U. FLORIDA (US) — Whale sharks are the world’s largest fish, but the body of scientific knowledge surrounding them is surprisingly small.
Now, a whale shark expert says tourists armed with cameras may be a new source of data about the gentle giants, often seen in the Gulf of Mexico. Photographs could help scientists gauge the shark’s abundance and shed light on its longevity, migratory patterns, breeding habits, and other information needed for conservation efforts.
A study published in the current issue of the journal Wildlife Research examines whale shark photographs and video still images posted online by vacationers on diving or sightseeing excursions who had seen the creatures. The researchers concluded that the material was often suitable for use in scientific studies that identify and track individual whale sharks.
“We need to consider all available information to try and fill the gaps of knowledge for data-deficient, vulnerable species like whale sharks,” says Juliane Struve, a research assistant professor with the University of Florida’s Institute of Food and Agricultural Sciences. “Citizen photos are as useful as researcher photos if they meet the requirements of photo identification.”
Whale sharks can be individually identified because each one has a unique pattern of spots and lines on its back, giving the creature a visual signature akin to a fingerprint, Struve says. And, unlike many large marine species, whale sharks often swim close to the surface, making them accessible to photographers.
In certain areas, large congregations of whale sharks appear annually, and tourism industries have sprung up to help people get close to the fish, which can reach a maximum length of more than 40 feet and a weight of more than 45,000 pounds.
Worldwide, there are believed to be about 100,000 whale sharks, which eat plankton and pose no threat to man. Though not classified as endangered, whale sharks are killed for their meat and fins, and sometimes die after being accidentally caught in tuna nets.
The study focused on images captured in the Republic of the Maldives, a chain of islands southeast of India, in a part of the Indian Ocean where whale sharks often congregate. Researchers examined about 300 images from tourists and 300 taken by scientists.
Images were considered acceptable if they provided a clear view of the left side of the whale shark’s body, clearly showing the spot pattern near the gills.
About 85 percent of the images from amateurs were good enough to allow identification of an individual whale shark, Struve says. Thus, online efforts to solicit and collect tourists’ whale shark photos could help scientists gain a better understanding of the species for conservation efforts, she says.
Learn more about whale shark photographs and their use in scientific research.
Source: University of Florida