Swimming with wild dolphins offers a thrilling opportunity to get close to one of the world’s most intelligent species, but a new study has shown that the activity may be harmful to the well-being of the animals. While organizations such as the Humane Society have long criticized captive swim with the dolphins (SWTD) programs, less attention has been paid to the effects of wild SWTD programs. The new study, conducted by British researchers from Newcastle University who analyzed the effects of SWTD tours on bottlenose dolphins off the coast of Tanzania, found that these programs are highly stressful for dolphins because they disrupt natural resting, feeding and social behavior.

Both wild and captive SWTD programs often market themselves as therapeutic or educational experiences for tourists, a means of connecting with the animals and raising environmental awareness. However, organizations like the World Society for the Protection of Animals have condemned captive SWTD programs for their inhumane treatment of dolphins. Of the dolphins that survive the capturing process, 53 percent die within the first three months of captivity, after being exposed to chemicals, human infection and stress-related illnesses. Food deprivation is often used to train dolphins to perform crowd-pleasing tricks like voluntarily beaching themselves and kissing visitors.

Wild dolphin populations face a different set of challenges from those in SWTD programs. While wild dolphins are allowed to swim freely and are not subject to capture, the findings of the new study highlight that wild SWTD programs can still be cause for concern. Interference caused by human presence can force relocation and disrupt normal feeding and resting patterns. Furthermore, wild SWTD programs can cause psychological distress to the animals. These effects are not immediately visible to participants. In Hawaii, wild programs target areas where dolphins seek safety from predators, so dolphins have few options other than tolerating human presence.

Naomi Rose of the International Mammal Project argues that there are very few or no viable means of regulating either captive or wild SWTD programs to become more ethical. The only circumstances where swimming with the dolphins is ethical, she believes, are in the very rare cases when the dolphins’ own curiosity drives them to explore the human presence. Meanwhile, the physical requirements needed for captive SWTD programs to be humane would be prohibitively expensive.

SWTD programs are often portrayed as educational, therapeutic or conservation-friendly for the human participants. One SWTD tour operator touts that the experience will “inspire you to respect the sea and its inhabitants,” but the new research suggests that the programs are highly stressful for the dolphins themselves. In fact, Rose argues that one of the most harmful effects of such programs has been spreading the misconception that “dolphins want to be with us as much as we want to be with them.”