Whale Sharks Filmed Feeding Off Western Australia

Off Western Australia, researchers have filmed whale sharks at close range to gain a clearer picture of their feeding habits.

Footage recorded using small cameras temporarily attached to several animals provides a viewpoint rarely captured in the marine environment. It reveals that these giant fish do not feed solely close to the surface, as was long assumed. Instead, they adjust their technique according to depth, currents and food availability.

Cameras attached to fins

The study took place around Ningaloo Reef, on Australia’s west coast. At certain times of year, this area is known for hosting major gatherings of whale sharks. Although they are exceptionally large, these animals are still hard to observe for extended periods without affecting their behaviour.

Teams from the Australian Institute of Marine Science therefore fitted tags to the fins of several individuals. Each unit combined tracking equipment with a miniature camera. The tags were set to detach naturally after 24 hours.

“The whale sharks continued on their way without altering their swimming, while researchers retrieved footage recorded in the heart of their environment.”

This approach marks a significant improvement on conventional tags. Standard devices mainly provide information on location, depth or travel route. They do not show exactly what an animal is doing while moving. Video now allows scientists to connect its movements with specific actions: opening its mouth, changing course, speeding up or descending towards the seabed.

Thirty-six feeding behaviours identified

Researchers compared the filmed sequences with more than one hundred scientific papers focused on the species. Their work produced a catalogue of 36 distinct feeding-related behaviours. According to the institute, it is the most comprehensive repertoire yet compiled for whale sharks.

The findings challenge a widely held assumption. These animals were chiefly associated with feeding near the surface, where they can consume large volumes of plankton, fish eggs or tiny crustaceans. The footage shows that they actually search much of the water column, including areas close to the seabed.

An open mouth, even while descending

One of the behaviours recorded is a particularly energy-efficient technique. The whale shark slowly descends towards the bottom with its mouth open. Water then passes through its gills, while its filtering structures trap edible particles. This method requires little energy, a valuable advantage in tropical oceans where prey is not evenly distributed.

Conversely, the animal can use a far more active approach. When a school of krill or a dense patch of food appears near the surface, it speeds up and actively pursues the resource. It is therefore not reliant on one single method, but selects its strategy according to the opportunity.

• Slow feeding during descents towards the seabed;
• Foraging at several depths;
• Faster pursuits near the surface;
• Continuous adaptation to areas where prey is concentrated.

A giant reliant on scattered resources

The whale shark is the largest fish known on Earth. Some individuals are well over ten metres long. Despite its size, it does not hunt large prey. It is a filter feeder: it draws in vast quantities of water before retaining the tiny organisms that make up its meal.

Its diet may include zooplankton, larvae, fish eggs, crustaceans and krill. The difficulty is that these resources often occur in highly localised, short-lived patches. One area may be abundant for a few hours, then nearly empty the following day.

“The recorded behaviours suggest that the whale shark offsets the irregularity of its resources with a much broader range of techniques than expected.”

This flexibility partly explains its ability to range across huge areas of ocean. However, it does not shield the species from every threat. Whale sharks are classified as threatened and remain vulnerable to ship strikes, accidental capture in fishing gear, habitat degradation and disturbance at heavily visited tourist sites.

How this whale shark footage could improve protection

Knowing where whale sharks genuinely feed can help shape protective measures. If scientists establish that a seabed area or a particular layer of water regularly serves as a feeding ground, they can better assess risks associated with shipping, fishing or certain offshore works.

Seasonal gatherings also draw many tourists. Managed viewing can fund local research and raise public awareness, provided strict distances are respected. Getting too close, having too many boats nearby or remaining in an animal’s path for too long can disrupt its swimming and its access to food.

Monitoring that could expand to other oceans

Researchers now hope to fit cameras to more whale sharks at gathering sites in different parts of the world. Ningaloo Reef represents only one part of the vast range used by this species, which occurs in warm seas off several continents.

The term “water column” refers to the space between the surface and the seabed. The latest observations show that this whole space matters to whale sharks. Feeding may begin near the waves, continue at mid-water and sometimes end very close to the ocean floor. This mobility makes the animals harder to study, but it also offers a practical direction: protecting whale sharks means looking beyond the surface alone.