The Outer Banks Center for Dolphin Research (OBXCDR) has begun our spring research season, studying the bottlenose dolphins in Roanoke Sound! As the sound waters warm, more dolphins will move into the sound through Oregon Inlet, in search of fish and calm shallow waters for their calves. The OBXCDR is a volunteer-based organization; every spring our trained volunteers assist aboard research surveys to search for dolphins, photograph the dorsal fins, and record key information about the dolphin groups. Especially during the summer, our volunteers may spend long hot days out on the water to collect this information. People delight in seeing wild dolphins, but why do we study them?
One of the most important reasons to study dolphins is for their role as indicators of environmental health. Monitoring changes in the dolphins can teach us about the health of our marine environment. Especially in the Outer Banks, a healthy marine environment is critical to our local economy. There are several traits that make dolphins good indicators:
1) Dolphins live for long periods of time.
Male bottlenose dolphins are known to live into their forties, and females may live into their fifties. Long-term sighting histories of dolphins let us estimate their ages. One of our oldest known males, Onion, has been sighted since the early nineties suggesting he is at least 39 years old! The teeth of stranded dolphins can also give us hints about their age; “Moe,” the newest dolphin skeletal display at Jennette’s Pier in Nags Head, had teeth that were worn down almost completely to his gum line when he stranded, a sign of age in dolphins. Since dolphins live for many years, signs of environmental change are visible in their ranging patterns and habitat use.
2) Dolphins are top predators.
Animals at the top of the food chain are easily influenced by changes lower down the chain. Dolphins may hunt different fish or change their habitat when their food source changes. Since dolphins also eat many fish that people eat (such as drum and croaker), a healthy dolphin population could signal a healthy fish population as well.
3) Dolphins store environmental toxins in their blubber over time.
In biology class, many of us have learned the term, “bioaccumulation.” In essence, this means that chemicals in the environment are transferred up the food chain. As top predators, dolphins store these chemicals in their blubber. Just as with people, high contaminant loads in the body can make dolphins sick. Toxins are not always anthropogenic either; red tides caused by dinoflagellate algae can also affect dolphins, fish, and other marine species. Signs of disease in the dolphins can alert us to dangers in our marine environment on which many of our livelihoods depend.
The efforts of our long-term study of the Outer Banks dolphins aim to learn more about our local dolphin population and the health of our marine environment. Even though we speak different languages, dolphins tell us important information about the waters we share. To make these waters healthier and safer for people and dolphins follow these tips: Dispose of your trash in designated areas, refrain from feeding wild dolphins, recycle used fishing line, and report all marine mammal strandings to the local stranding response network at (252) 455-9654. You could also become an OBXCDR volunteer; the hot, long days out on the water that are swiftly approaching could never compare to the continued excitement on our survey boat when we sight our first group of dolphins for the day!