As on land, underwater anthropogenic noise and its potential impacts on marine ecosystems have been a growing concern in the past three decades. Initially focusing on louder noise sources, acute physical and behavioral impacts on marine mammals and commercial fish, governmental agencies started to integrate soundscapes into marine spatial planning. However soundscape science has to deal with a large number of metrics and variables (time, space, frequencies, species, types of impacts, sound sources,…) and uncertainties to be able to bring a scientifically robust and reliable support to decision making process. This is a real challenge to integrate and communicate to a vast diversity of stakeholders. To address this challenge, we present a study of the impact of shipping noise on the St Lawrence Estuary and Gulf ecosystems and in particular on endangered marine mammals. The methodology uses probabilistic underwater acoustic modelling to produce 3D-maps of acoustic-field statistics and risk of impacts at daily, weekly, monthly and annual scale over few year-cycles. Those maps are then fed into a web application capable of handling terabytes of geospatial raster’s which allows to produce statistics on user-defined area interactively in order to explore and support collaborative decision making process between marine spatial planner and stakeholders. Details on probabilistic methodology and practical examples will be shown, with concluding remarks on gaps and remaining challenges.

As a part of the Canada’s Ocean Protection Plan, Fisheries and Oceans Canada has joined the efforts to better understand and monitor the effects of anthropogenic noise on marine environmental quality. Since 2017, underwater acoustic observatories were put in place across endangered whale habitats leading to the acquisition of big underwater acoustic dataset to process and analyze. In the Estuary and Gulf of St. Lawrence, underwater noise has been continuously monitored at 13 locations (6 to 10 simultaneously) between 2018 and 2023 at sampling rate up to 256 ksps in order to better understand the effect of shipping noise on marine environmental quality of the endangered St. Lawrence estuary beluga habitat. In this presentation, the data analysis pipeline from in situ sampling to processing is detailed, including recording schemes, data quality and control, soundscape cube, source separation, multi-scale statistics on noise levels and risk of impacts on habitat quality and visualization. These steps are used to identify, characterize and quantify daily to interannual spectral variability of underwater noise and their relationship with local environmental forcings such as shipping, wind, ice, tides, and currents at targeted locations. Ultimately, these results are used to provide support to (1) marine conservation and spatial planning initiatives from DFO and the Saguenay St. Lawrence Marine Parc; and (2) assess the predictability power of the outputs of soundscape modeling.

A network of 10 passive acoustics monitoring stations is used to examine patterns of habitat use at diel and tidal timescales by St. Lawrence Estuary beluga during summer 2018 and 2019. An occurrence index of vocal activity within the preferred frequency band of communications for belugas is used as a proxy for presence at the stations. Diel and tidal patterns of activity and mean residency time are extracted from statistics of hourly occurrence timeseries at the 10 stations. Spatially, diel and tidal occurrence levels of beluga communication sounds show patterns of variation that differ among the stations, but tend to be locally stable from one summer to next. Mean residency time at the 9 Estuary stations vary between 4 to 15 hours and most have an occurrence maximum during early morning. The Saguenay fjord station shows a distinct profile, with a mean residency time of 30 hours and high level of activity at evening and night. This work underlines the ability of passive acoustics, through continuous monitoring at high spatio-temporal resolution, to reveal the complexity of the habitat use by this confined marine mammal population and understand its responses to diel and tidal forcings of the ecosystem.

The spatial-temporal distribution pattern of St. Lawrence Estuary (SLE) beluga is examined with a passive acoustic monitoring network of 13 stations from June 2018 to October 2021. A beluga calling index, correlated with beluga density, is used as a proxy for habitat use by the population at weekly, monthly, and yearly scales. The seasonal pattern along SLE upstream-downstream axis was repeated annually. In summer, beluga habitat was confined to a 150 km segment of the SLE, with higher occurrences in its ∼20 km central portion, including the head of the Laurentian Channel and Saguenay Fjord mouth. During fall, the distribution gradually shifted to the downstream portion of the SLE and into the Northwestern Gulf, leaving low to no occurrences upstream in winter, until the spring return, characterized by the highest upstream occurrences. Occurrences off Ste. Marguerite Bay, 25 km upstream in Saguenay Fjord, were essentially from June to October. This multi-year continuous habitat use pattern provides a baseline for year-round SLE beluga distribution dynamics for assessing and mitigating anthropogenic threats to this endangered population, such as shipping noise. It also provides insights for optimizing the assessments of population size from aerial line transect surveys.

This study addresses the problem of determining optimal design of passive acoustic monitoring (PAM) systems for detecting and localizing whale calls in real-time in variable-noise environments. The performance of various PAM system is assessed using the detection theory and simulation modeling applied to the context of North Atlantic right whale (NARW) upcalls in feeding grounds and noisy shipping corridor of the Gulf of St. Lawrence. Realistic simulations are performed using an estimated NARW upcall source level (SL), the actual shipping traffic, measured local fleet ship SLs, and transmission loss (TL) from a regional 2.5-D propagation model accounting for the bathymetric and environmental structures. The comparisons consider single-hydrophone and hydrophone-array PAM systems, mounted on buoys, gliders, or cabled to shore and three families of NARW upcall detectors. The targeted performance is a low false-alarm rate of 1 per day and a detection probability > 0.5. The time-frequency-based detector offers the best trade-off between detection performance and robustness against NARW upcall variability. The effective detection ranges are similar to 15 times lower with single-hydrophone systems compared to hydrophone-arrays, whose beamforming enhances the signal in the upcall direction while damping interfering discrete noise from nearby transiting ships in other directions. Detecting and localizing NARWs in the large target areas (>10000-km(2) scale) is possible with a few well-located arrays of 10-20 hydrophones, which appears as the optimal cost/performance trade-off. Crown Copyright (C) 2021 Published by Elsevier Ltd. All rights reserved.

The acoustic data were collected between 2015 and 2019 at six stations in the southern Gulf of St. Lawrence using two different deployment configurations. The dataset also includes audio samples from the Gulf of Maine recorded in 2009, which were part of the DCLDE 2013 Challenge dataset (https://soi.st-andrews.ac.uk/static/soi/dclde2013/documents/WorkshopDataset2013.pdf). The acoustic data are supplemented by expert annotations indicating the presence/absence of North Atlantic right whale upcalls. Spectrogram images are also provided. These data have been used to train a deep neural network to detect North Atlantic right whale upcalls, as described in the article Performance of a Deep Neural Network at Detecting North Atlantic Right Whale Upcalls by Kirsebom, Frazao, Simard, Roy, Matwin, and Giard (doi:10.1121/10.0001132), which also contains a detailed description of the data. The software developed as part of this work is available on Zenodo (doi:10.5281/zenodo.3736625) under a GPLv3 license. This includes Python scripts for building training and test datasets, computing signal-to-noise ratios, visualizing spectrograms, training the deep neural network, and using the network to analyze continuous audio recordings.

Passive acoustics is used to monitor the threatened St. Lawrence estuary beluga between 2007 and 2017 from a site downstream of the beluga summer habitat. Acoustic metrics of presence and occurrence based on beluga acoustic band activity (BABA) are extracted by a dedicated algorithm adapted for the shipping noise from the St. Lawrence Seaway. A formal optimization process is used to set the algorithm parameters. Results evidence a year-round occurrence of belugas in the region, seasonal and diel patterns, and significant inter-annual variations. This study shows how passive acoustics methodology can be applied to monitor a loquacious species over multi-year periods in a shipping-noise-dominated environment, in order to understand its use of the habitat over the continuum of ecologically significant time scales.

Passive acoustics provides a powerful tool for monitoring the endangered North Atlantic right whale (Eubalaena glacialis), but robust detection algorithms are needed to handle diverse and variable acoustic conditions and differences in recording techniques and equipment. This paper investigates the potential of deep neural networks (DNNs) for addressing this need. ResNet, an architecture commonly used for image recognition, was trained to recognize the time-frequency representation of the characteristic North Atlantic right whale upcall. The network was trained on several thousand examples recorded at various locations in the Gulf of St. Lawrence in 2018 and 2019, using different equipment and deployment techniques. Used as a detection algorithm on fifty 30-min recordings from the years 2015-2017 containing over one thousand upcalls, the network achieved recalls up to 80% while maintaining a precision of 90%. Importantly, the performance of the network improved as more variance was introduced into the training dataset, whereas the opposite trend was observed using a conventional linear discriminant analysis approach. This study demonstrates that DNNs can be trained to identify North Atlantic right whale upcalls under diverse and variable conditions with a performance that compares favorably to that of existing algorithms.

Gervaise, C., Simard, Y., Aulanier, F., and Roy, N. 2019. Performance study of passive acoustic systems for detecting North Atlantic right whales in seaways: the Honguedo strait in the Gulf of St. Lawrence. Can. Tech. Rep. Fish. Aquat. Sci. 3346: ix + 53 pp. This report addresses the problem of detecting and localizing whales located in a noisy seaway with passive acoustic monitoring (PAM) systems reporting the detections in real time. This general problem is methodologically addressed using the detection theory, and relevant formulas to assess the PAM performance are provided. The method is applied to the special case of North Atlantic right whales (NARW) in the Honguedo strait seaway of the Gulf of St. Lawrence. The relevant scales at stake in the area are first established before setting the parameters of realistic simulations fed with the actual shipping traffic, transmission loss (TL) from a regional acoustic propagation model accounting for the bathymetric and environmental structures, estimated NARW upcall source level (SL), and measured ship SLs of the local fleet. The tested scenarios include single hydrophone and hydrophone array PAM systems located either in the seaway, from buoys or gliders, or cabled to the coast. Three families of NARW upcall detectors, providing different levels of minimal signal to noise ratio (SNR) for detection, are compared for each scenario. A low falsealarm rate of 1 false detection per day is imposed and a probability of detection larger than 50% is retained as indicator of good performance. Results show that PAM systems located in the seaway have the lowest detection range and performance, because of the frequent masking of whale calls by the noise field radiated by each individual transiting ship. Moving the PAM system away from the seaway increases the detection probability, because the relative distance of the whale and the ships to the PAM increases, which favors higher occurrences of SNRs exceeding the detection threshold. Because the main noise sources (i.e. individual transiting ships) are localized in space, hydrophone arrays are showing the best performances as their directional hearing capacity with beamforming processing can greatly enhance the SNR. The most promising PAM system offering an effective solution to the detection of NARWs located in the Honguedo seaway, with reasonable and affordable efforts, appears to be the setup of two coastal-cabled hydrophone arrays, one on the Gaspesian coast and the other on the Anticosti Island.

Gervaise, C., Simard, Y., Aulanier, F., and Roy, N. 2019. Optimal passive acoustic systems for real-time detection and localization of North Atlantic right whales in their feeding ground off Gaspé in the Gulf of St. Lawrence. Can. Tech. Rep. Fish. Aquat. Sci. 3345: ix + 58 p. This report addresses the problem of detecting and localizing whales located in a feeding ground bordering a noisy seaway with passive acoustic monitoring (PAM) systems reporting the detections and the localization in real time. This general problem is methodologically addressed using the detection theory, and the relevant formulas for assessing the PAM performance are provided. The method is applied to the special case of North Atlantic right whales (NARW) in the feeding ground area (FGA) off Gaspé in the Gulf of St. Lawrence. The relevant scales at play in the area are first established before setting the parameters of realistic simulations fed with the actual shipping traffic, transmission loss (TL) from a regional acoustic propagation model accounting for the bathymetric and environmental structures, estimated NARW upcall source level (SL), and measured ship SLs of the local fleet. The tested scenarios include single hydrophone and hydrophone-array PAM systems cabled to the coast at six pre-defined positions where simple deployments with short cables are possible. The simultaneous use of two coastal stations is considered to achieve NARW localization or to maximize the area of good detection. Three families of NARW upcall detectors, providing different levels of minimal signal to noise ratio (SNR) for detection, are compared for each scenario. A low false-alarm rate of 1 per day is imposed and a probability of detection greater than 0.5 is retained as indicator of good performance. Time Frequency Based Detector (TFBD) prevailed as the best trade-off between performance of detection and robustness against natural variability of NARW upcalls. For PAM systems equipped with a single hydrophone, the Effective Surface of Detection (ESD, 256 ± 91 km, 1.6 % of the FGA surface) and the Effective Range of Detection (ERD, 12 ± 2 km) are small. A coastal singlehydrophone PAM system failed to cover the entire width of the FGA from the Gaspesian coast. A total of 62 single-hydrophone offshore PAM buoys or gliders are required to monitor the entire FGA. The use of a hydrophone array provides an ESD that is 14 times larger than the ESD of single-hydrophone PAM systems. A coastal PAM system equipped with a hydrophone array and TFBD detects NARW upcalls over an area of 2664 km (15 % of the FGA surface). The combination of 2 such PAM systems, optimally positioned on the Gaspesian coast, detects NARW upcalls over an area of 4 240 km (25 % of the FGA surface); the size of the corresponding Inclusive Rectangular Box (IRB) of the Good Detection Area (GDA) is then 100 km × 96 km. A combination of 5 coastal PAM systems equipped with an hydrophone array and TFBD, plus one autonomous offshore PAM buoy, well located, is able to monitor the whole surface of the FGA. For localizing and tracking NARWs at a hotspot of interaction with human activities within the FGA, 2 cooperating coastal PAM systems equipped with a hydrophone array and TFBD, 20-km apart between Gaspé and Percé, can localize and track NARW upcalls within an area of 30 km ×30 km, with a North-South accuracy of 1.5 km and an East-West accuracy of 5 km.

This paper contributes to documenting a change in the distribution of North Atlantic right whales Eubalaena glacialis (NARWs) that occurred in the 2010s, when the whales largely abandoned their traditional summering grounds in the Gulf of Maine/Bay of Fundy/Scotian shelf. Data from a year-round passive acoustic monitoring (PAM) network in the Gulf of St. Lawrence were exploited to build the time series of NARW incursions into this inland sea of the Northwest Atlantic, from June 2010 to November 2018. NARWs visited the southern Gulf of St. Lawrence every year from June to January, until ice freeze-up. The earliest detections were made at the end of April and the latest in mid-January. Call occurrence peaked between August and the end of October. NARW contact calls were not detected at the most upstream station at Les Escoumins, in the Lower St. Lawrence estuary, or at the northeastern connection of Belle Isle Strait with the Atlantic, which was monitored from November 2010 to November 2011. The mean daily occurrence of NARWs in the feeding grounds off Gaspe quadrupled after 2015 compared to 2011-2014. Long-term continuous PAM data provided invaluable information to document this marine mammal distribution shift.

Pour suivre la fréquentation du parc marin du Saguenay–Saint-Laurent par le rorqual bleu ( Balaenoptera musculus ) et le rorqual commun ( Baleanoptera physalus ) ainsi que la concentration de leur nourriture, le krill, un observatoire acoustique a été opéré de 2007 à 2017 à l’est du parc. L’information nouvelle qu’apportent ces séries temporelles décennales montre que : a) la présence des rorquals est relativement stable, et que les deux espèces ont visité la région chaque année, particulièrement dans la 2 e moitié de l’an, jusqu’à l’apparition des glaces; b) les dates de début et de fin varient, et cette fréquentation saisonnière est plus intense tard en automne qu’au cours de l’été, alors que l’écotourisme d’observation des baleines bat son plein; c) la concentration de krill est élevée (50 % du temps supérieure à 176 t/km 2 ) mais subit d’importantes fluctuations sur de courtes périodes, sans lien particulièrement fort avec des forçages physiques ou biologiques de plus d’un jour, tel celui des marées semi-mensuelles, d’après les analyses de rythmes effectuées. La concentration quotidienne de krill tendait vers un maximum de la mi-décembre à la mi-février. Dans un contexte de réchauffement planétaire, la présence hivernale des rorquals pourrait se prolonger si la période englacée diminue.

Canadian Arctic and Subarctic regions experience a rapid decrease of sea ice accompanied with increasing shipping traffic. The resulting time-space changes in shipping noise are studied for four key regions of this pristine environment, for 2013 traffic conditions and a hypothetical tenfold traffic increase. A probabilistic modeling and mapping framework, called Ramdam, which integrates the intrinsic variability and uncertainties of shipping noise and its effects on marine habitats, is developed and applied. A substantial transformation of soundscapes is observed in areas where shipping noise changes from present occasional-transient contributor to a dominant noise source. Examination of impacts on low-frequency mammals within ecologically and biologically significant areas reveals that shipping noise has the potential to trigger behavioral responses and masking in the future, although no risk of temporary or permanent hearing threshold shifts is noted. Such probabilistic modeling and mapping is strategic in marine spatial planning of this emerging noise issues.

Monitoring Arctic wildlife is important due to the increasing potential impact of environmental and industrial changes. Passive acoustic monitoring (PAM) can be an important tool for wildlife management through observations of several species simultaneously along with abiotic elements such as industrial activity. Here, we use PAM methods to monitor the occurrence of marine mammals over an 8-month period (Oct 2012–May 2013) in Scott Inlet, Nunavut. When marine mammals were present, we investigated possible environmental correlates. Sea ice coverage strongly influenced detections of marine mammal sounds: narwhals and bowhead whales were only present before full ice cover occurred in the fall, while bearded seals and walruses could only be detected after ice formation. Tidal phase, time of the day, water temperature at 300 m depth, and air temperature all influenced detections of narwhal clicks. This PAM study provides a baseline measure for the presence of marine mammals over the fall to spring in Scott Inlet. Long-term PAM in the same location would allow us to document changes in the phenology of marine mammals at this site in relation to environmental changes.

The Estuary and the Gulf of St. Lawrence constitute a large marginal sea of Northwest Atlantic of ∼260,000 km2, which is crossed by the main shipping route to the Great Lakes and where ∼125 ships are cruising every time. This inland sea is also part of the habitat of the endangered Northwest Atlantic blue whale population, which frequent these waters throughout the year as indicated by a recent passive acoustic study. The present study aims at estimating the degree of blue whale exposure to shipping noise, in space and time, and the risks of auditory damages, behavioral responses and communication masking in this region. First, shipping noise radiated from the AIS-monitored traffic is modeled, mapped with a high time-space resolution, and validated using in situ measurements from a dedicated ANSI-compliant acoustic observatory along the seaway. The latter is also used to estimate the source levels of the ships. Shipping noise statistics over the region are then computed and risk metrics of blue whale exposure to shipping noise are estimated and mapped. These probability maps provide a useful tool to marine spatial planning management and to assess acoustic quality of blue whale habitats.

Soundscape patterns result from sounds radiated by several sources governed by diverse processes acting at different scales. Acoustic measurements are sampling this multi-scale variability pattern at particular locations and times. To facilitate soundscape analysis, the identification and separation of the different contributors, and soundscape comparisons, an approach, called soundscape cube, is introduced. For any acoustic measurement time-series, a probability of occurrence is estimated for all time-frequency samples of sound pressure levels (SPL) from the cumulative density functions (cdfs) of the sound spectra computed for consecutive time-windows. These spectral cdfs are then stacked along the time axis to generate a 3D block that piles up the time-frequency surfaces of the spectral SPL quantiles. This soundscape cube can then be explored by various mathematical operators to characterize and separate intra-soundscape SPL patterns emerging across the cube. The soundscape cube can also be split into its ambient-noise and structured-signal components, which respond to different forcing and timespace scales. Inter-soundscape cube operators can highlight the differences and similarities among sites, years,and their scales of autocorrelation, recurrence, etc. Application examples of this approach are given for acoustic measurements from the Canadian Arctic, the St. Lawrence Estuary, and the Mediterranean Sea.

An ensemble of 255 spectral source levels (SSLs) of merchant ships were measured with an opportunistic seaway acoustic observatory adhering to the American National Standards Institute/Acoustical Society of America S12.64-2009 standard as much as possible, and deployed in the 350-m deep lower St. Lawrence Seaway in eastern Canada. The estimated SSLs were sensitive to the transmission loss model. The best transmission loss model at the three measuring depths was an empirical in situ function for ranges larger than 300 m, fused with estimates from a wavenumber integration propagation model fed with inverted local geoacoustic properties for [300 to 1 m] ranges. Resulting SSLs still showed a high variability. Uni- and multi-variate analyses showed weak intermingled relations with ship type, length, breadth, draught, speed, age, and other variables. Cluster analyses distinguished six different SSL patterns, which did not correspond to distinctive physical characteristics of the ships. The broadband [20-500 Hz] source levels varied by 30 dB or more within all four 50-m length categories. Common SSL models based on frequency, length and speed failed to unbiasly replicate the observations. This article presents unbiased SSL models that explain 75%-88% of the variance using frequency, ship speed, and three other automatic identification system ship characteristics.

A setup for measuring spectral source levels (SSLs) of ships transiting along a seaway, the traffic density and shipping noise, is presented. The results feed shipping-noise modeling that reproduces the actual in situ observations to map shipping-noise variability over space and time for investigating its effects on aquatic organisms. The ship’s SSL databank allows sorting the different contributors to total shipping noise for assisting in exploring mitigation approaches (e.g., fleet composition, rerouting). Such an acoustic observatory was deployed since November 2012 for a complete annual cycle of measurements in the deep downstream part of the St. Lawrence Seaway.