How Tourists Are Giving Stingrays Insomnia

Thanks to swim-with programs, some stingrays in the Cayman Islands are no longer nocturnal creatures.

A tourist "kisses" a string ray in the waters off Grand Cayman. (Photo: danielshereck.com)
writes about environment and energy for the NYT, Popular Science, OnEarth Magazine, and more.

Imagine slipping off a boat into warm, aqua blue, waist-deep, Caribbean water. Suddenly, there are hundreds of stingrays swarming around you, sliding against your legs. For some people this is a nightmarishly, terrifying scenario. For others, it's a tropical wildlife paradise. Either way, it's what tourists to Stingray City in the Cayman Islands drop millions of dollars each year to experience.

Each stingray on this sandbar off Grand Cayman earns the islands about $500,000 every year in tourism revenue. Globally, this kind of interactive wildlife experience is big business, generating about $165 billion each year worldwide. Moreover, interacting with animals can make even the least outdoorsy among us passionate about protecting wildlife.

But what about the stingrays? How is this normally solitary creature handling life in the public spotlight?  

"We'd love to be able to ask the stingrays how they feel about all of this," said Dr. Bradley Wetherbee of  the University of Rhode Island."Short of that, we can at least outfit them with microchips and see how their behavior is changing as a result of all the attention."

And that's just what Dr. Wetherbee and his team of researchers from Nova South-eastern University's Guy Harvey Research Institute in Hollywood, Florida did in a stingray study that lasted over two years. Careful monitoring of these primordial-looking creatures revealed that the lifestyle of stingrays on the sandbar was barely recognizable as natural stingray behavior at all. It wasn't all bad news but the study did raise questions about how wild animals can be left a little more wild while still letting people have life-changing,  personal experiences with them.

For Dr. Wetherbee,  the most surprising discovery was that the rays of Stingray City were no longer nocturnal. In the wild stingrays hang out by themselves all day on the bottom of the ocean and only at night do they become active and swim into shallower waters to hunt for mollusks. But the rays Dr. Wetherbee tagged were active all day long in very shallow water, just waiting for the next boatload of tourists to come with their packages of squid meat from the supermarket.

"These rays have just completely reversed their normal behavior," explained Dr. Wetherbee.  "And this species of stingray has been around for thousands of years, and stingrays in general have been around for millions of years and almost all of them are strictly nocturnal. So ever since they have been in existence they have been active at night and just lazed about during the day. There's a lot that goes into a nocturnal creature reversing their lifestyle biological clocks, hormones -- all their physiology has evolved to be nocturnal -- and now, they're just not."

The rays of the sandbar were also much more aggressive towards each other, hardly surprising as they are used to being on their own, not packed into a quarter of a square mile. They also mated all year round and did not have normal body composition, a direct result of eating little else but squid brought by visitors.

"I think Stingray City is an amazing place for people who can't snorkel or scuba dive," said Dr. Wetherbee. "But it couldn't hurt to try and feed them a more normal and varied diet and do more research to see how their strange behavior is affecting the overall health of the population overtime. Part of the experience should be to see a wild animal, and these rays are getting farther and farther away from that."

Comments ()