Sperm whale foraging behaviour during pulsed and continuous navy sonar exposures

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  • Saana Isojunno, Sea Mammal Research Unit, Scottish Oceans Institute, East Sands, University of St Andrews, Storbritannien
  • Paul Wensveen, Faculty of Life and Environmental Sciences, University of Iceland, Island
  • Frans-Peter Lam, Netherlands Organisation for Applied Scientific Research (TNO), Holland
  • Peter Kvadsheim, Norwegian Defence Research Establishment, Norge
  • Alexander von Benda-Beckmann, Netherlands Organisation for Applied Scientific Research (TNO), Holland
  • Lucía Martina Martín López, Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Storbritannien
  • Lars Kleivane, LKARTS, Norge
  • Eilidh Siegal, Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Storbritannien
  • Jacqueline Bort, U.S. Naval Facilities Engineering Command, USA
  • Benjamin Benti, Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Storbritannien
  • Peter Tyack, Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Storbritannien
  • Viivi Pöyhönen
  • ,
  • Kalliopi Gkikopoulou, Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Storbritannien
  • Ilias Foskolos
  • Miguel Neves, Fisheries and Oceans Canada, Canada
  • Nicoletta Biassoni, University of St Andrews, Storbritannien
  • Patrick Miller, Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Storbritannien
Anthropogenic noise sources range from intermittent to continuous, with seismic and navy sonar technology developing applications with more continuous transmission schemes. Continuous active sonar (CAS) may be used at a lower source level than traditional pulsed active sonar (PAS), but with potential for greater cumulative exposure over time and increased auditory masking concern. We conducted at-sea experiments to contrast the relative effects of navy PAS vs. CAS on sperm whale behaviour using animal-attached sound and movement-recording tags (n=16 individuals) in Norway. Changes in foraging effort and proxies for foraging success and cost during sonar exposures were assessed while accounting for baseline variation (individual effects, time of day, bathymetry, blackfish [killer whale or pilot whale] presence) in generalised additive mixed models. We found no reduction in time spent foraging during exposures to medium-level PAS (MPAS) transmitted at the same source sound pressure level (SPL) as CAS. In contrast, time spent in a non-foraging active behaviour state increased by a factor of 2.4 and 3.3 during CAS and higher source level PAS (HPAS) (Wald test, F=9.9-19.8, p<0.003) at similar received sound exposure levels (SEL; squared pressure integrated over signal duration), providing clear support for received SEL over SPL as the response predictor. The responses were relatively short in duration and less than 8% of the individual-average time budget was affected. On-going analysis of acoustic indicators of prey search (clicking depth, inter-click intervals) and prey capture attempts (buzz click rates, duration) will test for changes in echolocation behaviour that may indicate responses to auditory masking. The importance of exposure context including the potential impact of presence of blackfish is discussed. Our results highlight the benefit of using SEL to account for noise sources with different signal duration and/or duty cycle, and the need to consider masking effects for more continuous sources.
OriginalsprogEngelsk
Udgivelsesår9 dec. 2019
StatusUdgivet - 9 dec. 2019
BegivenhedWorld Marine Mammal Conference: Barcelona 2019 - Centre de Convencions Internacional de Barcelona , Barcelona, Spanien
Varighed: 7 dec. 201912 dec. 2019
https://www.wmmconference.org/

Konference

KonferenceWorld Marine Mammal Conference
LokationCentre de Convencions Internacional de Barcelona
LandSpanien
ByBarcelona
Periode07/12/201912/12/2019
Internetadresse

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