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

AimSpecies distribution models (SDMs) are essential tools in ecology and conservation. However, the scarcity of visual sightings of marine mammals in remote polar areas hinders the effective application of SDMs there. Passive acoustic monitoring (PAM) data provide year‐round information and overcome foul weather limitations faced by visual surveys. However, the use of PAM data in SDMs has been sparse so far. Here, we use PAM‐based SDMs to investigate the spatiotemporal distribution of the critically endangered Antarctic blue whale in the Weddell Sea.LocationThe Weddell Sea.MethodsWe used presence‐only dynamic SDMs employing visual sightings and PAM detections in independent models. We compared the two independent models with a third combined model that integrated both visual and PAM data, aiming at leveraging the advantages of each data type: the extensive spatial extent of visual data and the broader temporal/environmental range of PAM data.ResultsVisual and PAM data prove complementary, as indicated by a low spatial overlap between daily predictions and the low predictability of each model at detections of other data types. Combined data models reproduced suitable habitats as given by both independent models. Visual data models indicate areas close to the sea ice edge (SIE) and with low‐to‐moderate sea ice concentrations (SIC) as suitable, while PAM data models identified suitable habitats at a broader range of distances to SIE and relatively higher SIC.Main ConclusionsThe results demonstrate the potential of PAM data to predict year‐round marine mammal habitat suitability at large spatial scales. We provide reasons for discrepancies between SDMs based on either data type and give methodological recommendations on using PAM data in SDMs. Combining visual and PAM data in future SDMs is promising for studying vocalized animals, particularly when using recent advances in integrated distribution modelling methods.

Integration of passive acoustic monitoring data into OBIS-SEAMAP, a global biogeographic database, to advance spatially-explicit ecological assessments

Navy training events involving the use of explosives pose a potential threat to marine mammals. This study used passive acoustic and visual monitoring data to evaluate marine mammals’ behavioral responses to noise from explosive events. Monitoring was conducted during five training events in the Virginia Capes (VACAPES) Range Complex during August/September of 2009–2012. Passive acoustic monitoring methods ranged from a single hydrophone to an array of sonobuoys monitored in real time. Visual monitoring effort over the five events totaled approximately 34 h (day before events: 10.1 h; days of events: 22.3 h; day after events: 1.5 h), yielding a total of 27 marine mammal sightings. Approximately 54 h of acoustic data were collected before, during, and after the five events. Behavioral changes were evaluated based on analysis of vocalizations detected before, during, and after explosions and concurrent data from visual sightings. For time periods with both visual and acoustic monitoring data, detection methods were compared to evaluate effectiveness. Continuing use and evaluation of both visual and passive acoustic methods for monitoring of explosive training events will improve our knowledge of potential impact resulting from explosive events and help improve management and conservation of marine mammals.

Basic information on marine mammal habitat use is necessary for informing ecosystem-based management plans and for mitigating human impacts. Massachusetts Bay is an important marine mammal foraging area in the Gulf of Maine and a region of high human activity, but little is known about toothed whale habitat use, particularly during winter months. Passive acoustic monitoring, particularly from autonomous platforms, provides advantages in studying habitat use in unfavorable conditions. The goal of this work is to use acoustic monitoring to investigate temporal and spatial occurrence patterns of toothed whale species in Massachusetts Bay during late fall/early winter using ocean gliders equipped with passive acoustic recorders. Slocum gliders were deployed in western Massachusetts Bay in 2014, 2015, and 2016. Toothed whales were detected on 92 (72%) of 128 deployment days. Detections occurred more often at night. Ongoing work includes acoustic identification of species and assessing relationships between detections and environmental conditions. These data provide the first evidence of a consistent presence of toothed whales in Massachusetts Bay during late fall and winter, and demonstrate the potential for ocean gliders as a tool to detect toothed whales in areas/times that are difficult to survey with traditional visual methods.

Spatial variability in total and organic mercury levels in Antarctic krill Euphausia superba across the Scotia Sea

Visual monitoring has been the primary method of detecting marine mammals during offshore activities for many years. The effectiveness of which is reduced when animals are not at the surface of the water and during periods of poor visibility. Towed Passive Acoustic Monitoring (PAM) is another tool in the ‘monitoring tool box’. It is a method to detect the presence of marine mammals beneath the sea surface and estimate their location relative to a hydrophone array being towed from a moving vessel. Marine mammal species are identified by the specific characteristics of the detected click and whistle sounds, the interpretation of which requires a specialist operator to maximise detection/identification efficiency and reduce the likelihood of false detections. PAM is increasingly considered as a best available tool for conducting marine mammal monitoring at sea during night time or poor visibility conditions when visual observation methods are less effective. The performance of towed PAM systems in the field is highly variable. The presence and characteristics of ambient acoustic noise relative to animal vocalisations, availability of experienced operators and levels of technical support are contributing factors to determining the overall operational performance of PAM systems. Recent experience of deploying towed PAM systems under real-time industry conditions has identified some practical challenges and potential improvements when using PAM as a mitigation monitoring tool during offshore oil and gas related activities such as seismic surveys. Lessons learned from industry experience in the field will increase the understanding of current capabilities and limitations and will lead to further improvement of the technology.

The Patagonian Sea is one of the most productive ecosystems in the Southern Hemisphere. Unlike other coastal regions, however, few studies exist on the top predators in its pelagic zone. In March 2017, a survey of seabirds and marine mammals was carried out on board the R/V Puerto Deseado in the Patagonian Sea, which extends from the South Atlantic Ocean to the north of the South Orkney Islands, Antarctica. Four of the five oceanographic regimes described in this region were studied, and 23 seabird species and five marine mammal species were recorded. Great shearwater Puffinus gravis , Antarctic prion Pachyptila desolata , and fin whale Balaenoptera physalus were the most abundant species. In the 2615 km traveled, two hotspots for top predators were found, coinciding with frontal zones: one in the shelf-break front and the other in the Southern Front of the Antarctic Circumpolar Current. The highest bird diversity and the greatest cetacean concentrations were recorded in the polar regime in the presence of low ice-field debris (5%). The results suggest that at the end of the austral summer, the distribution of top predators in this section of the South Atlantic Ocean is highly unequal. Some oceanic areas have a few species aggregations which contrast with the vast pelagic areas that have scarce species presence and activity. The hotspots were associated with high-productivity areas, but it is likely that they were also facilitated by the time of year (post-reproductive season), as most of the species were concentrated and had fed prior to their migrations. Citation: Orgeira J L. Occurrence of seabirds and marine mammals in the pelagic zone of the Patagonian Sea and north of the South Orkney Islands. Adv Polar Sci, 2018, 29(1): 25-33, doi: 10.13679/j.advps.2018.1.00025

: The long-term goal of this collaborative research effort is to enhance understanding of how variability in physical, biological and acoustic signals impact marine mammal habitat use. In particular, what are the effects of manmade underwater sound on marine mammal health and physiology, and what are the consequences of these effects at the marine mammal population level? A major component of this research is to use passive ambient sound to identify the physical environment present, and then to use this information to interpret the biological data collected. This report describes the passive component of this project.

The Scotia Sea is one of the most biologically rich regions of Antarctica, and it hosts a large community of upper trophic-level predators. Long-term at-sea monitoring provides valuable information on the Antarctic marine ecosystem and relationships among top predators. This paper presents the results of at-sea monitoring of seabirds and cetaceans over five consecutive summer seasons (2010—2014) in the Scotia Sea, Antarctica. A total of 11 656 flying birds belonging to 24 species were recorded in 884 ten-minute counts. Six Procellariiformes species were abundant: Black-browed Albatross, Cape Petrel, Southern Fulmar, Antarctic Prion, Wilson’s Storm-petrel, and Black-bellied Storm-petrel. Only three of these species accounted for 82% of the total abundance: Antarctic Prion (40%), Southern Fulmar (22%), and Cape Petrel (20%). A total of 678 baleen whalesbelonging to five species were recorded along a sampling effort of 2 351 nautical miles: Humpback, Sei, Southern Right, Fin, and Minke whales, which had different abundances during the study. The Fin Whale had the highest mean encounter rate for the 5 years (0.29 whales per nautical mile), followed by the Humpback Whale (0.09 whales per nautical mile). Annual dissimilarity in abundance of both seabirds and cetaceans occurred in conjunction with changes in the sea surface temperature and ice cover, showing the dependence of top predators on environmental changes. The largest aggregations of all top predators (seabirds and cetaceans) were recorded in two regions, west and south of the South Orkney Islands, suggesting important prey availability (especially krill) in those areas. Citation: Orgeira J L, Alderete M C, Jimenez Y G, et al. Long-term study of at-sea distribution of seabirds and marine mammals in the Scotia Sea, Antarctica. Adv Polar Sci, 2015, 26: 158-167, doi: 10.13679/j.advps.2015.2.00158

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.

Visual monitoring has been the primary method of detecting marine mammals during offshore operations for many years. The effectiveness of visual detection is reduced however, when animals are not at the surface and during periods of poor visibility. Towed passive acoustic monitoring (PAM) offers an opportunity to detect and indicate the location of marine mammal vocalisations relative to a hydrophone streamer being towed from a moving vessel. Vocalising marine mammal species may be identified by the characteristics of their calls and sonar clicks. Though basic automatic detection and species recognition functionality may be available, experienced and specialised operators are required to maximise detection/identification efficiency and minimise the likelihood of false detections. PAM is becoming an increasingly important monitoring tool during marine mammal population studies. When used as a monitoring tool in conjunction with mitigation measures, PAM provides the potential to reduce the risk of impacts from human activities on marine mammals. Though considered particularly useful for monitoring during periods of poor visibility, current towed PAM technology requires further development and field testing in order to provide a consistent and reliable real-time monitoring tool at sea. There is increased regulatory interest in using PAM as a means of monitoring marine mammals at sea during seismic survey operations at night or during periods of low visibility. As with any new technology, there is a need to ensure that both capabilities and limitations of the method during real-time Industry conditions are understood before requiring its use as a monitoring tool. Lessons learned from industry experience using PAM systems in the field will increase the understanding of current capabilities and limitations and will lead to further improvement of the technology. Recent experience of deploying towed PAM systems and testing a new; standardised user interface under real-time industry conditions, has identified some practical challenges of using PAM as a mitigation monitoring tool during offshore operations.

Passive acoustic monitoring (PAM) data collection has been growing exponentially, resulting in petabytes of data that document ocean soundscapes, how they change over time, and what animals use these ecosystems at varying timescales. Efficiently extracting this critical information and comparing it to other datasets in the context of ecosystem-based management is a Big Data challenge that traditional desktop processing methods cannot address. The curation, management, and dissemination of PAM datasets is another challenge in need of collaborative progress. To meet these exigencies, a multi-agency funded Sound Cooperative (SoundCoop) project is building community-focused, national cyberinfrastructure capability for PAM data to promote improved, scalable and sustainable accessibility and applications for management and science. Driven by partnerships and framed by four case studies, the SoundCoop has established guidance on the standardized processing of sound level metrics using free software toolkits and begun developing core cyberinfrastructure components that future PAM projects can leverage. U.S. and international scientists contributed PAM data collected across 10 long-term monitoring projects to operationalize the production of hybrid-millidecade spectra across a diversity of labs/instruments. Collectively, the contributed data demonstrate the value of standardized processing that enables the creation of comparable results from disparate monitoring efforts.

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.

The growing interest in generating electrical power from tidal currents using tidal turbine generators raises a number of environmental concerns, including the risk that marine mammals might be injured or killed through collision with rotating turbine blades. To understand this risk, information on how marine mammals use tidal rapid habitats and in particular, their underwater movements and dive behaviour is required. Porpoises, which are the most abundant small cetacean at most European tidal sites, are difficult animals to tag, and the limited size of tidal habitats means that any telemetered animal would be likely to spend only a small proportion of time within them. Here, an alternative approach is explored, whereby passive acoustic monitoring (PAM) is used to obtain fine scale geo-referenced tracks of harbour porpoises in tidal rapid areas. Large aperture hydrophone arrays are required to obtain accurate locations of animals from PAM data and automated algorithms are necessary to process the large quantities of acoustic data collected on such systems during a typical survey. Methods to automate localisation, including a method to match porpoise detections on different hydrophones and separate different vocalising animals, and an assessment of the localisation accuracy of the large aperture hydrophone array are presented.

Marine and freshwater mammals are increasingly threatened due to human activity. To improve conservation practice, decisions should be informed by the available evidence on the effectiveness of conservation actions. Using a systematically collated database of studies that test the effectiveness of actions to conserve marine and freshwater mammals, we investigated the gaps and biases in the available scientific evidence base. While there is a growing evidence base covering actions to address key threats (e.g. fisheries and bycatch) to marine and freshwater mammal populations, we identified large geographic and taxonomic biases. There was no relationship between the number of studies and marine mammal species per ecoregion and we found biases towards coastal areas of the Global North, with many regions and species having little or no evidence available. The number of studies per species did not correlate with (1) the threat level, (2) evolutionary distinctiveness or (3) the public ‘popularity’ of the study species. We also found a mismatch between actions tested and the actions suggested as needed in the International Union for the Conservation of Nature (IUCN) Red List. Several of these gaps and biases likely reflect the feasibility of researching marine mammal populations; many species can be difficult to access, with limited baseline information on populations and threats, and testing actions can require costly long‐term monitoring. Prioritizing the most cost‐effective conservation strategies for marine and freshwater mammal species will require a comprehensive evidence base on the effects of actions. Continuing to build the necessary baseline data, and focusing future research and funding towards the priority gaps identified in this study will be important to deliver this target.