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Thode AM, Blackwell SB. A statistical acoustics approach for estimating population-scale bowhead whale migration speed and direction. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 155:1969-1981. [PMID: 38466044 DOI: 10.1121/10.0025288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 02/25/2024] [Indexed: 03/12/2024]
Abstract
Bowhead whales vocalize during their annual fall migration from the Beaufort Sea to the Bering Sea, but the calling rates of individual animals are so low that tracking an individual trajectory is impractical using passive acoustic methods. However, the travel speed and direction of the migrating population can be inferred on a statistical basis by cross-correlating time sequences of call density measured at two locations spaced several kilometers apart. By using the triangulation abilities of a set of vector sensors deployed offshore the Alaskan North Slope between 2008 and 2014, call density time sequences were generated from 1-km wide and 40-km tall rectangular "zones" that were separated by distances ranging from 3.5 to 15 km. The cross-covariances between the two sequences generate a peak corresponding to the average time it takes for whales to travel between the zones. Consistent westward travel speeds of ∼5 km/h were obtained from four different locations on 6 of the 7 years of the study, independent of whether the zones were separated by 3.5, 7, or 15 km. Some sites, however, also revealed a less prominent eastern movement of whales, and shifts in migration speed were occasionally detectable over week-long time scales.
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Affiliation(s)
- Aaron M Thode
- Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, California 92093-0238, USA
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2
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Elemans CPH, Jiang W, Jensen MH, Pichler H, Mussman BR, Nattestad J, Wahlberg M, Zheng X, Xue Q, Fitch WT. Evolutionary novelties underlie sound production in baleen whales. Nature 2024; 627:123-129. [PMID: 38383781 DOI: 10.1038/s41586-024-07080-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 01/16/2024] [Indexed: 02/23/2024]
Abstract
Baleen whales (mysticetes) use vocalizations to mediate their complex social and reproductive behaviours in vast, opaque marine environments1. Adapting to an obligate aquatic lifestyle demanded fundamental physiological changes to efficiently produce sound, including laryngeal specializations2-4. Whereas toothed whales (odontocetes) evolved a nasal vocal organ5, mysticetes have been thought to use the larynx for sound production1,6-8. However, there has been no direct demonstration that the mysticete larynx can phonate, or if it does, how it produces the great diversity of mysticete sounds9. Here we combine experiments on the excised larynx of three mysticete species with detailed anatomy and computational models to show that mysticetes evolved unique laryngeal structures for sound production. These structures allow some of the largest animals that ever lived to efficiently produce frequency-modulated, low-frequency calls. Furthermore, we show that this phonation mechanism is likely to be ancestral to all mysticetes and shares its fundamental physical basis with most terrestrial mammals, including humans10, birds11, and their closest relatives, odontocetes5. However, these laryngeal structures set insurmountable physiological limits to the frequency range and depth of their vocalizations, preventing them from escaping anthropogenic vessel noise12,13 and communicating at great depths14, thereby greatly reducing their active communication range.
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Affiliation(s)
- Coen P H Elemans
- Sound Communication and Behaviour Group, Department of Biology, University of Southern Denmark, Odense, Denmark.
| | - Weili Jiang
- Department of Mechanical Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Mikkel H Jensen
- Sound Communication and Behaviour Group, Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Helena Pichler
- Department of Behavioral and Cognitive Biology, Faculty of Life Sciences, University of Vienna, Vienna, Austria
| | - Bo R Mussman
- Department of Radiology, Odense University Hospital, Odense, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Jacob Nattestad
- Department of Radiology, Odense University Hospital, Odense, Denmark
| | - Magnus Wahlberg
- Sound Communication and Behaviour Group, Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Xudong Zheng
- Department of Mechanical Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Qian Xue
- Department of Mechanical Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - W Tecumseh Fitch
- Department of Behavioral and Cognitive Biology, Faculty of Life Sciences, University of Vienna, Vienna, Austria.
- Vienna Cognitive Science Hub, University of Vienna, Vienna, Austria.
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Palmer KJ, Tabbutt S, Gillespie D, Turner J, King P, Tollit D, Thompson J, Wood J. Evaluation of a coastal acoustic buoy for cetacean detections, bearing accuracy and exclusion zone monitoring. Methods Ecol Evol 2022. [DOI: 10.1111/2041-210x.13973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Sam Tabbutt
- SMRU Consulting Friday Harbor Washington USA
| | - Douglas Gillespie
- Sea Mammal Research Unit, Scottish Oceans Institute University of St. Andrews St. Andrews UK
| | | | - Paul King
- SMRU Consulting Friday Harbor Washington USA
| | | | | | - Jason Wood
- SMRU Consulting Friday Harbor Washington USA
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4
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The influence of sea ice on the detection of bowhead whale calls. Sci Rep 2022; 12:8553. [PMID: 35595792 PMCID: PMC9122979 DOI: 10.1038/s41598-022-12186-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 05/04/2022] [Indexed: 12/02/2022] Open
Abstract
Bowhead whales (Balaena mysticetus) face threats from diminishing sea ice and increasing anthropogenic activities in the Arctic. Passive acoustic monitoring is the most effective means for monitoring their distribution and population trends, based on the detection of their calls. Passive acoustic monitoring, however, is influenced by the sound propagation environment and ambient noise levels, which impact call detection probability. Modeling and simulations were used to estimate detection probability for bowhead whale frequency-modulated calls in the 80–180 Hz frequency band with and without sea ice cover and under various noise conditions. Sound transmission loss for bowhead calls is substantially greater during ice-covered conditions than during open-water conditions, making call detection ~ 3 times more likely in open-water. Estimates of daily acoustic detection probability were used to compensate acoustic detections for sound propagation and noise effects in two recording datasets in the northeast Chukchi Sea, on the outer shelf and continental slope, collected between 2012 and 2013. The compensated acoustic density suggests a decrease in whale presence with the retreat of sea ice at these recording sites. These results highlight the importance of accounting for effects of the environment on ambient noise and acoustic propagation when interpreting results of passive acoustic monitoring.
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Palmer KJ, Wu GM, Clark C, Klinck H. Accounting for the Lombard effect in estimating the probability of detection in passive acoustic surveys: Applications for single sensor mitigation and monitoring. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:67. [PMID: 35105031 DOI: 10.1121/10.0009168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
The detection range of calling animals is commonly described by the passive sonar equations. However, the sonar equations do not account for interactions between source and ambient sound level, i.e., the Lombard effect. This behavior has the potential to introduce non-linearities into the sonar equations and result in incorrectly predicted detection ranges. Here, we investigate the relationship between ambient sound and effective detection ranges for North Atlantic right whales (Eubalaena glacialis) in Cape Cod Bay, MA, USA using a sparse array of acoustic recorders. Generalized estimating equations were used to model the probability that a call was detected as a function of distance between the calling animal and the sensor and the ambient sound level. The model suggests a non-linear relationship between ambient sound levels and the probability of detecting a call. Comparing the non-linear model to the linearized version of the same model resulted in 12 to 25% increases in the effective detection range. We also found evidence of the Lombard effect suggesting that it is the most plausible cause for the non-linearity in the relationship. Finally, we suggest a simple modification to the sonar equation for estimating detection probability for single sensor monitoring applications.
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Affiliation(s)
- K J Palmer
- School of Biology, University of St. Andrews, Sir Harold Mitchell Building, St. Andrews, Fife KY16 9TH, United Kingdom
| | - Gi-Mick Wu
- Helmholtz Centre for Environmental Research, Permoserstraße 15 Leipzig, 04318, Germany
| | - Christopher Clark
- K. Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, 159 Sapsucker Woods Road, Ithaca, New York 14850, USA
| | - Holger Klinck
- K. Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, 159 Sapsucker Woods Road, Ithaca, New York 14850, USA
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Blackwell SB, Thode AM, Conrad AS, Ferguson MC, Berchok CL, Stafford KM, Marques TA, Kim KH. Estimating acoustic cue rates in bowhead whales, Balaena mysticetus, during their fall migration through the Alaskan Beaufort Sea. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 149:3611. [PMID: 34241095 DOI: 10.1121/10.0005043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 05/05/2021] [Indexed: 06/13/2023]
Abstract
Eight years of passive acoustic data (2007-2014) from the Beaufort Sea were used to estimate the mean cue rate (calling rate) of individual bowhead whales (Balaena mysticetus) during their fall migration along the North Slope of Alaska. Calls detected on directional acoustic recorders (DASARs) were triangulated to provide estimates of locations at times of call production, which were then translated into call densities (calls/h/km2). Various assumptions were used to convert call density into animal cue rates, including the time for whales to cross the arrays of acoustic recorders, the population size, the fraction of the migration corridor missed by the localizing array system, and the fraction of the seasonal migration missed because recorders were retrieved before the end of the migration. Taking these uncertainties into account in various combinations yielded up to 351 cue rate estimates, which summarize to a median of 1.3 calls/whale/h and an interquartile range of 0.5-5.4 calls/whale/h.
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Affiliation(s)
- Susanna B Blackwell
- Greeneridge Sciences, Inc., 5266 Hollister Avenue, Santa Barbara, California 93111, USA
| | - Aaron M Thode
- Marine Physical Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA
| | - Alexander S Conrad
- Greeneridge Sciences, Inc., 5266 Hollister Avenue, Santa Barbara, California 93111, USA
| | - Megan C Ferguson
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way Northeast, Seattle, Washington 98115, USA
| | - Catherine L Berchok
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way Northeast, Seattle, Washington 98115, USA
| | - Kathleen M Stafford
- Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA
| | - Tiago A Marques
- Centre for Research into Ecological and Environmental Modelling, School of Mathematics and Statistics, University of St Andrews, The Observatory, Buchanan Gardens, St Andrews, Fife KY16 9LZ, Scotland
| | - Katherine H Kim
- Greeneridge Sciences, Inc., 5266 Hollister Avenue, Santa Barbara, California 93111, USA
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Fournet MEH, Silvestri M, Clark CW, Klinck H, Rice AN. Limited vocal compensation for elevated ambient noise in bearded seals: implications for an industrializing Arctic Ocean. Proc Biol Sci 2021; 288:20202712. [PMID: 33622137 PMCID: PMC7934916 DOI: 10.1098/rspb.2020.2712] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 01/28/2021] [Indexed: 11/12/2022] Open
Abstract
Vocalizing animals have several strategies to compensate for elevated ambient noise. These behaviours evolved under historical conditions, but compensation limits are quickly being reached in the Anthropocene. Acoustic communication is essential to male bearded seals that vocalize for courtship and defending territories. As Arctic sea ice declines, industrial activities and associated anthropogenic noise are likely to increase. Documenting how seals respond to noise and identifying naturally occurring behavioural thresholds would indicate either their resilience or vulnerability to changing soundscapes. We investigated whether male bearded seals modified call amplitudes in response to changing ambient noise levels. Vocalizing seals increased their call amplitudes until ambient noise levels reached an observable threshold, above which call source levels stopped increasing. The presence of a threshold indicates limited noise compensation for seals, which still renders them vulnerable to acoustic masking of vocal signals. This behavioural threshold and response to noise is critical for developing management plans for an industrializing Arctic.
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Affiliation(s)
- Michelle E. H. Fournet
- Center for Conservation Bioacoustics, Cornell Laboratory of Ornithology, Cornell University, Ithaca, NY 14850, USA
| | - Margherita Silvestri
- Department of Environmental Biology, Marine Ecology Lab, Sapienza University of Rome, Viale dell'Università 32, 00185 Rome, Italy
| | - Christopher W. Clark
- Center for Conservation Bioacoustics, Cornell Laboratory of Ornithology, Cornell University, Ithaca, NY 14850, USA
| | - Holger Klinck
- Center for Conservation Bioacoustics, Cornell Laboratory of Ornithology, Cornell University, Ithaca, NY 14850, USA
- Marine Mammal Institute, Department of Fisheries and Wildlife, Oregon State University, Newport, OR 97365, USA
| | - Aaron N. Rice
- Center for Conservation Bioacoustics, Cornell Laboratory of Ornithology, Cornell University, Ithaca, NY 14850, USA
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Thode AM, Blackwell SB, Conrad AS, Kim KH, Marques T, Thomas L, Oedekoven CS, Harris D, Bröker K. Roaring and repetition: How bowhead whales adjust their call density and source level (Lombard effect) in the presence of natural and seismic airgun survey noise. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2020; 147:2061. [PMID: 32237830 DOI: 10.1121/10.0000935] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 03/02/2020] [Indexed: 06/11/2023]
Abstract
Over 500 000 automated and manual acoustic localizations, measured over seven years between 2008 and 2014, were used to examine how natural wind-driven noise and anthropogenic seismic airgun survey noise influence bowhead whale call densities (calls/km2/min) and source levels during their fall migration in the Alaskan Beaufort Sea. Noise masking effects, which confound measurements of behavioral changes, were removed using a modified point transect theory. The authors found that mean call densities generally rose with increasing continuous wind-driven noise levels. The occurrence of weak airgun pulse sounds also prompted an increase in call density equivalent to a 10-15 dB change in natural noise level, but call density then dropped substantially with increasing cumulative sound exposure level (cSEL) from received airgun pulses. At low in-band noise levels the mean source level of the acoustically-active population changed to nearly perfectly compensate for noise increases, but as noise levels increased further the mean source level failed to keep pace, reducing the population's communication space. An increase of >40 dB cSEL from seismic airgun activity led to an increase in source levels of just a few decibels. These results have implications for bowhead acoustic density estimation, and evaluations of the masking impacts of anthropogenic noise.
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Affiliation(s)
- Aaron M Thode
- Marine Physical Laboratory, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0238, USA
| | - Susanna B Blackwell
- Greeneridge Sciences, Inc., 90 Arnold Place, Suite D, Santa Barbara, California 93117, USA
| | - Alexander S Conrad
- Greeneridge Sciences, Inc., 90 Arnold Place, Suite D, Santa Barbara, California 93117, USA
| | - Katherine H Kim
- Greeneridge Sciences, Inc., 90 Arnold Place, Suite D, Santa Barbara, California 93117, USA
| | - Tiago Marques
- Departamento de Biologia Animal, Centro de Estatística e Aplicações, Faculdade de Ciências, Building C2-Level 2, Campo Grande, 1749-016 Lisbon, Portugal
| | - Len Thomas
- CREEM/University of St Andrews, Fife KY16 9LZ, Scotland
| | | | | | - Koen Bröker
- Shell Exploration and Production Company, 3601 C Street, Anchorage, Alaska 99503, USA
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Blackwell SB, Nations CS, Thode AM, Kauffman ME, Conrad AS, Norman RG, Kim KH. Effects of tones associated with drilling activities on bowhead whale calling rates. PLoS One 2017; 12:e0188459. [PMID: 29161308 PMCID: PMC5697844 DOI: 10.1371/journal.pone.0188459] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 11/07/2017] [Indexed: 11/19/2022] Open
Abstract
During summer 2012 Shell performed exploratory drilling at Sivulliq, a lease holding located in the autumn migration corridor of bowhead whales (Balaena mysticetus), northwest of Camden Bay in the Beaufort Sea. The drilling operation involved a number of vessels performing various activities, such as towing the drill rig, anchor handling, and drilling. Acoustic data were collected with six arrays of directional recorders (DASARs) deployed on the seafloor over ~7 weeks in Aug-Oct. Whale calls produced within 2 km of each DASAR were identified and localized using triangulation. A "tone index" was defined to quantify the presence and amplitude of tonal sounds from industrial machinery. The presence of airgun pulses originating from distant seismic operations was also quantified. For each 10-min period at each of the 40 recorders, the number of whale calls localized was matched with the "dose" of industrial sound received, and the relationship between calling rates and industrial sound was modeled using negative binomial regression. The analysis showed that with increasing tone levels, bowhead whale calling rates initially increased, peaked, and then decreased. This dual behavioral response is similar to that described for bowhead whales and airgun pulses in earlier work. Increasing call repetition rates can be a viable strategy for combating decreased detectability of signals arising from moderate increases in background noise. Meanwhile, as noise increases, the benefits of calling may decrease because information transfer becomes increasingly error-prone, and at some point calling may no longer be worth the effort.
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Affiliation(s)
- Susanna B. Blackwell
- Greeneridge Sciences, Incorporated, Santa Barbara, California, United States of America
- * E-mail:
| | - Christopher S. Nations
- Western EcoSystems Technology, Incorporated, Cheyenne, Wyoming, United States of America
| | - Aaron M. Thode
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
| | - Mandy E. Kauffman
- Western EcoSystems Technology, Incorporated, Cheyenne, Wyoming, United States of America
| | - Alexander S. Conrad
- Greeneridge Sciences, Incorporated, Santa Barbara, California, United States of America
| | - Robert G. Norman
- Greeneridge Sciences, Incorporated, Santa Barbara, California, United States of America
| | - Katherine H. Kim
- Greeneridge Sciences, Incorporated, Santa Barbara, California, United States of America
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Ozanich E, Gerstoft P, Worcester PF, Dzieciuch MA, Thode A. Eastern Arctic ambient noise on a drifting vertical array. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 142:1997. [PMID: 29092535 DOI: 10.1121/1.5006053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ambient noise in the eastern Arctic was studied from April to September 2013 using a 22 element vertical hydrophone array as it drifted from near the North Pole (89° 23'N, 62° 35'W) to north of Fram Strait (83° 45'N, 4° 28'W). The hydrophones recorded for 108 min/day on six days per week with a sampling rate of 1953.125 Hz. After removal of data corrupted by non-acoustic transients, 19 days throughout the transit period were analyzed. Noise contributors identified include broadband and tonal ice noises, bowhead whale calling, seismic airgun surveys, and earthquake T phases. The bowhead whale or whales detected are believed to belong to the endangered Spitsbergen population, and were recorded when the array was as far north as 86° 24'N. Median power spectral estimates and empirical probability density functions along the array transit show a change in the ambient noise levels corresponding to seismic survey airgun occurrence and received level at low frequencies and transient ice noises at high frequencies. Median power for the same periods across the array shows that this change is consistent in depth. The median ambient noise for May 2013 was among the lowest of the sparse reported observations in the eastern Arctic but comparable to the more numerous observations of western Arctic noise levels.
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Affiliation(s)
- Emma Ozanich
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0238, USA
| | - Peter Gerstoft
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0238, USA
| | - Peter F Worcester
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0238, USA
| | - Matthew A Dzieciuch
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0238, USA
| | - Aaron Thode
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0238, USA
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Thode AM, Blackwell SB, Conrad AS, Kim KH, Michael Macrander A. Decadal-scale frequency shift of migrating bowhead whale calls in the shallow Beaufort Sea. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 142:1482. [PMID: 28964081 DOI: 10.1121/1.5001064] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Automated and manual acoustic localizations of bowhead whale calls in the Beaufort Sea were used to estimate the minimum frequency attained by their highly variable FM-modulated call repertoire during seven westerly fall migrations. Analyses of 13 355 manual and 100 009 automated call localizations found that between 2008 and 2014 the proportion of calls that dipped below 75 Hz increased from 27% to 41%, shifting the mean value of the minimum frequency distribution from 94 to 84 Hz. Multivariate regression analyses using both generalized linear models and generalized estimating equations found that this frequency shift persisted even when accounting for ten other factors, including calling depth, call range, call type, noise level, signal-to-noise ratio, local water depth (site), airgun activity, and call spatial density. No single call type was responsible for the observed shift, but so-called "complex" calls experienced larger percentage downward shifts. By contrast, the call source level distribution remained stable over the same period. The observed frequency shift also could not be explained by migration corridor shifts, relative changes in call detectability between different frequency bands, long-term degradation in the automated airgun detector, physiological growth in the population, or behavioral responses to increasing population density (estimated via call density).
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Affiliation(s)
- Aaron M Thode
- Marine Physical Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0238, USA
| | - Susanna B Blackwell
- Greeneridge Sciences, Inc., 90 Arnold Place, Suite D, Santa Barbara, California 93117, USA
| | - Alexander S Conrad
- Greeneridge Sciences, Inc., 90 Arnold Place, Suite D, Santa Barbara, California 93117, USA
| | - Katherine H Kim
- Greeneridge Sciences, Inc., 90 Arnold Place, Suite D, Santa Barbara, California 93117, USA
| | - A Michael Macrander
- Shell Exploration and Production Company, 3601 C Street, Anchorage, Alaska 99503, USA
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Thode A, Bonnel J, Thieury M, Fagan A, Verlinden C, Wright D, Berchok C, Crance J. Using nonlinear time warping to estimate North Pacific right whale calling depths in the Bering Sea. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:3059. [PMID: 28599521 DOI: 10.1121/1.4982200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Calling depth distributions are estimated for two types of calls produced by critically endangered eastern North Pacific right whales (NPRWs) in the Bering Sea, using passive acoustic data collected with bottom-mounted hydrophone recorders. Nonlinear time resampling of 12 NPRW "upcalls" and 20 "gunshots" recorded in a critical NPRW habitat isolated individual normal mode arrivals from each call. The relative modal arrival times permitted range estimates between 1 and 40 km, while the relative modal amplitudes permitted call depth estimates, provided that environmental inversions were obtained from high signal-to-noise ratio calls. Gunshot sounds were generally only produced at a few meters depth, while upcall depths clustered between 10 and 25 m, consistent with previously published bioacoustic tagging results from North Atlantic right whales. A Wilcoxon rank sum test rejected the null hypothesis that the mean calling depths of the two call types were the same (p = 2.9 × 10-5); the null hypothesis was still rejected if the sample set was restricted to one call per acoustic encounter (p = 0.02). Propagation modeling demonstrates that deeper depths enhance acoustic propagation and that source depth estimates impact both NPRW upcall source level and detection range estimates.
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Affiliation(s)
- Aaron Thode
- Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, California 92093-0238, USA
| | - Julien Bonnel
- ENSTA Bretagne, UMR CNRS 6285 Lab-STICC, 2 rue Francois Verny, 29806 Brest Cedex 9, France
| | - Margaux Thieury
- ENSTA Bretagne, UMR CNRS 6285 Lab-STICC, 2 rue Francois Verny, 29806 Brest Cedex 9, France
| | - Aileen Fagan
- United States Coast Guard Academy, New London, Connecticut 06320, USA
| | - Chris Verlinden
- United States Coast Guard Academy, New London, Connecticut 06320, USA
| | - Dana Wright
- Marine Mammal Laboratory, Alaska Fisheries Science Center, 7600 Sand Point Way NE, Seattle, Washington 98115, USA
| | - Catherine Berchok
- Marine Mammal Laboratory, Alaska Fisheries Science Center, 7600 Sand Point Way NE, Seattle, Washington 98115, USA
| | - Jessica Crance
- Marine Mammal Laboratory, Alaska Fisheries Science Center, 7600 Sand Point Way NE, Seattle, Washington 98115, USA
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