US Navy

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Marine Species Monitoring

Mid-Atlantic Offshore Cetacean Study

Introduction & Objectives

The United States (U.S.) Navy routinely conducts training and testing activities in the Virginia Capes (VACAPES) Operating Area (OPAREA) off the mid-Atlantic. 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 United States based on 3 years of surveys conducted by the Cetacean and Turtle Assessment Program (CETAP 1982). More recent, still on-going, broad-scale surveys by the National Marine Fisheries Service, including the Atlantic Marine Assessment Program for Protected Species (AMAPPS) and marine mammal stock-assessment reports (Waring et al. 2016) show the same pattern.

Cetacean species known to be common in some seasons in outer shelf and slope waters include both baleen whales and odontocetes, including fin whales (Balaenoptera physalus), sei whales (Balaenoptera borealis), minke whales (Balaenoptera acutorostrata), humpback whales, sperm whales (Physeter macrocephalus), beaked whales (Ziphius cavirostris, Mesoplodon spp.), long-finned and short-finned pilot whales (Globicephala melas and Globicephala macrorhynchus), Risso’s dolphins (Grampus griseus), bottlenose dolphins (Tursiops truncatus), short-beaked common dolphins (Delphinus delphis), Atlantic white-sided dolphins (Lagenorhynchus acutus), Atlantic spotted dolphins (Stenella frontalis), and striped dolphins (Stenella coeruleoalba) (CETAP 1982; Kenney and Winn 1986,Waring et al. 2016; NEFSC 2012, 2013). Fin, sei, and sperm whales are all listed as endangered under the U.S. Endangered Species Act.

Aerial surveys by University of North Carolina Wilmington (UNCW) (McAlarney  et al. 2016), the Virginia Aquarium (VAQ) (Mallette et al 2016), and HDR (DoN 2013); vessel surveys by HDR (Aschettino et al. 2016); and passive acoustic monitoring (PAM) by Duke University and Scripps Institute of Oceanography (Hodge et al. 2016), suggest that baleen whales, sperm whales, and other deep diving odontocetes may be more common to the area of interest than has been previously known, and that the outer shelf area off Virginia in the VACAPES OPAREA would be a good location for more focused research.

Taking into consideration the multiple intermediate scientific objectives in the U.S. Navy’s Strategic Planning Process, 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 near the continental shelf break within the VACAPES OPAREA, and how does occurrence fluctuate seasonally?

•What is the baseline ecology and behavior 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, years?

•What is the seasonal extent of cetacean movements within and around 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?

Technical Approach

In order to address the gaps in focused research for offshore waters in the VACAPES OPAREA, a combination of techniques are being used, including: (1) photo-ID and behavioral data collection to provide baseline assessments of animal movement patterns, site fidelity, habitat use, life history, and behavior; (2) biopsy sampling for incorporation into existing genetic studies (where opportunities exist) to identify individuals, determine foraging patterns, and assist in delineating stock boundaries; and (3) satellite-linked tagging techniques to provide information on residency patterns and habitat use across intermediate time scales (weeks to months). Following nearly 5 years of data collection using these methods, an additional tag type will soon be incorporated to better describe habitat use on a finer scale.  Digital Acoustic Recording Tags (DTAG) will be deployed on sperm whales in order to examine their behavioral ecology, acoustic cue rates, and diving ecology.

Residency and movement patterns are of particular interest given the potential for repeated exposure to U.S. Navy training and testing activities known to occur within the area. Tagging efforts will provide longer-term movement patterns to identify extent of overlap with offshore training and testing activities including nearby offshore gunnery exercises (GUNEX), missile exercises (MISSILEX), and Anti-Submarine Warfare (ASW) exercises typically conducted within the VACAPES OPAREA. Given the duration of the tag attachments and experience from previous tagging studies in waters off Cape Hatteras, North Carolina, we would expect the potential to track tagged animals to OPAREAS outside of VACAPES, including the Cherry Point OPAREA to the south and the Atlantic City OPAREA to the north. Satellite tagging is conducted using a Wildlife Computers Smart Position and Temperature (SPOT6) Argos-linked satellite tags as well as SPLASH and SPLASH-F variations that also record diving behavior and integrate Fastloc GPS (Wildtrack Telemetry Systems Ltd). All tags are in the Low-Impact Minimally-Percutaneous External-electronics Transmitter (LIMPET) configuration.

The DTAG will record the underwater movements of whales over short durations (hours to day). In addition to measuring depth, tags can record valuable data such as three-dimensional acceleration, bearing, pitch, roll, and oceanographic data, and also provide a hydrophone that records sound produced by the whale during foraging and social bouts as well as sound within its surrounding environment. Fine-scale tags will be paired with LIMPET-configured Mk10 SPLASH tags whenever possible, as a means to better define longer duration movement and dive behavior as the individuals utilize the AFTT. The continuation of this long-term study with the addition of these high-resolution tags will provide valuable insights on underwater animal behavior and potential impacts from anthropogenic effects.

Visual surveys, tagging, and biopsy sampling are conducted from mid-size offshore charter vessels as weather allows with a focus on even coverage of the study area throughout all seasons.

Progress & Results

Fifty-seven surveys have been completed between April 2015 and June 2020. Initially eight surveys were conducted as a pilot study as part of the Mid-Atlantic Humpback Whale Monitoring Project, and the remaining 49 as the current project. During the 57 surveys there were 939 sightings of 20 cetacean species recorded (including sightings over the continental shelf en route to the study area). Priority species encountered were fin whales (n=71), sperm whales (n=44), humpback whales (n=16), minke whales (n=7), Sowerby’s beaked whales (n=3), Cuvier’s beaked whales (n=3), True’s beaked whales (n=2), North Atlantic right whales (n=2),  pygmy sperm whales (n=2), blue whale (n=1), dwarf sperm whales (n=1), and sei whales (n=1). The species most often sighted were pilot whales (Globicephala sp.) (n=306), bottlenose dolphins (n=198), and short-beaked common dolphins (n=139). Additional observations of Atlantic spotted dolphins (n=29), Risso’s dolphins (n=32), striped dolphins (n=9), and harbor porpoise (n=2) were also recorded.

Photo-ID catalogs have been created for sperm whales (95 identified individuals), fin whales (90 identified individuals), minke whales (10 identified individuals), sei whales (2 identified individuals), Sowerby’s beaked whales (14 identified individuals), True’s beaked whales (2 identified individuals), and Cuvier’s beaked whales (2 identified individuals), and pilot whales (93 identified individuals; created by Danielle Waples from Duke University). A total of thirty-three biopsy samples have been collected, 8 from fin whales, 23 from sperm whales, and 2 from humpback whales. Forty-five LIMPET-configured satellite-monitored tags (SPOT6, SPLASH, and SPLASH-F) have been deployed to date on fin whales (n=16),sperm whales (n=28), and Sowerby’s beaked whales (n=1). Preliminary tag results suggest site-fidelity to the Norfolk Canyon by sperm whales over periods of weeks, while fin whales show a mix of both minimal and extreme movement patterns within and outside of the study area. Continuing data collection efforts, as well as further analyses of satellite tag data, including switching state space modeling, will provide more detail on foraging ecology and habitat use in this region.

Surveys are on-going and are currently funded through 2021. Tagging will focus on sperm whales with the addition of DTags although satellite-linked tags will still be deployed opportunistically of fin ann beaked whales.

Blog Posts, Presentations, and Publications
Sowerby's beaked whales encountered at Norfolk Canyon
Sowerby's beaked whale tagged offshore of Virginia
Sperm whales tagged off Virginia Beach

Cetacean occurrence off Virginia's outer continental shelf (SMM 2017)
Re-sight occurrence and frequency of satellite tagged humpback, fin, and sperm whales off Virginia, USA (SMM 2019)
Diving Behavior and Movements of a Sowerby’s Beaked Whale Tagged near Norfolk Canyon (SMM 2019)

Blue whale (Balaenoptera musculus) sightings off the coast of Virginia (Marine Biodiversity Records, 2020)