Danielle Cholewiak

Underwater components of humpback whale bubble-net feeding behaviour

Summary Humpback whales (Megaptera novaeangliae) employ a unique and complex foraging behaviour — bubble-netting — that involves expelling air underwater to form a vertical cylinder-ring of bubbles around prey. We used digital suction cup tags (DTAGs) that concurrently measure pitch, roll, heading, depth and sound (96 kHz sampling rate), to provide the first depiction of the underwater behaviours in which humpback whales engage during bubble-net feeding. Body mechanics and swim paths were analysed using custom visualization software that animates the underwater track of the whale and quantifies tag sensor values. Bubble production was identified aurally and through spectrographic analysis of tag audio records. We identified two classes of behaviour (upward-spiral; 6 animals, 118 events and double-loop; 3 animals, 182 events) that whales used to create bubble nets. Specifically, we show the actual swim path of the whales (e.g., number of revolutions, turning rate, depth interval of spiral), when and where in the process bubbles were expelled and the pattern of bubble expulsion used by the animals. Relative to other baleanopterids, bubble-netting humpbacks demonstrate increased manoeuvrability probably aided by a unique hydrodynamicly enhanced body form. We identified an approximately 20 m depth or depth interval limit to the use of bubble nets and suggest that this limit is due to the physics of bubble dispersal to which humpback whales have behaviourally adapted. All animals were feeding with at

Description of sounds associated with Sowerby's beaked whales (Mesoplodon bidens) in the western North Atlantic Ocean.

Several groups of Sowerbys beaked whales (Mesoplodon bidens) were encountered on July 4, 2011, during a shipboard cetacean survey conducted off the eastern seaboard of the United States. Acoustic recordings were collected using a three-element towed hydrophone array. Many echolocation clicks were recorded during the encounter, but no tonal sounds were detected. A total of 2969 echolocation clicks were included in analyses of frequency and temporal characteristics. A Gaussian mixture model with four mixtures was fitted to the histogram of peak frequencies; four subsets of clicks were designated. The majority of clicks (n = 2048) contained a median peak frequency of 33 kHz, while the others contained a median peak frequency of 25 kHz (n = 324), 51 kHz (n = 304), or 67 kHz (n = 293). Most clicks did not contain a clear frequency-modulated upsweep, though some clicks exhibited a slight sweep from 30-36 kHz. Seven burst pulses were detected in the encounter, two of which were of high enough quality for detailed analysis. The acoustic characteristics of Sowerbys beaked whales have not previously been described; the current study will facilitate incorporation of these data into passive acoustic monitoring programs in the North Atlantic Ocean.

Management of acoustic metadata for bioacoustics

Abstract Recent expansion in the capabilities of passive acoustic monitoring of sound-producing animals is providing expansive data sets in many locations. These long-term data sets will allow the investigation of questions related to the ecology of sound-producing animals on time scales ranging from diel and seasonal to inter-annual and decadal. Analyses of these data often span multiple analysts from various research groups over several years of effort and, as a consequence, have begun to generate large amounts of scattered acoustic metadata. It has therefore become imperative to standardize the types of metadata being generated. A critical aspect of being able to learn from such large and varied acoustic data sets is providing consistent and transparent access that can enable the integration of various analysis efforts. This is juxtaposed with the need to include new information for specific research questions that evolve over time. Hence, a method is proposed for organizing acoustic metadata that addresses many of the problems associated with the retention of metadata from large passive acoustic data sets. A structure was developed for organizing acoustic metadata in a consistent manner, specifying required and optional terms to describe acoustic information derived from a recording. A client-server database was created to implement this data representation as a networked data service that can be accessed from several programming languages. Support for data import from a wide variety of sources such as spreadsheets and databases is provided. The implementation was extended to access Internet-available data products, permitting access to a variety of environmental information types (e.g. sea surface temperature, sunrise/sunset, etc.) from a wide range of sources as if they were part of the data service. This metadata service is in use at several institutions and has been used to track and analyze millions of acoustic detections from marine mammals, fish, elephants, and anthropogenic sound sources.

NEPAN: A U.S. Northeast Passive Acoustic Sensing Network for Monitoring, Reducing Threats and the Conservation of Marine Animals

I ncreasing anthropogenic activities in our oceans and their subsequent impacts onmarine ecosystems are clear conservation issues of national and global concern. Habitat degradation and the indirect impacts on marine vertebrates from activities associated with oil and gas exploration, renewable energy development, and shipping or fisheries operations threaten marine ecosystem health (Kappel, 2005; Halpern et al., 2007; Read, 2008; Davidson et al., 2012; Rolland et al., 2012). Efficient and cost-effective means to assess species distribution, abundance, and exposure to anthropogenic impacts are critical to the conservation of those species and their habitat. The mission of some federal agencies, such as National Oceanic and Atmospheric Administration (NOAA) in theUnited States, includes the conservation and recovery of depleted or endangered marine species, in accordance with the Marine Mammal Protection Act and the Endangered Species Act. Essential to these mandates is an adequate understanding of marine animal abundance, population trends, and seasonal occurrence, as well as an assessment of sources of risks associated with human activities. Among these risks are the effects of underwater noise introduced by human activities on marine animal acoustic communication, hearing and behavior, and the direct interactions of individual animals with fisheries and shipping operations (Cholewiak, Risch et al., 2013). Sound propagates more readily and over greater distances through water than light. Given this and the fact that light is limited at depth, sound is the primary modality of choice for marine animal communication, foraging, and navigation. Many marine species are highly vocal and much of their social, reproductive, and foraging behavior is acoustically mediated. Studies of the vocalizations that these animals emit—although completely reliant on the animals actually vocalizing—can provide information on their occurrence, distribution, relative abundance, and habitat use (e.g., Moore et al., 2006; Van Parijs et al., 2009; Širović & Hildebrand, 2011; Van Opzeeland et al., 2013a; Risch et al., 2014). In the past decade, passive acoustic approaches for studying marine animal populations have seen a rapid expansion in both the tools available and the geographic scope in which studies have been conducted. Substantial imMarch/A provements in the capabilities, availability, and price of acoustic recorders now provide a suite of cost-effective options for researchers to characterize the acoustic ecology of many species. They also provide means to quantify human-introduced noise levels in continuous records gathered in broad areas and over long periods. Recording devices include (a) fixed bottom-mounted acoustic recorders (BMARs) that can record up to several years in a single deployment, (b) hydrophone arrays towed behind survey vessels, (c) acoustic tags that record individual animal calls, (d) autonomous underwater vehicles (such as gliders) and unmanned surface vehicles (capable of navigating along assigned routes) or (e) anchored surface buoys that transmit underwater acoustic data to a land-based location in near real-time (Figure 1a). Hardware pril 2015 Volume 49 Number 2 71 and software refinements now allow data collection in remote areas and detection of species that are difficult to observe using aircraftor vesselbased visual surveys. Emerging theoretical methodologies applied to passive acoustic data provide novel ways to address largescale ecological and behavioral questions. For example, using acoustic indices tomonitor biodiversity and species richness (Fay, 2009; McWilliam & Hawkins, 2013; Staaterman et al., 2013; Staaterman & Paris, 2014), modeling loss of “communication space” (i.e., the space over which the sounds of an animal can be heard by conspecifics, or a listening animal can hear sounds of conspecifics) (Clark et al., 2009; Hatch et al., 2012; Williams et al., 2014), and integrating visual data with passively obtained acoustic data to increase the 72 Marine Technology Society Journa value of each technique (Thompson et al., 2014). Studies of marine mammals, especially cetaceans, have traditionally been conducted visually, from either vessel or aerial platforms. However, visual surveys are limited by daylight and weather conditions, as well as the short amount of time that marine mammals spend at the surface and are therefore detectable (e.g., Clark et al., 2010). Unconstrained by visual detection limitations, passive acoustic studies consistently provide a far richer characterization of marine mammal occurrence and habitat use information beyond seasons and regions where visual surveys previously documented them (e.g., Vu et al., 2012; Van Opzeeland et al., 2013b; Širović et al., 2014). Such passive acoustic studies highlight the need to transition to techniques that more completely characterize the actual disl tribution, occurrence, and relative abundance of marine mammals. Recent passive acoustic studies have also been used to identify spawning fish stocks, map their distribution, and define their seasonal occurrence and longterm persistence (Hernandez et al., 2013; Wall et al., 2012). Combined with active acoustic technology (i.e., in this case active acoustics refers to the high-frequency pinging sound produced by tags implanted in individual mature fish), which provides detailed information on behavior, movement patterns, sex ratios, and site fidelity of fish populations (Dean et al., 2012, 2014; Zemeckis et al., 2014a, 2014b, 2014c), this blended approach offers a novel direction for fisheries management and the conservation of fish stocks. Consequently, the use of passive acoustic methods to describe animal distribution, occurrence, abundance, and behavior is increasingly being recognized as tools not only for basic research but also with clear monitoring roles that substantially improve our capacity to inform conservation strategies. These are conservation and monitoring strategies that undoubtedly further the mission of NOAA and those of its partner agencies. NOAA’s Current Involvement in Passive Acoustic Research and Development Within NOAA, passive acoustic research has steadily grown in importance as a valued technique for improving and modernizing the collection of biological and anthropogenic data. NOAA Fisheries’ Offices of Science and Technology and Protected Resources and the National Ocean Service’s Office of National Marine Sanctuaries are currently finalizing an agency-wide Ocean Noise Strategy that aims to guide NOAA’s science FIGURE 1 (a) This image depicts the range of passive acoustic technologies currently available for collecting data. These include bottom-mounted archival marine acoustic recorders, acoustic recording tags deployed on animals, acoustic arrays towed behind survey vessels and autonomous underwater vehicles or gliders, as well as surface-mounted buoys that report back data in near real time. (b) This image depicts the possible “soundscape” of an ocean habitat composed of sound contributions from invertebrates, fish, marine mammals, weather events, and anthropogenic sources such as vessels. Long-term measurements of changes in soundscapes, such as the decrease in biological or increase in anthropogenic sound sources, will enable the relative “acoustic health” of a habitat to be monitored. and management decisions toward a longer-term vision for addressing noise impacts to marine life (http:// cetsound.noaa.gov). The Strategy highlights three major areas: (1) the importance of sound use and hearing for a diverse array of NOAA-managed species, (2) the importance of acoustic habi ta t in support ing NOAA ’ s management of these species, and (3) the data collection, tools, and approaches necessary to characterize soundscapes (e.g., Figure 1b) in order to support speciesand habitat-based management approaches. The Northeast Passive Acoustic Sensing Network (NEPAN) is a premier example of how to go about collecting data to inform the Strategy in a broad reaching manner. NOAA’s Northeast Regional Passive Acoustic Research At NOAA’s Northeast Fisheries Science Center (NEFSC), the Passive Acoustic Research Program’s primary focus is collecting passive acoustic data throughout the westernNorth Atlantic Ocean using a variety of the fixed and mobile platforms identified above. Our work—along with research partners at the Stellwagen Bank National Marine Sanctuary (SBNMS) and regular collaborative interactions withNationalMarine Fisheries Service (NMFS) science centers and headquarters and academia—combines long-term monitoring of marine species to understand their distribution, abundance and ecology, and quantification of anthropogenic noise threats with research focusing on monitoring the soundscapes of various key habitats in our region. Ultimately, our aim is to support broad marine management and conservation strategies throughout NOAA as part of a larger network of scientists conducting passive acoustic research. A Vision for a Comprehensive Passive Acoustic Sensing Network We envision a passive acoustic monitoring network positioned over the continental shelf and upper continental slope off the East Coast of the United States that will employ archival and near real-time passive acoustic systems to meet pressing NOAAmanagement needs. The network would include both fixed and mobile assets that could monitor marine mammals, soniferous fish and ocean noise over both short (days to weeks) and long (months to years) time scales. Some of these assets would be deployed in sensitive or industrial areas, such as wind farm construction sites, shipping lanes, heavily fished areas, or marine reserves, while others would cover broad spatial scales to inform questions about species ’ ranges, migration routes, or presence in unexpected locations. Ideally, some network assets would be collocated with oceanographic observatories (e.g., Northeast Regional Association of Coastal an

Calling depths of baleen whales from single sensor data: Development of an autocorrelation method using multipath localization

Multipath localization techniques have not previously been applied to baleen whale vocalizations due to difficulties in application to tonal vocalizations. Here it is shown that an autocorrelation method coupled with the direct reflected time difference of arrival localization technique can successfully resolve location information. A derivation was made to model the autocorrelation of a direct signal and its overlapping reflections to illustrate that an autocorrelation may be used to extract reflection information from longer duration signals containing a frequency sweep, such as some calls produced by baleen whales. An analysis was performed to characterize the difference in behavior of the autocorrelation when applied to call types with varying parameters (sweep rate, call duration). The methods feasibility was tested using data from playback transmissions to localize an acoustic transducer at a known depth and location. The method was then used to estimate the depth and range of a single North Atlantic right whale (Eubalaena glacialis) and humpback whale (Megaptera novaeangliae) from two separate experiments.

5. Biologically Important Areas for Cetaceans Within U.S. Waters – Hawai‘i Region

Of the 18 species of odontocetes known to be present in Hawaiian waters, small resident populations of 11 species—dwarf sperm whales, Blainville’s beaked whales, Cuvier’s beaked whales, pygmy killer whales, short-finned pilot whales, melonheaded whales, false killer whales, pantropical spotted dolphins, spinner dolphins, rough-toothed dolphins, and common bottlenose dolphins—have been identified, based on two or more lines of evidence, including results from small-boat sightings and survey effort, photo-identification, genetic analyses, and satellite tagging. In this review, we merge existing published and unpublished information along with expert judgment for the Hawai‘i region of the U.S. Exclusive Economic Zone and territorial waters in order to identify and support the delineation of 20 Biologically Important Areas (BIAs) for these small and resident populations, and one reproductive area for humpback whales. The geographic extent of the BIAs in Hawaiian waters ranged from approximately 700 to 23,500 km. BIA designation enhances existing information already available to scientists, managers, policymakers, and the public. They are intended to provide synthesized information in a transparent format that can be readily used toward analyses and planning under U.S. statutes that require the characterization and minimization of impacts of anthropogenic activities on marine mammals. Odontocete BIAs in Hawai‘i are biased toward the main Hawaiian Islands and populations off the island of Hawai‘i, reflecting a much greater level of research effort and thus certainty regarding the existence and range of small resident populations off that island. Emerging evidence of similar small resident populations off other island areas in Hawaiian waters suggest that further BIA designations may be necessary as more detailed information becomes available.

Long-term passive acoustic recordings track the changing distribution of North Atlantic right whales (Eubalaena glacialis) from 2004 to 2014

Given new distribution patterns of the endangered North Atlantic right whale (NARW; Eubalaena glacialis) population in recent years, an improved understanding of spatio-temporal movements are imperative for the conservation of this species. While so far visual data have provided most information on NARW movements, passive acoustic monitoring (PAM) was used in this study in order to better capture year-round NARW presence. This project used PAM data from 2004 to 2014 collected by 19 organizations throughout the western North Atlantic Ocean. Overall, data from 324 recorders (35,600 days) were processed and analyzed using a classification and detection system. Results highlight almost year-round habitat use of the western North Atlantic Ocean, with a decrease in detections in waters off Cape Hatteras, North Carolina in summer and fall. Data collected post 2010 showed an increased NARW presence in the mid-Atlantic region and a simultaneous decrease in the northern Gulf of Maine. In addition, NARWs were widely distributed across most regions throughout winter months. This study demonstrates that a large-scale analysis of PAM data provides significant value to understanding and tracking shifts in large whale movements over long time scales.

Do spectral features of Risso's dolphin echolocation clicks vary geographically?

The ability to classify odontocetes to species and population from acoustic recordings leads to improvements in stock identification, abundance and density estimation, and habitat-based density modeling, which are crucial for conservation and management. Rissos dolphins off Southern California have distinctive peaks and valleys in their echolocation clicks, which allow researchers to easily distinguish them from other species in passive acoustic recordings. However, Rissos dolphin echolocation clicks from other geographic areas have not been described and it remains unknown whether they have similarly distinctive click spectra and whether stocks are acoustically distinct. We investigate the potential for using acoustics to identify populations by quantifying the acoustic structure of Rissos dolphin echolocation clicks recorded over wide-ranging geographic regions including the U.S. waters of the North Atlantic Ocean (north and south of Cape Hatteras), Gulf of Mexico, and North Pacific Ocean (Eastern Tr...

Tethys: A workbench for bioacoustic measurements and environmental data

A growing number of passive acoustic monitoring systems have resulted in a wealth of annotation information, or metadata, for recordings. These metadata are semi-structured. Some parameters are essentially mandatory (e.g., time of detection and what was detected) while others are highly dependent upon the question that a researcher is asking. Tethys is a metadata system for spatial-temporal acoustic data that provides structure where it is appropriate and flexibility where it is needed. Networked metadata are stored in an extended markup language (XML) database, and served to workstations over a network. The ability to export summary data to OBIS-SEAMAP is in development. The second purpose of Tethys is to serve as a scientific workbench. Interfaces are provided to networked databases, permitting the import of data from a wide variety of sources, such as lunar illumination or sea ice coverage. Interfaces currently exist for Matlab, Java, and Python. Writing data driven queries using a single interface ena...

A first description of rhythmic song in Omura’s whale (Balaenoptera omurai)

Omura’s whale is a recently described tropical Balaenopterid whale with virtually nothing known about their acoustic behavior. Recordings have revealed a stereotyped 15-50 Hz amplitude-modulated vocalization, rhythmically repeated in a typical Balaenoptera song manner. In order to describe the characteristics of the song, continuous recordings were made using archival recorders during 21 days at 4 sites off the northwest coast of Madagascar in documented Omura’s whale habitat. A total of 926 hours of recordings were manually browsed to identify all occurrences of the song vocalizations, logging 9117 individual song units. Occurrence varied among sites spread across 40 km of shelf habitat, indicating heterogeneous distribution of whales and use of habitat over space and days. Diel variation indicated higher incidence of song during daylight hours, counter to trends found in other Balaenopterid whales. A total of 215 different individual series were identified ranging from 3 to 252 consecutive song units. F...