Whale sharks are Endangered on the IUCN Red List of Threatened Species. The global population is estimated to have fallen by 50–79% over the last three generations — for a fish that takes 25 to 30 years to breed, that is roughly the past 120 years. Decades of targeted fishing did most of the damage. Today the biggest problems are whale sharks caught accidentally in fishing nets and whale sharks killed by ships, and neither is easy to count. This guide draws on Whale Sharks: Biology, Ecology, and Conservation, the first scientific textbook on the species, and on the current Red List assessment, which was led by MMF’s Dr Simon Pierce.
Why are whale sharks endangered?
Two things combined: a lot of killing, and a species built to recover slowly.
The killing came first. From the 1980s a market for whale shark meat, liver oil, and fins turned an occasional catch into a commercial fishery across the Indo-Pacific. The current Red List assessment infers a population reduction of more than 65% in the Indo-Pacific over three generations, and of at least 30% in the Atlantic. Roughly 75% of the world’s whale sharks live in the Indo-Pacific, so the global figure is dominated by that decline: 50–79% overall — Endangered, one step short of Critically Endangered.
The slow recovery is biology. Male whale sharks mature at around 25 years old, females later still, and the Red List uses a generation length of 40 years — meaning the average breeding animal alive today is four decades old. The oldest whale shark ever aged was 50. A species like that cannot replace the losses of one bad decade in the next one. Our reproduction guide covers what little is known about how they breed; the short version is that every adult female matters a great deal.
Two other features made whale sharks unusually easy to catch. They gather in predictable coastal places to feed, season after season — see the size guide for why those gatherings are mostly young males. And they feed slowly at the surface, unbothered by boats, so centuries-old methods still work on them. Being harmless to people has been no protection at all.
How many whale sharks are left?
Nobody knows, and any single global number you see quoted deserves suspicion.
What we do have is a count of individuals we can recognize. Every whale shark carries a unique pattern of white spots, so photographs work like fingerprints, and more than 17,000 individual whale sharks have now been identified in the global database hosted on Sharkbook.ai. A global review of over 50 aggregation sites, covering more than 13,000 identified sharks, which our own Dr Chris Rohner co-authored, gives the best sense of scale — and the striking result is how small the numbers are. Those catalogs count individuals recognized over many years, not animals present at one time. At Ningaloo Reef in Western Australia, the largest known aggregation site, about 2,500 individual sharks have been identified since the 1980s, from more than 30,000 encounters with sharks. Most other long-running sites have identified hundreds to low thousands.
There is a second way to ask the question: not how many are there, but how much of the species’ former range still holds healthy, fully functioning populations. The IUCN Green Status of Species does exactly that, scoring a species against its own unimpacted state. Our team built the first Green Status assessment for whale sharks, published in the textbook, and the answer was a Species Recovery Score of about 29%. That score is not a headcount. It divides the species’ range into spatial units and scores each one as absent, present, viable, or ecologically functional, so 100% would mean whale sharks were functional in every unit they historically occupied. The plausible range ran from 29% to 55%, and that width is itself the finding: we lack long-term abundance data for the Atlantic and eastern Pacific.
Are whale sharks still hunted?
Targeted hunting is now rare. It was not always, and that history explains the decline.
The fisheries that caused the crash
Whale sharks were caught commercially from at least the 1850s, mostly for liver oil used to waterproof wooden hulls. Then the market changed. Before 1985, a multi-ton whale shark sold in Taiwan for US$200–300; by 1997 whale shark was the most expensive shark meat in the country, and a 10-ton animal could fetch around US$70,000. Taiwanese catches peaked at 272 sharks in 1996. Rising prices pulled in suppliers elsewhere: 624–627 whale sharks were taken from four Philippine fishing sites between 1990 and 1997, and when the Philippines protected the species in 1998 — the Maldives having closed its own whale shark fishery in 1995 — Indian exporters encouraged fishers there to target it instead. Surveys in Gujarat recorded about 600 landed in 1999–2000 alone.
Then the fisheries closed, one after another — the Maldives in 1995, the Philippines in 1998, India in 2001, and Taiwan through quotas cut to zero between 2001 and 2007. That was a genuine conservation victory. Mainland China is the outstanding uncertainty: interview surveys in 2008–2010 estimated more than 1,000 whale sharks a year taken there as incidental catch, and an investigation of the Puqi processing hub in Zhejiang province documented at least 600 sharks a year between 2010 and 2013. Chinese shark processing has since contracted sharply, but small quantities of whale shark products still turn up in trade surveys, and the current status of that catch is unclear.
Bycatch is the bigger problem now
“Bycatch” means caught by accident while fishing for something else. It is now the leading known cause of whale shark deaths, and far harder to manage than a fishery you can simply close.
Whale sharks follow tuna, so tuna nets find whale sharks. In the western and central Pacific, observers recorded 1,809 whale sharks encircled by purse-seine vessels between 2006 and 2016. Most are released, and best-practice release methods are now mandatory in the Indian and Pacific Oceans, where deliberately setting nets around whale sharks is banned. An expert survey estimated that about 10% still die after release. Where sharks are lifted by the tail or released with ropes attached, the real figure will be worse.
Gillnets are the greater worry. Tuna gillnets in the northern Indian and Pacific Oceans can be over 30 kilometers (19 miles) long and account for around a third of Indian Ocean tuna catch, with almost no observer coverage. Coastal gillnets and ring nets catch whale sharks throughout the tropics. India protected the species in 2001, yet 79 whale sharks were accidentally caught and landed there in the following decade — and those are only the ones somebody counted. Most bycatch goes unrecorded unless a survey is looking for it.
Do boats kill whale sharks?
Yes, and this is the threat we have most underestimated.
Whale sharks spend much of their lives in the top few meters of water, exactly where ships are. Combining satellite tracks with global vessel-traffic data, an international study we contributed to found that 92% of whale shark space use overlapped with large cargo and tanker traffic, and that tracked sharks spent almost half their time in water shallower than 20 meters (66 feet). More disturbingly, several tags recorded the signature of a shark sinking, apparently dead, after passing through a busy shipping route. Collision risk also correlated with reported ship-strike deaths.
That points to a hidden death toll. Whale sharks are negatively buoyant: a dead one sinks rather than washing ashore. For large whales, which float, only a fraction of fatal strikes are recorded — for whale sharks, essentially none are. This “cryptic” mortality may explain the uncomfortable pattern conservationists keep meeting: populations still declining despite legal protection and very little fishing.
The visible injuries are the tip of it. In Oman, about half the sharks we examine carry propeller scars. Whale sharks do heal remarkably well — major wounds close quickly, though the rate depends on the type of injury — but the scarred sharks we photograph are, by definition, the ones that survived, so visible injuries cannot measure the full lethal toll. Whale sharks are unlikely to survive propeller or impact wounds from large vessels, which is why the worst collisions are the ones least likely to leave a living animal to record. In the Maldives, injured sharks stayed longer in the tourism area, which is not a good sign for their condition. A follow-up analysis ranking priority sites for collision management, co-authored by Chris Rohner, found most core whale shark habitats small enough that rerouting or slowing ships would cost industry very little.
Is whale shark tourism bad for whale sharks?
Badly run tourism harms sharks. Well-run tourism is one of the strongest reasons countries protect them. Both statements are true, and the difference is management.
The harm is real but mostly sublethal. Our work at Praia do Tofo in Mozambique showed that how close a boat comes predicts whether a shark takes evasive action, and shortens the encounter — the study that produced Mozambique’s first code of conduct. Research at Panaon Island in the Philippines reached the same conclusion about vessel proximity and swimmer behavior. Touching, blocking a shark’s path, free-diving at its head, and flash photography all trigger avoidance, which interrupts feeding — and since a feeding bout can last hours, that costs energy at exactly the wrong moment. Across sites, the Red List assessment finds that growing whale shark tourism without effective risk management has been associated with declining abundance, higher injury rates, and changes in behavior. Tourism also concentrates small boats where sharks feed, and that is where propeller injuries come from.
The counterweight is money and attention. Swim-with tourism now operates at 27 wild sites in 19 countries and territories, drawing around 980,000 people a year and worth more than US$139 million as of 2019 — numbers that give governments a reason to act. We measured US$1.5 million from a single three-month season at Nosy Be in Madagascar with the Madagascar Whale Shark Project, and roughly US$2.4–3.6 million at Mafia Island in Tanzania in 2025, where 46% of visitors told us they would not have come without the sharks. A live whale shark is worth far more, for far longer, than a dead one, and well-managed tourism can generate sustained local benefits. Whether it does depends on how the industry is run: the textbook is blunt that the people who earn from tourism are often not the ones who were fishing, that a few large operators can capture most of the trade, and that unequal access has caused real conflict between neighboring communities.
Because tourism happens at a handful of specific sites, it affects a minority of the world’s whale sharks and kills very few. It is a local management problem, not a driver of the global decline. If you are planning a trip, our guide to swimming with whale sharks explains how to pick a good operator.
How will climate change affect whale sharks?
Mostly by moving them, and by moving their food.
Whale sharks track warm water: their seasonal range roughly follows the 21–22°C (70–72°F) line at the surface. As that line shifts toward the poles, so do the sharks. There are now records from the Azores, mainland Portugal, and even the Mediterranean, places they were not previously known to reach. Models project that this poleward creep continues while the overall range shrinks slightly, as parts of the current tropical range become less suitable.
The complication is that redistribution does not happen in a vacuum. A study we co-authored found that as warming pushes whale sharks into new water, their future core habitat is projected to overlap more heavily with shipping — climate change and ship strikes compound each other rather than acting separately. Falling oxygen levels in the open ocean are a further concern, because low-oxygen water effectively removes usable habitat.
Direct heat death looks unlikely: whale sharks tolerate a wide temperature range and can dive to cool off. The risk runs through their food. Many gatherings depend on one narrow seasonal event — a plankton bloom, or a fish spawning aggregation — and those events are sensitive to temperature. A gathering that exists because of one predictable pulse of food can stop existing if the pulse moves.
Do whale sharks eat plastic?
They do, unavoidably, because they filter enormous volumes of water. In work we co-authored off Java in Indonesia, a feeding whale shark was estimated to take in up to about 137 pieces of plastic an hour. Confirmed deaths from plastic have been reported from Japan, Malaysia, the Philippines, and Thailand — a hardened straw that punctured the gut, a plastic bag blocking the intestine, litter lodged in the gills.
Honesty matters here: those are individual cases, not a measured population effect. Plastic is assessed as a low-impact threat globally, mainly because it is data-deficient rather than proven harmless. Sublethal effects — hormone disruption, chemical uptake from plastic surfaces — are plausible and barely studied. Whale sharks make a good flagship for the plastics problem, but plastic’s contribution to their population decline has not been quantified.
What happened to Mozambique’s whale sharks?
They collapsed. Whale shark sightings at Praia do Tofo fell by 87% over 15 years, and the largest sharks — those approaching breeding size — fell by 99%. It is the clearest, hardest evidence we have that this species is still in trouble, and it is our own data.
Our early logbook analysis at Praia do Tofo recorded a 79% decline in standardized whale shark sightings between 2005 and 2011. Extending the work to a 15-year series covering 706 identified sharks, we documented an 87% decline in sightings and an 89% fall in abundance. Sharks of 7 meters or more — the ones approaching breeding size — declined by 99%. It is among the steepest declines recorded at any major whale shark aggregation, and it happened while the sharks were nominally safe from targeted fishing.
Mafia Island in Tanzania is the useful counterexample. Capture-mark-recapture models fitted to eight years of photo-identification there show a stable population with high survival. We published a caveat alongside it: only a change of roughly 30% would have been detectable over that period. More transient aggregations may need 15 to 20 years of data before any trend can be called. Two sites, 1,500 kilometers apart, one collapsing and one holding steady. That is why long-term monitoring is not optional, and why we keep going back to the same places year after year.
Are whale sharks protected?
Yes. Whale sharks are listed on Appendix I of both the Convention on Migratory Species and CITES, and more than 60 countries and territories protect them nationally. That protection is comprehensive on paper and uneven in practice.
Whale sharks were listed on Appendix II of the Convention on Migratory Species (CMS) in 1999 and uplisted to Appendix I in 2017, which obliges range states to prohibit taking the species and to conserve its habitat and migration routes. MMF led the technical proposal behind that uplisting. International trade was regulated under CITES Appendix II from 2003, and at the 20th Conference of the Parties in November 2025 whale sharks were uplisted to Appendix I — a full ban on commercial international trade — in force from 5 March 2026.
National protection now covers most of the species’ range: more than 60 countries and territories protect whale sharks specifically or ban commercial shark fishing outright. The Philippines protected them in 1998 and India in 2001. Mozambique banned their capture under its 2020 marine fisheries regulations, in force from January 2021, after years of our research and advocacy, and Madagascar wrote a whale shark tourism code of conduct into law in December 2023. Gaps remain in a few countries with significant aggregations, including Oman and Qatar.
The honest caveat is the one the textbook makes: a signature on a treaty is not a management action. There is a persistent gap between countries accepting a listing and countries implementing it, usually because of capacity and funding rather than intent. Mozambique’s numbers show what that gap costs.
What is being done to save whale sharks?
Fishing and vessel strikes are the two priorities, and both have practical, affordable answers.
Safe release training for net fisheries. Whale sharks caught in nets often survive if handled properly and die if they are not. Programs in India and Pakistan have shown that training fishers in release technique works. Better reporting of where and how often sharks are entangled is the missing input.
Speed limits and rerouting at aggregation sites. This is the transferable win. Ship-strike measures already work for large whales, and whale shark gatherings are small and seasonal — the analysis of priority sites for collision management found most core habitats compact enough that slowing or shifting traffic would cost operators little.
Site protection where the sharks actually are. Whale sharks return to the same places, which makes area-based protection effective even for an animal that crosses oceans. At Mafia, acoustic tags showed that sharks which vanish from the surface between March and September do not leave at all — they stay inside a core area of about 13 square kilometers. Speed limits and net restrictions in an area that size would deliver real protection.
Enforced codes of conduct for tourism. The elements are well established: no touching, no blocking a shark’s path, no flash, one boat per shark, minimum distances, capped operator numbers, trained guides, and real penalties. Voluntary codes work as well as legislation where operators police each other, and fail where nobody does.
Forensic tracing of anything found in trade. We argue in the textbook that when whale shark products do turn up for sale, genetic techniques already used on other sharks could identify which population they came from, which would tell enforcement agencies where to look.
Fixing the research-permit bottleneck. The same trade rules that restrict whale shark products make it very hard to send even tiny tissue samples between countries for analysis, and the resulting delays — months to years — hold up the global genetic work needed for regional assessments. We flag this as a problem needing reform, not a solved one.
Long-term monitoring. Nothing above can be evaluated without it. Our Global Whale Shark Program runs continuous photo-identification, tagging, and abundance modeling at five sites, and feeds the results into the global assessments that drive policy. The Mozambique decline was only detectable because somebody had been counting for 15 years.
How can I help whale sharks?
Adopt a whale shark, choose your tour operator carefully, and report your sightings. Those three things genuinely help, and we use all three.
Adopt a whale shark. Adoptions fund the fieldwork — the surveys, the tags, the boat time — that produces the population trends behind Red List and CITES decisions.
Choose your tour operator carefully. Tourism revenue is the reason several countries protect this species, so going is better than not going — provided you go with an operator that keeps its distance, does not chase or crowd sharks, and briefs you properly. Our swim-with-whale-sharks guide covers what to look for.
Report your sightings. Photograph the left flank of the shark, behind the gills and above the pectoral fin, and submit it to Sharkbook.ai — the spot pattern identifies the individual. Photographs from divers and tourists make up a large share of the global catalog, and several trends on this page rest on them.
Why it matters for conservation
The whale shark is the largest fish alive, it is harmless, and it is in trouble for reasons that are fixable. The hard part — stopping the fisheries — has largely been done. What remains is unglamorous and achievable: counting the bycatch, slowing the ships at a few dozen places, enforcing the rules that already exist. Our Green Status work put whale shark recovery potential at 100% within a century, a rare thing to be able to say about an Endangered species. It only happens with sustained effort.
You can support that work directly by adopting a whale shark.
Further Reading:
- Pierce, S.J., Rohner, C.A., Perry, C.T., Jabado, R.W., Norman, B., Reynolds, S., Womersley, F., Robinson, D., Graham, R. & Araujo, G. 2025. Rhincodon typus. The IUCN Red List of Threatened Species 2025: e.T19488A126673248. Read the assessment
- Rowat, D., Womersley, F., Norman, B.M. & Pierce, S.J. 2021. Global threats to whale sharks. In: Dove, A.D.M. & Pierce, S.J. (eds), Whale Sharks: Biology, Ecology, and Conservation, pp. 265–286. CRC Press.
- Pierce, S.J., Grace, M.K. & Araujo, G. 2021. Conservation of whale sharks. In: Dove, A.D.M. & Pierce, S.J. (eds), Whale Sharks: Biology, Ecology, and Conservation, pp. 287–312. CRC Press.
- Ziegler, J.A. & Dearden, P. 2021. Whale shark tourism as an incentive-based conservation approach. In: Dove, A.D.M. & Pierce, S.J. (eds), Whale Sharks: Biology, Ecology, and Conservation, pp. 199–236. CRC Press.
- Womersley, F.C., Humphries, N.E., Queiroz, N., et al. 2022. Global collision-risk hotspots of marine traffic and the world’s largest fish, the whale shark. PNAS 119: e2117440119. doi:10.1073/pnas.2117440119
- Auditore, L-M., Pierce, S.J., Prebble, C.E.M., et al. 2025. A 15-year time series shows major declines in whale sharks in southern Mozambique. Aquatic Conservation 35: e70224. doi:10.1002/aqc.70224