Bottlenose dolphins are a common sight at Outer Banks beaches. On any calm day throughout the summer, dolphins can be seen traveling along the oceanfront, feeding, or playing in the waves. Dolphin watching is also a growing industry in the Roanoke Sound, with at least six eco-tour boats ready to take eager customers out on the water during the summer months to see these charismatic animals.
Researchers of the Outer Banks Center for Dolphin Research, a local nonprofit, travel out on the water to see the dolphins for a different reason. In our small outboard boat, we carry datasheets, tools for measuring water temperature and salinity, and a digital camera with a telephoto zoom lens. As we travel on a standardized route throughout the sound, we search for groups of dolphins to learn about who they are, how many are here, what are they doing, and ultimately, how we can better protect them.
Dolphins are considered marine mammals and have lungs to breathe air, just as people do. If you are ever able to get a closer look at a dolphin as it surfaces to breathe through its blowhole, you may notice that its dorsal fin is not completely smooth. Some fins are completely covered in notches and nicks. These markings are typically natural, make each dolphin distinctive, and are the key to learning about the lives of the dolphins.
We use a technique known as photo-identification to study the dolphins in the Roanoke Sound. Photo-identification involves taking pictures of the dorsal fin of each dolphin and matching the fins to a catalog, which allows us to track individuals over time. We also record information about where the dolphin groups are sighted, behaviors that we observe, and water temperature and salinity for each sighting to learn more about how the dolphins are using the sound.
Our long-term photo-identification research began in 2008. Since that time, we have documented more than 900 dolphins in the Roanoke Sound. A small number of these dolphins have been “frequent visitors” to the sound every summer. One very distinctive dolphin within this group was named Onion for the markings on his fin that resemble an onion bulb.
Over time, many of the dolphins have received names, such as Fatlip, Scarlet, Sequoia, Skylar, and Rake. Each summer, we use photo-identification to document these dolphins, known as Onion’s group, and any new dolphins in the sound.
Through collaborating with other researchers in North Carolina, we have learned that many of these dolphins are also sighted in the Beaufort, North Carolina area during the winter months. By trading notes, some dolphin such as Onion, have been tracked for more than 20 years.
As the warmer weather approaches, we anticipate swimming in the ocean, longer beach days, and the return of the dolphins to Roanoke Sound! And if you take a closer look, you might notice Onion from the deck of your boat or at your favorite beach!