The combined use of visual and acoustic data collection techniques for winter killer whale (Orcinus orca) observations (PDF)

Burham, R., R. Palm, D. Duffus, X. Mouy, and A. Riera

Global Ecology and Conservation 8: 24-30 (2016)

DOI: 10.1016/j.gecco.2016.08.001

Observations of cetaceans during the winter are difficult, if not impossible in some locations, yet their presence, habitat use, and behaviour during this period are important for conservation and management. Typically, observations come from vessel surveys, with citizen science networks increasingly adding significant sighting data. In compliment to this, acoustic data collection systems can be deployed to collect information remotely over long periods, and in almost any conditions. Here we describe how the combination of these data collection techniques works to fill knowledge gaps, with data from a well-established citizen science network, and a single passive acoustic monitoring (PAM) recorder integrated to identify killer whale presence during winter months in Clayoquot Sound, on the west coast of Vancouver Island.

Together these data show the overwinter use of Clayoquot Sound by killer whales is greater than previously thought. During the study period, February 21 to April 25, 2015, the citizen science network noted 14 visual encounters ranging from Amphitrite Point to Hot Spring Cove, Vancouver Island. The PAM recorded 17 acoustic encounters within the 10 km detection radius of the recorder, deployed off Siwash Point, Flores Island. This included 15 encounters not recorded by the visual network. Both resident and Bigg’s (transient) transient whale groups were recorded, although analysis of vocalizations determined that the majority of the encounters recorded acoustically were of northern resident killer whales. This may be a function of life history, with Bigg’s killer whales typically noted to be less acoustically active, or could represent greater site use by this group. This first use of acoustic monitoring over the winter, complemented with visual data, can establish a better understanding of year-round use of this area by killer whales and has broader application to other sites.

The under-ice soundscape in Great Slave Lake near the city of Yellowknife, Northwest Territories, Canada (PDF)

Martin, S.B. and P.A. Cott

Journal of Great Lakes Research 42: 248-255 (2016)

DOI: 10.1016/j.jglr.2015.09.012

Most recent research and monitoring of under-water “soundscapes” has focused on marine systems in open water conditions. Here we present the first long-term assessment of the diel and seasonal patterns of a fresh-water aquatic soundscape under-ice cover. Acoustic data recorded in Yellowknife Bay, Great Slave Lake in Canada's Northwest Territories, measured the under-ice soundscape near an ice road and airport. From December to late January, the soundscape consisted of geophony from ice cracking and anthrophony from snowmobiles, aircraft, and road vehicles. In late January, burbot spawning calls began and added a localized biophony source to the soundscape that increased the total sound pressure level due to an increase in sound levels in the 10–425 Hz frequency band. The median 1 min root-mean-square sound pressure level (rms SPL) in the period without burbot biophony was 90.3 dB re 1 μPa. The measured hourly rms SPL was negatively correlated with air temperature in the 200–800 Hz band but positively correlated with average hourly wind speed in the 800–8000 Hz band. The nightly mean rms SPL was 88 dB re 1 μPa and increased to 96 dB re 1 μPa in late afternoon. This diel cycle had a strong positive correlation with the number of minutes per hour where ice-road vehicles were detected. Further work is recommended to quantify the soundscape in deep-water areas of large lakes and to include particle motion. Such information will enable the assessment of cumulative impacts of anthrophony and geophony on aquatic biota.

Underwater acoustic behavior of bearded seals (Erignathus barbatus) in the northeastern Chukchi Sea, 2007–2010 (PDF)

Frouin-Mouy, H., X. Mouy, B. Martin, and D. Hannay

Marine Mammal Science 32: 141-160 (2016)

DOI: 10.1111/mms.12246

Bearded seal (Erignathus barbatus) calls were recorded using autonomous passive acoustic recorders deployed in the northeastern Chukchi Sea between October 2007 and October 2010. Continuous acoustic data were acquired during summer (August to mid-October), and overwinter data (mid-October through July) were acquired on a duty cycle of 40/48 min every 4 h. We investigated the spatio-temporal distribution and acoustic behavior of vocalizing bearded seals in this multiyear data set. Peaks in calling occurred in spring, coinciding with the mating period, and calls stopped abruptly in late June/early July. Fewer calls were detected in summer, and the vocal presence of seals increased with the formation of pack ice in winter. Vocal activity was higher at night than during the day, with a peak around 0400 (AKST). Monthly patterns in proportional use of each call type and call duration were examined for the first time. The proportion and duration of AL1(T) and AL2(T) call types increased during the mating period, suggesting that males advertise their breeding condition by producing those specific longer trills. The observed seasonal and diel trends were consistent between years. These results improve our understanding of occurrence and acoustic behavior of bearded seals across the northeastern Chukchi Sea.

Bayesian environmental inversion of airgun modal dispersion using a single hydrophone in the Chukchi Sea (PDF)

Warner, G.A., S.E. Dosso, J. Dettmer, and D.E. Hannay

Journal of the Acoustical Society of America 137: 3009-3023 (2015)

DOI: 10.1121/1.4921284

This paper presents estimated water-column and seabed parameters and uncertainties for a shallow-water site in the Chukchi Sea, Alaska, from trans-dimensional Bayesian inversion of the dispersion of water-column acoustic modes. Pulse waveforms were recorded at a single ocean-bottom hydrophone from a small, ship-towed airgun array during a seismic survey. A warping dispersion time-frequency analysis is used to extract relative mode arrival times as a function of frequency for source-receiver ranges of 3 and 4 km which are inverted for the water sound-speed profile (SSP) and subbottom geoacoustic properties. The SSP is modeled using an unknown number of sound-speed/depth nodes. The subbottom is modeled using an unknown number of homogeneous layers with unknown thickness, sound speed, and density, overlying a halfspace. A reversible-jump Markov-chain Monte Carlo algorithm samples the model parameterization in terms of the number of water-column nodes and subbottom interfaces that can be resolved by the data. The estimated SSP agrees well with a measured profile, and seafloor sound speed is consistent with an independent headwave arrival-time analysis. Environmental properties are required to model sound propagation in the Chukchi Sea for estimating sound exposure levels and environmental research associated with marine mammal localization.

Distance from shore as an indicator of disturbance of gray whales during a seismic survey off Sakhalin Island, Russia (PDF)

Muir, J.E., L. Ainsworth, R. Joy, R. Racca, Y. Bychkov, G. Gailey, V. Vladmirov, S. Starodymov, and K. Bröker

Endangered Species Research 29: 161-178 (2015)

DOI: 10.3354/esr00701

A seismic survey was conducted adjacent to the nearshore feeding ground of gray whales Eschrichtius robustus off northeastern Sakhalin Island, Russia. Scan surveys were conducted at 7 shore stations before, during and after the seismic survey. We investigated whether gray whales shifted their distribution with respect to distance from the shoreline in response to acoustic pulses from the seismic source. To do this, we used linear mixed effects modelling that included effects of detection, space and time. Data were tested for effects of magnitude and presence/absence of sound from seismic activity on whale distance from shore. Sound covariates were estimated over 3 temporal scales (8 h, 3 d and since the start of seismic activity) at locations 500 and 5000 m offshore each observation station. Sighting distance from shore was less in poor visibility and at earlier times of day. No significant effects of sound were identified, although data suggest that at most stations, sighting distance from shore increased slightly over the 2 wk of the seismic survey. The analysis was limited, however, by several factors that included low numbers of sightings throughout most of the study, non-availability of data on biomass of gray whale prey and sources of error that could not be accounted for in the model. Sensitivity to potential errors in sighting distance estimation was assessed using a correction factor based on known locations of vessels and gray whales when sighted. The model was refitted using distance-corrected sightings. Results were consistent with the original model.

Monitoring and impact mitigation during a 4D seismic survey near a population of gray whales off Sakhalin Island, Russia (PDF)

Bröker, K., G. Gailey, J. Muir, and R. Racca

Endangered Species Research 28: 187-208 (2015)

DOI: 10.3354/esr00670

A 4D seismic survey was conducted in 2010 near the feeding grounds of gray whales off Sakhalin Island, Russia. To minimize disruptions to the whales’ feeding activity and enhance understanding of the potential impacts of seismic surveys on gray whales Eschrichtius robustus, an extensive monitoring and mitigation plan (MMP) was developed. Typically, mitigation plans involve observers on seismic vessels to monitor for the presence of marine mammals in an exclusion zone so as to prevent physical injury to the animals. Due to the protected status of western gray whales, an additional protection zone based on a behavioural disturbance threshold of exposure of 156 dB re μPa2-s per pulse was applied for whales within their feeding habitat defined by the estimated 95% abundance contour. Real-time radio-transmitting acoustic recorders were deployed along this contour to verify modelled acoustic footprints within the feeding grounds. Shore- and vessel-based observation teams monitored for the presence and activity of whales. A real-time GIS workflow tracking procedure was developed that integrated acoustic and whale positioning data to determine if sound levels at a whales’ position within the feeding area exceeded the behavioural threshold, in which case a shut-down of the seismic source was implemented. Additionally, behaviour and distribution surveys were conducted before, during and after the seismic survey to evaluate the effectiveness of the MMP. No large changes in whale movement, respiration, or distribution patterns were observed during the seismic survey. This could be interpreted to mean that the MMP was effective in reducing the sound exposure and behavioural responses of gray whales to seismic sounds.

Monitoring the gray whale sound exposure mitigation zone and estimating acoustic transmission during a 4-D seismic survey, Sakhalin Island, Russia (PDF)

Racca, R., M. Austin, A. Rutenko, and K. Bröker

Endangered Species Research 29: 131-146 (2015)

DOI: 10.3354/esr00703

A seismic survey conducted in the proximity of the nearshore feeding grounds of gray whales Eschrichtius robustus off northeastern Sakhalin Island, Russia, required the development of a comprehensive monitoring and mitigation plan. Prior to the execution of the seismic survey, the sound levels from the airgun array source were modelled for all seismic acquisition lines. This yielded estimated shoreward boundaries for an assumed disturbance threshold of 156 dB re 1 µPa^2-s sound exposure level (SEL) that allowed an assessment of which lines would require more stringent mitigation. To enable prediction of the sound front under variable propagation conditions, a set of acoustic footprints with a realistic range of parameters was pre-computed. In the field, an acoustic monitoring network of 9 bottom-deployed stations with tethered radio buoys transmitted full waveform data to a shore-based monitoring post. The signals were processed to yield pulse levels for comparison to the model predictions. The appropriate footprint was selected on the basis of the pulse levels received during the initial minute of a seismic line and communicated to observation teams. To further ensure the sustained accuracy of the selected footprint during a line acquisition, the modelled levels were compared in real time to the measured readings as the source moved past the line of monitoring stations; they were consistently found to match the incoming received sound levels within an accepted tolerance of 3 dB. This selection approach resulted in the best available estimation of acoustic exposure even through significant temporal changes in the hydrological conditions.

Marine mammal audibility of selected shallow-water survey sources (PDF)

MacGillivray, A.O., R. Racca, and Z. Li

Journal of the Acoustical Society of America 135: EL35-EL40 (2014)

DOI: 10.1121/1.4838296

Most attention about the acoustic effects of marine survey sound sources on marine mammals has focused on airgun arrays, with other common sources receiving less scrutiny. Sound levels above hearing threshold (sensation levels) were modeled for six marine mammal species and seven different survey sources in shallow water. The model indicated that odontocetes were most likely to hear sounds from mid-frequency sources (fishery, communication, and hydrographic systems), mysticetes from low-frequency sources (sub-bottom profiler and airguns), and pinnipeds from both mid- and low-frequency sources. High-frequency sources (side-scan and multibeam) generated the lowest estimated sensation levels for all marine mammal species groups.

Song of the burbot: Under-ice acoustic signalling by a freshwater gadoid fish

Cott, P.A., A.D. Hawkins, D.G. Zeddies, B. Martin, T. Johnston, J.D. Reist, J.M. Gunn, and D.M. Higgs

Journal of Great Lakes Research 40: 435-440 (2014)

DOI: 10.1016/j.jglr.2014.02.017

Burbot (Lota lota) are northern freshwater gadoid fish that spawn under ice-cover, making their reproductive behavior largely unknown to science. Some members of the cod family vocalize as part of their mating system. These calls are produced by rapidly contracting drumming muscles on their swim bladders. Burbot also possess drumming muscles, like their marine counterparts, which may enable them to vocalize. To assess the potential for burbot to make calls, pre-spawning adult burbot were collected and placed in a large under-ice enclosure in Great Slave Lake, Northwest Territories, Canada, along with a recorder that monitored low frequency sound over their spawning period. The recorded acoustic data revealed that burbot called coincident with the onset of their spawning period and that the call signatures were stereotypical of swim bladder generated vocalizations made by other gadoid fishes. Burbot showed a wide repertoire of calls, from slow knocks to fast buzzing, similar to the closely related haddock (Melanogrammus aeglefinus). Although never-before documented, calling by fish under ice-cover is likely an important part of the mating system of under-ice spawning gadoids because light limitation would reduce the usefulness of visual cues. These under-ice communications may be affected by anthropogenic noise from increasing resource development in northern regions.

Acoustic occurrence and affiliation of fin whales detected in the Northeastern Chukchi Sea, July to October 2007–10 (PDF)

Delarue, J.J.-Y., B. Martin, D.E. Hannay, and C.L. Berchok

Arctic 66: 159-172 (2013)

DOI: 10.14430/arctic4287

Fin whales are common throughout the North Pacific region, particularly in the Gulf of Alaska and the Bering Sea, even though these areas were heavily depleted by decades of whaling. Whalers also took fin whales in the southwestern Chukchi Sea, but only five sightings have been reported for the entire Chukchi Sea in the past 30 years. Large-scale arrays consisting of 26 – 44 bottom-mounted acoustic recorders were deployed in the northeastern Chukchi Sea from July to October in 2007 to 2010. Fin whales were detected off Cape Lisburne and Point Lay in 2007, 2009, and 2010. Large interannual variations in the number of acoustic detections may be related to environmental conditions. Calls detected during summer months consisted primarily of irregular sequences. Stereotyped sequences, called songs, were also detected at the end of the recording period in 2007 and 2010. Their structure matched that of one of the songs recorded in the Bering Sea, suggesting that only one of the stocks occurring in the Bering Sea extends its range into the northeastern Chukchi Sea. These detections currently represent the northernmost fin whale records in the North Pacific region.

Marine mammal acoustic detections in the northeastern Chukchi Sea, September 2007–July 2011

Hannay, D.E., J. Delarue, X. Mouy, B.S. Martin, D. Leary, J.N. Oswald, and J. Vallarta

Continental Shelf Research 67: 127-146 (2013)

DOI: 10.1016/j.csr.2013.07.009

Several cetacean and pinniped species use the northeastern Chukchi Sea as seasonal or year-round habitat. This area has experienced pronounced reduction in the extent of summer sea ice over the last decade, as well as increased anthropogenic activity, particularly in the form of oil and gas exploration. The effects of these changes on marine mammal species are presently unknown. Autonomous passive acoustic recorders were deployed over a wide area of the northeastern Chukchi Sea off the coast of Alaska from Cape Lisburne to Barrow, at distances from 8 km to 200 km from shore: up to 44 each summer and up to 8 each winter. Acoustic data were acquired at 16 kHz continuously during summer and on a duty cycle of 40 or 48 min within each 4-h period during winter. Recordings were analyzed manually and using automated detection and classification systems to identify calls.

Underwater noise from offshore oil production vessels (PDF)

Erbe, C., R.D. McCauley, C.R. McPherson, and A. Gavrilov

Journal of the Acoustical Society of America 133: EL465-EL470 (2013)

DOI: 10.1121/1.4802183

Underwater acoustic recordings of six Floating Production Storage and Offloading (FPSO) vessels moored off Western Australia are presented. Monopole source spectra were computed for use in environmental impact assessments of underwater noise. Given that operations on the FPSOs varied over the period of recording, and were sometimes unknown, the authors present a statistical approach to noise level estimation. No significant or consistent aspect dependence was found for the six FPSOs. Noise levels did not scale with FPSO size or power. The 5th, 50th (median), and 95th percentile source levels (broadband, 20 to 2500 Hz) were 188, 181, and 173 dB re 1 μPa @ 1 m, respectively.

Local acoustic particle motion guides sound-source localization behavior in the plainfin midshipman fish, Porichthys notatus (PDF)

Zeddies, D.G., R.R. Fay, M.D. Gray, P.W. Alderks, A. Acob, and J.A. Sisneros

Journal of Experimental Biology 215: 152-160 (2012)

DOI: 10.1242/jeb.064998

Sound-source localization behavior was studied in the plainfin midshipman fish (Porichthys notatus) by making use of the naturally occurring phonotaxis response of gravid females to playback of the male's advertisement call. The observations took place outdoors in a circular concrete tank. A dipole sound projector was placed at the center of the tank and an 80–90 Hz tone (the approximate fundamental frequency to the male's advertisement call) was broadcast to gravid females that were released from alternative sites approximately 100 cm from the source. The phonotaxic responses of females to the source were recorded, analyzed and compared with the sound field. One release site was approximately along the vibratory axis of the dipole source, and the other was approximately orthogonal to the vibratory axis. The sound field in the tank was fully characterized through measurements of the sound pressure field using hydrophones and acoustic particle motion using an accelerometer. These measurements confirmed that the sound field was a nearly ideal dipole. When released along the dipole vibratory axis, the responding female fish took essentially straight paths to the source. However, when released approximately 90 deg to the source's vibratory axis, the responding females took highly curved paths to the source that were approximately in line with the local particle motion axes. These results indicate that the acoustic cues used by fish during sound-source localization include the axes of particle motion of the local sound field.

Mapping cumulative noise from shipping to inform marine spatial planning (PDF)

Erbe, C., A.O. MacGillivray, and R. Williams

Journal of the Acoustical Society of America 132(5): EL423-EL428 (2012)

DOI: 10.1121/1.4758779

Including ocean noise in marine spatial planning requires predictions of noise levels on large spatiotemporal scales. Based on a simple sound transmission model and ship track data (Automatic Identification System, AIS), cumulative underwater acoustic energy from shipping was mapped throughout 2008 in the west Canadian Exclusive Economic Zone, showing high noise levels in critical habitats for endangered resident killer whales, exceeding limits of “good conservation status” under the EU Marine Strategy Framework Directive. Error analysis proved that rough calculations of noise occurrence and propagation can form a basis for management processes, because spending resources on unnecessary detail is wasteful and delays remedial action.

Tracking of Pacific walruses in the Chukchi Sea using a single hydrophone (PDF)

Mouy, X., D.E. Hannay, M.M. Zykov, and B. Martin

Journal of the Acoustical Society of America 131: 1349-1358 (2012)

DOI: 10.1121/1.3675008

The vocal repertoire of Pacific walruses includes underwater sound pulses referred to as knocks and bell-like calls. An extended acoustic monitoring program was performed in summer 2007 over a large region of the eastern Chukchi Sea using autonomous seabed-mounted acoustic recorders. Walrus knocks were identified in many of the recordings and most of these sounds included multiple bottom and surface reflected signals. This paper investigates the use of a localization technique based on relative multipath arrival times (RMATs) for potential behavior studies. First, knocks are detected using a semi-automated kurtosis-based algorithm. Then RMATs are matched to values predicted by a ray-tracing model. Walrus tracks with vertical and horizontal movements were obtained. The tracks included repeated dives between 4.0 m and 15.5 m depth and a deep dive to the sea bottom (53 m). Depths at which bell-like sounds are produced, average knock production rate and source levels estimates of the knocks were determined. Bell sounds were produced at all depths throughout the dives. Average knock production rates varied from 59 to 75 knocks/min. Average source level of the knocks was estimated to 177.6 ± 7.5 dB re 1 μPa peak @ 1 m.

Acoustic detections of beluga whales in the Northeastern Chukchi Sea, July 2007 to July 2008 (PDF)

Delarue, J.J.-Y., M. Laurinolli, and B. Martin

Arctic 64: 15-24 (2011)

DOI: 10.14430/arctic4076

Beluga calls were detected during two consecutive deployments of autonomous acoustic recorders in the northeastern Chukchi Sea. During the first deployment, calls were recorded between July and October 2007, primarily near the Barrow Canyon in July and August. During the second deployment, calls were detected in November 2007 off Point Lay and again between mid-April and June 2008 in a broad area 90 – 150 km off Point Lay and Wainwright, Alaska. The summer and fall 2007 detections were consistent with movement and residency patterns identified through satellite tagging studies. In the following spring, detections were recorded by four out of five monitoring stations for 19 to 37 consecutive days (depending on the station) between 13 April and 21 June 2008. These acoustic detections provide additional information about the timing and distribution of beluga migrations in the Chukchi Sea in spring.