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.

During HDR Inc.’s 2023/24 field season, baleen whale sightings included humpback whales, NARWs, fin whales, minke whales (Balaenoptera acutorostrata), and sei whales (Balaenoptera borealis). This report will focus on the photo-ID results from all baleen whale sightings, photogrammetry results from the drone, and status of the MAHWC and Happywhale matching. See Aschettino et al. (2025) and Engelhaupt et al. (2025) for further information and details from the vessel survey and tagging efforts, and Ozog and Engelhaupt (2025) for details from the supporting aerial surveys.

A total of 22 nearshore and mid-shelf vessel surveys were completed during the 2024/25 field season. In total, 60 baleen whale sightings, including 40 sightings of humpback whales (Megaptera novaeangliae) totaling 59 individuals, 10 sightings of North Atlantic right whales (NARWs; Eubalaena glacialis) totaling 22 individuals, 7 sightings of fin whales (Balaenoptera physalus) totaling 14 individuals, and 3 sightings of individual minke whales (Balaenoptera acutorostrata), occurred during the 2024/25 field season. A total of 24 aerial surveys were flown during the 2024/25 field season in association with this effort and the Offshore Cetacean Study (OCS) (A. Engelhaupt et al. 2026); see Ozog and Engelhaupt 2026 for additional details regarding the aerial surveys. Baleen whale sightings from the aerial surveys included humpback (n=45), NARWs (n=8), fin (n=11), and minke (n=3) whales (Ozog and Engelhaupt 2026). During the OCS surveys, baleen whale sightings included fin whales (n=12), humpback whales (n=7), a blue whale (Balaenoptera musculus; n=1), a minke whale (n=1), and an NARW (n=1) (A. Engelhaupt et al. 2026). Across this project and the OCS effort, satellite-linked telemetry tags were deployed on one humpback whale, one fin whale, and one NARW. Customized Animal Tracking Solution tags were deployed on two NARWs and two humpback whales. One biopsy sample was collected from the satellite-tagged humpback whale.

Baseline undisturbed behavior and social patterns of blue (Balaenoptera musculus) and fin whales (B. physalus) are not well described and are needed to identify and understand potential effects of anthropogenic activities. Behavioral data for blue and fin whales were collected during line-transect and focal-follow effort. Initially observed behavior state, heading, and minimum and maximum interindividual dispersal distance were recorded during line-transect sampling. Focal groups were circled for 10-60+ minutes and videotaped from outside Snell’s sound cone to avoid disturbance. During 24,736 km of survey effort, 51 fin whale sightings (85 individuals) and 49 blue whalesightings (81 individuals) were seen. Over 7 hours of video was collected for16 blue and 15 fin focal follows. During the summer seasons, blues (n=48) were seen more commonly than fins (n=35); in fall, fins (n=16) were seen significantly more frequently than blues (n=1). Mean group size was 1.7 whales for both species. Initially observed blue behavior was usually travel (85%) or mill (11%). Observed fin whale behavior was also mostly travel (90%), mill (4%), or surface-active travel (4%). Both species were seen socializing in fall but not summer; foraging was observed in summer through fall. Mean initial dispersal for blues and fins was 9.1 and 14.2 body lengths, respectively. In summer, blues were most frequently (26%) seen headed S; in fall (n=2), they were headed only inshore (E). In summer, fin whales were most commonly headed SSW (26%) or WNW (26%); in fall, they were headed mostly NE (38%) or WSW (38%). Dive/respiration/behavioral event rates were also collected. Both species may directly compete for food based on observations of inter-specific maneuvering for a bait ball. Data represent the most extensive record of systematic undisturbed behavior on these species in SOCAL and include social interactions not previously documented in this region.

Baseline undisturbed behavior and social patterns of blue (Balaenoptera musculus) and fin whales (B. physalus) are not well described and are needed to identify and understand potential effects of anthropogenic activities in the SCB. In 2008-2012, 72,467 km of aerial line transect and focal-follow effort was conducted in the SCB. Initially observed location, group size, behavior state, heading, and minimum and maximum inter-individual dispersal distance were recorded. Focal groups were circled for 10-60+ minutes and videotaped from outside the plane’s sound cone to avoid disturbance. A total of 122 fin whale sightings (208 individuals) and 65 blue whale sightings (104 individuals) were made. Behavior, occurrence and distribution were related to season, location, bathymetry, and time of day. Blue whales were seen only from summer-fall and concentrated primarily close to shore (

Baseline undisturbed behavior/social patterns of blue/fin whales are not well described and are needed to identify and understand potential effects of anthropogenic activities. Behavioral data were collected during aerial effort. Initially observed behavior state, heading, minimum/maximum inter-individual dispersal distance were recorded during line-transect sampling. During the summer seasons, blues were seen more than fins; in fall, fins were seen more. Initially observed blue behavior was usually travel or mill. Observed fin behavior was mostly travel, mill, or surface-active travel. Both species were seen socializing in fall but not summer; foraging was observed in summer through fall. In summer, blues were seen headed S; in fall, headed inshore. In summer, fins were headed SSW or WNW; in fall, they were headed NE or WSW. Data represent the most extensive record of systematic undisturbed behavior on these species in SOCAL and include social interactions not previously documented in this region.

Baseline undisturbed behavior and social patterns of blue (Ba/aenoptera musculus) and fin whales (8. physa/us) are not well described and are needed to identify and understand potential effects of anthropogenic activities. Behavioral data for blue and fin whales were collected during aerial survey line-transect and focal-follow effort. Initially-observed behavior state, group size, heading, and minimum and maximum inter-individual dispersal distance were recorded during line-transect sampling and / or subsequent verification circling by the aircraft. Focal groups were circled for 3- 60+ minutes and videotaped from outside Snell's sound cone to avoid disturbance. During 24,736 km of survey effort, 51 fin whale sightings (86 individuals) and 49 blue whale sightings (84 individuals) were seen . Over 7 hours of video was collected for 16 blue and 15 fin focal follows. During the summer, blues (n=48) were seen more commonly than fins (n=35); in fall, fins (n=16) were seen much more frequently than blues (n= 1 ). Mean group size was 1. 7 whales for both species. Initially observed blue behavior was usually travel (85%) or mill (11%). Observed fin whale behavior was also mostly travel (87%), mill (6%), or surface-active travel (3%). Both species were seen socializing (e.g., touching) in fall but not summer; foraging was observed in summer through fall. Mean initial dispersal for blues and fins was 8 and 16 body lengths, respectively. In summer, blues were most frequently (26%) seen headed S; in fall (n=2), they were headed only inshore (E). In summer, fin whales were most commonly headed SSW (26%) or WNW (26%); in fall, they were headed mostly NE (38%) or WSW (38%). Both species directly compete for food based on observations of inter-specific maneuvering for a bait ball. Data represent the most extensive record of systematic undisturbed behavior on these species in SOCAL and include social interactions not previously documented in this region. Dive / respiration / behavioral event rates were also collected and are currently being analyzed. Bacon, C., M.A. Smultea, B. Wursig, K. Lomac-MacNair, and J. Black.

Effects of mixed-species associations (MSA [at least two differentspecies swimming together and/or interacting]) on cetacean behavior rarely have been quantified, but are important for identifying and differentiating potential anthropogenic impacts. Baseline marine mammal behavior was assessed during 77,390 km of U.S. Navy supported aerial line-transect surveys in the Southern California Bight during 2008-2013. Multinomial logistic regression was used to assess effects of MSA on group size, maximum nearest neighbor distance (a “cohesion” index, in body lengths), behavior state, and heading. Two percent (43) of 2,330 sightings were MSA involving 13 species (5 baleen whales, 7 toothed whales, 1 pinniped). Behavior and group size of some species differed significantly in MSA vs. non-MSA. MSA were predominated by Risso’s dolphins (44%; 19 of 43 MSA). Risso’s dolphins were most frequently associated with bottlenose dolphins (37% of 19 Risso’s MSA groups) followed by northern right whale dolphins (NRWD; 3% of 19). Risso’s dolphins tended to change headings more often in MSA (p

This study investigates mixed-species associations among marine mammals in the Southern California Bight, focusing specifically on Risso's dolphins (Grampus griseus). Over a six-year period, aerial surveys were conducted to record the frequency and nature of these associations, revealing that Risso's dolphins were the most commonly observed species in mixed interactions. The results indicate a significant decline in the proportion of Risso's dolphins involved in such associations compared to historical records, possibly due to an increase in their relative abundance. The findings underline the importance of monitoring mixed-species associations to understand marine mammal dynamics and ecological interactions.

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.

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).

The overall goal of this study was to include the 2018 survey data in the previous 1991–2014 modeling dataset in order to improve SMDs for the CCE study area. Specific objectives included: Generating multi-year average density surfaces for the Navy and others to use in their long-term (2–7 year) environmental planning efforts; and Providing updated abundance and “minimum population size (Nmin)” estimates as defined in the Guidelines for Assessing Marine Mammal Stocks (National Oceanic and Atmospheric Administration 2016).

In this study, winter and spring density estimates for the entire CCE study area were made from SWFSC summer and fall model predictions (temporal extrapolation) and CalCOFI winter and spring model predictions (spatial extrapolation) for short-beaked common dolphin ( Delphinus delphis delphis ), Pacific white-sided dolphin ( Lagenorhynchus obliquidens ), Dall's porpoise ( Phocoenoides dalli ), and fin whale ( Balaenoptera physalus ).

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.

Rapid progress and affordability of photographic technology with increasing improvements in image resolution have facilitated advancements in efficiency and alternative approaches in data collection for marine mamma ls. We report these recent improvements by comparing marine mammal photographs taken during 2008-2013 aerial surveys of 16 marine mammal species in the Southern California Bight, shore-based studies of bottlenose dolphins (Tursiops truncatus) in Galveston Bay, Texas (2011 - 2013), and gray whales (Eschrichtius robustus) off Sakhalin Island, Russia (2004 -2010).

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 present study provides new and current estimates of cetacean density for the six most commonly encountered cetacean species off southern California based on sighting data collected during 37 quarterly CalCOFI cruises from 2004 to 2013. The current study resulted from a high survey repetition rate that allowed for the examination of inter-annual and seasonal trends in density as well as temporal and spatial patterns of distribution for six common cetacean species off southern California: blue whales, fin whales, humpback whales, short-beaked common dolphins, Pacific white-sided dolphins, and Dall’s porpoise.

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.

Trends in cetacean density and distribution off southern California were assessed through visual line-transect surveys during thirty-seven California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from July 2004–November 2013. From sightings of the six most commonly encountered cetacean species, seasonal, annual and overall density estimates were calculated. Blue whales (Balaenoptera musculus), fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) were the most frequently sighted baleen whales with overall densities of 0.91/1000km2 (CV=0.27), 2.73/1000km2 (CV=0.19), and 1.17/1000km2 (CV=0.21) respectively. Species specific density estimates, stratified by cruise, were analyzed using a generalized additive model to estimate long-term trends and correct for seasonal imbalances. Variances were estimated using a non-parametric bootstrap with one day of effort as the sampling unit. Blue whales were primarily observed during summer and fall while fin and humpback whales were observed year-round with peaks in density during summer and spring respectively. Short-beaked common dolphins (Delphinus delphis), Pacific white-sided dolphins (Lagenorhynchus obliquidens) and Dall’s porpoise (Phocoenoidesdalli) were the most frequently encountered small cetaceans with overall densities of 705.83/1000km2 (CV=0.22), 51.98/1000km2 (CV=0.27), and 21.37/1000km2 (CV=0.19) respectively. Seasonally, short-beaked common dolphins were most abundant in winter whereas Pacific white-sided dolphins and Dall’s porpoise were most abundant during spring. There were no significant long-term changes in blue whale, fin whale, humpback whale, short-beaked common dolphin or Dall’s porpoise densities while Pacific white-sided dolphins exhibited a significant decrease in density across the ten-year study. The results from this study were fundamentally consistent with earlier studies, but provide greater temporal and seasonal resolution. Keywords: Cetaceans; Line transect; Density; Abundance; Distribution; Trends; Southern California; CalCOFI

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.

This project is intended to provide baseline information on the species composition, density, distribution, and basic behavior of marine mammals and sea turtles present within the United States (U.S.) Navy’s Virginia Capes (VACAPES) Operating Area (OPAREA). This study is part of a larger, multi-institutional, marine mammal and sea turtle monitoring program of U.S. Navy range complexes along the U.S. Atlantic Coast and Gulf of Mexico supporting Atlantic Fleet Training and Testing (AFTT)

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.

This report forms part of a multi-institutional monitoring project intended to provide information on the species composition, population identity, density, and baseline behavior of marine mammals and sea turtles present in United States (U.S.) Navy range complexes along the U.S. Atlantic Coast.

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.

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.

Navy Research Funded Year Three Project Reports

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.

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 Pacific Missile Range Facility (PMRF) off Kauai, 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.

Documenting year-round diversity and distribution of marine mammals off Southern California is important for assessment of effects of potentially harmful anthropogenic activities. Although the waters off Southern California have been surveyed extensively for marine mammals over the past 18 years, such surveys have been periodic and were conducted primarily from summer to fall, thereby missing potential seasonal shifts. We examined seasonal abundance and population density of cetaceans off Southern California from 16 shipboard line-transect surveys conducted quarterly during 2004–08. The study area consisted of 238,494 km² of coastal, shelf, and pelagic oceanic habitat from near-shore waters to 700 km offshore.

The global distribution of fin whales Balaenoptera physalus is not fully understood. Existing maps can be divided into two conflicting categories: one showing a continuous global distribution and another showing an equatorial hiatus (gap in the global distribution) between approximately 20°N and 20°S. Questions also remain about the seasonal distribution of fin whales. To explore the suggested equatorial hiatus and seasonal distribution patterns, we synthesised information on fin whale distribution in the post-whaling era (1980–2012) from published literature, publicly available reports and studies conducted by various organisations. We created four seasonally stratified maps showing line-transect density estimates, line-transect survey effort, acoustic detections, and sightings. An equatorial hiatus in the global distribution of fin whales during the postwhaling era is supported by numerous line-transect surveys and by the rarity of equatorial acoustic detections and sightings, and corroborated by whaling era reports, morphological analyses, and genetic analyses. Our synthesis of post-whaling era data is consistent with results from other studies indicating that fin whales are more abundant at higher latitudes during warmer months and more abundant at lower latitudes (although these latitudes are still greater than 20°) during colder months. However, our synthesis and results from other studies also indicate that some fin whales in both hemispheres remain in higher latitudes (50°–60° north or south) during colder months and in lower latitudes (to approximately 20°–30° north or south) during warmer months, indicating that seasonal fin whale movements differ from the seasonal migrations of blue whales Balaenoptera musculus and humpback whales Megaptera novaeangliae. Our maps of global fin whale distribution provide a comprehensive picture of current knowledge and highlight important geographical and temporal data gaps. Surveys should be conducted within the identified data gaps in order to increase fine-scale spatial and temporal knowledge of distribution patterns, improve fin whale taxonomy, and identify areas of elevated fin whale densities that may require management of threats, such as ship strikes.

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).

Taking into consideration the multiple intermediate scientific objectives in the U.S. Navy’s Strategic Planning Process (DoN 2013b), 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 over the outer continental shelf to the east of NSN, 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

Taking into consideration the multiple intermediate scientific objectives in the U.S. Navy’s Strategic Planning Process (DoN 2013b), 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 over the outer continental shelf to the east of NSN, 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

Taking into consideration the multiple intermediate scientific objectives in the U.S. Navy’s Strategic Planning Process (DoN 2013b), 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 over the outer continental shelf to the east of NSN, 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

This report summarizes data collected during small-vessel surveys for cetaceans in the Southern California Bight (SCB), with a focus on the Southern California Offshore Range Complex (SCORE), from June 2010–January 2014. Detailed annual progress reports were prepared after each survey year through 2013 and are available online through the Naval Postgraduate School. This final report emphasizes analyses that combine data across study years, particularly with respect to two focal species: Cuvier’s beaked (Ziphius cavirostris, Zc) and fin (Balaenoptera physalus, Bp) whales.

Results from the second year of a three-year project investigating the distribution, demographics, and behavior of cetaceans in the US Navy’s Southern California operational area are summarized. Eighteen small vessel surveys for cetaceans, which included species verification tests in conjunction with M3R (Marine Mammal Monitoring on Navy Undersea Ranges) acoustic monitoring at the Southern California Anti-submarine Warfare Range (SOAR), as well as photo-identification, satellite tagging, and biopsy sampling of species of interest, were conducted in July 2011 and January and March 2012. 112 groups of 14 cetacean species were encountered. Twenty-one satellite tags, some depth reporting, were deployed on four species, with an emphasis on Cuvier’s beaked and fin whales. Among other findings, preliminary results of photo-identification studies combined with results from satellite tag data suggest that both Cuvier’s beaked whales and fin whales may have population sub-units with higher than expected residency to the Southern California Bight. Beaked whales particularly show this higher than expected residency to SOAR.

Fin whales (Balaenoptera physalus) along the western United States are managed as a single stock whose range overlaps with the California Current System (CCS). We used sighting histories of 932 individual fin whales photographed in the CCS from 1987 to 2018 to investigate movements and residency patterns within and among latitudinal regions. While 167 whales (18%) were sighted in multiple years, only 4 were documented in both the Northern and Southern CCS, with a boundary at 38.5 °N. A permutation test of annual recaptures suggested movements among latitudinal regions of the CCS occurred significantly less than expected if whales moved freely within current stock boundaries.

To monitor for the presence of marine mammals, a High-frequency Acoustic Recording Package (HARP) recorded within the Navy’s Virginia Capes Range Complex, offshore from Cape Hatteras (HAT), between April 2015 and January 2016. The HAT site was located approximately 75 nm offshore in about 1000 m of water.

A High-frequency Acoustic Recording Package (HARP) was deployed from August 2014 to July 2015, with recordings made between August 2014 and May 2015, to detect marine mammal and anthropogenic sounds in the Navy’s Jacksonville Range Complex. The HARP was located 83 nm off the Florida coastline on the continental slope.

A passive acoustic monitoring survey using mobile underwater gliders was conducted from 7 February to 31 March 2020 in the Southern California Bight, with the goal of characterizing the temporal and spatial distribution of odontocetes and mysticetes in the region. Initially, the focus of this Project was on beaked whales. However, upon recovery of the gliders post-deployment, it was discovered that neither glider recorded any useable data above 2.5 kilohertz, well below the frequency of beaked whale vocalizations. It was then decided to analyze the available data for baleen whale and sperm whale (Physeter macrocephalus) vocalizations, which was originally a focus of secondary importance for the Project.

Fin whale song is a ubiquitous low-frequency pulsing that has been recorded in every ocean basin. In recent years, the complexity of fin whale song has been realized. In the North Atlantic, this song is made up of two low-frequency note types (A and B notes) and one higher-frequency note type (upsweeps). The A and B notes are produced with both singlet and doublet inter-note intervals. These song patterns are interwoven throughout an individual’s song and have been observed to shift over time, both gradually and suddenly. Like many baleen whales, the population size of fin whales is poorly defined. Passive acoustic monitoring has been suggested as a way to estimate abundance if a cue rate or calling rate can be determined. In this study, we used recordings from 119 fin whale tracks from 2013–2023 generated from passive acoustic recorders in the North Atlantic to define fin whale song patterns in this ocean basin, identify changes in these song patterns over time, and calculate cue rates. T

Male fin whales sing using 20 Hz pulses produced in regular patterns of inter-note intervals, but little is known about fin whale swimming behavior while they are singing. Even less is known about fin whales in Hawaiian waters because they have rarely been sighted during surveys and passive acoustic monitoring has been limited to sparse hydrophone systems that do not have localization capabilities. We hypothesized that fin whale kinematics may be related to their singing behavior, or external variables such as time and sea state. To investigate this hypothesis, we analyzed 115 tracks containing 50,034 unique notes generated from passive acoustic recordings on an array of 14 hydrophones from 2011 to 2017 at the U.S. Navy Pacific Missile Range Facility off Kauai, Hawaii.

Male fin whales sing by producing 20 Hz pulses in regular patterns of inter-note intervals. While singing, fin whales may also alternate the frequency ranges of their notes. Different song patterns have been observed in different regions of the world's oceans. New song patterns suddenly emerging in an area have been hypothesized to either be indicators of new groups of whales in the area or signs of cultural transmission between groups. Since the status of fin whales around Hawaii is unknown and visual surveys are expensive and difficult to conduct in offshore areas, passive acoustic monitoring has been proposed as a way to monitor these whales. We used passive acoustic recordings from an array of 14 hydrophones to analyze the song patterns of 115 fin whale encounters made up of 50,034 unique notes off Kauai, Hawaii from 2011 to 2017.

Fin whale song consists of low frequency notes arranged in regular, repeating patterns of note type pairings and inter-note intervals (INIs). In the central North Pacific, fin whales use two downswept note types (A and B notes) with both singlet and doublet INIs that are interwoven throughout a song. These song patterns have been observed to change over time. Fin whale population size, structure, distribution, and connectedness are poorly understood, but monitoring their songs can help fill these knowledge gaps. In this study, we examine fin whale song patterns and their evolution across 12 years (2011–2023) with a focus on the most recent 5.5 years (2017–2023), expanding on our previous work.

Marine mammal surveys, initiated as part of the CalCOFI cruises in 2004, were continued during 2016-2017. Visual monitoring incorporated standard line-transect survey protocol which includes two experienced observers scanning for marine mammals during transits between CalCOFI stations.

Passive acoustic monitoring was conducted at two sites in the Navy’s Southern California Range Complex during April 2010 – April 2011. These data provide information on the presence of marine mammals and anthropogenic sound sources. High‐frequency acoustic recording packages documented sounds between 10 Hz and 100 kHz with nearly continuous temporal coverage at a site near Santa Barbara Island (site M) and a site south of San Clemente Island (site N). For this reporting period, 8,099 hours of acoustic recordings were obtained from site M and 7,779 hours of recordings from site N. Data analysis methods consisted of analyst scans of long‐term spectral averages and spectrograms. The data were divided into three frequency bands and each band was analyzed for the sounds of marine mammal species or anthropogenic sources. Representative sounds are presented.

This report summarizes the underwater sounds detected during a series of deployments of a High Frequency Acoustic Recording Package (HARP) in the southern California (SOCAL) offshore region. The HARP records broadband (10 Hz – 100 kHz) acoustic data, including both marine animal and anthropogenic sound. This report summarizes initial analysis to detect the presence of marine mammals by species as well as the occurrence of naval sonar and other anthropogenic sound events.

This report summarizes data analysis for deployment of a High Frequency Acoustic Recording Package (HARP) in the southern California (SOCAL) offshore region. The HARP records broadband (10 Hz – 100 kHz) acoustic data, including both marine animal and anthropogenic sound. This report summarizes initial analysis to detect the presence of marine mammals by species as well as the occurrence of naval sonar and other anthropogenic sound events.

Passive acoustic monitoring was conducted using High-frequency Acoustic Recording Packages (HARPs) deployed in waters offshore of Virginia, North Carolina, and Florida with support from the US Navy during 2016 - 2017. The HARPs recorded underwater sounds between 10 Hz and 100 kHz. 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) Lowfrequency, between 10-1000 Hz, (2) Mid-frequency, between 1,000-5,000 Hz, and (3) Highfrequency, between 1-100 kHz.

This report summarizes data analysis for deployment of a High Frequency Acoustic Recording Package (HARP) in the southern California (SOCAL) offshore region. The HARP records broadband (10 Hz – 100 kHz) acoustic data, including both marine animal and anthropogenic sound. This report summarizes initial analysis to detect the presence of marine mammals by species as well as the occurrence of naval sonar and other anthropogenic sound events.

This report summarizes the underwater sounds detected during a series of deployments of a High Frequency Acoustic Recording Package (HARP) in the southern California (SOCAL) offshore region. The HARP records broadband (10 Hz – 100 kHz) acoustic data, including both marine animal and anthropogenic sound. This report summarizes initial analysis to detect the presence of marine mammals by species as well as the occurrence of naval sonar and other anthropogenic sound events.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between July 2010 and June 2011 in Onslow Bay at Site A in 171 m. This HARP sampled at 200 kHz for 5 minutes of every 10 minutes and recorded for 216 days between 30 July 2010 and 3 March 2011. Long-Term Spectral Averages (LTSAs) were created for two frequency bands (10 Hz – 1000 Hz and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations. Calls of blue whales, fin whales, minke whales, North Atlantic right whales, possible sei whales, Kogia spp., Risso’s dolphins, sperm whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between October 2012 and August 2013 in Onslow Bay at Site E in 853 m. This HARP sampled at 200 kHz for 5 minutes of every 10 minutes and recorded for 250 days between 24 October 2012 and 30 June 2013. 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 blue whales, fin whales, minke whales, possible sei whales, Blainville’s beaked whales, Cuvier’s beaked whales, Gervais’ beaked whales, Kogia spp., Risso’s dolphins, sperm whales, and unidentified odontocetes and mysticetes were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between March and October 2012 in the Cape Hatteras survey area at Site A in approximately 950 m. This HARP sampled continuously at 200 kHz and recorded for 28 days between 15 March 2012 and 11 April 2012. Long-Term Spectral Averages (LTSAs) were created for two frequency bands (10 Hz – 1000 Hz and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations. Calls of fin whales, minke whales, beaked whales, Kogia spp., Risso’s dolphins, sperm whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between October 2007 and May 2008 in Onslow Bay at Site A in 162 m. This HARP sampled at 200 kHz for 5 minutes of every 10 minutes, with the exception of the period from January 1 – 16, 2008, when it recorded continuously due to an instrumentation malfunction, and recorded for 98 days between 10 October 2007 and 16 January 2008. Long-Term Spectral Averages (LTSAs) were created for two frequency bands (10 Hz – 1000 Hz and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations. Calls of blue whales, fin whales, minke whales, possible sei whales, Kogia spp., Risso’s dolphins, sperm whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between November 2009 and February 2010 in Onslow Bay at Site A in 171 m. This HARP sampled at 200 kHz for 5 minutes of every 15 minutes and recorded for 108 days between 8 November 2009 and 24 February 2010. Long-Term Spectral Averages (LTSAs) were created for two frequency bands (10 Hz – 1000 Hz and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations. Calls of blue whales, fin whales, minke whales, possible sei whales, Kogia spp., Risso’s dolphins, sperm whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between November 2009 and April 2010 in Onslow Bay at Site C in 335 m. This HARP sampled at 200 kHz for 5 minutes of every 15 minutes and recorded for 163 days between 8 November 2009 and 20 April 2010. Long-Term Spectral Averages (LTSAs) were created for two frequency bands (10 Hz – 1000 Hz and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations. Calls of blue whales, fin whales, minke whales, humpback whales, possible sei whales, Kogia spp., Risso’s dolphins, sperm whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between July 2010 and February 2011 in Onslow Bay at Site D in 338 m. This HARP sampled at 200 kHz for 5 minutes of every 10 minutes and recorded for 210 days between 30 July 2010 and 24 February 2011. Long-Term Spectral Averages (LTSAs) were created for two frequency bands (10 Hz – 1000 Hz and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations. Calls of blue whales, fin whales, minke whales, possible sei whales, Kogia spp., Risso’s dolphins, sperm whales, and unidentified odontocetes were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between August 2011 and July 2012 in Onslow Bay at Site E in 952 m. This HARP sampled at 200 kHz for 5 minutes of every 10 minutes and recorded for 105 days between 19 August 2011 and 1 December 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 blue whales, fin whales, minke whales, possible sei whales, an unidentified beaked whale species, Blainville’s beaked whales, Cuvier’s beaked whales, Gervais’ beaked whales, killer whales, Kogia spp., Risso’s dolphins, sperm whales, and unidentified delphinids were detected in the data.

The primary objectives of the passive acoustic 26 monitoring program are to: 1) Determine the patterns of occurrence at each monitoring site; 2) Compare patterns of occurrence to better understand distributional patterns; and 3) Document species-specific characteristics of the vocalizations of marine mammal species 30 in each area.

The U.S. Navy has been using High-frequency Acoustic Recording Packages (HARPs) to conduct passive acoustic monitoring in waters offshore of Virginia, North Carolina, and Florida to determine patterns of occurrence and distribution of cetacean species and anthropogenic sounds since 2007. The datasets discussed in this annual report came from seven HARP deployments made from 2012 through 2016: one near Norfolk Canyon, off the coast of Virginia (982 meter [m] depth) between June 2014 and April 2015; four off Cape Hatteras, North Carolina (850–980 m depths) between October 2012 and April 2016; and two off Jacksonville, Florida (800–806 m depths) between August 2014 and April 2016.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between August 2014 and July 2015 in the Jacksonville, FL, survey area at Site D in 806 m. This HARP sampled continuously at 200 kHz and recorded for 279 days between 23 August 2014 and 29 May 2015. The data were divided into three frequency bands (10 Hz – 1000 Hz, 500 Hz – 5000 Hz, and 1 kHz – 100 kHz) and scanned manually for marine mammal vocalizations using Long-Term Spectral Averages (LTSAs) and automated computer algorithm detection when possible. Vocalizations of fin whales, minke whales, sei whales, Kogia spp., Risso’s dolphins, sperm whales, Blainville’s beaked whales, Gervais’ beaked whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between June 2014 and April 2015 in Norfolk Canyon, VA, at Site A in 982 m. This HARP sampled continuously at 200 kHz and recorded for 290 days between 19 June 2014 and 5 April 2015. The data were divided into three frequency bands (10 Hz – 1000 Hz, 500 Hz – 5000 Hz, and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations using Long-Term Spectral Averages (LTSAs) and automated detectors. Vocalizations of blue whales, fin whales, minke whales, sei whales, humpback whales, Kogia spp., Risso’s dolphins, sperm whales, Cuvier’s beaked whales, Gervais’ beaked whales, possible Sowerby’s beaked whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between October 2012 and May 2013 in the Cape Hatteras, NC, survey area at Site A in 970 m. This HARP sampled continuously at 200 kHz and recorded for 212 days between 9 October 2012 and 9 May 2013. The data were divided into three frequency bands (10 Hz – 1000 Hz, 500 Hz – 5000 Hz, and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations using Long-Term Spectral Averages (LTSAs) and automated detectors. Vocalizations of blue whales, fin whales, minke whales, sei whales, North Atlantic right whales, humpback whales, Kogia spp., Risso’s dolphins, sperm whales, Cuvier’s beaked whales, Gervais’ beaked whales, Blainville’s beaked whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between May 2013 and March 2014 in the Cape Hatteras, NC, survey area at Site A in 970 m. This HARP sampled continuously at 200 kHz and recorded for 290 days between 29 May 2013 and 15 March 2014. The data were divided into three frequency bands (10 Hz – 1000 Hz, 500 Hz – 5000 Hz, and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations using Long-Term Spectral Averages (LTSAs) and automated detectors. Vocalizations of blue whales, fin whales, minke whales, sei whales, North Atlantic right whales, humpback whales, Kogia spp., Risso’s dolphins, sperm whales, Cuvier’s beaked whales, Gervais’ beaked whales, Blainville’s beaked whales, possible Sowerby’s beaked whales, and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between May 2014 and April 2015 in the Cape Hatteras, NC, survey area at Site A in 850 m. This HARP sampled continuously at 200 kHz and recorded for 217 days between 9 May 2014 and 11 December 2014. The data were divided into three frequency bands (10 Hz – 1000 Hz, 500 Hz – 5000 Hz, and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations using Long-Term Spectral Averages (LTSAs) and automated detectors. Vocalizations of blue whales, fin whales, minke whales, sei whales, North Atlantic right whales, humpback whales, Kogia spp., Risso’s dolphins, sperm whales, Cuvier’s beaked whales, Gervais’ beaked whales, Blainville’s beaked whales, and unidentified delphinids were detected in the data.

This report forms part of a multi-institutional monitoring project intended to provide information on the species composition, population identity, density and baseline behavior of marine mammals and sea turtles present in Navy range complexes along the Atlantic coast. This program began in 2007, with baseline aerial and vessel surveys and a passive acoustic monitoring program in Onslow Bay, North Carolina and has since expanded to include study areas off Jacksonville, Florida and Cape Hatteras, North Carolina. In Onslow Bay, six years of monitoring have yielded a comprehensive picture of the density, distribution and abundance of marine mammals and sea turtles and provided new insights into residency patterns among pelagic delphinid cetaceans in this region. More than four years of monitoring in Jacksonville have provided similar information on the density and distribution of marine mammals and sea turtles in this area. In Cape Hatteras, almost three years of surveys have provided preliminary information on the complex patterns of distribution and diversity of the marine mammals and sea turtles in this highly productive area. The current report builds on this past body of work and describes passive acoustic monitoring activities that occurred at these three sites between January and December 2013.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between February 2014 and August 2014 in the Jacksonville, FL, survey area at Site C in 88 m. This HARP sampled continuously at 200 kHz and recorded for 188 days between 17 February 2014 and 23 August 2014. The data were divided into three frequency bands (10 Hz – 1000 Hz, 500 Hz – 5000 Hz, and 1 kHz – 100 kHz) and scanned for marine mammal vocalizations using Long-Term Spectral Averages (LTSAs). Vocalizations of fin whales, minke whales, humpback whales, Risso’s dolphins, and unidentified delphinids were detected in the data. A 5-pulse signal, previously described in the Jacksonville area, was also heard.

In October 2005, the U.S. Department of the Navy proposed the installation of an Undersea Warfare Training Range (USWTR) in one of four sites along the Atlantic coast, for the purpose of anti-submarine warfare training using mid-frequency tactical sonar (1-10 kilohertz [kHz]) in shallow waters. The initial preferred site for the USWTR was Onslow Bay, North Carolina.

Intermediate-duration archival tags were attached to eight blue whales (Balaenoptera musculus; four females, three males, one of unknown sex), and five fin whales (B. physalus; two females, one male, two of unknown sex) off southern California, USA, in summer 2014 and 2015. Tags logged 1-Hz data from tri-axial accelerometers, magnetometers, and a depth sensor, while acquiring Fastloc GPS locations.

We fitted movement models to 14 years of blue whale satellite tracking data and 13 years of fin whale data to characterize their movement persistence, with higher move persistence values representing more directional movement and lower move persistence values representing less directional movement. Models were evaluated against a range of physical and biological environmental predictors to identify significant correlates of low move persistence (i.e., presumed intensified foraging behavior). We then used data from a subset of sensor-equipped tags that monitored vertical behavior (e.g., dive and feeding), in addition to movement, to test the relationship between vertical behavior and movement persistence.

Argos satellite telemetry is used globally to track terrestrial and aquatic megafauna, yet the accuracy of this system has been described empirically only for a limited number of species. We used Argos-linked archival tags with Fastloc GPS deployed on free-ranging sperm (Physeter macrocephalus), blue (Balaenoptera musculus), and fin (B. physalus) whales to derive empirical estimates of Argos location errors for these species, examine possible behavior-related differences, and test the effect of incorporating species-specific error parameters on performance of a commonly used movement model.

We conducted 18 aerial surveys in the marine waters around San Clemente Island, California, from October 2008 to July 2013, to obtain both observations of marine mammal behavior and data suitable for developing marine mammal density estimates. The primary platform used was a Partenavia P68-C or P68-OBS (glass-nosed) high-wing, twin-engine airplane. Density and abundance estimates were made using line-transect methods and the software DISTANCE 6.0.

We report 20 photo-documented sightings of a blue/fin whale hybrid between 2004 and 2020, in its wintering and summering ranges in the Gulf of California, Mexico, and southern California, USA, respectively. The whale was confirmed to be a hybrid by genetic testing using a reference dataset of non-hybrid blue and fin whales. It was also tracked by satellite for 28 days in 2015, showing its feeding range extended to the Big Sur area of central California. Information is presented to assist in field identification of blue/fin whale hybrids.