Behavioural responses of common dolphins to naval sonar

Despite strong interest in how noise affects marine mammals, little is known for the most abundant and commonly exposed taxa. Social delphinids occur in groups of hundreds of individuals that travel quickly, change behaviour ephemerally and are not amenable to conventional tagging methods, posing ch...

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Main Authors: Brandon L. Southall, John W. Durban, John Calambokidis, Caroline Casey, James A. Fahlbusch, Holly Fearnbach, Kiirsten R. Flynn, Selene Fregosi, Ari S. Friedlaender, Samantha G. M. Leander, Fleur Visser
Format: Article
Language:English
Published: The Royal Society 2024-10-01
Series:Royal Society Open Science
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Online Access:https://royalsocietypublishing.org/doi/10.1098/rsos.240650
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author Brandon L. Southall
John W. Durban
John Calambokidis
Caroline Casey
James A. Fahlbusch
Holly Fearnbach
Kiirsten R. Flynn
Selene Fregosi
Ari S. Friedlaender
Samantha G. M. Leander
Fleur Visser
author_facet Brandon L. Southall
John W. Durban
John Calambokidis
Caroline Casey
James A. Fahlbusch
Holly Fearnbach
Kiirsten R. Flynn
Selene Fregosi
Ari S. Friedlaender
Samantha G. M. Leander
Fleur Visser
author_sort Brandon L. Southall
collection DOAJ
description Despite strong interest in how noise affects marine mammals, little is known for the most abundant and commonly exposed taxa. Social delphinids occur in groups of hundreds of individuals that travel quickly, change behaviour ephemerally and are not amenable to conventional tagging methods, posing challenges in quantifying noise impacts. We integrated drone-based photogrammetry, strategically placed acoustic recorders and broad-scale visual observations to provide complementary measurements of different aspects of behaviour for short- and long-beaked common dolphins. We measured behavioural responses during controlled exposure experiments (CEEs) of military mid-frequency (3–4 kHz) active sonar (MFAS) using simulated and actual Navy sonar sources. We used latent-state Bayesian models to evaluate response probability and persistence in exposure and post-exposure phases. Changes in subgroup movement and aggregation parameters were commonly detected during different phases of MFAS CEEs but not control CEEs. Responses were more evident in short-beaked common dolphins (n = 14 CEEs), and a direct relationship between response probability and received level was observed. Long-beaked common dolphins (n = 20) showed less consistent responses, although contextual differences may have limited which movement responses could be detected. These are the first experimental behavioural response data for these abundant dolphins to directly inform impact assessments for military sonars.
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spelling doaj-art-d5177e7bc3fa4624a72254bf095d36c72025-08-20T02:09:47ZengThe Royal SocietyRoyal Society Open Science2054-57032024-10-01111010.1098/rsos.240650Behavioural responses of common dolphins to naval sonarBrandon L. Southall0John W. Durban1John Calambokidis2Caroline Casey3James A. Fahlbusch4Holly Fearnbach5Kiirsten R. Flynn6Selene Fregosi7Ari S. Friedlaender8Samantha G. M. Leander9Fleur Visser10Southall Environmental Associates, 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USASouthall Environmental Associates, 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USACascadia Research Collective, 218 ½ W 4th Ave, Olympia, WA 98501, USASouthall Environmental Associates, 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USACascadia Research Collective, 218 ½ W 4th Ave, Olympia, WA 98501, USASR3 - SeaLife Response, Rehabilitation and Research, 2003 S. 216th St. #98811, Des Moines, WA 98198, USACascadia Research Collective, 218 ½ W 4th Ave, Olympia, WA 98501, USASouthall Environmental Associates, 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USASouthall Environmental Associates, 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USASouthall Environmental Associates, 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USAKelp Marine Research, Hoorn, CJ 1624, The NetherlandsDespite strong interest in how noise affects marine mammals, little is known for the most abundant and commonly exposed taxa. Social delphinids occur in groups of hundreds of individuals that travel quickly, change behaviour ephemerally and are not amenable to conventional tagging methods, posing challenges in quantifying noise impacts. We integrated drone-based photogrammetry, strategically placed acoustic recorders and broad-scale visual observations to provide complementary measurements of different aspects of behaviour for short- and long-beaked common dolphins. We measured behavioural responses during controlled exposure experiments (CEEs) of military mid-frequency (3–4 kHz) active sonar (MFAS) using simulated and actual Navy sonar sources. We used latent-state Bayesian models to evaluate response probability and persistence in exposure and post-exposure phases. Changes in subgroup movement and aggregation parameters were commonly detected during different phases of MFAS CEEs but not control CEEs. Responses were more evident in short-beaked common dolphins (n = 14 CEEs), and a direct relationship between response probability and received level was observed. Long-beaked common dolphins (n = 20) showed less consistent responses, although contextual differences may have limited which movement responses could be detected. These are the first experimental behavioural response data for these abundant dolphins to directly inform impact assessments for military sonars.https://royalsocietypublishing.org/doi/10.1098/rsos.240650noisecetaceansmid-frequency sonarDelphinuscontrolled exposure experiment
spellingShingle Brandon L. Southall
John W. Durban
John Calambokidis
Caroline Casey
James A. Fahlbusch
Holly Fearnbach
Kiirsten R. Flynn
Selene Fregosi
Ari S. Friedlaender
Samantha G. M. Leander
Fleur Visser
Behavioural responses of common dolphins to naval sonar
Royal Society Open Science
noise
cetaceans
mid-frequency sonar
Delphinus
controlled exposure experiment
title Behavioural responses of common dolphins to naval sonar
title_full Behavioural responses of common dolphins to naval sonar
title_fullStr Behavioural responses of common dolphins to naval sonar
title_full_unstemmed Behavioural responses of common dolphins to naval sonar
title_short Behavioural responses of common dolphins to naval sonar
title_sort behavioural responses of common dolphins to naval sonar
topic noise
cetaceans
mid-frequency sonar
Delphinus
controlled exposure experiment
url https://royalsocietypublishing.org/doi/10.1098/rsos.240650
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