This study investigates the biogeographic patterns of Pacific white-sided dolphins (Lagenorhynchus obliquidens) in the Eastern North Pacific based on long-term passive acoustic records. We aim to elucidate the ecological and behavioural significance of distinct echolocation click types and their implications for population delineation, geographic distribution, environmental adaptation and management.

HDR, Inc. provided comprehensive monitoring services for an in-water pile driving construction project at Naval Base Kitsap Bangor, Washington. Using highly trained marine species observers, field technicians, and acousticians, we ensured client compliance in the face of complex regulatory requirements.

Marine mammal (MM) monitoring was conducted during inwater pile driving (PD) at Naval Base Kitsap Bangor, Washington in Hood Canal during Fall 2011. Vessel-based monitoring was performed on construction days, during both active-construction (“AC”, defined as 30 minutes prior to, during, and 30 minutes after PD) and non-construction (“NC”, downtime) periods. Baseline surveys were also conducted throughout Hood Canal on days when no PD occurred. Monitoring and baseline surveys occurred over 53 days, during which Marine Mammal Observers (MMOs) recorded 1,207 sightings totaling 2,269 individual MM. Species observed included California sea lion (Zalophus californianus), Steller sea lion (Eumetopias jubatus), harbor seal (Phoca vitulina), and harbor porpoise (Phocoena phocoena). Harbor seals were the most frequently observed MM on construction days (n=782 sightings) and baseline survey days (n=197 sightings). The only cetaceans observed were harbor porpoise (n=68 construction, 34 baseline sightings). Harbor seal sighting rates were lower on construction days than on baseline days (0.73 and 1.80 sightings/observer hour [obs hr], respectively). Likewise, harbor porpoise were sighted less often on construction days than on baseline days (0.13 and 0.31 sightings/obs hr, respectively). On construction days, harbor seal sighting rates were actually higher during AC periods than NC periods (3.31 and 0.23 sightings/obs hr, respectively). This is consistent with MMOs’ qualitative observations that harbor seals (particularly juveniles) appeared to be attracted to PD, and often moved towards the construction area when PD was initiated. On construction days, pinnipeds were most often observed “diving,” “looking,” “sinking,” and “swimming”. During AC, 4% more pinnipeds were observed “diving” vs. NC periods (n=124). On construction days, harbor porpoise were most often observed “traveling”. During AC, 27% fewer harbor porpoise were observed “traveling” vs. NC periods (n=18). Overall, minor behavioral disruptions were observed in relation to PD, and were within “take” numbers in the issued Incidental Harassment Authorization.

Status report for the acoustic and visual survey for cetaceans in Behm Canal and Southern Clarence Strait, Alaska, FY22.

The HDR Monitoring Team is tasked to initiate a monitoring project that will provide quantitative data and information on the seasonal occurrence, distribution, and density of protected species (marine mammals and sea turtles) in Chesapeake Bay waters near Naval Air Station (NAS) Patuxent (PAX) River, roughly from Drum Point, south to Smith Point along the western shore and over to the coastal waters of the eastern shore.

A total of 23 nearshore and mid-shelf vessel surveys were completed during the 2023/24 field season. In total, 43 baleen whale sightings, including 33 sightings of humpback whales (Megaptera novaeangliae) composed of 43 individuals, 6 sightings of North Atlantic right whales (Eubalaena glacialis) composed of 9 individuals (1 deceased), 3 sightings of minke whales (Balaenoptera acutorostrata) composed of 3 individuals, and 1 sighting of a fin whale (Balaenoptera physalus) composed of 1 individual occurred during the 2023/24 field season.

Preliminary Results from a Deep‐water Ecological Acoustic Recorder (EAR) Deployed off NW Ni‘i hau during RIMPAC‐2010

Two ecological acoustic recorders (EARs) were deployed on July 17, 2010, one at a depth of 800 meters (m) off the northwest coast (21° 59.613' N, 160° 12.167' W), and the other at a depth of 16 m off the southeast coast of Ni'ihau (21° 47.306' N, 160° 11.964' W). These two sites were selected by personnel from the Naval Facilities Engineering Command, Pacific to provide acoustic data during the 2010 Rim of the Pacific (RIMPAC) exercise in the Hawaii Range Complex.

Ecological acoustic recorders (EARs) have been deployed around the islands of Oahu and Kauai in a project sponsored by the Office of Naval Research. Detailed information on the EAR was published by Lammers et al. (2008). EARs have been deployed from February, 2009 to the present time around Oahu and from February, 2009 until April, 2011 around Kauai. From April, 2011 four EARs in the waters of Kauai have been deployed along the southern coast.

Ecological acoustic recorders (EARs) have been deployed at several locations in Hawaii and in other western Pacific locations to study the foraging behavior of deep-diving odontocetes. EARs have been deployed at depths greater than 400 m at five locations around the island of Kauai, one at Ni’ihau, two around the island of Okinawa, and four in the Marianas (two close to island of Guam, one close to the island of Saipan and another close to the island of Tinian).

NOAA Fisheries Science Centers have recently incorporated drifting acoustic spar buoy recorders (DASBRs) into their standard large-scale survey designs. Drifting autonomous instruments have many advantages, especially for species that are difficult to see at the surface, are vocal at depth, and whose sounds have been well characterized such that they can be readily identifiable from autonomous recordings. Pacific Islands Fisheries Science Center deployed DASBRs throughout the survey region with the goal of collecting data on the occurrence of beaked whales and other cryptic deepdivers. Traditional line-transect assessments for those species are often challenged by very low encounter rates, resulting in density and abundance estimates with high uncertainty, or in some cases, no estimates if groups were not seen during the ‘on-effort’ portions of the survey. Previous experience in the Marianas suggested that encounter rates for beaked whales on the DASBRs would be orders of magnitude higher within the DASBR data than in the visual survey or towed array datasets, likely enabling examination of density for some beaked whale species using the newly developed methods of Barlow et al. (2021a). Here, we detail our methodology to estimate density and abundance using 2021 survey dataset and how 2018 survey data were used to inform the detection parameters. This analysis has resulted in the first preliminary acoustic density and abundance estimates for Cuvier’s and Blainville’s beaked whales in the Mariana Islands region.

In August 2017, a marine mammal monitoring project was carried out combining boat-based field efforts and passive acoustic monitoring on and around the Pacific Missile Range Facility (PMRF). Commander, Pacific Fleet (PACFLT) funded five days of small-boat effort and the National Marine Fisheries Service funded an additional six days of effort. Information obtained was compared to previous sightings during small-boat effort by Cascadia Research Collective (CRC) off Kauai and Niihau, during 1,119 hr of effort (19,194 km) over nine different years from 2003 through 2016 (see Baird 2016)

A joint project in February 2013 of the Pacific Missile Range Facility (PMRF) combined passive acoustic monitoring and boat-based field efforts. There were 1,010 kilometers (km) (55.9 hours [hr]) of small-vessel field effort over the course of the 8-day project. Of the 55.9 hr of survey effort, 64.2 percent was spent within the PMRF instrumented hydrophone range boundaries, and 14.8 percent of the effort was in depths greater than 1,000 meters (m).

A joint project in July and August 2013 on and around the Pacific Missile Range Facility (PMRF) combined passive acoustic monitoring and boat-based field efforts. There were 671 kilometers (36.6 hours [hr]) of small-vessel survey effort over the course of the 8-day project, with 55.1 percent of time (20.2 hr) spent within the PMRF instrumented hydrophone range boundaries. A total of 33.0 hr of acoustic monitoring coincided with the small-vessel field effort.

A joint project in February 2014 on and around the Pacific Missile Range Facility (PMRF) was carried out utilizing combined passive acoustic monitoring and boat-based field efforts. There were 1,287 kilometers (km) (66.3 hours [hr]) of small-vessel survey effort over the course of the 10 day project, with 44.6 percent of search time (29.6 hr) spent within the PMRF instrumented hydrophone range boundaries. A total of 81.7 hr of acoustic monitoring was undertaken during the field effort. There were 26 sightings of five species of odontocetes, six of which were directed by acoustic detections from the Marine Mammal Monitoring on Navy Ranges (M3R) system.

A joint project in February 2015 on and around the Pacific Missile Range Facility (PMRF) was carried out utilizing combined boat-based field efforts and passive acoustic monitoring from the Marine Mammal Monitoring on Navy Ranges (M3R) system. There were 1,132 kilometers (63.4 hours [hr]) of small-vessel survey effort over the course of the 13-day project. Weather conditions precluded field operations on 4 days, and strong westerly winds and/or range operations limited access to PMRF on seven additional days, with only 15.1 percent of search time (9.6 hr) spent within the range boundaries.

As part of a long-term U.S. Navy-funded marine mammal monitoring program, in February 2016 a combining boat-based field effort and passive acoustic monitoring was carried out on and around the Pacific Missile Range Facility (PMRF). The U.S. Navy funded five days of small-boat effort and the National Marine Fisheries Service funded an additional two days of effort. There were 859 kilometers (49 hours) of small-vessel survey effort over the course of the seven day project.

As part of a long-term U.S. Navy-funded marine mammal monitoring program, in August 2017 a combination of boatbased field effort and passive acoustic monitoring was carried out on and around the Pacific Missile Range Facility (PMRF) off Kaua‘i prior to a Submarine Command Course scheduled for mid-August 2017. The U.S. Navy funded five days of small-boat effort and the National Marine Fisheries Service funded an additional six days of effort. There were 1,113 kilometers (77.4 hours) of small-vessel survey effort over the course of the 11 day project.

As part of a long-term U.S. Navy-funded marine mammal monitoring program, in August 2018 a combination of vessel-based field effort and passive acoustic monitoring was carried out on and around the Pacific Missile Range Facility (PMRF) Kaua‘i prior to a Submarine Commander Course scheduled for mid-August 2018. The purpose of the monitoring effort was to assess the spatial movement patterns and habitat use of cetaceans that are exposed to mid-frequency active sonar and how those patterns influence exposure and potentially responses.

As part of a long-term U.S. Navy-funded marine mammal monitoring program, in February 2020 a combination of vesselbased field effort and passive acoustic monitoring was carried out on and around the Pacific Missile Range Facility (PMRF) off Kaua‘i prior to a Submarine Command Course scheduled for mid-February 2020. The purpose of the monitoring effort was to assess the spatial movement patterns and habitat use of cetaceans that are exposed to midfrequency active sonar and how those patterns influence exposure and potentially responses. Results from this effort were compared with previous Cascadia Research Collective (CRC) survey effort and photo-identification and tag data from Kaua‘i, based on surveys in 11 different years since 2003.

The Pacific Missile Range Facility (PMRF) off the island of Kaua‘i is the site of regular United States (U.S.) Navy training, some of which involves mid-frequency active sonar (MFAS) use from different types of military sound sources. PMRF includes acoustic instrumentation which allows for passive acoustic monitoring (PAM) capabilities to detect and localize sounds such as vocalizing marine mammals. Recent boat-based studies at PMRF have utilized real-time PAM (in conjunction with the Marine Mammal Monitoring on Navy Ranges project) to detect odontocetes for vectoring a field tagging boat to groups in order to increase the likelihood of deploying satellite tags. The resulting data have allowed for an assessment of habitat use and range of several different species. Some of these boat-based tagging efforts were timed to occur just before Submarine Commanders Courses (SCCs) occurring on PMRF so that animal movements and diving behavior could be measured both before and during sonar use.

As part of the long-term United States (U.S.) Navy-funded Marine Species Monitoring Program, from 11–19 February 2024, Cascadia Research Collective (CRC) carried out a vessel-based field effort in conjunction with passive acoustic monitoring undertaken by the U.S. Navy (Navy) scientists on and around the underwater hydrophone ranges of the Pacific Missile Range Facility (PMRF). The effort was timed to occur immediately prior to the start of a Submarine Command Course (SCC) to allow for collection of movement and dive data that could be used to examine exposure and response of cetaceans to Navy mid-frequency active sonar (MFAS; see Henderson et al. 2021). Eight days of field effort were funded by the Navy, and one day of field work was funded by National Oceanic and Atmospheric Administration (NOAA) Fisheries. Wildlife Computers SPLASH10-F satellite tags were funded by the Navy for deployment on Navypriority species, and additional tags were provided by Wildlife Computers or CRC for deployment on other species (e.g., humpback whales [Megaptera novaeangliae]). Tags were programmed to collect dive behavior and Fastloc®-Global Positioning System (GPS) data from the time deployed until three and a half days after the end of the SCC and continue to transmit the dive and Fastloc®-GPS data for an additional six days. Starting on either May 2nd or May 3rd, the tags were duty cycled to transmit only every second day, to provide longer-term tracks of individual movements. During the period that tags were collecting dive and Fastloc®-GPS data, tags were programmed to try to obtain Fastloc®-GPS locations only for the 12 hours of the day when there were no or limited satellite overpasses. This programming change from previous Kauaʻi field efforts was taken to minimize temporal gaps in location data during the period that overlapped with and immediately followed the SCC. Field efforts were undertaken out of Kikiaola small boat harbor when conditions allowed for working on or near PMRF, or out of Port Allen when conditions on or near PMRF were not workable.

Unique morphological and acoustic characteristics of beaked whales (Mesoplodon sp.) off the west coast of Baja California, Mexico

This ongoing project will study explosions recorded by passive acoustic monitoring in the Southern California (SOCAL) region between 2009 and 2012, and provide a description of their characteristics and frequency of occurrence. In this region, explosions are used both by the Navy as part of training exercises, and by the commercial fishing industry as a deterrent for marine mammals

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from January 2013 to June 2017 to detect marine mammal sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at four locations: west of San Clemente Island (1,000 m depth, site H), south of San Clemente Island (1200 m depth, site N), northwest of San Clemente Island (900 m depth, site M) and west of La Jolla, California (500 m depth, site P).

We present progress on the development of methods to investigate the potential impacts of sonar and other anthropogenic activities on calling animals. The basis for this effort is previously collected PAM data from four sites in the years 2006 to 2015. Recording effort at these sites varied between 674 and 2,284 days per site, resulting in 19 years of cumulative acoustic recording during 79 instrument deployments and 227 TB of acoustic recordings. As part of the work in this progress report, automated routines have been established and/or modified to detect and classify acoustic signals of blue whales (Balaenoptera musculus) and Cuvier’s beaked whales (Ziphius caviostris) as well as Mid-Frequency Active (MFA) sonar pings and explosions.

Understanding the distribution of cetacean species and their populations over space and time is relevant to conservation, management, and mitigation goals. Geographic differences in Blainville’s beaked whale (Mesoplodon densirostris) frequency-modulated (FM) echolocation pulses are investigated as a potential tool for population-level discrimination.

Passive acoustic monitoring (PAM) provides extensive datasets to examine the behavioral response of cetaceans to anthropogenic sound. Using broadband passive acoustic monitoring, the full range of cetacean sounds and the sounds of naval and other anthropogenic sources are recorded. We have been collecting high-frequency PAM data in the Southern California (SOCAL) region since 2006. Within this dataset are many instances of anthropogenic sound as well as cetacean presence at the locations of naval training.

Marine ambient sound was recorded on autonomous high-frequency acoustic recording packages (bandwidth 10 Hz to 100 kHz) during long term deployments at multiple sites across the North Pacific, from the high latitude Aleutian Islands to tropical Palmyra Atoll in depths of 600–1 000 m. Most intertropical but no temperate locations showed a distinct diel pattern in ambient sound. The soundscape at each location was unique, yet there was a similar recurring sound of unknown origin in lower latitude locations. This sound had a peak frequency around 3–5 kHz and was recorded only for several hours after sunset. Additionally, at some locations, a broadband acoustic signal with bandwidth up to 60 kHz was recorded at night with crepuscular peaks. Both sound patterns were lunar dependent with lower acoustic levels during full moon phases. Site-specific diel and seasonal acoustic patterns have been observed for various odontocete species. Correlations between odontocete presence and levels of ambient sound are investigated. [Work supported by NOAA-Pacific Islands Fisheries Science Center, US Navy-N45/PACFLT, ONR, Pacific Life, Ocean Foundation, University of California, San Diego.]

Mesoscale oceanographic features are a major force in structuring the marine environment through processes such as eddy-induced upwelling, and as such effect distribution and aggregation patterns of all organisms along the food chain. It has been shown that top pelagic predators such as cetaceans react to these environmental changes in different ways. We present analysis of frequency-modulated (FM) echolocation pulses of Cuvier’s beaked whale (Ziphius cavirostris), Blainville’s beaked whale (Mesoplodon densirostis), and an unknown beaked whale species producing FM pulse type “BWC,” possibly ginkgo-toothed beaked whale (M. ginkgodens), at five locations in the central Pacific. The recordings were collected at Pearl and Hermes Reef (Northwestern Hawaiian Islands), Kona (Main Hawaiian Islands), Wake Atoll, Tinian, and Saipan (Northern Mariana Islands) between 2008 and 2015, ranging from 4 to 8 years per site. All three beaked whale species were present at all sites in different proportions throughout the recording periods, with a strong nocturnal pattern only for the “BWC” pulse type, yet without seasonal pattern. We examine the varying presence in the context of remotely sensed oceanographic data, including sea surface height deviation, temperature, and salinity, as well as chlorophyll a and derived primary productivity.

Two Slocum gliders equipped with digital acoustic monitoring (DMON) instruments were deployed and operated in the mid-Atlantic Bight to the north and south of Cape Hatteras during the winter of 2018-2019. The gliders were remotely piloted to survey along pre-determined transects as local currents allowed, and sensor data were relayed to shore every 2 hours and posted on a publicly accessible website, dcs.whoi.edu. DMON data were reviewed daily by trained NAVFAC personnel, and the results of their review were posted on the same website, distributed to interested parties by text and email message, and made available for display in the Whale Alert app. Of the four baleen whale species monitored, humpback whales were the most commonly encountered, followed by fin, sei, and right whales. Only a single bout of right whale calls was detected by the glider deployed to the north of Cape Hatteras.

For the last five months, Dr. Will Gough has been working at the Marine Mammal Research Program (MMRP) on a number of goals that will build capacity within Hawaii and advance the Navy’s goals related to the long-term health of protected marine mammal species. These goals relate to Dr. Gough’s expertise working with accelerometry-based biologging tags and include: setting up infrastructure at the MMRP to maintain large quantities of tag data, collecting novel data and expanding existing datasets through field efforts, training members of the Navy and MMRP to work effectively with accelerometry data and biologging devices, develop training materials and short-form workshops to disseminate knowledge of accelerometry data processing and analysis more broadly within the Hawaiian community, and use new and existing datasets to answer questions of relevance to the Navy and other organizations tasked with monitoring and management of protected species.

The National Oceanic and Atmospheric Administration (NOAA) Alaska Fisheries Science Center has maintained passive acoustic recorder moorings in areas of interest to the US Navy in the Gulf of Alaska (GOA). Archival data from three of these sites were analyzed for the timing and occurrence of key cetacean species. In addition, three subsurface passive acoustic moorings were deployed for a year (fall 2023 to fall 2024) in areas of mutual interest to NOAA and the Navy. Two of these new moorings, located along the western GOA slope, were redeployed in 2024.

Three subsurface passive acoustic moorings were deployed in the western Gulf of Alaska on the EcoFOCI fall mooring cruise onboard the F/V Aquila 15 Aug – 14 Sep 2023; recovery is planned for September 2024, funding permitting. These mooring will allow investigation into the seasonal occurrence of many species of vocalizing marine mammals including North Pacific right (NPRW), blue, fin, humpback, minke, gray, sperm, killer, and beaked whales, Dall’s and harbor porpoise, general pinniped sounds, and anthropogenic noise sources such as vessels and seismic airguns. This is important data that the Navy needs to prepare environmental planning documentation, including those for the National Environmental Policy Act (NEPA), Marine Mammal Protection Act (MMPA), and ESA documents and consultations. It is also needed to inform the National Marine Fisheries Service Alaska Regional Office’s NPRW critical habitat expansion decision. In addition to the field work, processing of existing passive acoustic recordings from three moorings in the WGOA is ongoing, with one site (Barnabus Trough) completed for the high-frequency band. Killer whale vocalizations were detected on 214 of the 358 days with recordings.

In marine ecosystems, cetaceans are large mobile predators that depend on maximizing foraging efficiency. Their presence within a habitat can therefore be strongly related to the modulation of local prey by oceanographic conditions. Understanding how cetaceans are impacted by prey responses to the physical environment is challenging due to the difficulty of collecting presence data of cetaceans and their prey over long, comparable time periods. We used passive and active acoustic recordings collected from moorings within the San Diego Trough, along with physical oceanographic sampling (i.e. in situ, satellite-derived, and ocean general circulation model measurements), to elucidate relationships between cetaceans, their prey, and the physical environment. Our results show that the predator-prey dynamics of some cetaceans within the San Diego Trough are influenced by seasonal changes in the physical oceanographic conditions and processes that shape their prey resources. Specifically, common dolphin Delphinus delphis foraging activity increased during conditions associated with increased presence of diel vertically migrating fish prey. Blue whale Balaenoptera musculus foraging-associated acoustic activity increased during periods with increased presence of mid-water crustacean zooplankton and was replaced with breeding-associated acoustic activity during conditions associated with the waning of mid-water crustacean zooplankton. Fin whale B. physalus foraging-associated calling activity was more complex to model, most likely because these animals have a generalist diet and occupy this area year-round. Our results highlight environmental conditions and features relevant to cetaceans inhabiting this region and may aid in developing better spatially explicit management actions.

The U.S. Navy’s Atlantic Fleet conducts training and testing activities within the Northwest Atlantic Ocean and Gulf of Mexico, including the use of active sonar and explosives. In order to evaluate the impacts of these activities on marine mammals and other protected marine species, the Navy implemented a monitoring program to collect data on baseline animal presence, as well as exposure and response to Navy training and testing activities. Passive acoustic monitoring is an important component of the Navy’s monitoring efforts. Between 2009 and 2013, the Navy utilized effort-based monitoring metrics and targeted a number of different training and testing events for monitoring. Passive acoustic data was collected to monitor mysticete migration patterns in the mid-Atlantic, the effects of MFAS on odontocete vocalizations in North Carolina and Florida, and the potential effects of explosive training events off the coast of Virginia Beach, VA. Platforms included Marine Autonomous Recording Units (MARUs), High Frequency Acoustic Recording Packages (HARPs), Ecological Acoustic Recorders (EARs), and sonobuoys, among others. Additionally, the Marine Species Monitoring Program has funded the deployment of acoustic recording tags on several marine species including pilot whales and North Atlantic right whales, as well as behavioral response playback experiments with short-finned pilot whales off Cape Hatteras, North Carolina. In November 2013, the Navy began replacing effort-based monitoring metrics with objective based monitoring projects as a result of new environmental permits for Atlantic Fleet Training & Testing (AFTT). Passive acoustic monitoring remains a cornerstone of the revised long term goals, and continues to provide key data on marine mammal presence and behavior. Future work will focus on species classification and animal behavior.

Since the closure of a power plant in the southern part of San Diego Bay, a collaborative monitoring effort among the Navy, the National Marine Fisheries Service (NMFS) and others has been underway to better understand changes in the movement and behavior of the green sea turtle so that the Navy and this turtle can continue to share the resources in the bay. San Diego Bay is home to one of the largest U.S. Navy complexes in the world and California’s second largest incorporated city. Today, more than 25 percent of the U.S. Navy fleet is homeported in San Diego. Maintaining readiness in this ecosystem without causing harm to the natural resources is an ongoing challenge. There are a variety of threatened and endangered species that rely on the San Diego Bay ecosystem at different stages of their lives. One of these is the East Pacific green sea turtle. The East Pacific green sea turtle is a federally threatened species in San Diego Bay. While the majority of the population has traditionally lived in the quieter south part of the bay, the turtles may be venturing into areas more frequently used for U.S. Navy, recreational, and commercial activities. An increased presence of turtles outside of the southern portion of the bay may have potential implications for management of this species, as there is a higher likelihood of boat strikes and other potentially adverse human interactions.

Cetacean distribution, density and abundance in the Southern California Bight were assessed through visual and acoustic surveys during five California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from August 2012-November 2013. Visual monitoring incorporated standard line-transect protocol during all daylight transits while acoustic monitoring employed a towed hydrophone array during transits and sonobuoys at oceanographic sampling stations. Visual effort included 584 observation hours covering 10,900 kilometers yielding 565 sightings of 15 identified cetacean species.

Spatial and temporal distribution patterns, density and abundance of cetaceans in the southern California Bight were assessed through visual and acoustic surveys during five California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from August 2011 – July 2012. Visual monitoring incorporated standard line-transect protocol during all daylight transits while acoustic monitoring employed a towed hydrophone array during transits and sonobuoys at oceanographic sampling stations.

This report summarizes small boat based research conducted on cetaceans off southern California by the Scripps Institution of Oceanography (SIO) in collaboration with Southwest Fisheries Science Center (SWFSC) from August 2009 – July 2010. The primary objectives of this research were to use sighting, photo-identification, biopsy and acoustical sampling techniques to assess the occurrence, distribution and population structure of small cetaceans in a region that is subject to frequent naval exercises; this information is needed to evaluate possible effects from Mid Frequency Active Sonar (MFAS) trials and ultimately for the development of appropriate management protocols.

Using a network of drifting acoustic buoys in controlled exposure experiments, we investigated the effects of mid-frequency (3–4 kHz) active sonar (MFAS) on whistle production in short-beaked (Delphinus delphis delphis) and long-beaked common dolphins (Delphinus delphis bairdii) in southern California. Given the complexity of acoustic behavior exhibited by these group-living animals, we conducted our response analysis over varying temporal windows (10 min– 5 s) to describe both longer-term and instantaneous changes in sound production. We found that common dolphins exhibited acute and pronounced changes in whistle rate in the 5 s following exposure to simulated Navy MFAS.

In order to further investigate potential changes in behavior in response to MFAS exposure, sounds of marine mammals were recorded in the vicinity of three U.S. Navy training exercises before, during, and after the use of MFAS in Onslow Bay, North Carolina (July 2008), and near Jacksonville, Florida (September–October, and December 2009). The resulting passive acoustic data were analyzed using automated signal-detection software to detect individual sonar transmissions (“pings”), and sounds of North Atlantic right, minke, fin, and sperm whales. In addition, putative right whale “gunshot” sounds that had been detected in an earlier, separate analysis of the Jacksonville recordings were reviewed by two experienced marine mammal acoustic analysts.

Passive acoustic monitoring was conducted during a survey of marine mammals in nearshore waters surrounding Pagan Island, a remote volcanic island in the western tropical Pacific, part of the Commonwealth of the Northern Marianas Islands. The objective was to collect baseline information for Department of Defense's CNMI Joint Military Training Environmental Impact Statement. The primary effort was conducted over 11 days in August 2013. Visual/acoustic line-transect surveys were conducted using a towed hydrophone array system during daytime, and moored sonobuoys were deployed at night. Fourteen acoustic encounters occurred during line-transect surveys consisting of the following (subtotal in parentheses): bottlenose dolphin (1), spinner dolphin (1), beaked whales (4), and unidentified dolphins (8). Of this total, eleven were acoustic only encounters and three were concurrently sighted by observers. The four beaked whale acoustic encounters could not be classified in the field so data were post-processed resulting in the following classifications: Blainville's beaked whales (3) and Cuvier's beaked whale (1). Localization ranges (perpendicular to trackline) were between 0.3 and 2 km and varied by species/species groups. Sonobuoys were moored in depths of 30-50m at two sites located off sand beach areas on the west side of the island. Approximately 67 hours of recordings were made for an average recording duration of 7.4 hours per night. The majority of detection events (55) were of dolphins (undetermined species). Sperm whales were detected once by each sonobuoy. In summary, passive acoustic methods were able to detect delphinids, as well as deep diving species during both line-transect surveys and shallow water sonobuoy monitoring sites. Although brief in duration, this effort provided important information about the occurrence of several species of marine mammals documented for the first time at this remote island.

Beaked whales are among the most poorly understood marine mammals. They are deep-diving odontocetes, spending most of their time submerged with infrequent, short surface intervals. Due to this behavior, they are difficult to study using visual observation methods alone . However, recent advancements in passive acoustic detection and survey techniques have shown to provide viable methods for stu dying beaked whales (Yack et al. 2013). In the Gulf of Alaska (GOA), there is little known abo ut beaked whale abundance and distribution.

A diverse group of toothed whale species inhabits the pelagic habitats of the western North Atlantic, competing for overlapping prey resources. Historical data deficits have limited fundamental research into many of these species, such as establishing baselines of distribution and abundance, so their occurrence and habitat use patterns are not well characterized. Periodic cycles in activity have been reported at a range of temporal scales for odontocetes in other regions, such as seasonal movements, foraging activity modulated by lunar cycles, and diel activity patterns. A variety of spatial, temporal, and behavioral separation strategies have also been observed among predator guilds in both marine and terrestrial systems, and these may also contribute to observed spatiotemporal patterns in activity. Recently, passive acoustic data has been applied to monitor odontocete species continuously, with improved detection and species discrimination for some cryptic species. We used a long-term passive acoustic data set collected at sites spanning the western North Atlantic shelf-break region to quantify presence and characterize seasonal, lunar, and diel activity patterns for 10 species. Our results demonstrated strong regional preferences and clear patterns of spatiotemporal separation between species with similar foraging ecology. Latitudinal shifts in seasonal presence peaks may suggest meridional seasonal migrations for some dolphin species. We also observed strong diel activity patterns that were modulated by both seasonal and lunar cycles. This study reveals complex behavioral patterns arising in response to natural cycles playing out over multiple temporal scales and provides new insights into habitat partitioning among toothed whale species.

A combination of machine learning and expert analyst review was used to detect odontocete echolocation clicks, identify dominant click types, and classify clicks in 32 years of acoustic data collected at 11 autonomous monitoring sites in the western North Atlantic between 2016 and 2019. Previously-described click types for eight known odontocete species or genera were identified in this data set: Blainville’s beaked whales (Mesoplodon densirostris), Cuvier’s beaked whales (Ziphius cavirostris), Gervais’ beaked whales (Mesoplodon europaeus), Sowerby’s beaked whales (Mesoplodon bidens), and True’s beaked whales (Mesoplodon mirus), Kogia spp., Risso’s dolphin (Grampus griseus), and sperm whales (Physeter macrocephalus)

Remote biopsy sampling has been used for almost 40 yr (Winn et al. 1973) to obtain tissue samples for various analyses, and is particularly important because most cetaceans are difficult or impossible to capture safely at sea (Noren and Mocklin 2011). It is generally assumed that there are few, if any, detrimental effects on the fitness of sampled animals. In support of this assumption, there has only been one documented case of death of a cetacean from a biopsy dart (Bearzi 2000), although it is possible deaths have occurred that have not been described in the published literature. Failure of the dart stopper and the poor body condition of the common dolphin (Delphinus delphis) were believed responsible for the death of this animal, as the dart penetrated through its thin blubber layer.

The Pacific Marine Assessment Program for Protected Species (PacMAPPS) survey occurred from 1 August to 26 August 2021, beginning and ending in Kodiak, AK. Over the course of the survey, a total of 2,330 km of on-effort tracklines were surveyed in suitable weather conditions, and a total of 687 sightings of marine mammals were documented (including duplicates and resights).

This survey implemented visual line transect and passive acoustic methods to assess the presence and distribution and to estimate density and abundance of cetaceans in Behm Canal and central Clarence Strait.

Bayesian mark-recapture estimates of survival, abundance, and trend are reported for Cuvier's beaked whales (Ziphius cavirostris) using a Navy training range off southern California. The deep-diving beaked whale family is exceptionally vulnerable to mid-frequency active sonar (MFAS), which has been implicated in mass strandings and altered foraging behavior. Extremely low sighting probabilities impede studies of population-level impacts of MFAS on beaked whales. The San Nicolas Basin hosts a Navy training range subject to frequent MFAS use and attracts high densities of Z. cavirostris. An 11-year (2007–2018) photo-identification program leveraged automated acoustic detection and location capabilities on the range's 1,800-km2 hydrophone array to enhance capture probability.

This report provides equations to the Commander, Pacific Fleet Environmental Readiness Division to calculate expected levels of the underwater sound field created from explosive sources that may be applied to environmental characterization or UNDET training mission planning on the Pu`uloa Range with respect to possible noise exposure to marine mammals and turtles.

This study assesses the acoustic presence of humpback (Megaptera novaeangliae), sei (B. borealis), fin (B. physalus), and blue whales (B. musculus) over a decade, based on daily detections of their vocalizations.

HDR vessel-based visual monitoring for marine mammals was conducted 1–9 February 2014 in conjunction with Cascadia Research Collective (CRC) satellite-tagging and real time acoustic monitoring by the Marine Mammal Monitoring on Navy Ranges (M3R) team. These efforts were to aid species-validation projects conducted in and around the Pacific Missile Range Facility (PMRF) instrumented range, northwest of Kauai in the Hawaii Range Complex (HRC). The monitoring survey was conducted prior to the commencement of the U.S. Navy’s Submarine Commanders Course (SCC) that took place 17–21 February 2014, which included the use of mid-frequency active sonar.

Over 25 species of cetaceans utilize the shelf break regions of the US eastern seaboard, including several endangered species. Understanding patterns in species distribution, and the anthropogenic and environmental drivers that may impact their distribution, are critical for appropriate management of marine habitats. To better understand patterns in species distribution and vocal activity, NOAA’s Northeast Fisheries Science Center (NEFSC) and Scripps Institution of Oceanography (SIO) collaboratively deployed long-term high-frequency acoustic recording packages (HARPs) at eight sites along the western North Atlantic shelf break. This work was conducted from 2015-2021, with financial support from the Bureau of Ocean Energy Management (BOEM). Likewise, the U.S. Navy has been monitoring the shelf break region at 3 to 4 sites since 2007. Together these combined efforts bring the total to 11 recording sites spanning the U.S. eastern seaboard, from New England to Florida. This project focuses on analyses of the datasets collected from 2015-2021, with the inclusion of older (pre-2015) datasets where relevant. The focus of our efforts in 2025 have been to make substantial progress in the review of various detector classifications.

Passive acoustic monitoring was conducted to detect the presence of marine mammal and anthropogenic sounds in the Navy’s Northwest Training Range Complex (NWTRC) from September 14, 2012 until June 30, 2013. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at the shelf slope near Quinault Canyon. Data analysis methods consisted of detection of sounds by analyst scans of long-term spectral averages (LTSAs) and spectrograms, and by automated computer algorithms when possible. The data were divided into three frequency bands for analysis of marine mammal vocalizations and anthropogenic sounds.

Passive acoustic monitoring was conducted in the Gulf of Alaska Temporary Maritime Activities Area (GATMAA) from June 2013 to May 2014 to detect marine mammal and anthropogenic sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at five locations: a shelf site offshore Kenai Peninsula (200 m depth, site CA), a continental slope site in deep water (850 m depth, site CB), a slope site offshore Kodiak Island (230 m depth, site KO), a deep offshore site at Pratt Seamount (1000 m depth, site PT), and a deep offshore site at Quinn Seamount (930 m depth, site QN).

Cetacean distribution, density and abundance in the Southern California Bight were assessed through visual and acoustic surveys during eighteen California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from February 2012-April 2016. Visual monitoring incorporated standard line-transect protocol during all daylight transits while acoustic monitoring employed a towed hydrophone array during transits and sonobuoys deployed at oceanographic sampling stations. Visual effort included 2,031 observation hours covering 31,807 kilometers. A total of 1,914 sightings were made, which included 18 different cetacean species. Acoustic effort included 1m027 sonobuoy deployments and 478 towed array deployments.

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from December 2012 to January 2014 to detect marine mammal and anthropogenic sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at three locations: near Santa Barbara Island (880 m), west of San Clemente Island (1000 m), and southwest of San Clemente Island (1300 m). Six baleen whale species were recorded: blue whales, Bryde’s whales, fin whales, gray whales, humpback whales, and minke whales.

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from January to July 2014 to detect marine mammal and anthropogenic sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at three locations: west of San Clemente Island (1,000 m depth, site H), southwest of San Clemente Island (1,200 m depth, site N), and west of La Jolla, California (550 m depth, site P). Sites H and N are located offshore, whereas site P is located nearer to the coast.

To monitor for the presence of marine mammals, High-frequency Acoustic Recording Packages (HARPs) were deployed at two sites within the Navy’s Virginia Capes Range Complex. There were three deployments at one site, located offshore from Cape Hatteras (HAT), between October 2012 and December 2014. There was one deployment at the other site, located offshore from Norfolk Canyon (NFC), between June 2014 and April 2015. Both sites were located approximately 75 nmi offshore in about 1000 m of water.

High-frequency Acoustic Recording Packages (HARPs) were deployed from May 2013 to August 2014 to detect marine mammal and anthropogenic sounds in the Navy’s Jacksonville Range Complex. The HARPs recorded sounds between 10 Hz and 100 kHz at a site located 60 nm east off the Florida coastline on the continental shelf. Technical malfunctions resulted in loss of data for the period from June 8, 2013 through February 16, 2014. Data analysis consisted of analyst scans of long-term spectral averages (LTSAs) and spectrograms, and automated computer algorithm detection when possible. Three frequency bands were analyzed for marine mammal vocalizations and anthropogenic sounds: (1) Low-frequency, between 10300 Hz, (2) Mid-frequency, between 10-5,000 Hz, and (3) High-frequency, between 1-100 kHz. Three baleen whale species were detected: fin whales, humpback whales, and minke whales. Fin whale detections were limited to February 2014. Humpback whale calls were detected from February to June 2014 with a peak in March 2014. Minke whales were detected in late-February through March 2014. An additional sound called the 5-pulse signal, presumably from a baleen whale, was detected from February to September 2014, with a peak in July. One known odontocete species was detected, Risso’s dolphins, which were detected in low numbers in July 2014. Odontocete signals that could not be distinguished to species were common throughout the recordings. However, eight distinct click types of unknown species origin were found to be present (CT 17, CT 22, CT 25, CT 26, CT 27, CT 27A, CT 30 and CT32). The following anthropogenic sounds were detected: broadband ship noise, Mid-Frequency Active (MFA) sonar, and echosounders. Broadband ships were common throughout the recordings with a peak in detections in May 2014. MFA sonar was detected during all months with recordings, with a peak in June 2013. Echosounder pings were prevalent throughout the recordings.

Passive acoustic monitoring was conducted at two sites in the US Navy’s Jacksonville Range Complex during August 2010 – July 2011. These sites are located 50 and 61 nm east of the Florida coastline on the shelf and shelf break at water depths of 40 m – 90 m. Acoustic data collected at these sites provide information on the presence of marine mammals and anthropogenic sound sources. High-frequency Acoustic Recording Packages (HARPs) documented sounds between 10 Hz and 100 kHz with recording cycles of 5 minutes every 15 minutes. The data were divided into three frequency bands and data analysis was conducted with analyst scans of long-term spectral averages and spectrograms. Four mysticete whale species were recorded: fin, minke, sei, and humpback. No blue whale, North Atlantic right whale, or Bryde’s whale calls detected. A new call, designated the “5-pulse” was detected and is presumed to be produced by a mysticete whale due to its character, prevalence and intensity. Site A has more hours with calling mysticete whales than site B. However, humpback whale calls were detected only at site B, though these detections were few. The largest number of odontocete detections were attributed to unidentified odontocetes, thought to be primarily bottlenose and Atlantic spotted dolphins. Unidentified odontocetes were detected throughout the year. Overall numbers of detections were higher at site A than site B. There was a diel acoustic activity pattern with greater numbers of echolocation clicks produced at night, likely due to nighttime foraging. Risso’s dolphin echolocation clicks were only detected at site A and only occurred August through March. Five click types, yet to be associated to an odontocete species, were characterized and their seasonal and diel occurrence described. Ship noise was the most common anthropogenic sound at both sites A and B. Both sites had Mid-Frequency Active (MFA) sonar events throughout the period of data collection. At site A, a total of 2,437 MFA sonar pings were detected with a maximum peak-to-peak received level of 173 dB re 1 μPa. Similarly, a total of 2,496 MFA sonar pings were detected at site B, reaching a maximum peak-to-peak level of 166 dB re 1 μPa. Echosounder pings with a variety of primary frequencies (4 – 80 kHz) were found at both sites A and B. Explosions were recorded at both sites, though were more prevalent at site B. A low-frequency tone, referred to as the 130 Hz tone, was recorded at site A. High noise levels, possibly caused by instrument strumming and fluid flow at the sensor, occurred intermittently at both sites and likely decreased the detection range for low-frequency sounds.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between August 2010 and February 2011 in the Jacksonville, FL, survey area at Site A in 90 m. This HARP sampled at 200 kHz for 5 minutes of every 15 minutes and recorded for 153 days between 26 August 2010 and 25 January 2011. Long-Term Spectral Averages (LTSAs) were created for three frequency bands (10 Hz – 1000 Hz, 500 Hz – 5000 Hz, and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations. Calls of fin whales, minke whales, possible sei whales, Risso’s dolphins, and unidentified delphinids were detected in the data. A new call type, the “5-pulse” call, presumed to be produced by a mysticete, was also detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between August 2010 and February 2011 in the Jacksonville, FL, survey area at Site B in 35 m. This HARP sampled at 200 kHz for 5 minutes of every 15 minutes and recorded for 160 days between 26 August 2010 and 1 February 2011. Long-Term Spectral Averages (LTSAs) were created for three frequency bands (10 Hz – 1000 Hz, 500 Hz – 5000 Hz, and 1 kHz – 100 kHz). Segments of data that did not allow for further analysis due to disk malfunctions or strumming noise were identified. The usable data were then scanned for marine mammal vocalizations. Vocalizations of unidentified delphinids were detected in the data. All of the low- and mid-frequency data for this deployment were unusable, thus preventing detection of mysticete calls and mid-frequency active sonar.

Passive acoustic monitoring was conducted within the Navy’s Cherry Point OPAREA during August – December 2011 and July – October 2012 for a total of 105 and 81 days respectively. This site is located approximately 100 miles from the North Carolina coastline on the shelf break. The 2011 deployment was at a water depth of 952 m and the 2012 deployment was at a water depth of 914 m. Acoustic data collected at this site provide information on the presence of marine mammals and anthropogenic sound sources. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz with recording cycles of 5 minutes every 10 minutes. The data were divided into three frequency bands and data were analyzed by scans of long-term spectral averages and spectrograms. Four baleen whale species were recorded: blue, fin, minke, and sei whales. The detections of their calls were made between late August and early December 2011. Blue whale calls were the only baleen whale call type detected in the 2012 deployment. No Bryde’s, humpback, or North Atlantic right whale calls were detected in either deployment. Several different toothed whale species were recorded: Blainville’s, Cuvier’s, and Gervais’ beaked whales, killer whales, pygmy or dwarf sperm whales (Kogia spp.), Risso’s dolphins, sperm whales, and unidentified odontocetes. All species except killer whales were recorded in 2011 and 2012. Killer whales were detected only in 2011. Ship noise was the most common anthropogenic sound in both deployments. MFA was noted during both deployments. A total of 391 pings were detected in 2011 with a maximum peak-to-peak received level of 156 dB re 1 μPa. In 2012, a total of 492 pings were detected with a maximum peak-to-peak received level of 167 dB re 1 μPa. Few echosounder pings over a variety of frequencies (4-80 kHz) were detected during both deployments. Explosions were detected in both deployments, though they were more prevalent in 2011 than 2012. High noise levels, possibly caused by instrument strumming and fluid flow at the sensor, occurred intermittently in both deployments and likely decreased the detection range for low-frequency sounds. This strumming was most prevalent in 2012.

The Rice’s whale (Balaenoptera ricei; formerly Gulf of Mexico Bryde's whale) is estimated to have a population size of 51 individuals in U.S. waters (Garrison et al., 2020), and was listed as endangered under the ESA in 2019 (84 Federal Register 15446, 87 Federal Register 8981). The majority of modern sightings occur within waters between the 100 and 400 meter isobaths within an area near the De Soto Canyon off northwestern Florida (Rosel et al., 2021; Soldevilla et al., 2017), an area defined as the Rice’s whale core distribution area (Rosel & Garrison, 2022). Occurrence patterns from long-term passive acoustic monitoring (PAM) over the 2010–2024 period and from summer and fall visual surveys during 2018 and 2019 indicate that the whales are found year-round within the core distribution area, but also suggest there may be seasonal movements throughout, and potentially out of, this area. High densities of anthropogenic activities occur throughout the Gulf of America (formerly Gulf of Mexico, hereafter GOA), including oil and gas exploration and extraction, fisheries, shipping, and military activities. Many of these activities, including U.S. Navy readiness activities, and Eglin Air Force Base activities, overlap with the whales’ core distribution area. Understanding seasonal distribution and density of Rice’s whales throughout this area will improve understanding of potential impact of human activities, improve the accuracy and precision of impact assessments, and assist in developing effective mitigation measures as needed. To improve management of human-based activities in the core distribution area of these endangered whales, the SEFSC deployed a sparse array of 17 PAM units concurrent with one long-term High-frequency Acoustic Recording Package (HARP) from May 2021 to March 2023. The PAM moorings were deployed in two lines of nine units each to nearly completely cover the core distribution area over a nearly 2-year period to improve understanding of seasonal and interannual distribution, movement patterns, and habitat use. The moorings used SoundTrap ST500 or ST600 STDs, calibrated long-term recorders capable of continuously recording underwater sound in the 20 Hertz to 48 kHz frequency range, including Rice’s whale calls and ambient noise, for up to 6 months. Additionally, the study leveraged a long-term HARP deployed by the SEFSC, Scripps Institution of Oceanography, and collaborators, at the De Soto Canyon site in the Rice’s whale core distribution area over the August 2020 to July 2025 period. At this site, they have continuously recorded ambient noise and other acoustic events in the 10 Hertz to 100 kHz frequency range since 2010 to monitor the impacts of the Deepwater Horizon oil spill and subsequent restoration activities on cetaceans. Analyses from the combined DC HARP and sparse array of SoundTrap deployments over the 2021-2023 period suggested Rice’s whale detections occurred at all PAM stations throughout the entire year, with detections occurring more commonly on the inshore line compared to the offshore line, and suggested call detections increased to the south in winter and to the north in summer. Additional data collection was recommended to determine whether these patterns were consistent over longer periods, as needed to understand seasonal distribution and density of Rice’s whales. To meet this need, a new 3-year project is being conducted from June 2025 to June 2028 that includes redeploying the PAM array for at least one more year, and conducting analyses of Rice’s whale spatiotemporal occurrence across the new (2025-2026) and historic (2021-2023) datasets. The project objectives include 1) characterizing spatiotemporal distribution of calling Rice’s whales throughout the CDA over three years to understand interannual variation in year-round occurrence patterns; 2) evaluating whether intra-annual habitat use patterns represent consistent seasonal cycles over time; and 3) evaluating longer-term trends in occurrence of calling Rice’s whales as needed for monitoring population recovery. Results from 2021-2023 will be combined with the current effort to yield the three full years of broad coverage passive acoustic data collection. The project is off to a successful start. In June 2025, 17 SoundTrap ST600 STD recorders were deployed at the same study sites from the 2021-2023 period, along with the De Soto Canyon HARP. In January 2026, all 17 SoundTrap recorders were successfully retrieved. Upon initial inspection, acoustic recordings from each instrument were of high quality, yielding a total of 3,524 instrument-days of recording effort. The instruments recorded for a median of 6.9 months each, with most recordings ending in late December or early January. All 17 SoundTrap recorders were serviced and redeployed for another 6-month deployment. They will be retrieved, along with the HARP, in June 2026. Data analyses, including Rice’s whale call detection, localization, and call density estimation will begin in fall 2026.

The project’s goal is analysis of passive acoustic monitoring recordings that were obtained by scientists at Hawaii Institute of Marine Biology (HIMB) using Ecological Acoustic Recorders (EAR) devices. The information to be extracted from the recordings is on the presence of marine mammals and the nature of the sounds they make. Some of these historical recordings from 2009 and 2010 coincide with Naval training events in the areas around the islands of Oahu and Kauai. In optimal situations, analysis of days of recordings from a few days before, during, and a few days after the training events were available to characterize the baseline environmental acoustic state before and after events as well as any changes that may occur during events

Whales and dolphins use sound for different functions including echolocation and social communication, and thus changes in sound production patterns are a likely component of any behavioral response to anthropogenic sounds such as military mid-frequency sonar (MFA). To simultaneously log whale and dolphin movements, sound production and reception, and anthropogenic sound exposure levels, we used Dtags (Woods Hole Oceanographic Institution) and bioacoustic probes (Greeneridge Sciences). Tags were deployed on wild, free-ranging cetaceans in Southern California waters. Tagged animals were then exposed to simulated MFA or, as a control, pseudo-random noise (PRN). In total, the August-September 2010 SoCal10 behavioral response study included 28 playbacks: 19 to blue whales (11 MFA, 8 PRN), 5 to fin whales (3 MFA, 2 PRN), 2 to a single sperm whale (1 MFA, 1 PRN), 1 to a Risso’s dolphin (MFA), and 1 to a Cuvier’s beaked whale (MFA). For this analysis we focus first on baleen whale call production and reception rates (particularly blue whale D calls and variable calls) in relation to sound exposure level, dive behavior, and lunge feeding rates. We then examine echolocation-based foraging behavior and social call production by the toothed whales as a function of sound exposure level. This rich dataset, including multiple cetacean species of conservation concern, provides insight into the wide potential range of responses to sound, and the dependence of those responses on ecological, social and behavioral context. Investigations like SoCal10 can help guide inferences for related topics, such as assessment of population effects of anthropogenic noise.

In order to train with mid-frequency active sonar (MFAS), the United States (U.S.) Navy has obtained a permit from the National Marine Fisheries Service (NMFS) under the Marine Mammal Protection Act (MMPA) and a Biological Opinion under the Endangered Species Act (ESA). The Navy has developed Monitoring Plans for individual Navy Range Complexes, guided by the Integrated Comprehensive Monitoring Program (ICMP), to provide marine mammal and sea turtle monitoring guidelines as required under the MMPA and the ESA (Department of the Navy 2010). The Hawaii Range Complex (HRC) Monitoring Plan, implemented in 2014, was developed with NMFS to comply with the requirements under the permits (Department of the Navy 2014). The ICMP provides the overarching framework for coordination of the U.S. Navy Monitoring Program (Department of the Navy 2010). The ICMP outlines objectives for range/project-specific Monitoring Plans and U.S. Navy-funded research relating to the effects of naval training and testing activities on protected marine species (Department of the Navy 2010).

A marine mammal species verification and satellite tagging test was carried out as part of the Marine Mammal Monitoring on Navy Ranges (M3R) program in collaboration with the Cascadia Research Collective from 11 June to 02 August 2012 at the Pacific Missile Range Facility (PMRF). The primary objective of the test was to acoustically detect marine mammals at PMRF and vector observers to vocalizing animals. This allowed the team to: 1) Visually verify at-sea species acoustically detected on the PMRF undersea range 2) Deploy satellite tags on marine mammals prior to the Rim of the Pacific Exercise (RIMPAC) to monitor animals’ movement before, during and after navy training. 3) Photograph animals to create a photo-ID record for the Hawaii Range Complex 4) Collect biological samples (fecal/biopsy) 5) Document group composition and behavior

In the Pacific the Marine Mammal Monitoring on Navy Ranges (M3R) program maintains systems that automatically detect, classify and localize marine mammals in real-time on the U.S. Navy’s deep-water Southern California Antisubmarine Warfare Range (SOAR) in Southern California and Pacific Missile Range Facility (PMRF) off Hawai’i. Long-term archive data collected on these ranges allows for numerous types of studies on species inhabiting the ranges, including the monitoring of abundance and distribution, behavioral responses to naval activities, and habitat usage. They also provide the opportunity to study ambient noise and soundscapes.

Beaked whale abundance and vocal behavior were examined at two different U. S. Navy training ranges: for Cuvier’s beaked whale (Ziphius cavirostris) at the Southern California Anti-Submarine Warfare Range (SOAR) between August 2010 through October 2019, and for Blainville’s beaked whales (Mesoplodon densirostris) at the Pacific Missile Range Facility (PMRF) between 2015 and 2018. The yearly and monthly abundance, mean number of group vocal periods (GVPs), mean duration of the GVPs in minutes, and the mean number of clicks detected per beaked whale group were calculated.

Cuvier’s beaked whale abundance estimates have been obtained at the U.S. Navy’s Southern California Anti-Submarine Warfare Range (SOAR) for the period from August 2010 through November 2018. Data for December 2018 through January 2019 are currently being processed. The data were corrected for effort and spatial variation by applying correction factors as in DiMarzio et al (2017). Since 2010, the Cuvier’s beaked whale abundance at SOAR appears to be stable or slightly increasing.

In 2016, corrected Cuvier’s beaked whale (Ziphius cavirostris, Zc) abundance estimates at SOAR were completed for 2010 -2014. The estimates showed no decline in abundance over this 5-year period on the instrumented Southern California Anti-Submarine Warfare Range (SOAR). In 2017, these estimates were updated with data from 2015 through September of 2017 to provide a yearly estimate from 2010 to 2017. Periods of node or in-water hardware outages in past estimates and new data were isolated. Correction factors for these periods were calculated, and revised abundance estimates were produced. As before, the data do not show a decline in abundance on SOAR over the last eight years.

In FY20 the M3R program had six areas of focus for SOAR and PMRF: 1) long‐term data collection and the evaluation of abundance and distribution of Cuvier’s beaked whales at SOAR and Blainville’s beaked whales at PMRF; 2) the effect of two types of mid‐frequency active sonar (MFAS), hull‐mounted and dipping sonar, on Cuvier’s beaked whales at SOAR and Blainville’s beaked whales at PMRF; 3) evaluation of the M3R low‐frequency detector algorithm at SOAR; 4) determination of Autogrouper detection statistics for Blainville’s beaked whales at PMRF; 5) the development of tools to automatically characterize the ambient noise at SOAR using archive files; and 6) the support of on‐site field exercises at SOAR and PMRF with real‐time monitoring using the M3R system.

In the Pacific, the Marine Mammal Monitoring on Navy Ranges (M3R) program maintains systems that continuously run algorithms to detect, classify and localize marine mammals year-round on the U.S. Navy’s deep-water Southern California Antisubmarine Warfare Range (SOAR) in Southern California and the Pacific Missile Range Facility (PMRF) off Kaua‘i, Hawai‘i. Long-term archive data collected on these ranges allow for numerous types of studies on species inhabiting the ranges, including the monitoring of abundance, behavioral responses to naval activities, and habitat usage. They also provide the opportunity to study ambient sound levels and soundscapes. In FY24 the M3R program had five goals for SOAR and PMRF: Support real-time monitoring of on-water tagging operations Collection and postprocessing of M3R binary archives and periodic broadband recordings Data preservation: conversion of Alesis recordings to M3R packet recorder format SOAR Continuous Active Sonar Behavioral Response Study (CAS BRS) DICASS sonobuoy receiver adaption in preparation for deployment at SOAR.

In the Pacific, the Marine Mammal Monitoring on Navy Ranges (M3R) program maintains systems that continuously run algorithms to detect, classify and localize marine mammals year-round on the U.S. Navy’s deep-water Southern California Antisubmarine Warfare Range (SOAR) in Southern California and the Pacific Missile Range Facility (PMRF) off Kaua‘i, Hawai‘i. Long-term archive data collected on these ranges allow for numerous types of studies on species inhabiting the ranges, including the monitoring of abundance, behavioral responses to naval activities, and habitat usage. They also provide the opportunity to study ambient sound levels and soundscapes.

Nine Marine Autonomous Recording Units (MARU’s) were deployed in a rectangular array at a site coinciding with the United States (U.S.) Navy’s planned Undersea Warfare Training Range (USWTR) approximately 60150 km offshore Jacksonville, FL (13 September to 8 October and 3 December to 8 January, 2009–2010) at shallow, mid-depth, and deep sites (45, 183, 305 m). Data were reviewed in detail using TRITON (Wiggins, 2007). Event logs were created for each day at every site. Custom-written MATLAB scripts were used to calculate the probability of minke whale vocalization events occurring in the presence and in the absence of mid-frequency sonar. Minke whale vocalization events were completely absent in the fall deployment period, but occurred almost continuously during the winter deployment, indicating a strong seasonal pattern of occurrence. Minke whale vocalizations were detected most frequently at deep-water sites, and only at low levels (

Autonomous acoustic recorders are effective for investigating the distribution, occurrence, and acoustic behaviors of a variety of marine mammals in remote and deep-water locations. Nine Marine Autonomous Recording Units (MARU’s) were deployed in a rectangular array at a site coinciding with the United States (U.S.) Navy’s planned Undersea Warfare Training Range (USWTR) approximately 60-150 kilometers offshore Jacksonville, FL. All 9 units were deployed for 26 days in fall (13 September to 8 October) and 37 days in winter (3 December to 8 January) 2009-2010 at shallow, mid-depth, and deep sites (45, 183, 305 meters). The timing of the deployments allowed recordings of cetacean vocalizations and sonar activity to be made before, during, and after two U.S. Navy training exercises. The goal of this study was to characterize minke whale vocal activity in relation to U.S. Navy mid-frequency sonar signals. Data were reviewed in detail using the MATLAB program Triton (Wiggins 2007). Event logs were created for each day at every site. Custom-written MATLAB scripts were used to calculate the probability of minke whale vocalization events occurring in the presence and in the absence of mid-frequency sonar. Minke whale vocalization events were completely absent in the fall deployment period, but occurred almost continuously during the winter deployment, indicating a strong seasonal pattern of occurrence. Minke whale vocalizations were detected most frequently at deep-water sites, but only at low levels (

Visually validated towed hydrophone array recordings made in the presence of four killer whale communities (northern and southern residents, offshores, and west coast transients) were collected during the Pacific Orca Distribution Surveys (PODS) conducted by the Northwest Fisheries Science Center in the winters of 2006-2009, 2012, 2013, and 2015. Killer whale communities are known to exhibit differences in their prey preferences, genetic structure, and acoustic call repertoire, but little is known about differences in echolocation clicks. Over 20,000 echolocation clicks were measured from 49 independent killer whale acoustic encounters that were recorded during these cruises to compare signal parameters between communities. Echolocation click parameters were measured automatically using tools available in PAMGuard software. Results of pairwise comparisons indicated that duration, center frequency, peak frequency, sweep rate, number of zero crossings, and inter-click interval were significantly different (Kolmogorov-Smirnov test, p

We fitted hidden Markov models to 627 tracks that were reconstructed from 3 years of minke whale (B. acutorostrata) vocalizations recorded before, during, and after naval training events at the U.S. Navy’s Pacific Missile Range Facility, Kauai, Hawaii. The fitted models were used to identify different movement behaviors and to investigate the effect of sonar activity on these behaviors. Movement was faster and more directed during sonar exposure than in baseline phases. The mean direction of movement differed during sonar exposure, and was consistent with movement away from sonar-producing ships. Animals were also more likely to cease calling during sonar.

Passive acoustic monitoring has been conducted along the U.S. west coast, from Central California to Cape Flattery, to monitor movements of endangered Southern resident killer whales (SRKW). Since 2008, four to seventeen Ecological Acoustic Recorders (EARs) have been deployed, depending on the year and available funding. The rate of successful data acquisition has varied each year due to fishery interactions and equipment failures. EARs were programmed to record on a 5–10% duty cycle depending on the year of deployment, resulting in 30–90 seconds of continuous recording every 300–600 seconds with a sampling rate of 25 kHz.

We used passive acoustic monitoring at 15 sites along the coast of Washington State, USA, to assess habitat use patterns of 2 sympatric populations of fish-eating killer whales Orcinus orca: northern residents (NRKW) and southern residents (SRKW).

In this study, we co-located Ecological Acoustic Recorders (EARs) and SoundTraps at five locations along the Washington coast, analyzed each data set separately, and compared the results. Preliminary analysis of these data resulted in a 1.6 to 3.4 times increase in the number of days with RKW detections in the SoundTrap data compared to the EAR data depending on location. We will present the results of this comparison, investigate potential causes of the differences between recorder type, and highlight the implications of these differences to previous knowledge of RKW movements along the Washington coast.

Taking into consideration the multiple intermediate scientific objectives in the U.S. Navy’s Strategic Planning Process (DoN 2013), the goals of this study are to assist the U.S. Navy and regulatory agencies with environmental planning and compliance by addressing the following questions: Which cetacean species occur within the VACAPES OPAREA off Virginia, and how does occurrence fluctuate seasonally? What are the baseline behaviors and ecological relationships of offshore cetaceans within the study area? Do individual cetaceans exhibit site fidelity within specific regions of the study area over periods of weeks, months, or years? What is the seasonal extent of cetacean movements within and around U.S. Navy VACAPES training range boxes? Do cetaceans spend significant time within or primarily move through areas of U.S. Navy live-fire or Anti-Submarine Warfare training events?

The United States (U.S.) Navy routinely conducts training and testing activities in the Virginia Capes (VACAPES) Operating Area (OPAREA) off the mid-Atlantic and Southeast U.S. The region encompassing the deeper waters of the continental shelf, shelf break, and continental slope has been recognized as an important habitat for multiple species of cetaceans. Kenney and Winn (1986) showed that the shelf edge from Cape Hatteras to Georges Bank was the second most intensively used cetacean habitat off the northeastern U.S. based on 3 years of surveys conducted by the Cetacean and Turtle Assessment Program (CETAP 1982). This progress report includes all offshore monitoring activities conducted in 2021. The goals of this effort focus on addressing fundamental information gaps related to marine mammal occurrence, exposure, and response as identified by the U.S. Navy’s Integrated Comprehensive Monitoring Program (DoN 2010) and recommendations provided by a Scientific Advisory Group review (DoN 2011).