Every Wednesday, interns from the University of South Carolina Beaufort board research vessel Spartina for a dolphin survey.
A telephoto lens and a quick trigger finger aim to capture the dorsal fin of Atlantic Bottlenose dolphins (not porpoises) in the May River. Each dorsal fin is unique to the individual like a fingerprint. Interns in Dr. Eric Montie’s Bioaccoustics Lab have a catalog of permanent resident dolphins in Beaufort County. Fifteen passengers also join in the search to observe the interns collecting data and get an overview of the purpose of the research being conducted in the May River.
Listening to the Fish
Did you know three data recorders in the May River record fish vocalizations every 20 minutes for two-minute sound bites over a three-month interval…and have for the past three years? These data recorders also record your boat as it passes by.
One intern is studying the effect of boat noise on fish vocalizations. When passengers hear the fish sounds recorded by the lab, they are surprised that fish make so much noise. These fish are red drum, black drum, silver perch, oyster toadfish and spotted sea trout. All of these fish have a swim bladder and specialized muscles that make sound as they strike this air-filled sac—just like a drum! Each species picks different months to communicate, although some overlap. They usually use the sound to attract mates to spawn…generally at dusk.
When the vocalizations are heard, students can determine abundance and spawning intervals. This air-filled swim bladder is also the reason your fish finder can detect fish. The air conserved in the swim bladder changes the sound path emitted and reflects energy back. The fish finder detects this reflected energy and converts it into fish images on the screen.
What Does This Have to Do with Dolphins?
As much as I would like to think that the dolphins are here in Beaufort County to be close to us, this is not the case. They are here for their food which is thriving in the salt marsh estuary.
It is interesting to note that when dolphin whistles are recorded in the background, the fish become very quiet. Hmmmm, why would a fish not want a dolphin to hear it? You got it! Dolphins eat fish, of course. Dolphins hunt with sight and see very well, focusing their vision in air and in water—but they can’t see through murky water, so they hear their food, too! One fish that is vocal throughout the year is the oyster toadfish. Nothing really wants to eat him, so he can be as loud as he wants. Dolphins in the May also use echolocation to find food in the dark. They use a method similar to your fish finder, using sound waves to detect the air-filled bladders of fish.
How Is This Beneficial?
The interns are usually in the lab, going through sound files that produce an image on the screen. It is easier to determine the species of fish by observing the sound frequency image that corresponds to the sound produced rather than listening to each recording.
It is important to support this research, relating fish populations to the health of the May River. Bluffton is the fastest growing city in South Carolina, and this rapid development will have an effect on the salt marsh estuary. With the empirical data the interns are collecting, we will have a solid prediction for what is to come and time to consider what action may be taken to conserve our natural resources. Without the fish, the dolphins will not stick around.
I support this research by donating 25% of the tour ticket price to Dr. Montie’s lab. Interns are usually unpaid, but their work is incredibly important. The data recorders are heavy and tedious and the pluff mud is treacherous. The lab is not exhilarating, but the work is essential. They are gaining knowledge, but they have to eat too!
Research vs Sightseeing Tour
It is always fun to see dolphins. I never tire of seeing them. These are all Atlantic Bottlenose dolphins, scientific name: Tursiops, truncatus. A porpoise would be a very rare site in this area.
But do you know why feeding dolphins was outlawed in 1992? Do you know where dolphins get fresh water to hydrate? Do you know how long they gestate and how long before they wean their calves? Where is the hair on a dolphin? How do you tell the difference between male and female dolphins? Did you know that sound does not come out of a dolphin’s mouth?
Learn Flipper’s secrets by joining us for some scientific enlightenment! To reserve your seat, contact Spartina Charters at (843) 338-2716 or book online at SpartinaCharters.com.
Meet The Crew
Aga is a graduate of the University of Gdánsk in Poland, with a master’s degree in Marine Biology. She studied dolphins in the Mediterranean Sea. Same species we have here, just a different population.
Somers is a graduate student at the University of Miami completing an internship in Montie’s Lab. Prior to graduate school, she trained dolphins at a Navy base in Georgia. She has a lot to add when speaking about behavior.
They all report to Dr. Montie, who earned his doctorate in Marine Biology from Woods Hole Oceanographic Institution, MIT (Massachusetts Institution of Technology) and is a tenured professor at the University of South Carolina Beaufort Campus.
And Captain Amber Kuehn—that’s me. My master’s degree is in Marine Biology from NOVA Southeastern University Oceanographic Center. I manage the HHI Sea Turtle Protection Project, but I know a thing or two about dolphins, as well.
Written by Amber Hester Kuehn with photos courtesy of Amber Hester Kuehn.