World's largest fish is on the increase at Ningaloo
A combined study involving ECOCEAN scientists and Earthwatch volunteers has revealed numbers of the whale shark - the world's largest fish and one of its rarest - are holding steady, and evidence suggests they may even be increasing in one of its vital habitats.
The remarkable success of the online survey of whale sharks carried out by Earthwatch volunteers, tourists, divers and researchers at Ningaloo, Western Australia, has prompted scientists to issue a worldwide call to holidaymakers 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.
"Besides showing 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," says Brad Norman, Earthwatch Project Coordinator and founder of the ECOCEAN whale shark project.
ECOCEAN has pioneered this new technology - which uses pattern recognition software that allows members of the public to help monitor and ultimately protect wildlife - both in the sea and potentially on land through the development of similar programs for other endangered species.
"Thanks to increasing levels of data collection," says Norman, "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."
The team's new findings have been published in the journal Endangered Species Research (ESR) and Jason Holmberg, lead author on the ESR study states that "using an unprecedented number of photographs and video collected from the public and from the dive industry at NMP, we have been able to create statistical models demonstrating a modestly increasing annual population of around 150 sharks".
He continues: "We're also seeing an increase in the number of smaller whale sharks feeding at the reef and returning in subsequent years. Why are more and more juveniles arriving on the reef? It's unclear, but it's positive news."
This study complements a collaborative study with Curtin University, Western Australia, the results of which were published in the Journal of Ecotourism (JE), acknowledging the whale shark ecotourism industry as a boon for local communities working to protect this threatened species.
"Our results indicate that without whale sharks at NMP, up to AUD 4.6 million would be lost from the local economy," notes Norman, "And similar economic benefits could be available at other whale shark ‘hotspots' around the world."
"Therefore, providing it is well-managed, this form of non-consumptive exploitation should continue to be promoted as a sustainable alternative to unsustainable hunting of this threatened species," he says.
Holmberg explains the team's findings and techniques are useful beyond Western Australia: "For the first time, our study demonstrates a set of population models that can be expanded to incorporate other whale shark aggregations in the Indian Ocean if and when sharks can be linked between them."
"Data from Ningaloo represent only a snapshot of the migrations of these sharks, but it's a significant, long-term baseline. Moving forward, we can now begin to cooperatively integrate and analyse data from other study sites and obtain a broader picture of the species."
"For such a long-lived, far-ranging animal, a big-picture view is important - especially to promote global protection. It is important to note that the whale shark is still considered 'vulnerable to extinction', and with such a small population, continuing caution and protection is imperative," says Holmberg.
The research team notes that despite the sophisticated tools pioneered at Ningaloo, some fundamental mysteries remain.
"There is still a large amount of mystery surrounding these sharks, and there remains a fair amount of fundamental exploration ahead. Of over 1,300 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," says Norman.
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."
"Whale sharks remain very poorly understood and application of our tools and techniques to other whale shark study areas will help clarify the real pressure on the species," Norman says.
Earthwatch Executive Director Richard Gilmore says: "As our oceans come under increasing pressure from factors such as over-harvesting, pollution and coastal development, there is a need for teams of international ‘citizen scientists' to support the scientific investigations into these critical issues and to help find solutions. The positive research results from Ningaloo demonstrate the valuable contribution that Earthwatch volunteers can make to conservation."
The ECOCEAN Library has recordings of more than 500 individual whale sharks visiting NMP since the industry began in 1993. Earthwatch has been supporting ECOCEAN’s whale shark research since 2006 and has sent over 80 Australian volunteers to help scientists study whale sharks in that time.