Six Reasons Why You Should Not Swim with Wild Spinner Dolphins

September 28, 2021

Would you swim with wild spinner dolphins if you knew that they were trying to sleep?

Feature Story |

Pacific Islands

Swimmers and boats that come to visit wild spinner dolphins close to shore during the day could be disturbing their rest and potentially harming them. Wild spinner dolphins feed off-shore at night and return to sheltered bays and coastlines during the day to rest, socialize, tend to their young, and avoid predators. Any energy used towards responding to human activity—even if they appear to just be curious and enjoy the interaction—is energy not being used for these behaviors that are critical for survival. When their rest is interrupted, especially if it happens many times in a day, it can affect their health and well-being.
Swimming with resting spinner dolphins may constitute "harassment" under the Marine Mammal Protection Act. Any act of pursuit, torment, or annoyance that has the potential to disrupt a marine mammal's behavior is "harassment" under this Act and is, therefore, against the law. In addition, a new law in Hawaiʻi, effective October 28, 2021, prohibits swimming with, approaching, or remaining within 50 yards (45.7 meters) of a Hawaiian spinner dolphin (for persons, vessels, and objects), including approach by interception (86 FR 53819).

Photo courtesy: Julian Tyne, PhD.
Frequent close encounters with wild spinner dolphins, like swimming with or closely approaching spinner dolphins, can cause harm. Numerous studies found that close encounters with human activity can significantly disrupt spinner dolphins’ natural behavior. In some dolphin populations around the world, frequent close interactions with humans have been linked to biologically significant impacts, such as habitat abandonment, reduced female reproductive success, impeded activity and energy budgeting, and increased vigilance.
Although spinner dolphins may not appear to be sleeping when you see them in near-shore waters, they often are. Spinner dolphins have to move and breathe while resting and therefore swim slowly and occasionally surface for air while allowing half their brain to sleep at a time. It is important to stay back and give them enough space (at least 50 yards/45 meters) and not swim with them so that they can get enough sleep to survive.
If spinner dolphins are regularly disturbed while in their nearshore resting habitat, they may be forced to move to another location that's less protected, putting themselves at risk from predators like sharks. They may also be forced to use more energy to reach this location–energy that would otherwise be used to breed, nurse, and take care of their young. Hawaiian spinner dolphins choose certain sheltered, sandy bottom areas to rest because they are close to their feeding sites and the white sand background makes it easier for them to see predators.
Wild dolphins must maintain natural behaviors to thrive in the wild. The wild dolphins you encounter are not trained dolphins in an aquarium. Although dolphins may seem curious, many of their behaviors are often misinterpreted as “friendly” when they actually are, in fact, signs of disturbance or aggression. If a dolphin approaches you in the water, do not engage, pursue, or otherwise interact with the dolphin, and take immediate steps to move away.