Swimming With Whale Sharks

Wildlife researchers and tourists are heading to a tiny Mexican village to learn about the mystery of the largest fish in the sea

  • By Juliet Eilperin
  • Photographs by Brian Skerry
  • Smithsonian magazine, June 2011, Subscribe
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Whale shark Weighing up to several tons, whale sharks are also notable for their markings. Each pattern of spots is unique and scientists identify individual fish using computer programs first developed to study star constellations.

Brian Skerry

 

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    Diver deploying tag on whale shark

    Swimming With Whale Sharks

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    Getting to Know Sharks

    Author Juliet Eilperin reveals what she learned about the predators of the sea and how humans have little to fear of them


    Related Links

    Mote Marine Laboratory

    Related Books

    Demon Fish: Travels Through the Hidden World of Sharks

    by Juliet Eilperin
    Pantheon, 2011

    The Lady and the Sharks

    by Eugenie Clark
    Peppertree Press, 2010

    More from Smithsonian.com

    At the moment, Rafael de la Parra has but one goal: to jump into water churning with whale sharks and, if he can get within a few feet of one, use a tool that looks rather like a spear to attach a plastic, numbered identification tag beside the animal’s dorsal fin. De la Parra is the research coordinator of Proyecto Dominó, a Mexican conservation group that works to protect whale sharks, nicknamed “dominoes” for the spots on their backs.

    He slips off the fishing boat and into the water. I hurry in after him and watch him release a taut elastic band on the spear-like pole, which fires the tag into the shark’s body. De la Parra pops to the surface. “Macho!” he shouts, having seen the claspers that show it’s a male.

    The biggest fish in the sea, a whale shark can weigh many tons and grow to more than 45 feet in length. It’s named not only for its great size but its diet; like some whale species, the whale shark feeds on plankton. A filtering apparatus in its mouth allows it to capture tiny marine life from the vast amount of water it swallows. But it is a shark—a kind of fish with cartilage rather than bone for a skeleton—a slow-moving, polka-dotted, deep-diving shark.

    De la Parra and a group of American scientists set out this morning from Isla Holbox off the Yucatán Peninsula. The sleepy tourist island, whose primary vehicles are golf carts, has become a research center where scientists study whale sharks. The animals spend most of their lives in deep water, but they congregate seasonally here off the coast of the Yucatán, as well as off Australia, the Philippines, Madagascar and elsewhere. No one knows for sure how many whale sharks are in these waters, but the best estimate is 1,400. The global whale shark population may number in the hundreds of thousands.

    Researchers have fastened IDs to about 750 whale sharks here since the scientists started studying them in earnest in 2003, and they hasten to say the procedure does not seem to hurt the animal. “They don’t even flinch,” says Robert Hueter, a shark biologist at the Sarasota, Florida-based Mote Marine Laboratory, which collaborates with Proyecto Dominó. The researchers have outfitted 42 sharks with satellite tags, devices that monitor water pressure, light and temperature for one to six months, automatically detach and float to the surface, then transmit stored information to a satellite; scientists use the data to recreate the shark’s movements. Another type of electronic tag tracks a shark by transmitting location and temperature data to a satellite every time the animal surfaces.

    Despite all the new information, says Ray Davis, formerly of the Georgia Aquarium, “there are a lot of unanswered questions out there. Everyone’s admitting they don’t know the answers, and everybody’s working together to get the answers.”

    Eugenie Clark is Mote’s founding director and one of the pioneers of shark research. The first whale shark she observed, in 1973, was a dead one caught in a net in the Red Sea. Once she began studying live ones, in the 1980s, she was hooked. On one occasion, she grabbed the skin under a whale shark’s first dorsal fin as it cruised by. She held on, going ever deeper underwater until, at some point, it occurred to her she’d better let go.

    “It was incredible,” Clark remembers. “When I finally came up, I could barely see the boat, I was so far away.”


    At the moment, Rafael de la Parra has but one goal: to jump into water churning with whale sharks and, if he can get within a few feet of one, use a tool that looks rather like a spear to attach a plastic, numbered identification tag beside the animal’s dorsal fin. De la Parra is the research coordinator of Proyecto Dominó, a Mexican conservation group that works to protect whale sharks, nicknamed “dominoes” for the spots on their backs.

    He slips off the fishing boat and into the water. I hurry in after him and watch him release a taut elastic band on the spear-like pole, which fires the tag into the shark’s body. De la Parra pops to the surface. “Macho!” he shouts, having seen the claspers that show it’s a male.

    The biggest fish in the sea, a whale shark can weigh many tons and grow to more than 45 feet in length. It’s named not only for its great size but its diet; like some whale species, the whale shark feeds on plankton. A filtering apparatus in its mouth allows it to capture tiny marine life from the vast amount of water it swallows. But it is a shark—a kind of fish with cartilage rather than bone for a skeleton—a slow-moving, polka-dotted, deep-diving shark.

    De la Parra and a group of American scientists set out this morning from Isla Holbox off the Yucatán Peninsula. The sleepy tourist island, whose primary vehicles are golf carts, has become a research center where scientists study whale sharks. The animals spend most of their lives in deep water, but they congregate seasonally here off the coast of the Yucatán, as well as off Australia, the Philippines, Madagascar and elsewhere. No one knows for sure how many whale sharks are in these waters, but the best estimate is 1,400. The global whale shark population may number in the hundreds of thousands.

    Researchers have fastened IDs to about 750 whale sharks here since the scientists started studying them in earnest in 2003, and they hasten to say the procedure does not seem to hurt the animal. “They don’t even flinch,” says Robert Hueter, a shark biologist at the Sarasota, Florida-based Mote Marine Laboratory, which collaborates with Proyecto Dominó. The researchers have outfitted 42 sharks with satellite tags, devices that monitor water pressure, light and temperature for one to six months, automatically detach and float to the surface, then transmit stored information to a satellite; scientists use the data to recreate the shark’s movements. Another type of electronic tag tracks a shark by transmitting location and temperature data to a satellite every time the animal surfaces.

    Despite all the new information, says Ray Davis, formerly of the Georgia Aquarium, “there are a lot of unanswered questions out there. Everyone’s admitting they don’t know the answers, and everybody’s working together to get the answers.”

    Eugenie Clark is Mote’s founding director and one of the pioneers of shark research. The first whale shark she observed, in 1973, was a dead one caught in a net in the Red Sea. Once she began studying live ones, in the 1980s, she was hooked. On one occasion, she grabbed the skin under a whale shark’s first dorsal fin as it cruised by. She held on, going ever deeper underwater until, at some point, it occurred to her she’d better let go.

    “It was incredible,” Clark remembers. “When I finally came up, I could barely see the boat, I was so far away.”

    Clark, who is 89 and continues to do research, recalls the ride with impish delight. At one point, as we sit in her Florida office, she casually mentions a recent dive, then catches herself. “Don’t mention how deep I went,” she whispers. “I’m not supposed to do that anymore.” Then she explodes in laughter.

    As she studied feeding behavior in whale sharks, she noticed that juveniles, less than 35 feet long, fled from humans, but larger animals didn’t seem to mind nearby divers.

    The fish have mostly been a mystery. Only in 1995 did scientists determine how whale sharks come into the world, after Taiwanese fishermen pulled up a dead female carrying 300 fetuses in various stages of development. These sharks are “aplacentally viviparous,” meaning the young develop inside eggs, hatch, then remain in the mother’s body until the pups are born. With the astonishing number of eggs, the whale shark became known as the most fecund shark in the ocean.

    When two male whale sharks at the Georgia Aquarium died within several months of each other in 2007, scientists traveled to Atlanta to observe the necropsies. Analysis of the bodies helped researchers understand the 20 sieve-like pads the animals use for filter-feeding. Recent research by Hueter, De la Parra and others has shown that whale sharks primarily eat zooplankton in nutrient-rich coastal waters, like those near Isla Holbox; in other areas they seek out fish eggs, especially those of the little tunny. If they gulp something too big, they spit it out.

    Rachel Graham, a conservation scientist at the Wildlife Conservation Society, was the first to attach a depth tag to one of the giants, in Belize in 2000. One of the 44 satellite tags she eventually deployed told her that a whale shark had dived 4,921 feet—nearly a mile. A marine biologist named Eric Hoffmayer recorded the deepest dive yet: in 2008, he monitored a shark in the Gulf of Mexico that descended 6,324 feet. “Their ability to adapt to all sorts of different environments is an important part of their survival,” says Graham, who’s tracking whale sharks in the Western Car­ibbean, Gulf of Mexico and Indian Ocean. Scientists don’t know why the animals go so deep. Sharks lack a swim bladder that keeps other fish buoyant, so one idea is that whale sharks free-fall toward the seafloor to rest.

    In 2007, Hueter tagged a pregnant 25-foot-long female he nicknamed Rio Lady. Over the following 150 days, she traveled nearly 5,000 miles, from the Yucatán Peninsula through the Caribbean Sea to south of the Equator east of Brazil, ending up north of Ascension Island and south of St. Peter and St. Paul Rocks, roughly halfway between Brazil and Africa. No one is certain where whale sharks breed or give birth, but Hueter believes this area may be one of their elusive pupping grounds.

    Legend has it that Isla Holbox, a former pirates’ hide-out, got its name from a deep lagoon on the southern part of the island: Holbox means “black hole” in Mayan. But fresh water bubbling up from a spring in another lagoon was the island’s real draw: the Maya viewed it as a fountain of youth, and Spanish ships stopped there to take on fresh water. Mangroves divide the island, which is less than two miles wide.

    A tour guide describes islanders as “descendants of pirates, mestizos of several races, fishermen by trade.” Residents earned a living by trapping lobster until about 2000, when the excessively hunted crustacean grew scarce and fishermen wondered what to do next.

    Willy Betancourt Sabatini was one of the first Holboxeños to realize that the massive sharks that congregated near the island to feed might be the answer. He and his sister, Norma, a local environmentalist who now serves as project director for the island’s Yum Balam Protected Area, along with researchers and local entrepreneurs, established rules for a new industry, shark tourism. Only two divers and one guide can be in the water with a single shark; flash photography and touching the sharks are forbidden. Islanders had learned from the lobster debacle that they needed to set limits. “They know if we don’t take care, all of us are going to lose,” Norma Betancourt Sabatini says.

    “Conserve the whale shark,” says a sign on Isla Holbox. “It’s your best game.”

    Shark tourism is growing. Graham, in a 2002 study of whale shark visitors to the small Belize town of Placencia, estimated revenues of $3.7 million over a six-week period. In the Philippines’ Donsol region, the number of whale shark tourists grew from 867 to 8,800 over five years. And a study found whale shark tourists spent $6.3 million in the area around Australia’s Ningaloo Marine Park in 2006.

    “It’s simple and more predictable than fishing,” Willy Betancourt Sabatini says of shark watching. The 12 men who work for him as boat operators and guides earn twice as much as they did fishing, he adds. “We respect the rules. People understand it very well.”

    It had taken an hour for De La Parra, Hueter and others on the tagging expedition to reach the sharks. The water was smooth and thick with reddish plankton. “There’s one of them!” a researcher cried out, pointing to a large, shiny dorsal fin. We motored closer, and I found myself gazing at the largest shark—about 23 feet—I had ever seen. Its skin was dark gray, glinting in the sunlight, with mottled white dots.

    Suddenly it seemed as if whale sharks were everywhere, though we could see only a fraction of their massive bodies: their gently curved mouths, agape as they sucked in volumes of water, or the tips of their tails, flicking back and forth as they glided through the sea.

    I donned a mask, snorkel and fins and prepared to jump in. Hueter had told me he thought the sharks’ cruising speed was one to two miles an hour—slow enough, I thought, to swim alongside one without much difficulty.

    Wrong.

    I made a rookie’s mistake and jumped in near the shark’s tail. I never caught up.

    I tried again, this time hoping to swim out to an animal half a dozen yards away. It didn’t wait.

    Finally, I managed to plunge into the water near an animal’s head and faced an enormous, blunt-nosed creature, coming toward me at what seemed like a shockingly rapid rate. While I marveled at its massive nostrils and eyes on either side of its head, I realized I was about to be run over by a 3,000-pound behemoth. Never mind that it doesn’t have sharp teeth. I ducked.

    It cruised by, unperturbed. By the time I climbed back into the boat, everyone was ready with quips about how I had had to scramble to get away. I didn’t care. I had seen a whale shark.

    Adapted from Demon Fish: Travels Through the Hidden World of Sharks by Juliet Eilperin. Copyright © 2011. With the permission of Pantheon Books, a division of Random House, Inc.

    Juliet Eilperin is the national environmental reporter for the Washington Post. Brian Skerry, a specialist in underwater photography, is based in Uxbridge, Massachusetts.


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    Comments (16)

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    While not the same as swimming with them in the open ocean, the Georgia Aquarium has a snorkeling/diving program where you can swim with them in their salt water aquarium. Might be cheaper and/or safer than traveling to Mexico. Also, on the Planet Earth series, there was film of whale sharks feeding on schools of small fish.

    Posted by sparcboy on April 10,2012 | 03:53 PM

    Um, Kevin, they are not vegetarians. They eat zooplankton. Think tiny shrimp (though it includes much more.) So the largest fish in the ocean eats some of the smallest animals in the ocean.

    Posted by cb on January 31,2012 | 08:31 AM

    awesome! I just had an amazing whale shark experience - my first time snorkeling with them. I was in the Philippines. So incredible! I posted a few photos from the day here: http://Visit50.com/2011/12/whale-shark-snorkeling/

    Posted by Todd @ Visit50 on December 17,2011 | 03:58 PM

    Wonderful and gentle creatures they are!

    Posted by Ruth on July 12,2011 | 11:20 AM

    I am really delighted to read this story.Thanks for posting.
    Earlier Italian beauty not only jumps from planes but also swims with sharks...

    Posted by SAANVI on June 26,2011 | 12:22 PM

    While vacation on Playa Del Carmen with my daughter we went to swim with the whale sharks a week ago. It was the most amazing things we have ever experience. There were 30 plus whale sharks feeding in the clear blue water. The smaller ones were 25 ft. The bigger ones were 35 to 40ft. The season to swim with them off Isla Mujeres is June to Sept 15, according to our guide. It is a once in a life time experience. You must go if you ever visit Cacun area during the season.

    Posted by Eleanor Felbaum on June 22,2011 | 12:52 AM

    Through sheer good fortune I was able to swim with whale sharks at Bahia Gonzaga in Baja California a few years ago. Seeing fins in the water and being told that they were whale sharks, I quickly scrounged a canoe from a local and a mask from other visitors. My experiences were much like the author's: fruitlessly trying to chase them down, then finally intercepting one while it was surface feeding. I floated in the water as the behemoth continued on its path straight toward me. It was one thing to know that it was a vegetarian and wouldn't eat me, quite another to see the gaping maw that could swallow me whole. I frantically splashed out of the way, only to go too far and miss the touch. Of course I repeated the whole process again with another shark, this time staying just close enough to brush my fingertips along the base of its fin. The mixture of fear, awe and admiration still comes back to me.

    Posted by Kevin Smith on June 22,2011 | 04:24 PM

    Wife and I arranged to spend two days in Holbox swimming with the whale sharks in July 2007. Certainly the most enjoyably different of our diving trips over the last 15 years. A double treat was 8 or 10 giant mantas, with 10 to 12 foot wingspans, mixed in with the sharks.

    I sure hope Holbox remains as unspoiled as it was then.

    Posted by Bob Speir on June 6,2011 | 07:40 PM

    We where out last season with Rafael and the researchers from the Georga Aquarium off Isla Mujeres in the blue water swimming with a group of over 150 Whale Sharks in July. This time of the season the Whale Sharks gather in large groups just off the coast of Cancun and in 2009 the largest group ever recorded was 420 in a single day. The Whale Shark Festival on Isla Mujeres is the 15th till the 17th of July, right in the middle of the season. Traveling out to swim with Whale Sharks from Isla Mujeres is a muck shorter and easer trip from Cancun and the Rivera Maya than going all the way to Holbox. check out www.whalesharkfest.com for more info on Whale Sharks and a great event for the Family.
    John Vater.

    Posted by John Vater on May 26,2011 | 10:16 PM

    A dear memory of mine is not only spotting my first whale shark but enjoying the view of this graceful animal as he glided below my surfboard. Having yet to see a photo of one, I did at first panic at the sight of his tail fin and big white freckles, thinking maybe I was about to be eaten by a leopard shark (I grew up on the east coast of South Africa where tiger sharks are common so the idea of wild cat fish hybrids seemed plausible).

    Posted by Melissa on May 25,2011 | 01:20 AM

    On page 40 of the June 2011 issue of Smithsonian (and on page 4 of this online article), there's reference to a 23 foot whale shark. There's further reference to that whale shark being "a 3,000-pound behemoth." That's nonsense. A 23-foot whale shark would obviously weigh more than 3,000 pounds, probably closer to 30,000 pounds. I'm guessing this is an example of careless writing or editing or maybe careless printing.

    Posted by Dino Marino on May 25,2011 | 01:40 PM

    about 4 years ago my husband and i were on a whalewatch off the tip of cape cod on stallwagen banks when we saw a whaleshark and a calf swiming close to the boat we were on.it was an incredable site.

    Posted by mary ann power on May 22,2011 | 08:11 AM

    I'm going swimming with these whale sharks just as soon as I get back to Isla Mujeres!

    Posted by Laura Catherwood on May 20,2011 | 09:08 PM

    This is one of the most amazing articles, for me, in the Smithsonian this year. I was amazed because I always assumed that Whale Sharks would be the most dangerous of sharks, considering their size. To find out that I was not only wrong, but the trust was the opposite of my assumption- these beautiful creatures are docile!- I was blown away. Excited, and most of all: intrigued. I want to learn more now, swim with them, study them, teach my highschool about these grand, sweet, rulers of the sea!!! I am so happy to have read this article!!!

    Posted by Stephie Ossesia on May 19,2011 | 10:58 PM

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