Dolphins on the Beach

Dolphins are typically thought of as deep-diving marine mammals, reaching depths of 900 feet and holding their breath for up to 12 minutes while searching for food. But scientists have discovered a group of dolphins off the coast of Hilton Head, South Carolina that have an odd, yet efficient feeding strategy that brings them to the shore to earn a belly full of fish.

Swimming along the Atlantic shore, groups of bottlenose dolphins work together to simultaneously rush from the water onto exposed mud flats. Flailing their large muscular bodies and tail flukes in uncharacteristically graceless movements, the forward thrust of water rushes schools of fish into their mouths. With mud flying, water splashing and opportunistic seagulls screeching, this is a frenzied yet productive hunting method. Afterwards, the dolphins shimmy their way back to the water, repeating this feeding pattern until their hunger is satisfied.

Termed strand-feeding, this behavior is shocking at first sight, because whales and dolphins usually beach themselves only when they’re sick or injured. But scientists have concluded that this is an efficient way for these mammals to feed, and have found some populations off the coasts of Florida and Portugal that also share in this unusual behavior. However, they are unable to explain exactly why or how these mammals developed this behavior.

Dr. Diana Reiss, a Rutgers University researcher in dolphin communication and cognition, emphasizes the critical importance of studying the mammals’ behavior. “The more we know about dolphins’ social lives and their specific environments,“she says,” the better equipped we will be to protect and preserve their diminishing coastal habitats.”

During 1987 to 1988, a viral epidemic claimed the lives of more than 750 coastal migrating dolphins, but spared the resident animals. While researchers are still unable to explain why only a certain population was affected, they gained a better understanding of disease transmission and interactions among different groups.

Through studies of these land-feeding dolphins, scientists hope to emphasize the importance of conservation of all Atlantic bottlenose dolphins and their coastal ecosystems. Dr. David St. Aubin of the Mystic Marinelife Aquarium in Mystic, Connecticut is working with scientists in Hilton Head to better understand this odd feeding pattern. “This information may provide critical insight into environmental impacts and how one group affects the other,” he says.