How Long Do Great White Sharks Live? Age and Growth

How long do great white sharks live?

The best evidence today suggests that the great white shark is a long-lived, slow-growing fish. In the 2014 study, scientists dated the vertebrae of eight white sharks from the northwest Atlantic. The oldest male, measuring about 4.9 m (16 ft) from snout to the fork of the tail, was estimated at 73 years old, and the oldest female, about 5.3 m (17 ft) to the fork, at about 40 years.

These figures come from sharks in the northwest Atlantic. White sharks in other regions may grow and mature at somewhat different rates, and scientists are still studying them. There are no records from captivity to compare, since great whites have never survived long in aquariums.

How do scientists tell a shark’s age?

Sharks have no bones, but their vertebrae are made of cartilage hardened with calcium salts. As a shark grows, each vertebra adds layers, a little like the rings of a tree. In a thin slice of vertebra, these show up as light and dark bands. Scientists usually assume that one light band and one dark band, a band pair, form each year.

Counting band pairs works reasonably well in young sharks. In old sharks, though, growth slows so much that the outer bands become extremely thin and crowded at the edge of the vertebra. Some may be impossible to see, so counting bands can underestimate the age of large, old sharks. That is exactly what the radiocarbon study suggested.

The radiocarbon “bomb clock”

Nuclear weapons tests in the 1950s and 1960s released large amounts of radioactive carbon-14 into the atmosphere. This carbon spread into the oceans and into the food web, and its level peaked and then fell in a known pattern over time. Any animal growing during those years laid down this extra carbon-14 in its tissues.

In a white shark’s vertebrae, the layers formed during the 1960s carry this bomb signature. By finding the band with the carbon-14 spike and matching it to the known timeline, scientists can tell which calendar year that band formed. That gives an independent check on age, rather than relying on counting bands alone.

The results showed that, in older sharks, the band counts had missed many years. The study’s authors concluded that white sharks live much longer than previously estimated, perhaps 70 years or more, and are therefore more sensitive to fishing and other human-caused deaths than once thought.

Slow growth and late maturity

A 2015 study by two of the same researchers, based on vertebrae from sharks in the northwest Atlantic, estimated that males mature at about 26 years, when they are about 3.4 m (11 ft) long, and females at about 33 years and 4.6–4.9 m (15–16 ft). An influential study from 1985 had suggested maturity at only 9–10 years, which shows how much estimates have changed.

Once mature, females breed slowly. Pregnancy is thought to last about a year, litters of about 2–10 pups have been recorded, and a female probably gives birth only every two or three years. A shark that reaches maturity at 33 and lives into her 60s or 70s might therefore produce only a modest number of litters in her lifetime. How big these sharks become over all those years is covered in How big do great white sharks get?

What do great white sharks die from?

Young sharks face the greatest danger. Pups and juveniles can be eaten by larger sharks, including older white sharks. A 2018 study of white sharks off eastern Australia and New Zealand estimated that juveniles had an annual survival rate of more than 70% and adults more than 90%, so the chances of reaching old age rise sharply once a shark is fully grown.

Adults have only one regular natural predator, the orca, which has killed white sharks off California and South Africa. The main threats come from people: white sharks are caught by accident in longlines and gillnets, and they die in nets and baited lines set to protect swimming beaches in Australia and South Africa.

How great whites compare with other long-lived sharks

Many sharks live a long time, and several outlive the great white.

The Greenland shark of the cold North Atlantic and Arctic holds the record for any vertebrate. Its age was estimated from the lenses of its eyes, which grow layers throughout life, as explained in How long do Greenland sharks live? Animals from tortoises to quahog clams are compared in longest-living animals.

Why long lives make great whites vulnerable

A long life sounds like an advantage, but for a species that matures in its late 20s or 30s and has few young, it is a weakness when deaths increase. If too many sharks are killed before they breed, populations can take decades to recover.

This is one reason the IUCN lists the great white shark as Vulnerable worldwide and Critically Endangered in European and Mediterranean waters. Legal protection in countries such as South Africa, the United States and Australia has helped, and growing numbers off Cape Cod and California suggest that protected populations can recover, slowly.