Whales risk injury from increased boat traffic.
Every summer, hundreds of whale sharks gather off the Yucatan Coast near the Mexican tourist hubs of Cancun, Isla Mujeres and Isla Holbox. The sharks congregate 32 km offshore to gorge on the eggs of a fish called the little tunny, skimming them from the ocean’s surface with enormous, gaping mouths. In recent years, the spectacle has attracted legions of tourists to snorkel alongside the graceful, slow-moving giants.
When initially discovered by fishermen, the sharks gathered closer to Isla Holbox, a location too far from Cancun or Isla Mujeres for an easy day trip. In 2009 the sharks shifted farther east into the Yucatan upwelling zone, where currents draw in nutrients that also attract manta rays, sailfish, dolphins and turtles. That put the sharks within an hour's boat trip of many more tourists.
At first, only a handful of licenses were issued to boat operators, but the number has increased to more than 320. "Every year we ask them not to increase the number, and every year they increase the number," said Alistair Dove, 41, marine biologist and director of research and conservation at the Georgia Aquarium in Atlanta.
Although the practice pumps tourism dollars into Mexico's economy, experts are concerned increased human activity threatens the sharks’ welfare. Despite regulations requiring boats remain 5 metres away, between 20 and 30 percent of the sharks are injured by boat propellers. Up to 116 boats at a time scramble for position around the sharks. "No one has been injured by a boat yet, but I think it's a matter of time," he said. "With that combination of inexperienced people and the sheer number of boats, it's inevitable."
No more than two snorkelers per boat are allowed in the water with a guide at one time and time allowed in the water is limited. Snorkelers must maintain a minimum distance of a metre but not everyone follows the rules. "When there's no enforcement presence out there, which there rarely is, it's a free for all," Dove said. Some outfitters offer guarantees that customers will see a whale shark up close. If they don't, the customer doesn't pay. As a result, boat captains do everything they can to make that happen.
Dove believes most boat operators have good intentions. "They love the animals but get caught in a competitive situation. If they don't take people out there, the other guy will,” he said. Scientists believe the Caribbean whale shark population, which numbers about 1,500, to be generally healthy. In 2011, more than 400 animals occurred off the Yucatan, the biggest congregation known to science.