John Roach, National Geographic News 25 Aug 08;
Photos of giant whale sharks snapped by vacationing scuba divers and snorkelers are helping scientists track the elusive marine creatures across the oceans.
And the same technique may soon also help researchers track polar bears in Canada, giant Eurasian trout in Mongolia, and ocean sunfish in the Galápagos Islands.
Biologists have adapted a complex algorithm developed by scientists working for NASA. The original algorithm mapped stars. The new one analyzes photos of whale sharks, identifying each animal's unique pattern of white spots. The program determines if a particular shark has been seen before by other database users.
The participatory tracking technique is already lending new insight into the biology of whale sharks, according to Brad Norman, a research scientist from Murdoch University in Perth, Australia.
The tourist-collected tracking information is helping researchers learn more about where and when the fish migrate and their rate of return to particular areas, Norman said.
For example, at Ningaloo Marine Park in Western Australia, where the tracking technique was first tested, researchers found some sharks remain near the reef for up to three months.
And the global database of whale shark pictures indicates that some of the giant fish migrate between Mexico, Honduras, and Belize.
"We can use these data to highlight the need for international agreements to protect this threatened species," said Norman, who is a National Geographic Society emerging explorer, as well as the recipient of funding from the Rolex Awards for Enterprise.
(National Geographic News is owned by the National Geographic Society.)
Tracking Whales and Stars
Whale sharks are the world's largest living fish species, growing more than 40 feet (12 meters) long. They are listed as vulnerable to extinction by the World Conservation Union (IUCN), though little is known about their basic biology, ecology, breeding and migration patterns, and worldwide population size.
In 2000, Norman formed ECOCEAN, a nonprofit marine conservation organization based in Perth, to develop the participatory tracking system to facilitate whale shark studies.
The concept is based on an algorithm originally developed in 1986 to help NASA scientists match disparate images of stars made with instruments such as the Hubble Space Telescope.
Each giant whale shark is covered in a unique pattern of white spots, making them hard to miss when they swim by.
"We just adapted that from white spots on a black night sky to white spots on the flank of a whale shark," said ECOCEAN information architect Jason Holmberg, who lives in Portland, Oregon.
Zaven Arzoumanian, an astrophysicist at NASA Goddard Space Flight Center in Greenbelt, Maryland, led the algorithm's development.
Now, scientists and tourists can upload their whale shark pictures to www.whaleshark.org, an online photo identification database, along with information on where and when each giant fish was sighted.
The algorithm searches through the thousands of whale shark images in the database—currently 16,000 reported from 40 countries—for a match.
If one is found, the submitter will receive an email with a link to the identified shark and a history of its sightings.
So far, more than 1,300 whale sharks have been identified.
"Citizen science," or involvement by the public, "provides the opportunity for thousands of nonscientists to become involved and make a meaningful contribution to wildlife conservation," Norman said.
Applied to Other Species
Now that that the technique has been proven with whale sharks and is yielding results, the ECOCEAN team wants to extend it to other species.
In theory, the algorithm is adaptable to any creature with a telltale spot pattern that stays consistent over time. Think cheetahs, manta rays, spotted penguins.
This fall, biologists Jane Waterman and James Roth of the University of Central Florida will begin using the technique to track polar bears in Churchill, Manitoba.
The bears, which were recently listed as a threatened species in the U.S., have unique spots at the base of their whiskers. The algorithm is being tweaked to account for the size and placement of each spot.
(Related: Polar Bears Listed as Threatened Species [May 14, 2008])
Churchill is considered the best polar bear viewing site in the world and hosts hundreds of photo-snapping tourists each year.
"We can identify bears from year to year, so we can start looking at 'Do things change with the bears?'" Waterman said of the possibilities with the citizen-tracking technique.
"Are we seeing the same individuals coming into the area year upon year? Do we see a change in how long they stay in the tourist area? There are a lot of questions you can ask, if the technology works," she said.
National Geographic Emerging Explorer Tierney Thys has expressed interest in adapting the technique to her research on ocean sunfish, also known as mola.
One population of mola, the world's heaviest bony fish, resides in the Galápagos Islands and is photographed nearly every week by an underwater camera on a cruise ship.
Thys has secured access to those images and with Norman plans to look for identifiable markers that can be used for tracking.
"It would be a noninvasive way of answering questions about the sunfish in the Galápagos. For example, we could start to decipher if this is a resident population or not," she said.
Another emerging explorer, Zeb Hogan of the Megafishes Project, thinks the technique could be useful for tracking giant Eurasian trout.
"They have spotting on their head that doesn't appear to change as they age, which is the necessary requirement to use the technique," he said.
Catch-and-release fishing is thriving in Mongolia, where tourists flock to hook giant trout. Upon success, the tourists pose for a photo with their fish before releasing it.
Hogan and colleagues plan to compile a database of ten years' worth of snapshots of people holding their catch.
"Rather than having people diving with these giant sharks, we have people fishing for giant trout," he said. "It's pretty much exactly the same thing."
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