Unravelling the whale shark mystery

It is remarkable that a fish the size of a bus, which attracts so much attention, still harbours so many secrets.

The whale shark is a big enigma that researcher Brad Norman has spent more than 25 years trying to unravel.

Norman became interested in these mysterious giants in the early 90s, when, as an aspiring marine biologist, he went to Ningaloo Reef to assist a PhD student studying reef fish.

“Up at Ningaloo a fledgling ecotourism industry had already started around the whale sharks. While there, I found out more about them. Or more precisely, that not a lot was known about whale sharks.”

Many years later, Norman is still driving cutting-edge research to find out more about these gentle giants and is now Australia’s leading voice in whale shark research and conservation.

What we do know about whale sharks

Despite the name, whale sharks are not related to true whales. They are actually a type of shark and as such, are the biggest fish in the sea. They have been known to reach up to 20m in length, growing from around 0.5m at birth. They have a long life span of about 80-100 years and can travel many thousands of kilometres.

Truly creatures of the deep, whale sharks are thought to dive down as far as 1500-2000m with no need to surface, which, Norman says makes them tricky to study.

“They’re not like whales, dolphins, turtles or dugongs, or any air-breathing animals that come to the surface. These guys can stay down for months at a time if they want.”

Around the world whale sharks are found predominantly in regions with warmer waters, from the Tropic of Cancer to the Tropic of Capricorn, including Mexico, India, the Philippines, Mozambique and the Galapagos Islands. But Norman says that arguably the best place in the world to see and swim with whale sharks is at Ningaloo.

"Although we know they can exceed the length of a humpback whale, the majority of whale sharks seen in hotspots around the world, including Ningaloo Marine Park, have yet to reach maturity and are between four and eight metres," Norman says.

"Very rarely do you see whale sharks of a breeding age."

What Norman and other whale shark researchers are trying to find out is where those mature, larger whale sharks are.

Protecting our gentle giants

Researchers around the world are working to better understand this species. On a global scale, whale shark numbers are in decline, and they are listed internationally as Endangered.

“It’s mostly due to human factors, especially overfishing, primarily for their fins. Also because of habitat destruction and ship strike” Norman says.

Raising awareness of the threats facing whale sharks will be key to efforts aimed at protecting the species.

A whale shark project, pioneered by Norman's ECOCEAN research organisation two decades ago, provides an opportunity for the public to participate in whale shark research by monitoring and also learning about the species at the same time.

Wildbook for Whale Sharks is a publicly accessible online sightings database where ecotourists who view and take photos of whale sharks at Ningaloo can upload their photos. The images help with the ongoing identification of all whales sharks passing through the area. Anyone who submits images will receive email updates about any sharks they’ve photographed and be informed when any of those sharks are seen again.

Some of the animals on the ECOCEAN radar are among the longest-monitored whale sharks in the world. Two of the regulars, Stumpy and Zorro, have been recorded at Ningaloo Reef over a period of 22 years.

So far, more than 70,000 sighting reports and images have been uploaded to the database from people in over 50 countries worldwide. Almost 2,000 individual whale sharks have been identified from Ningaloo, including Stumpy and Zorro.

The system uses software adapted from the same software NASA scientists use to map stars in the night sky. In the case of the whale sharks, it’s used to ‘map’ the spots on their skin. Each whale has its own unique ID pattern of spots which the software identifies, a little like fingerprint recognition.

The monitoring program will be used to continually assess the size of the whale shark population at Ningaloo.

With many sharks going through this region for tourists to swim with each year, it’s hoped that Ningaloo is bucking the downward trend in global whale shark numbers.

For Norman, Ningaloo remains by far the best place in the world to experience a whale shark swim, in part because of the focus on their conservation and also just because of where it is.

“You can have a great day out with the whale sharks, all without interfering with their natural behaviour.

“And they’re right in our own backyard, with the spectacular backdrop of the pristine Ningaloo Reef and ancient Cape Range National Park.”

Twenty five years on, Norman says he is yet to tire of the experience of swimming with the whale sharks.

“They’re such friendly and graceful creatures. It’s amazing to see them in their natural environment in the deep blue. Every time I get in the water I still think it’s fantastic.”

RAC is a key supporter of the ECOCEAN organisation’s work with whale sharks, donating accommodation at the RAC Exmouth Cape Tourist Park during whale shark season.

By: Vanessa Pogorelic