Spinner dolphins sleep during the day, so when tourists, like this young woman, approach them, their rest is disturbed.

Wolfgang Pölzer/Alamy Stock Photo

Is swimming with dolphins a good idea?

Tourist spots around the globe offer people a chance to swim with whales and dolphins. But what impact do these activities have on the marine mammals, and should they be more strongly regulated? Maddalena Fumagalli, a cetacean biologist at the University of Otago in Dunedin, New Zealand, investigates these issues in a study on spinner dolphins (Stenella longirostris) published today in Royal Society Open Science. She spoke to Science about her findings. This interview has been edited for clarity and length.

Q: What do we know about the impact of these tourist activities on dolphins and whales?

A: It’s been difficult to say because you need to have sites you can compare—such as one with heavy tourism, one with an intermediate amount, and one without any. The tourists’ interactions always happen during a critical phase of spinner dolphins’ daily lives. These dolphins [slim animals with long beaks known for their acrobatic, spinning leaps] spend the nights offshore, diving for fish, and they come to lagoons at dawn to rest and sleep. So we’re interrupting their sleep. One long-term study in Hawaii showed that the spinner dolphins’ abundance has declined since the 1990s, and that may be linked to the increasing number of tourists disturbing their sleep.

Q: What sites did you study?

A: We made surveys of dolphins and tourists in the southern Egyptian Red Sea in the lagoons of Samadai and Satayah. We also surveyed dolphins at Qubbat’Isa, which is a military area, so there are no tourists. These are sandy, shallow lagoons inside coral reefs; the water is 2 to 8 meters deep. Tourists from nearby hotels are taken on boats to places in the lagoons where the dolphins are resting. It’s impossible to say how many tourists swim with the dolphins. While there is a ticketing system at Samadai, the stats aren’t made public. And access to Satayah reef is totally uncontrolled; we don’t know how many people are there on a given day.

The local government at Samadai has imposed regulations and zoning: The main area the dolphins use for resting is off-limits to swimmers; boats with outboard motors are allowed only in one area, away from the dolphins’ preferred zone; and swimmers and divers are only allowed from 8 a.m. to 3 p.m. At Satayah there are no regulations, and the dolphins are repeatedly approached by swimmers and motorboats up to 9 hours each day. During our surveys, there were more swimmers (a median of 13 at midday) and fewer boats at Samadai. Because of the dolphins-only zone there, it’s up to the dolphins to initiate contact with people. The Satayah dolphins have been exposed to these disturbances for a decade, and we think they may now be just “taking naps” when they can; they don’t really get to sleep.

Q: What were your main findings?

A: The dolphins typically rest in tight schools; they swim very slowly together and coordinate their breathing. They do very little acoustic communicating, and don’t make aerial displays. That changes when the tourists arrive. Other studies have shown that when disturbed from their sleep, the dolphins do more leaping. We saw this, too. The Satayah dolphins made more aerial displays than those at Samadai. It’s actually a sign they are not happy. Some can be curious and a little friendly. They’ll approach people from the side, not the front, and swim in circles and maybe whistle. But if they don’t want people near them, they just swim away.

The welfare of the Satayah dolphins is clearly being adversely affected by the unregulated tourism. And the dolphin protection measures at Samadai reduce these negative effects. But whenever tourists arrived at both sites, the dolphins consistently changed from resting in small, tight groups to being active. The time limits and zoning system at Samadai, though, helped by reducing the daily tourism interactions by about half.

Maddalena Fumagalli

courtesy of Maddalena Fumagalli

Q: Did you talk to the tourists about their impact on the dolphins?

A: Those at Satayah were surprised to hear that the dolphins were there to rest. They had no idea, and some of them were worried after they heard this. One said, “If I’d known, I wouldn’t have gone in the water.”

Q: Did the people ever hurt the dolphins or vice versa?

A: No, we never heard of the dolphins hurting the people. We’ve seen people trying to get very close, trying to touch a dolphin. The most danger—to both people and dolphins—comes from the crowd of swimmers and the number of speedboats going back and forth at Satayah. The sound of the motors also disturbs the dolphins’ sleep.

Q: Have you been swimming with the dolphins?

A: Yes, but not as a tourist, as a researcher. For another study about the composition of the dolphin groups, we needed to build a photo ID catalog of the dolphins when they were underwater.

They tend to be very curious about whatever is around them. Like people, some are more curious or friendly than others. It depended, too, on if they’d had a rough night feeding; then they really wanted to rest and would avoid us. We never forced any interactions; it was always up to them. They could be playful at times, but intimidating, too.

Sometimes, adult males can be threatening. One made a very direct, frontal approach and then assumed an S-shaped posture, which is a threat. At the same time, I could hear his train of echolocation clicks coming straight toward me. I immediately froze; I just stayed put, and he swam away. He made me realize that he—and perhaps the whole group—didn’t want me there. The dolphins also swim away if they don’t want you near them; we saw this happen with the tourists.

Q: What do you hope your research will accomplish?

A: We hope the Egyptian authorities and tour operators come up with a management plan that includes a sense of stewardship. The spinner dolphins are wild animals, and we shouldn’t impose ourselves on them. The tour companies that take people to swim with these dolphins need to acknowledge the dolphins’ need to rest, and develop their tourism program around that need by restricting the number of motorboats and using zones as they do at Samadai. They should also educate the tourists about the dolphins’ ecology and explain why they are in the lagoons. The tourist program at Samadai is regulated, but the tourists were still happy—and the dolphins were not so disturbed. That should be the goal of all cetacean tourism programs everywhere.