We recently encountered a group of approximately 50 Risso’s dolphins (Grampus griseus) while conducting a photo-ID and biopsy survey along the continental shelf break in Onslow Bay, NC. Risso’s dolphins are characteristic animals of the shelf break along the U.S. east coast, but we rarely see them in Onslow Bay. When we do find them they are usually moving so quickly that it’s difficult to obtain photo-ID images, let alone biopsy samples. This sighting was particularly interesting because this group of Risso’s was uncharacteristically approachable and included a number of individuals with distinctive dorsal fins. We collected five biopsy samples and about 600 photo-ID images. A subset of these images will be added to our Onslow Bay photo-ID catalog curated at the Duke Marine Lab. Genetic analyses of the biopsy samples along with the photo-identification images will address questions of social structure and residency patterns of Risso’s dolphins off our coast.
