By Jessica Taylor | Correspondent
As 2021 draws to a close and we plan for the new year ahead, I think about the discoveries we have made about the Outer Banks dolphins over the years and how far we have come in our quest to learn more about them.
The Outer Banks Center for Dolphin Research, a 501 c(3) nonprofit, will turn 14 years old this coming spring. We have discovered that it’s astonishing all we can learn about a dolphin’s life as it surfaces to breathe. When a dolphin breaks the surface of the water and its dorsal fin becomes visible, a brief glimpse can teach us about its identity, habitat use, health, behavior, and even who its best friends may be.
Through many brief glimpses over the years, we have made some exciting discoveries about the Outer Banks dolphins.
When I first began studying the Outer Banks dolphins in 2007 as a naturalist on the Nags Head Dolphin Watch, I became adept at recognizing the familiar fins of Onion, Fatlip, Rake, and Skylar, some of our most commonly seen dolphins in the sound.
Over time, dolphins acquire nicks and notches on their dorsal fins, making them individually distinct. The Outer Banks Center for Dolphin Research uses a technique known as photo-identification to study the dolphins, in which we photograph each dolphin’s dorsal fin, catalog the images, and compile a long-term sighting history for each dolphin in the sound.
Over the past 14 years, we have constructed sighting histories for Onion, Fatlip, and nearly 1,100 other dolphins. If you take a trip out on a local dolphin watch next summer, you are likely to see one of the members of “Onion’s group,” a small community of dolphins that consistently return to the Outer Banks every summer. The group is named after Onion, who is one of the most distinctive dolphins in the area.
Through comparing notes with researchers further south, we learned that Onion’s group frequents the central North Carolina coast during the winter. As time goes on, the group has appeared to grow, although we are likely just learning that more and more of our dolphins exhibit this seasonal movement pattern of spending their summers in the Outer Banks sounds and winters in the coastal waters of central North Carolina.
Most of the dolphins we see in the sound seem to be visitors to the sound, perhaps briefly stopping to check out the fish menu, then continuing on their way. However, scientists have noticed that as the climate warms, many marine species have ventured further north, drawn to unconventionally warm waters and potential food sources. Indeed, as I write this in late December, it is 60 degrees outside.
We would therefore expect dolphins to venture further north too, however, after years of comparing to northern photo-id catalogs, we have found that Onion’s group does not seem to travel further north than southern Virginia (so far). This important information teaches us more about the movement and ranging patterns of their stock or management unit which is useful to environmental managers for making conservation plans to best protect the dolphins.
If you have traveled to other areas along the East Coast, you may find that the Outer Banks hosts a relatively pristine marine environment, free from significant coastal development that occurs in other places. Coastal development can impact the health of the environment if not closely monitored, but there are clues that scientists can use to gauge how healthy an environment may be.
Dolphins are known to be important indicators of environmental health and provide early warning signs of problems in marine and estuarine ecosystems. Pollution can be visible through the health and presence of the local dolphin community. When a dolphin surfaces, not only is its dorsal fin visible but any skin diseases are observable as well. Skin disease in dolphins can be related to environmental stressors such as cold water, fresh water, or pollution. Over the years, we have documented at least six different type of skin diseases on dolphins in the area.
We are currently studying the relationship between the dolphins’ skin diseases and environmental factors as dolphins may become stressed by cold fresh water, but the question remains as to whether any of these skin diseases may be related to pollution. Luckily, the fact that we continue to see many healthy dolphins in the sound year after year leads us to believe that the dolphins and the sound environment are likely in good health.
In 2007, we knew there were lots of dolphin in Roanoke Sound but we did not know why? Why was the sound a special place for the dolphins and special enough to return year after year? Why not just stay out in the ocean? We still wonder this question after 14 years of research, but we are getting closer to discovering answers.
Over the years, spatial analyses have shown us that dolphins like to use the sound for feeding, playing, and traveling activity, and particular areas are popular for certain activities. For example, playing is common near Nags Head but feeding and eating is more likely to be seen closer to Oregon Inlet. We also see many mom and calf pairs in the sound which tells us that the sound is also an important nursery habitat for the dolphins.
It’s possible that one of the most important aspects of the sound may be the food. A significant and predictable food source would be essential to mom and calf pairs, in particular, as females would benefit from having an abundant food supply in the area while she nurses her calf. In the future, we hope to learn more about how the dolphin movements relate to movements of their prey to gain more insight into this important ecological relationship.
In the past 14 years, all of our new discoveries and new questions would not have been possible without our volunteers, board members, interns, colleagues, and foundations that have believed in our mission and supported us by dedicating long days out on the boat in the hot sun, spending even longer days at a computer analyzing dorsal fins, or entrusting us with funds to build our research program and public outreach campaigns to promote the conservation of these amazing animals.
In 2022, I hope that we discover even more answers about the Outer Banks dolphins and inspire others to take an active role in their conservation. It is exciting to contemplate the new discoveries that may come in 2022! And when you do catch a glimpse of a dolphin this year, think about all of mysteries that glimpse could unravel!