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© James Morgan / WWF
© James Morgan / WWF

Unlocking secrets of gentle giants – whale sharks and citizen science

Added to Blogs on 29 August 2019
Whale sharks (Rhincodon typus) are filter-feeding and highly migratory sharks, which travel between coastal waters and open oceans. Growing up to 20 meters in length (longer than a school bus) and weighing up to 34 tonnes (nearly as heavy as 6 large African elephants), they are by far the biggest living fish in the world. And yet, in spite of being one of the most iconic marine species, these sharks still hold many secrets waiting to be uncovered!

From the identified global population of around 10,500 individuals, 70% of whale sharks were categorised as male, with the majority likely to be immature adults. To this date, however, we know little about the more secretive females. We also still do not know for sure where these giants breed or give birth. In a historic first, a mating attempt was documented only this year.

These gentle giants grow slowly and mature very late, which makes them particularly vulnerable to major threats such as fishing, bycatch, or ship strikes. Being an iconic yet vulnerable species, they have been afforded international protection by a number of relevant conventions and agreements, including those on migratory species and international trade.[1] Classified as “Endangered” by the International Union for Conservation of Nature (IUCN), they are also protected in many countries around the world. Also just recently, the Inter-American Tropical Tuna Commission (IATTC) – an organisation responsible for managing fisheries in the eastern Pacific Ocean – introduced new measures to decrease their accidental bycatch and ensure safe release (read more here).

While marine biologists continue studying these enigmatic animals, almost anyone can become a citizen scientist and help to fill these knowledge gaps.[2] Thanks to their striking spot patterns, which are unique to each individual just like fingerprints are to humans, scientists can distinguish animals based on underwater photographs or video. With a growing whale shark tourism, dozens of potential “field researchers” can contribute. To do this, you should have your waterproof camera ready when swimming with these giants. Make sure to capture the spotting pattern on the shark’s left side (between the gills and the pectoral fin) as well as any scarring. Do remember to avoid getting too close or disturbing the shark while doing so – no photograph is ever worth causing harm to any animal or putting yourself in danger.[3]

Whale shark photographs can then be submitted to a global citizen science project such as the Wildbook for Whale Sharks, which helps scientists track the abundance and migration patterns of this species. There, cutting-edge software uses pattern recognition and photo-management tools to help with identification (think Facebook for humans and facial recognition). Since the start of the project in 1992, nearly 10,500 individuals have been identified, with this data often cited as the global population size for the species (including by the IUCN Red List assessment). Interestingly, whale sharks are a rare example of a marine fish whose population size can actually be estimated – that’s largely due to their low numbers and the very fact that specific individuals can be distinguished.

Over nearly three decades, 8,000 citizen scientists working alongside 194 researchers and volunteers have reported more than 66,600 whale shark sightings, with several animals sighted over 100 times. Since the project began, data collected by citizen science enthusiasts has already helped to unlock some whale shark secrets. For example, the number of known whale shark aggregation hot spots around the world increased from 13 to 20 and a high site fidelity among animals, with limited movements of sharks between neighbouring countries, was discovered when analysing the global data. With ever-growing popularity of whale shark tourism and Wildbook itself, the pace of reporting new sightings has picked up. Over the past 5 years, the number of recorded encounters more than doubled and the number of identified individuals increased by 75%. With so many secrets still left to uncover about these oceanic nomads, budding naturalists will hopefully continue contributing to science one whale shark photo at a time. 


© James Morgan / WWF
© James Morgan / WWF
Michael Radores, a Butanding Interaction Officer, swims alongside a whale shark near Donsol, Philippines. Here you can clearly see the area on the animal's left side that needs to be photographed for the identification purposes.
© Erkki Siirilä / WWF
© Erkki Siirilä / WWF
Whale shark feeding with its mouth wide open in La Paz, Baja California Sur, Mexico.

Our WWF shark conservation teams from around the world recognise the potential of citizen science and harness its power for whale shark conservation in many places, including Mexico, Pakistan, and the Philippines.

For a decade our team in Mexico has been collaborating with Tiburón Ballena México (Whale Shark Mexico) research project on their long-term whale shark population research in the La Paz Bay, Gulf of California. As part of the programme, annual monitoring of whale sharks is conducted and youth volunteers are recruited to support the research. These enthusiastic citizen scientists spend anything between 3 weeks up to 3 months in the Bay, where they receive the necessary training and then support the teams with shark spotting, identification, and analysing data. Right in time for this Whale Shark Day, WWF-Mexico published exciting updates on their whale shark conservation work.

In Pakistan, we have been working with local small-scale tuna fishermen to train them in safe handling and release techniques for whale sharks as these gentle giants sometimes get entangled in fishing nets by accident. All the trained fishermen share information on any accidental entanglement cases, successful releases, and even whale shark sightings with WWF. This information is then used by our team for further research and management. Training and release efforts have already significantly contributed to reducing whale shark bycatch mortality in Pakistan’s coastal waters. Since the start of the project in 2012, over 100 individual whale sharks have been safely released, including this whale shark pup.  

Our team in the Philippines has been working with the local authorities and tourism operators in Donsol for over 20 years to help develop successful and sustainable whale shark tourism while conserving the local butanding population, as these sharks are known there. Citizen scientists hailing from the local community are vital to our work in Donsol. Local fishermen, who go out to sea daily, inform local Butanding Interaction Officers (BIOs) if a whale shark is spotted so these can set sail. Once the animal is sighted, officers try to identify the whale sharks, describing their gender and age category. Data collected thanks to the local community in Donsol is invaluable to continue researching the local whale sharks and protect them even better. In addition to working with the local community in Donsol, WWF-Philippines also partners with LAMAVE (Large Marine Vertebrates Research Institute Philippines) to maintain a database of the local whale shark population, using photo-ID technique for distinguishing individual sharks. Images collected by the LAMAVE team and their volunteers help to continue studying the Donsol whale shark population trends and their movement patterns (more about the project here). To celebrate this Whale Shark Day, the WWF team in the Philippines has just released an exciting whale shark population update from Donsol, revealing that this year they've already identified over 100 new individual sharks - the highest number in years!


[1] Whale sharks are protected under the Convention on the Conservation of Migratory Species of Wild Animals (CMS) and the Convention of International Trade in Endangered Species of Fauna and Flora (CITES).

[2] Learn more about citizen science for sharks here: (refer to ‘Tool 6: Citizen Science’)

[3] You may learn more about responsible shark tourism in “Responsible Shark & Ray Tourism: A Guide to Best Practice”.




Magda Nieduzak

Senior Communications Officer, Sharks: Restoring the Balance, WWF-Hong Kong

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