Whale sharks are endangered, with estimates suggesting populations worldwide have plummeted by more than 50% over the past 75 years. Although they are protected in many countries, whale sharks are still killed by the fishing industry — caught deliberately for their fins (shark fin soup is a delicacy in parts of Asia) and as accidental bycatch, especially in tuna fishing areas where whale sharks and tuna swim close together. Whale sharks are also threatened by oil and gas drilling, vessel strikes and climate change.
To help protect the species, Australian marine biologist Brad Norman co-founded The Wildbook for Whale Sharks, a photo identification database that went online in 2003.
Members of the public, scientists and whale shark tour operators around the world contribute photos of whale sharks to the system, which uses NASA technology to map their locations and track their movements. Today, the database holds over 70,000 submissions from more than 50 countries — making it one of the biggest crowd-sourced conservation projects in the world.
Adventures with giant fish
Despite their imposing size — whale sharks can grow up to 20 meters (65 feet) long — these gentle giants don’t pose a danger to swimmers. Feeding on plankton and tiny marine organisms, they cruise at a leisurely maximum of three miles per hour, allowing snorkelers and divers to get up close.
Norman has been studying these charismatic creatures for over 25 years. He first swam with a whale shark in the turquoise waters of Ningaloo reef on Western Australia’s northern coast. “It was one of the most amazing experiences I’ve ever had,” he recalls. “I’ll never forget it.”
Marine biologist Brad Norman photographing a whale shark.
That whale shark — nicknamed Stumpy because of his deformed tail — was the first entry in a photo-identification library that Norman created in 1995. The library, later operated by Norman’s conservation organization ECOCEAN, became the foundation of The Wildbook for Whale Sharks.
A slow swimmer, Stumpy is relatively easy to keep up with, says Norman. “I see him nearly every year and … I think ‘G’day mate, how you goin’?”
Since that first encounter, Norman has swum with whale sharks on thousands of occasions — and says he still gets a buzz out of it every time.
Why NASA tech works for whale sharks
Images submitted to The Wildbook for Whale Sharks are analysed by an algorithm that scans the spots and stripes on the animal’s skin, which are as unique as a human fingerprint, says Norman. The algorithm identifies the shark by searching the database for a matching pattern.
Whale sharks are identified by the markings on their skin.
Adapted from technology first developed for NASA’s Hubble Space Telescope program, the algorithm works for whale sharks because their skin markings form patterns similar to stars in the night sky.
Norman says that collectively, the data on whale shark locations and migration routes informs decisions on management strategies for habitat protection. “I can only be in one place one at one time,” he says. “It’s so important to have members of the public assisting with our project.”
Is swimming with whale sharks good for them?
Norman says he would “encourage anybody that gets the opportunity to swim with a whale shark.”
But more boats, snorkelers and divers in whale shark areas could be problematic. Norman cautions that impact on the sharks must be minimized.
In Western Australia, whale shark tour operators are strictly regulated with limits on the numbers of people and licensed vessels in the water near the animals at any one time — and a percentage of sales going towards whale shark industry management.
However, regulation and enforcement are weaker in other places.
In the Maldives, whale sharks are a popular attraction but government guidelines designed to protect the sharks from harassment are frequently breached. This can cause stress for the animals, while boat collision injuries can impact their development and ability to travel long distances.
Whale sharks in the Philippines are routinely provided with food to attract them to places where visitors can easily see them. This can change the sharks’ diving patterns and metabolism, while a high level of scarring indicates increased boat strikes. The crowding from tourist activity and feeding can also lead to coral reef degradation.
But where whale shark tourism is practiced responsibly, it can help save the species. Norman hopes to see more data collection around the world, plugging information gaps and strengthening conservation efforts. He’s seeking what he calls “the Holy Grail” — finding out where the whale sharks go to mate. Protecting their breeding grounds is the “one big thing” needed to save the species in the long run, he says. The help of thousands of citizen scientists gives him a better chance of making that possible.