PROJECTS

Long-term passive acoustic monitoring has been conducted across four U.S. Navy operational areas along the western North Atlantic margin to characterize ambient sound levels and anthropogenic acoustic activity. Arranged geographically from north to south, these include Norfolk Canyon within the Virginia Capes Range Complex, Cape Hatteras within the Virginia Capes Range Complex, Onslow Bay within the Cherry Point Operating Area, and the Jacksonville Range Complex in the South Atlantic Bight. Acoustic data were collected using High-frequency Acoustic Recording Packages (HARPs; Wiggins & Hildebrand 2007), seafloor-mounted autonomous recorders designed to continuously sample the underwater acoustic environment over extended periods. Across all four regions, HARPs were deployed across shelf and slope habitats to capture multi-year records of ambient and anthropogenic sound sources.

The U.S. Navy’s Jacksonville Range Complex (JAX) is located in the South Atlantic Bight offshore northeastern Florida and southeastern Georgia. From 2009 to 2020, passive acoustic monitoring was conducted using High-frequency Acoustic Recording Packages (HARPs) deployed across a depth gradient spanning the continental shelf and slope. Three sites were located on the shallow shelf (A–C; approximately 40–90 m), and one site was located on the continental slope (D; approximately 730–800 m). These long-term acoustic data provide a comprehensive assessment of marine mammal occurrence and ambient sound conditions across the region.

From 2007 to2013,acomprehensive acoustic monitoring effort was conducted within the boundaries of the Onslow Bay study area to study marine mammal presence and ambient noise levels. The objective was to characterize the vocalizations of marine mammal species in the area, identify their seasonal presence patterns, and assess the potential impacts of naval operations on these species. This report presents the findings from the analysis of data collected using High-frequency Acoustic Recording Packages (HARPs; (Wiggins & Hildebrand 2007)), which were strategically deployed within the Onslow Bay study area across a shelf-to-slope gradient.

From 2012 to 2020, a comprehensive acoustic monitoring effort was conducted within the boundaries of the Virginia Capes Range Complex to study marine mammal presence and ambient noise levels. The objective was to characterize the vocalizations of marine mammal species in the area, identify their seasonal presence patterns, and assess the potential impacts of naval operations on these species. This report presents the findings from the analysis of data collected using 12 High-frequency Acoustic Recording Packages (HARPs; Wiggins & Hildebrand 2007), which were strategically deployed offshore from Cape Hatteras within the southern portion of the Virginia Capes Range Complex (Figure 1 & Table 1).

From 2014 to2021, a comprehensive acoustic monitoring effort was conducted within the boundaries of the Virginia Capes Range Complex to study marine mammal presence and ambient noise levels. The objective was to characterize the vocalizations of marine mammal species in the area, identify their seasonal presence patterns, and assess the potential impacts of naval operations on these species. This report presents the findings from the analysis of data collected using six High-frequency Acoustic Recording Packages (HARPs; Wiggins & Hildebrand 2007), which were strategically deployed within the Virginia Capes Range Complex near Norfolk Canyon (Figure 1 & Table 1).

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between April and September 2009 in Jacksonville, FL, at Site A in 82 m. This HARP sampled at 200 kHz for 5 minutes of every 15 minutes and recorded usable data for 54 days between 2 April 2009 and 25 May 2009. Long-Term Spectral Averages (LTSAs) were created for one frequency band (1 kHz – 100 kHz) and scanned for odontocete vocalizations. Vocalizations of sperm whales and unidentified delphinids were detected in the data.

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.

Passive acoustic monitoring was conducted at a site in the US Navy’s Jacksonville Range Complex during 9 March – 26 August 2010. The site is located 50 nm east of the Florida coastline on the continental shelf. Acoustic data collected at this site provide information on the presence of marine mammals and naval sonar. High-frequency Acoustic Recording Packages (HARPs) recorded sounds between 10 Hz and 100 kHz with recording duty cycles of 5 minutes every 10 minutes. The data were divided into two frequency bands: (1) low frequencies, between 1 – 1000 Hz, and (2) mid frequencies, between 500 – 5000 Hz. These data were not analyzed for high frequency marine mammal sounds, such as the echolocation clicks of delphinids. Data were analyzed by scans of long-term spectral averages and spectrograms. High ambient noise levels, caused by instrument strumming and fluid flow at the sensor, were prevalent during this deployment and decreased detection ability for low-frequency sounds. Only one species of baleen whale—the humpback whale—was detected. Humpback non-song calls were detected during two days in March 2010. No blue whale, fin whale, Bryde’s whale, minke whale, North Atlantic right whale, or sei whale calls were detected in this deployment. Anthropogenic sound in the form of Mid-Frequency Active Sonar (MFA) was detected throughout this deployment. It was most common in late March 2010.

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 July and October 2012 in Onslow Bay at Site E in 914 m. This HARP sampled at 200 kHz for 5 minutes of every 10 minutes and recorded for 81 days between 14 July 2012 and 2 October 2012. 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, Blainville’s beaked whales, Cuvier’s beaked whales, Gervais’ 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 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.

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 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 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 April and September 2009 in Onslow Bay at Site A in 174 m. This HARP sampled at 200 kHz for 5 minutes of every 10 minutes and recorded for 107 days between 24 April 2009 and 9 August 2009. 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. Vocalizations of 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 May and November 2008 in Onslow Bay at Site B in 232 m. This HARP sampled at 200 kHz for 5 minutes of every 10 minutes and recorded for 103 days between 30 May 2008 and 10 September 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. Vocalizations of blue 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 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 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 February and July 2011 in the Jacksonville, FL, survey area at Site B in 37 m. This HARP sampled at 200 kHz for 5 minutes of every 15 minutes and recorded for 163 days between 2 February 2011 and 14 July 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 humpback whales and unidentified delphinids were detected in the data.

A High-frequency Acoustic Recording Package (HARP; Wiggins and Hildebrand 2007) was deployed between February and July 2011 in the Jacksonville, FL, survey area at Site A in 91 m. This HARP sampled at 200 kHz for 5 minutes of every 15 minutes and recorded for 164 days between 1 February 2011 and 14 July 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. Vocalizations of Risso’s dolphins and unidentified delphinids were detected in the data. Much of the low- and mid-frequency data were unusable, thus preventing detection of mysticete calls and mid-frequency active sonar.

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.

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.