PROJECTS

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from April 2020 to 2021 to detect marine mammal and anthropogenic sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at four locations: two west of San Clemente Island (1,300 m depth, site E and 1,100 m depth, site H) and two southwest of San Clemente Island (1,300 m depth, site N and 1,200 m depth, site U). With the offshore expansion of the SOCAL range, future noise monitoring will be improved by the deployment of a recorder west of San Nicolas Island (site SN). This new site will replace site U, which is located in the Mexican Exclusive Economic Zone where instrument deployment is difficult.

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from November 2018 to May 2020 to detect marine mammal and anthropogenic sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at four locations: two west of San Clemente Island (1,300 m depth, site E and 1,000 m depth, site H) and two southwest of San Clemente Island (1,250 m depth, site N and 1,200 m depth, site U).

Over the past decade, underwater explosive sounds have been recorded in the U.S. Navy’s Southern California Range Complex. The majority of these events are related to the use of seal bombs by the fishing industry as a deterrent to depredation. In addition, a smaller number of explosions are from Navy ordnance use during training exercises, especially in the Southern California Anti-submarine Warfare (ASW) Range (SOAR).

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from July 2018 to May 2019 to detect marine mammal and anthropogenic sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at three locations: two west of San Clemente Island (1,300 m depth, site E and 1,000 m depth, site H) and one southwest of San Clemente Island (1,250 m depth, site N).

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from March 2017 to July 2018 to detect marine mammal and anthropogenic sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at three locations: northwest of San Clemente Island (1,300 m depth, site E), west of San Clemente Island (1,000 m depth, site H), and southwest of San Clemente Island (1,200 m depth, site N). In addition, an array of 9 HARPs, sampling at 20 kHz, was deployed in the San Diego Trough during the fall of 2017 to track baleen whale calls. One HARP from this array was analyzed for this report (1,051 m depth, site HP). While a typical southern California marine mammal assemblage is consistently detected in these recordings (Hildebrand et al., 2012), only a select sub-set of species including blue whales, fin whales, and beaked whales were analyzed for this report. The low-frequency ambient soundscape and the presence of Mid-Frequency Active (MFA) sonar and explosions were also analyzed.

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 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).

Underwater ambient and anthropogenic sounds were recorded over 5 years in the U.S. Navy’s Southern California Range Complex, at three sites ranging from ~500 m to 1300 m deep from June 2012 to June 2017. This report summarizes low-frequency ambient soundscape and anthropogenic sounds from mid-frequency active sonar and explosions over the 5-year period. Long-term average ambient sound pressure levels were highest at the shallow near-shore site (P) and lowest at the site (H) in the western San Nicolas Basin, likely related to nearby vessel activity.

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.

Fin whale song patterns were analyzed from High-frequency Acoustic Recording Package (HARP) data collected at four sites in the Southern California Bight collected between 2005 and 2014. The sites were chosen to cover both inshore (sites P and Q) and offshore (sites C and H) areas as well as southerly and northerly extent of the Bight. A single year of data, from September 2009 to September 2010, was analyzed from all sites and additional years of data were analyzed from two sites (H and C). Two days per months were selected to analyze song patterns over time. During the selected day, the start time of each 20 Hz pulse in a sequence was picked from a spectrogram and saved to a spreadsheet. After all the 20 Hz pulse start times were picked in a day, IPIs were calculated for each picked sequence

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from April 2016 to June 2017 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 (1200 m depth, site N), and west of La Jolla, California (500 m depth, site P). In addition, an array of 9 HARPs was deployed in the San Diego Trough, during the fall of 2017, to track baleen whale calls.

Passive acoustic monitoring (PAM) provides extensive datasets to examine the behavioral response of cetaceans to anthropogenic sound. Broadband passive acoustic monitoring permits the recording of the full range of cetacean sounds as well as signals produced by the Navy and other anthropogenic sources. We have been collecting broadband 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. We present a progress report on the development of methods to investigat

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from June 2015 to April 2016 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 (1200 m depth, site N), and west of La Jolla, California (500 m depth, site P). Data analysis was performed using automated computer algorithms. Calls of two baleen whale species were detected: blue whale B calls and fin whale 20 Hz calls. Both species were present at all sites, but at site H blue whale B calls were most common and the fin whale acoustic index representative of 20 Hz calls was highest. Blue whale B calls were least common at site P while the fin whale acoustic index was lowest at site N. Blue whale B call detections peaked from August to November 2015 and very few

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.

Progress is reported on efforts to estimate the density of Cuvier’s beaked whales (Ziphius cavirostris), using passive acoustic monitoring data collected with Navy support at sites in the Southern California Bight. Two methods for estimating weekly densities of beaked whales are presented, one based on the number of echolocation clicks detected (click counting) and the other based on the presence of clicks during 1-min time bins indicating the presence of animal groups (group counting). The click-based method requires an estimate of mean click production rate, while the group-based method requires the proportion of 1-min bins a group is vocally active. These parameters are obtained from tagging and tracking data collected for Cuvier’s beaked whales in Southern California and other locations.

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex from July 2014 to May 2015 to detect marine mammal and anthropogenic sounds. Highfrequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz at three offshore locations: west of San Clemente Island (1,000 m depth, site H), west of Catalina Island (900 m depth, site M), and southwest of San Clemente Island (1,200 m depth, site N).

A new method was developed to provide better metrics for quantifying Mid-Frequency Active Sonar (MFAS) occurrence and levels, and was applied to passive acoustic monitoring data collected in the Southern California (SOCAL) Range Complex. MFAS signals are composed of both tones and frequency swept ‘pings’, often with multiple pings grouped closely in time as packets. These packets often occur repeatedly at intervals >20 s over periods of hours as wave train events with gaps between events >1 h. The new approach uses a higher received level packet detection threshold (130 dBpp re 1 µPa) than previous analyses, which limits the detection range to about 20 km, reducing the number of overall detections but also reducing the false detection rate.

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.

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 during March 2012 through December 2012 to detect the presence of marine mammal and anthropogenic sounds. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz with continuous temporal coverage at a site near Santa Barbara Island (site M), at a site west of San Clemente Island (site H), and a site southwest of San Clemente Island (site N).

Passive acoustic monitoring was conducted in the Navy’s Southern California Range Complex during May 2011 – March 2012 to detect the presence of marine mammal and anthropogenic sounds. Highfrequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz with nearly continuous temporal coverage at a site near Santa Barbara Island (site M) and at a site west of San Clemente Island (site H). Data analysis consisted of detection of sounds of interest by analyst scans of long-term spectral averages and spectrograms, and by automated computer algorithm detection when possible. Representative sounds are presented in this report, as well as details of the computer algorithms used to detect them.

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.