Sharks have survived every mass extinction event in the past 450 million years, yet more than a third of all shark and ray species now face extinction driven by human activity. Their disappearance would ripple through marine ecosystems in ways scientists are still working to understand, and the scale of the problem dwarfs the policy tools currently deployed against it. The question of how to help is not just a matter of goodwill; it involves confronting illegal trade networks, rethinking fishing gear, and changing the way ordinary people interact with the ocean.
A Third of All Species Threatened
The most comprehensive assessment of shark and ray populations found that roughly a third of all chondrichthyans (the group that includes sharks, rays, skates, and chimaeras) are threatened with extinction. Of about 1,200 species assessed, around 90 were classified as critically endangered, 121 as endangered, and 180 as vulnerable. Rays turned out to be in slightly worse shape than sharks, with 36% of ray species threatened compared to about 31% of sharks.1Current Biology. Overfishing drives over one-third of all sharks and rays toward a global extinction crisis Less than half of all assessed species qualified as “least concern,” the category that indicates a population is relatively stable. These are not projections about what could happen decades from now. They describe the state of things as of the early 2020s.
What Sharks Actually Do in the Ocean
The conventional story about sharks runs something like this: they sit at the top of the food chain, control populations of mid-level predators, and keep the whole ecosystem balanced from the top down. Remove the sharks and everything below them spirals out of control. That framing has real support in some coastal systems. A landmark study of the northwest Atlantic found that as populations of 11 large shark species declined over 35 years, 12 of 14 smaller prey species, including rays, skates, and small sharks, increased. The cascading effect was dramatic enough that a boom in cownose rays wiped out a century-old bay scallop fishery.2PubMed. Cascading effects of the loss of apex predatory sharks from a coastal ocean
But the picture is messier than the textbook version. On coral reefs, a major study across Australia’s northern Great Barrier Reef found a fourfold difference in reef shark density between sites, yet no corresponding effect on the density or biomass of mid-level predators or prey fish. The diversity and complexity of coral reef food webs appeared to buffer against the kind of top-down cascading seen in simpler coastal systems.3PubMed. Revisiting the paradigm of shark-driven trophic cascades in coral reef ecosystems A broader review of reef shark ecology concluded that while sharks are often assumed to play a critical role in coral reef dynamics, the actual evidence for that role is thin outside a limited set of species and contexts.4PubMed Central. Defining ecological roles of sharks on coral reefs
So the honest answer is that shark declines can trigger trophic cascades in some ecosystems but not others. In simpler food webs, especially in coastal areas where a small number of large species dominate, losing sharks can reshuffle the entire community. In highly diverse systems like tropical reefs, other processes may compensate. A review of global patterns concluded that sharks can exert strong top-down forces capable of shaping marine communities over large areas and long timeframes, but those effects are not guaranteed everywhere.5PubMed. Patterns and ecosystem consequences of shark declines in the ocean
Beyond controlling prey populations, sharks contribute to ocean nutrient cycles in ways that get less attention. Gray reef sharks, for example, feed offshore and then return to nearshore reefs where they excrete nutrient-rich waste, effectively transporting fertilizer from open water to reef ecosystems and stimulating primary production.6One Earth. Integral functions of marine vertebrates in the ocean carbon cycle and climate change mitigation This kind of nutrient pumping is harder to quantify than predator-prey dynamics, but it adds another dimension to the ecological case for keeping shark populations intact.
Why Sharks Cannot Bounce Back Quickly
What makes shark conservation especially difficult is biology. Most shark species are slow to mature, produce few offspring per reproductive cycle, and have long gestation periods. That combination means depleted populations take decades to recover even under ideal conditions. The species that fetch the highest prices in fisheries, including makos, silky sharks, and bull sharks, tend to be among the largest and slowest to reproduce, which makes them the most likely to be threatened with extinction.7PubMed Central. Linking extinction risk to the economic and nutritional value of sharks in small-scale fisheries This creates a cruel feedback loop: the same traits that make a species economically valuable, large body size and high-quality flesh, also make it biologically unable to withstand heavy fishing pressure.
The Fin Trade and Fishing Pressure
The global shark fin trade remains one of the biggest drivers of overexploitation, and international regulation has struggled to keep pace. In 2013, five threatened shark species were listed under the Convention on International Trade in Endangered Species (CITES), meaning any uncertified or unreported export of their parts became illegal. But a study tracking what actually ended up in Hong Kong, the world’s largest shark fin market, found that fins from four of those five species remained common throughout the period from 2015 to 2021. Eighty-one percent of known shark fin-exporting nations never reported any trade of these species at all, a gap that strongly suggests widespread illegal and unreported trade.8PubMed Central. International trade regulations take a limited bite out of the shark fin trade
Separate monitoring of Hong Kong’s retail dried fin market confirmed the scale of the problem: CITES-listed hammerhead species were consistently among the top five species found in fin trimmings, appearing in every sampling event and at two-thirds of retail vendors surveyed between 2014 and 2016. Many of the countries that were known to land these species were not among those reporting trade to CITES, suggesting fins were frequently imported without the required documentation.9Conservation Letters. CITES‐listed sharks remain among the top species in the contemporary fin trade
DNA barcoding of fins in global markets has revealed that much of the supply comes from coastal fisheries rather than open-ocean operations. Shark fishing effort is concentrated within national waters, especially off the coasts of Australia, Indonesia, the United States, Brazil, Mexico, and Japan.10PubMed Central. Coastal sharks supply the global shark fin trade That finding matters for policy: it suggests that stronger local enforcement of coastal fishing regulations could make a real dent in the global fin supply.
Has CITES Made Any Difference?
Despite the enforcement gaps, CITES listings are not entirely toothless. A review of the impact across eight Southeast Asian countries found measurable, mostly positive changes in governance and fishery management in five of them after shark species were listed. Changes included new policies, better compliance frameworks, and adjustments to fishing effort. But in two countries the effects were predominantly negative, and across the board, the hardest sectors to change were markets, consumption patterns, and community awareness.11Fish and Fisheries. Examining the impact of CITES listing of sharks and rays in Southeast Asian fisheries The overall picture is that international listings create some institutional pressure, but translating that pressure into fewer dead sharks requires functioning enforcement on the ground and in ports, which many countries still lack.
Marine Protected Areas Are Not Enough on Their Own
Marine protected areas (MPAs) are one of the most popular tools in the shark conservation toolkit, and there is evidence they can work for certain species. Satellite tagging of grey reef sharks in the U.S. Pacific Remote Islands Marine National Monument found that two-thirds of tracked sharks were detected exclusively within the protected area for up to about 15 months, suggesting that large MPAs can provide meaningful refuge for reef-associated species with relatively small home ranges.12Biological Conservation. Assessing the effectiveness of a large marine protected area for reef shark conservation
The problem is that many shark species do not stay inside the lines. Highly migratory species like blue sharks and makos routinely cross MPA boundaries, and even shark sanctuaries face incidental mortality from longline fisheries that operate legally in surrounding waters. In Pacific island sanctuaries, longline bycatch mortality ranged from 600 individuals per year in Samoa to over 36,000 in the Federated States of Micronesia. For silky sharks specifically, unsustainable mortality levels were exceeded in two sanctuaries, meaning the sanctuaries were not even maintaining the populations they were created to protect.13PubMed Central. Quantifying longline bycatch mortality for pelagic sharks in western Pacific shark sanctuaries A broad evaluation concluded that while MPAs designed specifically for sharks may be somewhat more effective than general-purpose MPAs, both are generally insufficient as standalone conservation tools.14Fish and Fisheries. Sharks, rays and marine protected areas: A critical evaluation of current perspectives
Reducing Bycatch Without a Silver Bullet
A huge share of shark mortality happens as bycatch, when sharks are caught incidentally in fisheries targeting tuna, swordfish, or other species. Reducing that bycatch is technically possible but there is no single fix. A comprehensive review of gear modifications found that the most effective and practical measures include adding magnetic repellents to static gear, removing lightsticks from longlines, adding artificial lights to gillnets, using escape panels in trawl nets, and deploying non-entangling fish aggregating devices. Cutting leaders at the hook rather than trying to remove hooks from sharks also reduces post-release mortality.15Reviews in Fish Biology and Fisheries. Technical mitigation measures to reduce the bycatch of sharks: there is no silver bullet
Circle hooks, often promoted as a bycatch solution, illustrate the complexity. In pelagic longline fisheries targeting tuna, modeling suggests that combining circle hooks with catch-and-release policies for sharks and marlins can lead to net population increases over time.16Transactions of the American Fisheries Society. Circle Hooks for Pacific Longliners: Not a Panacea for Marlin and Shark Bycatch, but Part of the Solution But in deep-water longline fisheries, circle hooks performed no better than conventional J-hooks at reducing deep-water shark bycatch and actually produced higher catch rates of deep-water species.17Fisheries Research. First assessment of circle hooks as bycatch mitigation measure for deep-water sharks on longline fisheries The lesson is that gear modifications need to be tested in each fishery context rather than assumed to transfer across settings. Monofilament leaders, meanwhile, may cause catch and mortality rates of sharks to be underestimated in longline fisheries, since sharks can bite through them and escape with hooks still embedded, wounded but uncounted.18Fisheries Research. Shark bycatch and mortality and hook bite-offs in pelagic longlines: Interactions between hook types and leader materials
The Economic Argument for Living Sharks
One of the more persuasive arguments for shark conservation is economic. In Palau, researchers estimated that a population of about 100 sharks frequenting popular dive sites was worth far more alive than dead. If those sharks had been caught by fishers, they would have fetched roughly $10,800. As a tourist attraction, the same animals generated revenue across multiple sectors of the economy, including dive operators, hotels, restaurants, and government taxes. Local fishers actually earned more selling fish for consumption by shark divers than they would have earned catching sharks.19Biological Conservation. Socio-economic value and community benefits from shark-diving tourism in Palau: A sustainable use of reef shark populations That math has driven several nations to establish shark sanctuaries explicitly as economic policy, protecting an asset that generates recurring revenue rather than a one-time harvest.
How Media Coverage Shapes What People Think About Sharks
Public support is one of the softer factors in conservation, but it determines political will, funding, and the social acceptability of protective policies. Media coverage plays an outsized role in shaping attitudes toward sharks, and the effects are not entirely what you might expect. A study of how news headlines about sharks influenced public perception found that exposure to shark-related headlines increased both risk perception and acceptance of sharks. That combination seems paradoxical: reading about sharks made people feel the risk was higher but also made them more accepting of sharks as part of the marine environment.20Marine Policy. The impact of news media portrayals of sharks on public perception of risk and support for shark conservation
A separate analysis of U.S. public attitudes found that perceptions of shark bites tracked closely with aggregate media coverage. People who were exposed to more reporting on shark bites were more likely to believe the events are common, even though fatal shark encounters remain extraordinarily rare.21Biological Conservation. Values, attitudes, and media exposure: Public perception of sharks and shark conservation in the USA The takeaway for conservation advocates is that media framing matters enormously. Coverage that includes conservation context, not just the dramatic moment of a bite, can push public sentiment in a direction that supports protective policy.
Citizen Science and What Individuals Can Do
For people who want to contribute directly, citizen science programs have proven genuinely useful for shark research. In the Cayman Islands, a diver-based logging network generated enough data to detect differences in shark abundance between islands, between areas with different levels of human activity, and across seasons. The program identified eight shark species and found that shark abundance was higher in areas with less human disturbance and stronger currents, regardless of whether those areas fell within an official MPA.22PLoS One. The Sharklogger Network—monitoring Cayman Islands shark populations through an innovative citizen science program Similarly, citizen reports of whale shark sightings in the Gulf of Thailand identified 178 individual whale sharks over a 15-year period, with most data coming from a surge in reports driven by social media and local outreach.23PubMed. Citizen science reveals the population structure and seasonal presence of whale sharks in the Gulf of Thailand
Even recreational fishers can produce reliable data. An evaluation of species identifications submitted by shore-based shark anglers found an overall accuracy rate above 97%, meaning trained citizen observers can be trusted to identify what they are seeing.24PLOS ONE. Utility of citizen science data: A case study in land-based shark fishing If you dive, fish, or spend time in coastal waters, logging your encounters and submitting photos to platforms like Wildbook, Spot A Shark, or regional programs turns routine recreation into real data.
Consumer choices also play a role, sometimes in surprising ways. DNA testing of pet food and cosmetics that were not labeled as containing any shark-derived ingredients found that the majority of successfully tested pet food products contained shark, with about 70% of those identified as endangered shortfin mako. A smaller portion of cosmetics also tested positive, containing blue shark, scalloped hammerhead, and blacktip shark material.25Conservation Genetics. Genetic identification of threatened shark species in pet food and beauty care products The practical implication: shark products enter supply chains under generic labels like “fish oil,” “marine collagen,” or “ocean protein.” Choosing brands that source and label their marine ingredients transparently, or that have been independently tested, is one way to avoid accidentally funding the harvest of threatened species.
Cultural Protection Before Modern Conservation
Long before international treaties existed, some communities developed their own frameworks for protecting sharks. The Bajo people of eastern Indonesia hold customary laws that explicitly prohibit killing whale sharks. Their traditional ecological knowledge treats whale sharks and other large marine creatures as guarded by spirits. One elder described the belief plainly: “The fish is guarded by a spirit.” Fishers who accidentally catch a whale shark in a net are obligated to release it. These taboos predate any modern conservation legislation and are rooted in a cosmology that places large marine animals in a category of spiritual protection.26Conservation and Society. Prospects for Whale Shark Conservation in Eastern Indonesia Through Bajo Traditional Ecological Knowledge and Community-based Monitoring Integrating indigenous knowledge into formal conservation frameworks is increasingly recognized as both ethically important and practically effective, especially in regions where enforcement resources are thin and community compliance matters more than legal text.
Survivors Under New Pressure
Sharks survived the asteroid impact that killed the dinosaurs about 66 million years ago, an event that wiped out most large marine predators. Fossil records show that shark dental diversity, a proxy for the range of ecological roles they filled, remained nearly static across the extinction boundary while other top predators suffered dramatic collapses.27Current Biology. Sustained Fossil Shark Diversity Despite Marine Extinction A closer look at tooth shape data found that while overall shark diversity held steady, some apex predator species with large, triangular, blade-like teeth did disappear, suggesting the extinction was selective rather than random.28PLOS Biology. Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction The survivors went on to diversify extensively over the following tens of millions of years, filling the ecological niches vacated by the species that were lost. That resilience across geological timescales makes their current rate of decline all the more striking. The forces that failed to eliminate them, including catastrophic asteroid impacts, ocean chemistry shifts, and ecosystem collapses, bear little resemblance to the relentless, distributed pressure of modern fishing fleets and unregulated trade.