The presence of people swimming messes up the dolphins’ natural sleep cycles, and this impacts their long-term health, GrindTV reports.
Disturbing dolphins while they are resting can affect their long-term health and the health of the population, said Ann Garrett, the assistant regional administrator of the National Marine Fisheries Service’s (NMFS) protected resources division for the Pacific Islands, per the Associated Press.
Spinner dolphins use near-shore areas for their resting grounds and often swim and jump among swimmers, surfers and boaters, so it’s no surprise they are popular with tourists and locals. And when they come close to shore, crowds of onlookers gather.
The dolphins are popular enough, in fact, that scores of dolphin-encounter businesses have capitalized on this, and reports say there are more than 200 of these businesses in Hawaii. Sometimes as many as 20 tour boats can be seen at a time, dropping off tourists carrying snorkel masks and floaties, to intermingle with the pods of dolphins when they come into shore.
Spinner dolphins are nocturnal hunters and need to rest after foraging for food all night, and scientists worry that the increased attention from tourists may be harming them, Mashable reports. This is why the National Oceanic and Atmospheric Administration is preparing to propose rules to protect the dolphins.
There’s a good chance the agency may ban swimming with the marine mammals or prohibit people from swimming in shallow bays while the dolphins are resting.
The agency plans to propose rules in June, Garrett said. More than 200 dolphin-related businesses operating within the state, as well as recreational swimmers and other ocean-goers may be affected by the regulations.
Claudia Merrill co-owns Dolphin Discoveries in Kailua-Kona, located on the Big Island. She said she would welcome some regulations, especially if rules would prevent swimming with dolphins when the creatures are resting from late morning to mid-afternoon.
She added that tour operators must be taught to watch for signs that the dolphins are settling into their resting state. One such sign is when a pod of dolphins synchronizes its dives and swims, Mashable reports.
The industry should, and can be sustainable, Merrill noted.
While some Kona operators follow the guidelines established by local tours, which include avoiding four dolphin resting bays between 10 a.m. and 2 p.m., Merrill said only three of the 12 Kona coast tour operators follow the guidelines.
Spinner dolphins (Stenella longirostris), feed on fish and small crustaceans that surface from the depths at night. Once the sun rises, they make their way to shallow bays to hide from tiger sharks and other predators, Phys.org reports.
When these dolphins sleep, they rest half of their brains, keeping the other half awake to surface and breathe, meaning they may be sleeping even when they are sleeping.
According to Julian Tyne, an honorary postdoctoral researcher at Australia’s Murdoch University, said that during the three years he studied them, spinner dolphins off Hawaii’s Big Island were exposed to human interaction about 80 percent of the time — from 7 a.m. to 6 p.m.
The median time period between exposures was only 10 minutes, he added.
He doesn’t know if this much interaction with humans is changing dolphin behavior, but the dolphins may not be resting as deeply as they need, and that could harm their ability to forage for food at night, as well as their ability to reproduce.
In 2005, the NMFS first signaled it would consider implementing regulations because tour offerings had burgeoned during the previous decade.
But the agency didn’t propose rules. Instead, officials have sponsored research to gain a better understanding of spinner dolphin behavior, and have promoted a voluntary program that discouraged swimming with the creatures. However, that has not deterred dolphin swim tours.
Under the Marine Mammal Protection Act, it’s illegal to harass dolphins, but swimming with them falls into a grey zone, Phys.org reports.
In Florida, tour operators have been prosecuted for feeding bottlenose dolphins, but dolphin feeding hasn’t been a problem in Hawaii.
The IUCN Red List of Endangered Species had said the data is insufficient to determine the dolphin’s conservation status, but it has noted there are four subspecies of spinner dolphins–S. I longirostris (Gray’s spinner), S. l orientalis, (Eastern spinner), S. l centroamericana, (Central American Spinner, and S. l roseiventris, (Dwarf Spinner).
Note: The dolphins in the photo are merely for illustrative purposes and are not spinner dolphins.
