Havforskermøde - GEUS, Copenhagen, Denmark
Duration: 28 Jan 201530 Jan 2015

Conference

Conference18. Danske Havforskermøde
LocationGEUS
CountryDenmark
CityCopenhagen
Period28/01/201530/01/2015

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