Good news on Australia's whale shark population

Populations of the world's largest fish, the whale shark, are increasing at Western Australia's Ningaloo Reef, scientists report.

Researchers made the discovery using an online photo-identification technology called ECOCEAN which they used to track the sharks around the world.

The system works by encouraging members of the public to submit photos of whale sharks to the library’s database.

Scientists then identify the fish using pattern-recognition software which is then used to illustrate the whale sharks migratory habits.

More than 500 new whale sharks, considered vulnerable, have been discovered at Ningaloo reef since the project first began in 1993.

The team’s findings have been published in the journal Endangered Species Research (ESR).

Whale sharks migrate up to 12,000km and prior to the 1980s there had been only 350 confirmed sightings of the giant fish.

In some countries whale sharks are still harvested commercially.

Lead author on the ESR study Jason Holmberg says smaller whale sharks have also been discovered feeding at the reef during the study.

“Why are more and more juveniles arriving on the reef? It’s unclear, but it’s positive news,” Mr Holmberg said.

Founder of the ECOCEAN whale shark project and Murdoch University scientist Brad Norman says the research shows that whale sharks can increase where they are well-protected.

“We have also demonstrated the power of citizen-science, that ordinary people around the world can make a real contribution to serious research and conservation.”

“Thanks to increasing levels of data collection, we’re finally able to estimate how many whale sharks appear annually, how long they typically remain at Ningaloo Marine Park (NMP), their patterns of arrival and departure and shifts in their population structure,” he said.

Mr Norman recently discovered that whale sharks swim much faster than thought, nose-diving to the ocean floor for food and using their enormous weight and gravity for speed.

Curtin University researchers have also showed that whale shark ecotourism is a boon for local communities.

“Our results indicate that without whale sharks at Ningaloo Marine Park (NMP) up to $4.6 million would be lost from the local economy,” Mr Norman said.

“Similar economic benefits could be available at other whale shark ‘hotspots’ around the world,” he said.

The researchers hope now to use this technology to analyse data from other study sites and obtain a broader picture of the species.

Mr Norman warns that fundamental information on the whale sharks remains a mystery.

“Of over 1300 whale sharks we have tagged with our partners in the Indian and Pacific Oceans, very few have been sighted at other study locations, even though some whale sharks have been tracked for thousands of kilometres,” Mr Norman says.

He also cautions against making assumptions of how this may affect broader Indian Ocean populations, especially considering the migratory nature of whale sharks.

”Our models provide information only about the whale sharks visiting the northern region of NMP annually. While the number of sharks returning to that area in multiple seasons appears to be growing, we cannot make assumptions of how this may affect broader Indian Ocean populations, especially considering their migratory nature,” he said.

The success of the online survey has prompted scientists to issue a worldwide call to holiday-makers and divers to join in a global effort to monitor and protect the largest fish in the sea - thought to be at risk in the waters off many countries.

For further information on whale sharks visit http://www.whaleshark.org or call Earthwatch on 03 9682 6828.

Contributed by Tim Hochgrebe added 2009-05-14