Their curved fins cut clean wakes in the glistening sea. Every so often, one of them spews a plume of water into the air, spritzing the gaggle of gulls teeming above.
People gather at the water’s edge and point at the spectacle. Everyone loves these Atlantic bottlenose dolphins; everyone wants to get closer to them. Suddenly, as if they could read the humans’ thoughts, these great silvery beings roll into the water and vanish. (Above photo by Rob Kaufman)
TITANS OF TIDEWATER
The Atlantic bottlenose dolphin (Tursiops truncatus) is a familiar resident in Lowcountry waters. Its domain is the Atlantic Ocean and its striated tributaries — the sounds, rivers, and creeks. This is a powerful toothed whale: adults are about 12 feet in length, weigh 500 pounds or more, and can swim more than 20 miles an hour underwater. They eat 24-40 pounds of small fish, squid, and crabs daily. They have a highly developed social network, and use this for hunting and self-defense.
Joana McIntyre’s book, “Mind in the Waters” (1979) celebrated the remarkable instincts and intelligence of dolphins. They are big, fast, toothy (more than 80 teeth), and strong-jawed. Their key weapon is their remarkable ability of echolocation — the use of sound to locate prey and each other, escape predators and boats, and make their way through murky, sediment-rich waters such as May River and Calibogue Sound.
Researchers at Sea World Marine Parks have determined that the head of the dolphin is nature’s perfect sound system. The animal produces an array of high frequency “clicks” that pass through its swollen “melon” (forehead). This is the speaker that sends out sounds. These reflect back to the dolphin, which receives them through its long lower jaw, the receiver, or more accurately: tuning fork. Sound waves migrate through the ear channels and travel to the brain, which translates the sonic pulses into images. Bats and several bird species also use echolocation to navigate and hunt insects in the dark.
AMAZING DOLPHIN BEHAVIORS
Our local dolphins have developed specialized and acrobatic methods of catching a seafood meal. In the late 1990s, Dr. Cara Gubbins identified these behaviors in “local” dolphins that do not migrate from the Hilton Head Island-Daufuskie Island-Bluffton drainage basin. Some of these behaviors have also been observed in waters near Charleston and by kindred dolphins in the Amazon River:
Bubble Streams: Several dolphins emit huge bursts of air through their blowhole to confuse and corral fish.
Slaphappy: If you see a dolphin slap its tail on the water, it is trying to stun and eat a fish.
Stranding: Local dolphins rush at a saltmarsh bank or steep-sloped beach, forcing fish ashore in a huge gush of water. The dolphin lies on it side and swallows fish, shrimp, and crabs in the draining water, and then slides back into the sea.
DOLPHINS’ ONE WEAKNESS
Maybe it’s that smile, the friendly looking upturn of the dolphin’s mouth. Or those “Flipper” movies and dolphin dancing shows for tourists. And the latest: “swim with a dolphin” experiences sold from Florida to Australia. Dolphins are wild, strong, sea predators, but their most common downfall is often their attraction to humans.
Beginning in the 1980s, “Feed the Dolphins” tours were big business on Hilton Head Island. But what’s good for business isn’t always best. Hundreds of people paid $3-$5 a head for the opportunity to hand a dead fish to a wild dolphin. The local dolphins, being highly instinctual and knowing a good deal when they tasted one, soon learned to follow the tour boats, begging handouts.
I remember the early 1980s photograph in The Island Packet showing a young boy leaning far out of a small boat. He had a fish in his mouth and a very large dolphin was rising out of the water to grab it. During this period, marine biologists with the S.C. Department of Natural Resources reported people feeding hot dogs, sandwiches, pretzels and beer to local dolphins. Observers also chronicled dolphins aggressively pursuing boats, being sliced by propellers, getting hooked by fishing line, and even injuring local swimmers.
In 1993, the National Marine Fisheries Service developed standards under the Marine Mammals Protection Act that outlawed feeding and harassing dolphins. Some locals complained about loss of income, then quickly rebranded as “Dolphin Watch” eco-tours.
The best way we can conserve these exquisite creatures is to observe them from afar, keep our hands off, and learn. Dolphins know best how to thrive in their secret places.