Introduction & Objectives

The U.S. Navy’s marine species monitoring program in the Atlantic began with a multi-disciplinary approach intended to provide information on the species composition, population identity, abundance, and baseline behavior of marine mammals and sea turtles present in range complexes along the U.S. Atlantic Coast. This “baseline monitoring” included visual aerial and vessel line transect surveys, as well as towed-array and archival passive acoustic monitoring conducted by a consortium of researchers from Duke University, University of North Carolina Wilmington, and Scripps Institute of Oceanography.  Initial work began in Onslow Bay, North Carolina in 2007 and subsequently expanded to include study areas off the coast of Jacksonville, Florida (2009), Cape Hatteras, North Carolina (2011), and Virginia Beach, Virginia (2012). In 2011, line transect vessel surveys in JAX transitioned into opportunistic vessel work supporting biopsy sampling, photo-identification, and satellite telemetry tagging efforts to complement the ongoing aerial surveys.

Although the original standardized line transect visual surveys and archival passive acoustic monitoring have been discontinued in the Atlantic Fleet Training and Testing (AFTT) OPAREAs, that foundational work has provided a robust baseline for several ongoing tagging and behavioral response projects (see Atlantic Behavioral Response Study, Mid-Atlantic Offshore Cetacean Monitoring, and Mid-Atlantic Nearshore & Mid-shelf Baleen Whale Monitoring). Nearly a decade of baseline monitoring within the Jacksonville OPAREA (2009-2018) has provided a very detailed seasonal picture of the occurrence, distribution and abundance of marine mammals and sea turtles in the region (Foley et al. 2019) and serves as the basis for monitoring work that resumed in 2021 following the construction of the Jacksonville Shallow Water Training Range (JSWTR) and installation of a dedicated passive acoustic marine mammal monitoring system (Marine Mammal Monitoring on Navy Ranges - M3R). Small vessel surveys are now being used to support development and calibration of detection and classification algorithms for the M3R system through visual species verifications, while photo-ID, biopsy sampling, and tagging are continuing to support ecological and demographic studies.

Technical Approach

The M3R program began in 2000, with the development of a system to use the bottom-mounted hydrophones of the U.S. Navy’s test and training ranges to detect, classify, localize, and monitor marine mammals in real-time by listening for their vocalizations. The M3R system is currently installed at JSWTR as well as the Atlantic Undersea Test and Evaluation Center (AUTEC), Southern California Tactical Training Range (SOAR), Pacific Missile Range Facility (PMRF), and Canadian Forces Maritime Experimental and Test Ranges Nanoose Range. The system is capable of nearly continuous archive data recording for collaborative studies on marine mammal behavior, distribution, abundance, foraging, and habitat use. JSWTR has 223 active hydrophones mounted at depths ranging from 35 to 355 meters over a span of 2,000 km² and currently employs three detector/classifiers: a Fast Fourier Transform (FFT)-based detector, a Class-Specific Support Vector Machine (CS-SVM) detector/classifier, and a Blainville’s beaked whale foraging click matched filter. The CS-SVM classifier currently has six classes at JSWTR: Blainville’s beaked whale foraging and buzz clicks, Cuvier’s beaked whale foraging and buzz clicks, sperm whale clicks, and “generalized dolphin” clicks.

Small vessel surveys are being used in coordination with the M3R team to verify species identifications to support development and refinement of region-specific detectors and classifiers. Shore-based analysts use the M3R system to direct the field team to the location of an acoustic detection who then visually verify the species and potentially collect other data such as photo identification and biopsy samples.  The focal species for these efforts are short-finned pilot whales, bottlenose dolphins, Atlantic spotted dolphins, Risso’s dolphins, and Rough-toothed dolphins, although other species are likely also present on the range based on previous visual and passive acoustic monitoring.

Progress & Results

Nineteen days of coordinated field effort across five sessions have been conducted from 2021 to 2023 resulting in over 90 visual verifications of four species - bottlenose dolphin, Atlantic spotted dolphin, Risso’s dolphin, and rough-toothed dolphin. Loggerhead sea turtles were also common.

An opportunistic monitoring trip was also conducted by the M3R team (no vessel field support) for three days in February 2022.  The focus of the trip was to record acoustic data for the development of a suite of North Atlantic right whale classifiers.  Broadband recordings of the northern portion of the range were taken continuously.  An M3R analyst monitored opportunistically for this species as well as any baleen whale that could be used as a confusion species when training the classifiers.  The goal is to deploy a suite of NARW classifiers, where confidence in positive results is increased by the number of classifiers in agreement. This is a strategy in reducing false positives for a rare event.

Biopsies have also been taken from bottlenose dolphins, and genetic variation between the coastal and pelagic ecotypes of bottlenose dolphins that occupy distinct habitats and engage in different patterns of diving behavior was investigated.