This project evolved from a multi-institutional monitoring program intended to provide information on the species composition, population identity, density, and baseline behavior of cetaceans present in Navy range complexes along the Atlantic coast. The program began in 2007, with 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, Cape Hatteras, North Carolina, and a recently added study area in the vicinity of Norfolk Canyon.
In Cape Hatteras, five years of surveys have provided information on the complex patterns of distribution and diversity of the marine mammals and sea turtles in this highly productive area. The current project builds on this past body of work and focuses on the distribution and ecology of several deep-diving odontocete species using digital acoustic tags (DTAGs), including: beaked (Ziphius cavirostris and Mesoplodon spp.); short-finned pilot (Globicephala macrorhynchus); and sperm whales (Physeter macrocephalus). To achieve a more robust picture of the medium-term movement, spatial use, and diving patterns of these and other odontocete cetaceans off Cape Hatteras, we incorporated a satellite-tagging component in 2014 with Cascadia Research Collective. In addition, we collect photo-ID images and biopsy samples during these tagging efforts, which provide information on genetics, population structure, foraging ecology, and reproductive hormone levels of the individuals.
Our fieldwork is concentrated along the shelf break off Cape Hatteras, NC, where we consistently encounter high densities of deep-diving odontocete species. When conditions permit, we extend our surveys into deeper, pelagic waters beyond the shelf break. Whenever possible, we obtain photographs of odontocete cetaceans for individual photo-identification; we also use these photographs to confirm species identification for each sighting. We employ remote biopsy sampling methods to collect small skin and blubber samples using a variety of crossbows, depending on the species and sampling distance. Biopsy samples are collected with specialized 2.5 cm stainless biopsy tips attached to a modified bolt, typically fired from the bow of the survey vessel. All of our sighting data are contributed to OBIS-SEAMAP.
We select well-marked animals in discrete groups of whales as focal animals for DTAGs; we do not tag whales in groups that included neonates. Prior to tagging the focal animal, we obtain photographs of all individuals in the group. The DTAG is a small, lightweight tag that is attached to whales with four silicon suction cups; the tags are deployed using a carbon-fiber pole. The DTAG is equipped with a pressure sensor, three-axis magnetometer and accelerometers that measure depth, heading, pitch, and roll. The tag contains two hydrophones that record stereo sound continuously at a sampling rate of 192 kHz. The package also includes a VHF tag that allows us to track tagged animals at the surface and facilitates re-location of the tag when it is released from the whale. Data are archived on the tag and later downloaded for calibration and analysis. We are able to control the length of tag deployments by programming the release mechanism prior to attachment.
We are also employing two types of Argos-linked satellite tags, a location-only Smart Position and Temperature (SPOT5) or a location-depth Mk10-A (Wildlife Computers, Redmond, Washington), both in the LIMPET configuration (Andrews et al. 2008). Tags are remotely deployed using a pneumatic projector, and attached with two surgical-grade titanium darts with backward-facing petals. The target area for all tags is the dorsal fin or the base of the fin. Two dart lengths are used depending on the species. Each tag type has a specific programming cycle depending on species, and location-depth tags are programmed to provide dive statistics (start and end time, maximum depth, and duration) for any dives that exceeded a species-specific depth threshold.
This project commenced in 2013 with visual surveys and associated photo ID and biopsy sampling, with tagging activities beginning in 2014, including both DTags and satellite-linked tags. A total of 42 surveys days covering over 2400km have been logged since the project began in 2013. Eight DTag deployments have been made on Cuvier’s beaked whales short-finned pilot whales, as well as 59 satellite tag deployments on four species of odontocetes through the 2015 field season. Satellite tags have been deployed on short-finned pilot whales, bottlenose dolphins, Cuvier’s beaked whales, and short-beaked common dolphins. Many of these tags also transmitted dive data (Wildlife Computers Mk10-A). This work is considered to be baseline data collection and will continue through 2016 at which point it will become the foundation for a new behavioral response study beginning in 2017.
Location: Cape Hatteras
Funding: FY13 - $250k, FY14 - $510k, FY15 - $520k, FY16 - $420k
Principal Investigator (Dtags)
Dr. Andy Read
Duke University Marine Lab
Marine Ecology Conservation group
Principle Investigator (sat tags)
Dr. Robin Baird
Cascadia Research Collective
Joel T. Bell
NAVFAC Atlantic - Environmental Conservation Marine Resources Section