For decades, green sea turtles were considered an endangered species whose survival depended on rigorous protection. In late 2025, the International Union for Conservation of Nature (IUCN) drew the conclusion: it upgraded the species from "Endangered" directly to "Least Concern" and skipped intermediate categories "Vulnerable" and "Near Threatened". Since the 1970s, the global population of the green sea turtle has grown by 28 percent. This category jump is no coincidence: the IUCN skipped two categories because the recovery was deemed stable and broad enough.
From the Brink of Extinction: Half a Century of Decline
Around 1900, green sea turtles (Chelonia mydas) populated tropical and subtropical seas in large numbers. In the 20th century, populations collapsed: meat and eggs were considered delicacies, nesting beaches were developed, trawl nets caught turtles as unwanted bycatch. In the 1970s, scientists counted at major nesting beaches only fractions of historical nesting densities. The IUCN classified the species as endangered; the U.S. listed several regional populations in 1978 under the Endangered Species Act. In Tortuguero on the coast of Costa Rica, the world's most significant Caribbean nesting beach for this species, populations had fallen to historic lows.
The Turnaround: Protection Laws and a Critical Device
The reversal began in the 1970s with international agreements restricting trade and hunting. The technically most significant step came in 1989: the U.S. made so-called Turtle Excluder Devices (TEDs), flaps in trawl nets that let turtles pass, mandatory for domestic trawlers. According to NOAA data, the devices reduced annual bycatch losses from roughly 71,000 to under 4,600 animals, a reduction of 94 percent. NOAA estimates TED effectiveness at 97 percent when correctly installed. In parallel, nesting beaches were protected and monitored, and artificial light that disturbs nesting turtles was regulated. At Mexican nesting beaches, annual nest numbers increased by 134 percent between 1984 and 2023.
In Comparison: Animal Comebacks Through Consistent Protection
The comeback of the green sea turtle stands alongside other species brought back from the brink of extinction through targeted protection. The Iberian lynx numbered fewer than 100 individuals in Spain and Portugal in 2002; in 2024 there were over 2,000 according to the IUCN. The bearded vulture, extinct in the Alps in 1913, has been reintroduced since 1986; today over 300 animals fly free. The humpback whale recovered after an international whaling moratorium in 1986 without targeted reintroduction: from an estimated 5,000 to today over 80,000 animals. What unites these successes: protection had to be internationally coordinated. No turtle and no whale recovers if an important transit country or nesting region withdraws from the agreement.
What Still Threatens the Success
The IUCN downlisting is not an all-clear signal. Four of eleven regionally defined population segments continue to decline. Florida, the largest U.S. nesting area by area, still lists its local population as endangered under the Endangered Species Act. Three structural risks remain. Plastic in the world's oceans ends up in turtle stomachs and blocks digestion. Climate change raises sand temperatures at nesting beaches and alters the sex ratio of hatchlings: warmer sand produces more females, at strong warming threatens one-sided composition that long-term reduces reproductive potential. And bycatch in fisheries outside U.S.-regulated waters remains barely controlled. The recovery is real and measurable. It is the result of decades of state regulation and international cooperation, not a one-time intervention, and it remains fragile once these frameworks disappear.