Numbers about sharks come in several kinds. Some are counts of confirmed events: the International Shark Attack File confirmed 65 unprovoked shark bites on people worldwide in 2025. Some are counts of animals identified one at a time: in 2011 researchers counted about 219 mature and sub-adult white sharks off Central California by photographing dorsal fins, whose markings are unique to each shark, and whale sharks can be told apart in photos in a similar way, because each whale shark has its own spot pattern, like a fingerprint. Some are assessments of whole groups of species: in a 2021 global reassessment, 391 of 1,199 shark, ray and chimaera species, or 32.6 percent, were threatened with extinction (arithmetic: 391 divided by 1,199 is about 0.326, nearly one species in every three). And some state their own uncertainty, as when, as of November 2026, one study put the age of a large female Greenland shark at about 392 years, give or take 120.
A count of bites depends first on a definition. The International Shark Attack File calls a bite unprovoked only if a live person is bitten in the shark's natural habitat with no provocation of the shark, and it calls a bite provoked when a person starts the contact, for example by grabbing a shark or feeding it. Many reported shark attacks are not bites at all, or are caused by other animals. Two files can also count differently: the Attack File includes bites on people aboard boats, such as in fishing accidents, while the Australian Shark Incident Database does not, which can make their yearly totals confusing to compare.
The United States had 25 of the 65 unprovoked bites confirmed in 2025, or 38 percent (arithmetic: 25 divided by 65 is about 0.385), and Florida had 11. The 65 were close to the recent averages: 61 a year from 2020 to 2024, and 72 a year over ten years. So the 65 was 4 more than the 2020-2024 average and 7 fewer than the ten-year average (arithmetic: 65 minus 61, and 72 minus 65). Bite counts can look dramatic from year to year because the real numbers are small.
As of November 2026, worldwide there are about 70 unprovoked shark bites on people in a typical year. From 2004 to 2013 the number of people bitten ranged from 53 to 81 a year (a spread of 28, arithmetic: 81 minus 53), a very small number of bites next to the millions of people who go in the sea. Worldwide bites have not been climbing lately: as of November 2026, they fell over the last decade, likely thanks to beach safety and public awareness. A bite count can be sorted by species as well. Of the hundreds of kinds of sharks, three account for most unprovoked bites: the white, tiger and bull sharks. Next to more than 500 kinds of sharks as of November 2026, three kinds are fewer than 1 percent of the total (arithmetic: 3 divided by 500 is 0.006), so the count of bites is mostly a count of three kinds.
Counting what fishing takes is a different task from counting bites. Sharks are caught for their fins, meat and liver oil, and for sport, and shark fins are sold for shark fin soup, mostly in Asia. A 2006 study estimated that 26 to 73 million sharks are killed each year, working from fin auction records in Hong Kong. The team translated the weights of fins sold into numbers of sharks, and Nature called the estimate conservative. The top of the range is nearly three times the bottom (arithmetic: 73 divided by 26 is about 2.8). A 2013 study gave another estimate: about 100 million sharks killed each year, with a possible range of 63 to 273 million. The top of that range is more than four times the bottom (arithmetic: 273 divided by 63 is about 4.3), and the two ranges overlap only between 63 and 73 million (arithmetic: the 2013 range begins at 63 and the 2006 range ends at 73). The 2013 figure of 100 million is 27 million above the top of the 2006 range (arithmetic: 100 minus 73).
Several shark numbers point down. Sharks grow slowly and have few young, so fishing can wipe out a population faster than it recovers. As of November 2026, overfishing threatens every one of the 391 shark, ray and chimaera species at risk of extinction. As of November 2026, open-ocean sharks and rays have fallen 71 percent in numbers since 1970, which leaves 29 percent of the 1970 level (arithmetic: 100 minus 71), and about three-quarters of those species are threatened. In 2016 the IUCN classed the whale shark as Endangered, and its numbers were judged to have more than halved over about 75 years. As of November 2026, the great white is listed as Vulnerable by the IUCN, and its numbers are thought to be falling worldwide.
Some numbers are recovered from rock. As of November 2026, sharks have lived in the sea for more than 400 million years, long before the first trees about 385 million years ago (arithmetic: 400 minus 385 is 15, so the gap is at least 15 million years). Doliodus problematicus, an early shark, lived about 400 million years ago in the Devonian Period, long before the dinosaurs. Fossils from Pacific Ocean sediments show that about 19 million years ago the number of open-ocean sharks suddenly crashed, and about 90 percent of them vanished. As of November 2026, fossil shark scales from that die-off show a big loss in the variety of scale shapes, about 70 percent, which scientists read as a loss of about seven in every ten shark types. As of November 2026, scientists do not yet know why the die-off happened.
Estimates from the deep past can be disputed, and megalodon shows how. Megalodon was one of the largest sharks that ever lived, and it is known mostly from its teeth. Scientists disagree about how big it grew: as of November 2026, one study says no more than about 15 meters (50 feet), while another estimates 65 feet, a difference of 15 feet between the two (arithmetic: 65 minus 50). To make predictions about megalodon's body, researchers pooled measurements of five living sharks, not only the great white, namely the great white, the shortfin and longfin makos, the salmon shark and the porbeagle. Tooth-size estimates put most megalodon sharks at Panama's Gatun Formation in the newborn or juvenile stage, from about 2 meters (7 feet) up to about 10.5 meters (35 feet) long.
The date of megalodon's end has been revised as well. Complete fossil sharks are rare because cartilage is softer than bone, so scientists mostly find teeth, and as of November 2026 a reanalysis of megalodon fossils put its extinction around 3.5 to 3.6 million years ago, roughly a million years earlier than the 2.6 million years proposed before (arithmetic: 3.5 minus 2.6 is 0.9, and 3.6 minus 2.6 is 1.0). No reliable megalodon fossil is younger than about 3.6 million years old, so it probably went extinct then. The new window of 3.5 to 3.6 million years is only 0.1 million years wide (arithmetic: 3.6 minus 3.5), while the revision itself moved the date by about a million years.
Even a litter of pups is a count, and the counts vary from one kind of shark to another and from one source to another. Lemon sharks give birth to live pups after a pregnancy of about a year, 10 to 12 months, in litters of fewer than 20 pups: 4 to 19 by one count and 4 to 17 by another. Tiger shark litters are large for a shark, up to about 80 pups. Blue shark pregnancy lasts 9 to 12 months, and litters can be very large, with more than 100 pups documented, though usually they are smaller, about 15 to 50 pups. Reported as of November 2026, one whale shark female was found carrying about 304 embryos, a litter of more than 300 pups, which is more than six times the usual upper figure for a blue shark litter (arithmetic: 304 divided by 50 is about 6).
Age is a count in another sense too: how long a shark takes to become an adult. As of November 2026, Greenland sharks are thought to reach adulthood only at around 150 years old, and white sharks are thought to live from about 30 to more than 70 years. White sharks grow slowly: as of November 2026, males mature at about 26 years and females at about 33, a gap of 7 years (arithmetic: 33 minus 26), though some estimates for females say at least 30. A Greenland shark's age at adulthood is more than four times a female white shark's, at 33 years (arithmetic: 150 divided by 33 is about 4.5).
Some numbers state their own uncertainty, and some move when the method changes. The Greenland shark's age was worked out by radiocarbon dating the center of its eye lens, because its soft vertebrae have no growth bands. Scientists used the radiocarbon that nuclear-bomb tests of the 1950s and 1960s left in the ocean to age white sharks, and one male was about 73 years old, far older than earlier estimates. For shortfin mako sharks, the age estimate depends on whether the vertebrae add one growth band pair a year or two: some studies assumed two, others one, and recent work found one a year. Each of these ages is a number that carries its method with it.
Words to know
- unprovoked: without provocation
- chimaera: ratfish relative
- threatened: at risk
- radiocarbon: dating signal
