Sea Turtle Populations Increasing

NOAA – Once hammered by overhunting and habitat loss, sea turtles have persevered with new protections and conservation efforts. Their populations are now rebounding even as oceans change, a new review has found.

“Sea turtles are a shining light of marine conservation with recoveries of many nesting populations,” said Graeme Hays, Distinguished Professor and Chair in Marine Science at Deakin University in Australia. He and Jacques-Olivier Laloë from Deakin and NOAA Fisheries researcher Jeffrey Seminoff reviewed the status of the seven species of sea turtles around the world in Nature Reviews Biodiversity.

They found most sea turtle populations rebounding worldwide, with more turtles nesting at beaches with stronger protections in place. For instance, artificial lighting that can confuse baby turtles trying to find the ocean has been reduced or removed in many locations. Hunting turtles has fallen out of favor in some areas, and many fisheries around the world have adopted measures to avoid catching turtles.

The findings illustrate an important conservation success and support NOAA Fisheries’ responsibility to track protected marine species. The data on sea turtles helps biologists shape fishing seasons that reduce the risk of mistakenly catching them in fishing nets.

There are some exceptions to the trend. Pacific leatherback turtles—which make a treacherous round-trip migration from Indonesia to feed along the Pacific Coast of North America—are declining. Rare leatherbacks in the Caribbean are also on the decline. Climate change affects sea turtles, scientists said, but many populations are now in better shape to weather the impacts.

“When I think of sea turtles, the first word that comes into my mind is resilience,” said Jeffrey Seminoff, a research scientist who specializes in sea turtles at NOAA Fisheries’ Southwest Fisheries Science Center. “They are sensitive because they depend on the marine ecosystem, but give them a chance to thrive and they will take advantage of it.”

People Value Turtles

Seminoff said the increasing numbers of sea turtles around the world also reflect a change in public values. Younger generations don’t see turtles as commodities to hunt and eat. Instead, they see them as parts of a marine ecosystem that provides both environmental and economic benefits to coastal communities, he said. Former poachers in some places now lead visitors to view nesting turtles as a part of ecotourism that provides alternative livelihoods.

At one time, sea turtles were so numerous in the Caribbean they kept sailors up at night by knocking into the wooden hulls of boats. However, they also offered easy meals. Indiscriminate hunting quickly eliminated about 95 percent of the 19–33 million green sea turtles thought to live in the Caribbean at the time.

Other sea turtle species around the world declined with commercial hunting, entanglement in fishing nets, and loss of nesting beaches. Then, countries began more widely protecting the species as laws such as the Endangered Species Act in the United States took hold in the 1970s and 1980s. Conservation initiatives in many areas helped protect and monitor sea turtle nests to better understand their status.

Scientists reviewed records from nesting beaches around the world and other data on sea turtle populations. “These global evaluations show a generally encouraging picture of stable or upward trends across species and subpopulations,” the scientists wrote. They analyzed almost 300 different records of turtle numbers over time, finding that “significant population increases were three times more common than significant decreases. In an updated compilation of additional time series published in 2024, significant increases were six times more frequent than significant decreases.”

Many Sea Turtle Populations Increasing

Four of five regional populations of green sea turtles are increasing, according to records from nesting sites. Most nesting sites also showed increases in loggerhead turtles, some by nearly two orders of magnitude. For example, between 2008 and 2020 the annual number of loggerhead nests increased from around 500 to 35,000 in Cape Verde in the North Atlantic Ocean.

Less information is available about hawksbill, olive ridley, Kemp’s ridley, and flatback turtles, but most show increases in individual populations. U.S. and international endangered species protections still apply to most species. Leatherback turtles, the largest of all sea turtles, are struggling most, with several populations in decline. These turtles can grow to the size of a small vehicle and often migrate thousands of miles across the oceans in search of prey in between nesting seasons.

Climate change is warming oceans and nesting beaches. Higher nest incubation temperatures lead to more female offspring, which could eventually interfere with reproduction. However, new evidence shows that loggerhead sea turtles in the Mediterranean may be starting to nest in cooler areas that could keep the sex of offspring in better balance. “If newly colonized sites are in cooler locations than previous sites, the population could be buffered against future warming,” scientists said. Turtles could also begin nesting at some beaches earlier in the year, for example, before temperatures warm to the point of skewing sex ratios.

Scientists Outline Priorities

“The bottom line is: When you stop hunting and otherwise harming species and they regain their ecological foothold, they can again become a thriving part of the marine ecosystem,” Seminoff said. “There will always be surprises, but now many sea turtles have greater resilience going forward.”

The scientists concluded that the priorities for sea turtle conservation and management in the future are:

• Promote climate change resilience
• Reduce bycatch and hunting
• Better understand and reduce the impacts of plastics and other pollution
• Protect and restore foraging habitat, such as seagrass meadows, for some species

Hays credited the resurgence of sea turtles as “testimony to the hard work of hundreds of thousands of people around the world protecting nesting beaches, reducing illegal trafficking of sea turtle products, driving informed designation of conservation zones, reducing bycatch of turtles in fisheries. So humankind can reverse declines in biodiversity. We know how.”