How Long Do Sea Turtles Live? Lifespan by Species

Sea turtle lifespan by species

The table below uses NOAA Fisheries estimates for age at maturity and lifespan, which are among the most widely cited. Every figure is an estimate with a wide margin of error, and maturity ages differ between populations of the same species.

Two patterns stand out. Hard-shelled species that feed on slow-growing food, such as the green sea turtle grazing on seagrass, take the longest to mature. The leatherback sea turtle grows remarkably fast for a turtle, fueled by huge quantities of jellyfish, and reaches adulthood earlier despite becoming much bigger.

Why sea turtle lifespans are hard to measure

Several things make sea turtle ages difficult to pin down:

• They live longer than research projects. A turtle tagged as a hatchling may not return to a beach for 30 years, by which time tags have often fallen off or the study has ended.
• They disappear for years. Young turtles spend their first decade or more drifting in the open ocean, a period long known as the “lost years,” where they are rarely seen.
• The shell does not record age. Unlike tree trunks, the scutes on a turtle’s shell wear and peel, so they cannot be counted like rings.
• Growth slows with age. Adults grow very little, so two turtles of the same size can differ in age by decades.

Captive turtles do not solve the problem. They are fed regularly and protected from predators, so they grow faster and may live differently than wild turtles, and few have been kept long enough to give reliable maximum ages.

How scientists estimate a sea turtle’s age

The main method is skeletochronology. When a turtle dies and washes ashore, researchers can take its humerus, the upper bone of the front flipper, and cut a very thin cross section. Under the microscope, the bone shows growth layers, roughly one per year, much like tree rings. Counting the layers gives an age estimate, and comparing their widths shows how fast the turtle grew at different stages.

The method has limits. In older turtles, the innermost layers are gradually reabsorbed and the outermost layers become crowded together, so ages of very old turtles tend to be minimum estimates. Scientists check their counts against turtles of known age, for example individuals tagged as hatchlings or raised in captivity and later released.

Long-term tagging fills in the rest. Programs on nesting beaches in places such as Florida, Costa Rica and Australia have tagged thousands of females since the mid-20th century. Some females have been recorded returning to nest over periods of two decades or more, which shows that adults can keep breeding for a long time after maturity.

What decides how long a sea turtle lives?

Life expectancy changes dramatically with age. Eggs and hatchlings face ghost crabs, birds, raccoons and fish, and only a tiny fraction survive their first years at sea; see how many baby sea turtles survive? Once a turtle reaches the size of a dinner plate and larger, the risk from predators drops sharply, and a full-grown adult is threatened mainly by large sharks and, rarely, killer whales.

For adults, the biggest causes of early death today are human: drowning in fishing nets and on longlines, boat strikes, swallowed plastic and, in some places, illegal hunting. Disease, such as the tumor-causing fibropapillomatosis in green turtles, and cold-stunning during sudden winter cold snaps also kill turtles. Food supply matters too, because well-fed turtles grow faster, mature earlier and stay in better condition.

How sea turtles compare with other turtles

Sea turtles are long-lived, but they are not the longest-lived turtles. Giant tortoises on land hold the records, and some freshwater and box turtles can also pass 50 years. For a wider comparison, see how long do turtles live?

Popular claims that sea turtles routinely live for 150 years or more are not backed by evidence. The truth is impressive enough: a loggerhead sea turtle that hatches on a Florida beach today may not lay her first eggs until the 2060s and could still be nesting decades later.

Why a long life matters for conservation

Late maturity and a long life make sea turtles vulnerable. A population depends on adults surviving for many years and nesting again and again, so the loss of even a small number of adults, for example in fishing gear, can cause a decline that takes decades to show up and decades more to reverse. That is why protecting large juveniles and adults at sea is as important as guarding nests on the beach.