Decades of protection helped these sea creatures recover. So why are some scientists worried?
Scientists who study wildlife are often the bearers of bad news — this species or that is headed for extinction for the usual reasons, like deforestation or climate change. Just last week, for example, I wrote about new science showing that two valuable coral species in Florida were mostly killed off by global warming.
But earlier this month, researchers announced something overwhelmingly positive: Green sea turtles, the iconic marine species made famous by Finding Nemo that were once at risk of extinction, have bounced back. Dramatically.
According to researchers at the International Union for Conservation of Nature and Natural Resources (IUCN), the leading authority on endangered species, the global population of green sea turtles — one of the seven sea turtle species found worldwide — is up 28 percent since the 1970s. IUCN reclassified the sea turtles from “endangered” to “least concern,” a category reserved for species that are not threatened with extinction and plentiful in the wild.
Scientists measure sea turtle populations by counting their nests on beaches. And in some regions, such as Florida, the number of them has surged in recent years. In the 1980s, for example, researchers detected only around 40 nests each year in and around Archie Carr National Wildlife Refuge, a protected area along Florida’s east coast. Now, they’re consistently counting more than 20,000 of them, said Kate Mansfield, a professor at the University of Central Florida who runs the monitoring program. “The green turtles have just gone absolutely, wonderfully, exponentially higher,” Mansfield told me. “I’m cautiously optimistic.”
What’s so remarkable about the recovery is that it shows conservation efforts can actually work, said Nicolas Pilcher, a sea turtle expert. These animals didn’t recover by sheer chance, said Pilcher, who formerly co-chaired the group at IUCN that determines the status of marine turtles. Their population boom followed decades of projects to minimize threats, including by restricting certain kinds of fishing gear and turning nesting beaches into protected parks. “We can do this, we can save a species,” said Pilcher, who also runs a nonprofit in Malaysia called the Marine Research Foundation.
But there are a few glaring caveats with what is otherwise great news. For one, the recovery of green turtles is not even across the planet. At the largest nesting beach in the Western Hemisphere, located in Costa Rica, the number of green sea turtle nests is plummeting, indicating that these animals still face serious threats. Plus, sea turtles live long lives, in some cases reaching 70 or more years old. That means scientists need to see these trends sustained for years to come to truly show that greens have recovered, Mansfield said.
Until recently — and still today, in many places — the biggest threat to green sea turtles was the consumption of turtle meat. These iconic marine reptiles were actually a popular food in the US through the early 20th century, according to food writer and historian Becky Diamond.
“Since just one turtle could feed quite a crowd (some weighed over three hundred pounds), turtle soup was frequently the featured dish on inn menus and at large feasts or festivals,” Diamond wrote in 2018. “Demand for turtle was so high that hosts would advertise these upcoming events in the city’s newspapers and sometimes even sell tickets in advance.”
But even as consumption of sea turtles waned in some countries — in part because the animals became rare and thus harder to find — other human actions continued to erode their population. Sea turtles would get caught in fishing nets, for example, and eventually drown. The construction of hotels, fancy homes, and other buildings along coastlines, meanwhile, destroyed nesting grounds and polluted them with artificial light. (Nighttime lights tend to disorient sea turtles and their hatchlings, making it harder for them to navigate and avoid danger.)
