Presence Of Marine Mammals Research Articles

A deep learning model for detecting and classifying multiple marine mammal species from passive acoustic data

Underwater passive acoustics is used worldwide for multi-year monitoring of marine mammals. Yet, the large amount of audio recordings raises the need to automate the detection of acoustic events. For instance, the increasing number of Offshore Wind Farms (OWF) raises key environmental and societal issues relating to their impacts on wildlife. In this context, monitoring marine mammals along with information on their acoustic environment throughout the OWF life cycle is crucial. The objective of this study is to evaluate the ability of a single deep learning model to precisely detect and localize, in time and in frequency, the marine mammal sounds over a wide frequency range and classify them by species and sound types.A broadband hydrophone, deployed at the Fécamp OWF (Normandy, France), recorded the underwater soundscape including sounds from marine mammals occurring in the area. To visualize these sounds, 15-s spectrograms were computed. From these images, dolphin (D) and porpoise (P) sounds were manually annotated, including different types of sounds: Click-Trains (DCT, PCT), Buzzes (DB, PB) and Whistles (DW). The spectrograms were then split into five-fold cross-validation datasets, each containing one half of manual annotations and one half of only background noise. A Faster R-CNN model was trained to precisely detect and classify the marine mammal sounds in the spectrograms.Three model output configurations were used: (1) overall detection of marine mammals (presence vs. absence), (2) detection and classification of species (two classes: dolphin, porpoise) and (3) sound types (five classes: DCT, DB, DW, PCT, PB). For the simplest configuration (1) 15.4 % of the spectrogram dataset had detections while missing only 6.6 % of annotated spectrograms. For the more precise configurations, (2) and (3), the mean Average Precision (mAP) achieved were 92.3 % (2) and 84.3 % (3), and the macro average Area under the curve (AUC) 95.7 % (2) and 94.9 % (3).This model will help to speed up the annotation processes, by reducing the spectrogram quantity to be manually analyzed and having time-frequency boxes already drawn. Several model parameters can be adjusted to trade off missed detections and false positives which need to be carefully considered and adapted to the problem. For instance, these adjustments would be particularly relevant depending on the human resources available to manually check the model detections and the criticality of missing marine mammal sounds. These models are promising, ranging from the simple detection of marine mammal presence to precise ecological inferences over the long term.

Seasonal and diurnal marine mammal presence in the proposed marine protected area of Southampton Island, Hudson Bay, Nunavut as revealed by passive acoustic monitoring

Marine protected areas contribute to mitigating the effects of human activities on marine ecosystems. The waters of Southampton Island, Nunavut, Canada are under consideration to become a marine protected area, but baseline information of marine mammal presence and habitat use is lacking. This study represents the first passive acoustic monitoring of marine mammals in this area, with data collected in 2018 and 2019. Bioacoustics analyses and generalized linear models were used to investigate species seasonal and temporal vocalization trends; infer behavior and habitat use from vocal cues; and explore vocal activity correlation with sea ice. Over a diel period, bearded seals ( Erignathus barbatus (Erxleben, 1777)) and walruses ( Odobenus rosmarus (Linnaeus, 1758)) were found to increase their vocal activity at night, whereas belugas ( Delphinapterus leucas (Pallas, 1776)) mainly vocalized during daytime. Seasonally, bearded seals were recorded only during their breeding season at sea ice break-up, while walruses vocalized consistently throughout the open-water period outside their breeding season. Beluga vocal trends suggest their use of the area as a migratory corridor during sea ice break-up and freeze-up. Finally, bowhead whales ( Balaena mysticetus Linnaeus, 1758) were recorded later than expected, concurrently with the onset of their mating vocal displays during the fall migration at sea ice freeze-up.

Soundscape characterization in the Central Arctic Ocean ecosystem (Svalbard) using acoustic indices

An increasingly warmer, less frozen Arctic is opening further to vessel traffic, transforming dominant ambient noise sources in the underwater soundscape. Chief sources may be shifting from wind to ship noise. Collecting data that help explain the changing composition of the soundscape may offer insights to guide regulation of noise in the ocean, furthering management and conservation efforts. Hydrophones connected to field recorders were used in this study to characterize the soundscape and to study marine mammal presence and ship noise. Hydrophones were deployed at 44 locations from a 13.8 m Ovni 445 sailing vessel between 9° E and 19° E and 69° N and 80° N in April 2023. Acoustic indices were utilized to assess soundscape composition. Vessel locations were confirmed using Automatic Identification System (AIS) marine traffic data. Wind, waves, and ice (geophony) dominated the soundscape’s acoustic signature in remote locations, while human-caused sounds (anthrophony) were significant near Arctic shipping routes, fishing areas, and in fjords. Marine mammal vocalizations were detected near the ice edge, at fjord mouths, and in fjords. This acoustic characterization study provides a glimpse into the sonic sources and balance of sounds in the soundscape at present, essential data as the region rapidly transforms.

Seasonal acoustic presence of marine mammals at the South Orkney Islands, Scotia Sea.

Increased knowledge about marine mammal seasonal distribution and species assemblage from the South Orkney Islands waters is needed for the development of management regulations of the commercial fishery for Antarctic krill (Euphausia superba) in this region. Passive acoustic monitoring (PAM) data were collected during the autumn and winter seasons in two consecutive years (2016, 2017), which represented highly contrasting environmental conditions due to the 2016 El Niño event. We explored differences in seasonal patterns in marine mammal acoustic presence between the two years in context of environmental cues and climate variability. Acoustic signals from five baleen whale species, two pinniped species and odontocete species were detected and separated into guilds. Although species diversity remained stable over time, the ice-avoiding and ice-affiliated species dominated before and after the onset of winter, respectively, and thus demonstrating a shift in guild composition related to season. Herein, we provide novel information about local marine mammal species diversity, community structure and residency times in a krill hotspot. Our study also demonstrates the utility of PAM data and its usefulness in providing new insights into the marine mammal habitat use and responses to environmental conditions, which are essential knowledge for the future development of a sustainable fishery management in a changing ecosystem.

Where are the whales? Continued acoustic monitoring efforts of California’s Central Coast

Understanding and conserving ocean ecosystems is a difficult, but important task made easier with bioacoustic technology. Although marine mammal monitoring efforts can be done with visual surveys, they often lack temporal information on a finer scale. Long-term passive acoustic monitoring efforts of critical migratory species can provide detailed information about the region’s marine soundscape that is key to conservation efforts. The aim of our project is to establish a long-term bioacoustic monitoring station off the coast of central California and help close the gap in our understanding of marine mammal presence along the Pacific coastline. The goals put forth by the bioacoustic lab for this academic year include (1) determining probable species presence, (2) ascertaining temporal (day/night) variations of vocalizations, and (3) examining key differences in species and call type between two deployments from Fall 2022 and Winter 2023. These comparisons will be crucial to help develop a baseline understanding of seasonal and temporal variations of the soundscape in our region. We aim to implement various long-term deployments in order to gather more complete and consistent bioacoustic data in our local waters. These deployments and the subsequent analysis will contribute to large scale marine mammal monitoring and conservation efforts. [This project was made possible by a grant from the Santa Rosa Creek Foundation and the COAST undergraduate research fund.]

Assessing marine mammal diversity in remote Indian Ocean regions, using an acoustic glider

Many observations collected from whaling logbooks or more recent satellite tags and acoustic surveys report that the Indian Ocean is a very important place for large baleen whales. They undergo long seasonal migrations from Southern feeding grounds to tropical and subtropical mating and breeding grounds. However, whether and where they stop to rest or feed during their long travels are poorly known. The Indian Ocean is also home to many odontocete species such as sperm whales, killer whales and multiple delphinid species. In this paper, we analyze passive acoustic data collected by an electric glider around two steep bathymetric features located in the Western sub-tropical Indian Ocean (Walters Shoal) and in the mid sub-tropical Indian Ocean (St. Paul and Amsterdam islands), both included in Important Marine Mammal Areas (IMMAs). The acoustic data were manually reviewed and annotated by two analysts. The aim of this experiment was to improve the knowledge on marine mammal presence in these little studied IMMAs. We found that bioacoustic activity was quite high in both monitored areas with 40% of the records containing marine mammal sounds in Walters Shoal and 70% in St. Paul and Amsterdam islands. Calls from Antarctic blue whales, Southwestern and Southeastern Indian Ocean pygmy blue whales, fin whales and an unidentified baleen whale were detected at one or both sites. Odontocete clicks and whistles were also recorded at both sites. The discussion puts these marine mammal acoustic detections back into the context of their seasonal and geographical presence already described by other studies in the Indian Ocean and makes hypotheses about the role of the two studied areas for marine mammals.

Directional detection of simulated whale calls and ambient noise in a busy harbour

Timely information on marine mammal presence in, or near, sonar training areas can be used to minimize the risk of harming these animals. Defence Research and Development Canada (DRDC) has recently been investigating a variety of acoustic technologies to facilitate real-time marine mammal monitoring in high noise (including ship noise and sonar signals) environments. DRDC assessed the directional detection and localization capability of a network of sub-surface volumetric and vertical line arrays against the noisy backdrop of the busy harbour during an experiment conducted in Bedford Basin, NS. Playbacks of Southern Resident killer whale calls and North Atlantic right whale upcalls, as well as simulated calls, were transmitted. To assess variability in bearing estimates for whale calls in different frequency bands, an acoustic source was fixed at a single location for half of the experiment and dipped over the side of a boat at seven locations around the recorders during the other half. During this talk, ambient noise and environmental measurements will be presented along with acoustic localization results.

Effects of modelling assumptions of complex ocean floor topography on marine life

Passive acoustic monitoring (PAM) is an important technique to assess the presence of marine mammals and, if necessary, mitigate the effects of anthropogenic noise sources upon them. The complexity of the ocean acoustic environment makes accurate localisation of marine mammal vocalisations difficult. It is, therefore, important to be able to predict the detection and localisation performance of PAM to ensure sensors are optimally placed and any resulting actions are suitably informed. A variety of acoustic models can be used to predict the performance of a sensor field ranging from simple 1D models up to full 3D models. Each type of model has advantages and disadvantages. Simple 1D models offer the most advantages in terms of solution time and minimal inputs but their predictions can have reduced accuracy. This is especially true in areas of complex ocean floor topography, such as on a shelf break, where complex 3D acoustic effects can occur. This study investigates the variation in the predicted acoustic field from 1D up to 3D models on a shelf break and how with increasing model fidelity the picture of the acoustic environment changes and its impact on acoustic monitoring advice. © Crown copyright (2022), Dstl.

The influence of penguin activity on soil diatom assemblages on King George Island, Antarctica with the description of a new Luticola species.

BackgroundIce-free areas in the Antarctic region are strongly limited. The presence of marine mammals and birds in those areas influence soil properties and vegetation composition. Studies on the terrestrial diatom flora in soils influenced by sea birds in the Maritime Antarctic region are scarce.MethodsSamples were collected from two transects on the western shore of the Admiralty Bay region. Light and scanning electron microscopic observations and statistical analyses were conducted to consider the impact of penguin rookeries on soil diatom assemblages.ResultsThe disturbance associated with the presence of penguin rookeries clearly influences the soil diatom diversity. Assemblages from areas with the highest nutrient input were characterized by a much lower diversity with only few species dominating the flora. One of recorded taxa could not be assigned to any of the known species. Therefore, based on the combination of morphological features analyzed using light and scanning electron microscopes and comparison with similar taxa in the Antarctic region and worldwide, the species is described hereby as new to science–Luticola kaweckae sp.nov. The new species is characteristic for soil habitats with strong penguin influence.

TOSSIT: A low-cost, hand deployable, rope-less and acoustically silent mooring for underwater passive acoustic monitoring

Passive Acoustic Monitoring (PAM) has been used to study the ocean for decades across several fields to answer biological, geological and meteorological questions such as marine mammal presence, measures of anthropogenic noise in the ocean, and monitoring and prediction of underwater earthquakes and tsunamis.While in previous decades the high cost of acoustic instruments limited its use, miniaturization and microprocessor advances dramatically reduced the cost for passive acoustic monitoring instruments making PAM available for a broad scientific community. Such low-cost devices are often deployed by divers or on mooring lines with a surface buoy, which limit their use to diving depth and coastal regions.Here, we present a low-cost, low self-noise and hand-deployable PAM mooring design, called TOSSIT. It can be used in water as deep as 500 m, and can be deployed and recovered by hand by a single operator (more comfortably with two) in a small boat. The TOSSIT modular mooring system consists of a light and strong non-metallic frame that can fit a variety of sensors including PAM instruments, acoustic releases, additional power packages, environmental parameter sensors. The TOSSIT’s design is rope-less, which removes any risk of entanglement and keeps the self-noise very low.

Passive acoustic monitoring reveals year-round marine mammal community composition off Tasiilaq, Southeast Greenland.

Climate-driven changes are affecting sea ice conditions off Tasiilaq, Southeast Greenland, with implications for marine mammal distributions. Knowledge about marine mammal presence, biodiversity, and community composition is key to effective conservation and management but is lacking, especially during winter months. Seasonal patterns of acoustic marine mammal presence were investigated relative to sea ice concentration at two recording sites between 2014 and 2018, with one (65.6°N, 37.4°W) or three years (65.5°N, 38.0°W) of passive acoustic recordings. Seven marine mammal species were recorded. Bearded seals were acoustically dominant during winter and spring, whereas sperm, humpback, and fin whales dominated during the sea ice-free summer and autumn. Narwhals, bowhead, and killer whales were recorded only rarely. Song-fragments of humpback whales and acoustic presence of fin whales in winter suggest mating-associated behavior taking place in the area. Ambient noise levels in 1/3-octave level bands (20, 63, 125, 500, 1000, and 4000 Hz), ranged between 75.6 to 105 dB re 1 μPa. This study provides multi-year insights into the coastal marine mammal community composition off Southeast Greenland and suggests that the Tasiilaq area provides suitable habitat for various marine mammal species year-round.

Southern Resident killer whale acoustic monitoring and noise measurements to inform noise mitigation and potential management strategies

SMRU Consulting, in collaboration with the ECHO Program, the San Juan County MRC and DFO, has been monitoring Salish Sea underwater soundscapes for the presence of Southern Resident killer whales (SRKW), to measure ambient noise levels, evaluate the efficacy of noise mitigation measures and inform potential management strategies. This talk will highlight results from four projects across the years 2019–2021. This includes measurements from a cabled observatory at Lime Kiln Point State Park in support of the ECHO Program’s Haro Strait commercial vessel slowdowns; measurements from autonomous recorders at five locations in Burrard Inlet for the ECHO Program and the Tsleil-Waututh Nation to monitor trends in ambient noise and marine mammal presence; measurements from Coastal Acoustic Buoys at eight locations south of San Juan Island in support of San Juan County’s management efforts, and a Coastal Acoustic Buoy for Offshore Wind deployment near Point Roberts to allow DFO to evaluate acoustic technology. This talk will discuss the pros and cons of these four different acoustic systems and highlight trends in the data that may help inform mitigation and management strategies.

Measuring the soundscape of the Eastern United States outer continental shelf using an array of autonomous observatories

The Atlantic deep-water Ecosystem Observation Network project (https://adeon.unh.edu/) deployed seven autonomous long-term observatory landers in waters between 250 and 900 m deep along the east coast of the United States for three years (November 2017–November 2020). The objectives of the project included quantifying the variability of the soundscape along and across the outer continental shelf in time and frequency. An early objective of the project was publication of a soundscape standard, whose recommendations were subsequently applied to the data analysis. Here we show how monthly probability density functions of the 20, 80, 630, and 3150 Hz decidecade bands provided insight to the contribution of mammals, vessels, and wind to the measured soundscapes. At some stations the soundscape measurements were hampered by flow noise at low frequency. Clear relationships between stations by month and location changed with frequency band. Application of automated detectors and a standardized approach for validating their outputs provided information on the spatial and temporal presence of marine mammals. The application of standardized methods accelerates the analysis of large passive acoustic monitoring datasets and facilitates communication of results.

Tagging ocean soundscapes with machine learning and topological approaches

With a multitude of sources simultaneously contributing to the ambient ocean soundscape, it is important to disaggregate noise source contributions for better monitoring and assessing noise impacts. Our work adopts a modular set of neural networks and topological pipelines to analyze multiple representations of time-series samples of the ambient ocean noise. Specifically, a convolutional neural network (CNN) is used to broadly tag the presence of local shipping and marine mammal vocalizations from spectrogram representations. Multiple approaches are investigated using topological data analysis to predict a class label of the ship hull type or specific marine mammal species using the audio data as input. The datasets used in training, testing, and validation comprise hydrophone recordings across varying sensors and ocean environments to address the wide variation in ambient background noise and propagation paths. Algorithm performance is characterized by classification accuracy on labeled data. This approach demonstrates a generalized tagging cabilitility of the presence of marine mammals and local shipping activity.

Cetacean presence and distribution in the central Mediterranean Sea and potential risks deriving from plastic pollution

The Sardinian and Sicilian Channels are considered hotspots of biodiversity and key ecological passages between Mediterranean sub-basins, but with significant knowledge gaps about marine mammal presence and potential threats they face.Using data collected between 2013 and 2019 along fixed transects, inter and intra-annual cetacean index of abundance was assessed. Habitat suitability, seasonal hot spots, and risk exposure for plastic were performed using the Kernel analysis and the Biomod2 R-package.661 sightings of 8 cetacean species were recorded, with bottlenose and striped dolphins as the most sighted species. The north-eastern pelagic sector, the coastal waters and areas near ridges resulted the most suitable habitats for these species. The risk analysis identified the Tunis, Palermo, and Castellammare gulfs and the Egadi Island as areas of particular risk of plastic exposure.The study represents a great improvement for cetacean knowledge in this region and contributes to the development of effective conservation strategies.

Epimeletic behaviour in a Southern Resident Killer Whale (<i>Orcinus orca</i>)

Southern Resident Killer Whale (SRKW, Orcinus orca) may be found year round in the Salish Sea. These orcas comprise three matrilineal pods (J, K, and L) and were listed as Endangered under the Canadian Species at Risk Act in 2003 and under the United States Endangered Species Act in 2005 because of prey scarcity, vessel noise and disturbance, small population size, and exposure to toxins. Since 1993, the Whale Museum has been operating Soundwatch, a boater education program for vessels. Soundwatch personnel are on the water in the central Salish Sea throughout the summer educating boaters on how to maneuver near marine mammals legally and documenting vessel regulation violations and marine mammal presence and behaviour. Starting on 24 July 2018, Soundwatch documented an adult female SRKW of J pod (J35) carrying a dead neonate calf. J35 continued to carry her dead calf for 17 consecutive days covering ~1600 km. Her story riveted the attention of the people of the Salish Sea as well as people around the world, evoking empathy for J35 and her loss as well as the plight of the Endangered SRKW population. Here, we tell her story and evaluate whether the behaviour J35 displayed toward her dead calf was an example of epimeletic behaviour, animal grief.

Recycling data: An annotated marine acoustic data set that is publicly available for use in classifier development and marine mammal research

Barkley Canyon is a productive submarine canyon approximately 60 km southwest of Vancouver Island, Canada. The canyon's nutrient flow is affected by multiple regional currents, and draws aggregations of euphausiids, hake, herring, and various marine mammal species. A subset of the acoustic data collected from the 2013–2015 hydrophone deployment on the Barkley Canyon Upper Slope platform of Ocean Networks Canada's North-East Pacific Time-series Undersea Networked Experiments (NEPTUNE) observatory was manually annotated for marine mammal presence to investigate marine mammal habitat use and in support of development of a random forest classifier. This dataset, which is being made publicly available for further use, includes strong-label annotations of phonations from blue whales, fin whales, humpback whales, sperm whales, orcas, Pacific white-sided dolphins, Risso's dolphins, and other delphinids that could not be identified to species. All regional orca communities are represented within the dataset, and phonations are labelled to ecotype and pod level when possible. This dataset could be further used in a number of ways, including classifier development, investigations into habitat use and seasonality, or combining the acoustic data with data collected from co-located oceanographic instruments to investigate links between marine mammal presence and oceanographic conditions.

Seasonal trends in underwater ambient noise near St. Lawrence Island and the Bering Strait

We measured spatial and temporal patterns of ambient noise in dynamic, relatively pristine Arctic marine habitats and evaluate the contributions of environmental and human noise sources. Long-term acoustic recorders were deployed around St. Lawrence Island and the Bering Strait region within key feeding and migratory corridors for protected species that are inherently important to Native Alaskan cultures. Over 3000 h of data from 14 recorders at nine sites were obtained from October 2014 to June 2017. Spatial and temporal ambient noise patterns were quantified with percentile statistics in 1/3rd-octave bands (0.02–8 kHz). Ice presence strongly influenced ambient noise by influencing the physical environment and presence of marine mammals. High variability in noise was observed within and between sites, largely as a function of ice presence and associated factors. Acute contributions of biological and anthropogenic sources to local ambient noise are compared to monthly averages, demonstrating how they influence Arctic soundscapes.

Slocum Gliders Provide Accurate Near Real-Time Estimates of Baleen Whale Presence From Human-Reviewed Passive Acoustic Detection Information

Mitigating the effects of human activities on marine mammals often depends on monitoring animal occurrence over long time scales, large spatial scales, and in real time. Passive acoustics, particularly from autonomous vehicles, is a promising approach to meeting this need. We have previously developed the capability to record, detect, classify, and transmit to shore information about the tonal sounds of baleen whales in near real time from long-endurance ocean gliders. We have recently developed a protocol by which a human analyst reviews this information to determine the presence of marine mammals, and the results of this review are automatically posted to a publicly accessible website, sent directly to interested parties via email or text, and made available to stakeholders via a number of public and private digital applications. We evaluated the performance of this system during two 3.75-month Slocum glider deployments in the southwestern Gulf of Maine during the spring seasons of 2015 and 2016. Near real-time detections of humpback, fin, sei, and North Atlantic right whales were compared to detections of these species from simultaneously recorded audio. Data from another 2016 glider deployment in the same area were also used to compare results between three different analysts to determine repeatability of results both among and within analysts. False detection (occurrence) rates on daily time scales were 0% for all species. Daily missed detection rates ranged from 17 to 24%. Agreement between two trained novice analysts and an experienced analyst was greater than 95% for fin, sei, and right whales, while agreement was 83-89% for humpback whales owing to the more subjective process for detecting this species. Our results indicate that the presence of baleen whales can be accurately determined using information about tonal sounds transmitted in near real-time from Slocum gliders. The system is being used operationally to monitor baleen whales in U.S., Canadian, and Chilean waters, and has been particularly useful for monitoring the critically endangered North Atlantic right whale throughout the northwestern Atlantic Ocean.

X-Band Radar for Cetacean Detection (Focus on Tursiops truncatus) and Preliminary Analysis of Their Behavior

Cetaceans are protected species all over the world, most of them are vulnerable, endangered, or data deficient (according to International Union for Conservation of Nature - IUCN red list). X-band radars detect the echo of the electromagnetic signal reflected by an obstacle or a ship (target). The application of X-band radar to the detection of cetaceans is a new and innovative field of research that could improve the automation of marine mammal data collection, and this is the first time in the Mediterranean Sea. The aim of this work was to test the capability of X-band radar installed along the coast (ground-based) to detect and track cetaceans in a range of approximately 2.5 nautical miles from the radar antenna. Data collection included a part of field work, implemented through the acquisition of photographic images and target’s radar detection (by the panoramic terrace Santa Maria in Corniglia), and a part, performed in the laboratory, of data analysis. The work was undertaken between May and November 2018. During this period, 30 days of monitoring were carried out (about 300 h) and about 10,000 radar images were recorded. The first results showed that we were able to recognize the target “cetacean” from the other common targets (boats, buoys, etc.) detected by the radar. In particular 70 dolphins were sighted by visual census; 12 of them were recognized on radar images. Radar images allowed extraction of dolphin dive time (between 2 and 15 s). The next step will be to allow the radar to identify the presence of marine mammals itself since it also works at night and with low visibility. This technique could complement the protection measures of cetaceans, highlighting their presence at sea even if it is impossible with waves higher than 0.8 m and over distances greater than 2.5 km.