Hot weather may be driving whale sharks to deeper waters

MANILA, Philippines—The sizzling summer temperature may be driving the friendly whale sharks, or butanding, in Donsol Bay in Sorsogon to deeper and cooler waters.

While more tourists are hitting Donsol’s beaches this summer, there are fewer sightings of the main draw: the gentle whale sharks, the World Wide Fund for Nature-Philippines (WWF) said Saturday.

Donsol’s surface water temperature averages 28.3 degrees Celsius, 2 degrees hotter than the average of 26.1 degrees Celsius recorded in the 2010 summer, WWF said.

“Our initial findings seem to indicate that the whale sharks are staying in deep water, possibly to avoid the heat,” WWF whale shark expert Dave David said in a statement. “They are also highly migratory creatures, so it is not easy to regularly predict their whereabouts.”

In the summer of 2001, there were also very “few sightings” of the whale sharks.

On top of the warm sea surface temperatures, the human factor might have something to do with it, too, the international conservation group said.

“Donsol now has far more visitors than it can handle. Coupled with the fact that sightings are decreasing, more and more interaction violations are being reported,” WWF Donsol project manager Raul Burce said.

Quoting tourist Anton Lim, WWF said some swimmers were touching the sharks, and bancas were racing  to where a shark is spotted.

Under the rules, only a single boat of six swimmers is allowed per shark; swimmers should be 3 meters away from its body, and 4 meters away from its tail; they can only interact for 10 minutes, and they can neither touch nor resort to flash photography. Boats are allowed to tour for three hours.

WWF called on tourists, boatmen and guides to stick to the rules.

“The policies were designed not just to protect the whale sharks, but tourists as well. A 30-foot shark can accidentally swat a swimmer straying too close to its tail,” Burce said. “By respecting the rules, we’re minimizing our impacts on the ecosystem, especially the sharks.”

With fewer sightings, Donsol operators are also offering firefly and mangrove tours.

The WWF is attempting to track shark movements through state-of-the-art tracking monitors, instead of relying solely on the trained eyes of spotters.

“Using just your eyes can be difficult, particularly if it is raining or overcast,” said Allan Amanse, former president of the Butanding Interaction Officer Association. “When it rains, the chance of a successful interaction drops.”

The new trackers utilize stationary sonar modules, which bounce sound waves off all solid objects. Large creatures such as whale sharks or shoals of fish can easily be made out. The trackers also log water temperature, WWF said.