May 23: World Turtle Day

Céline Arétin, culture, women's issues and environment correspondent, May 23, 2025

Causes of the decline in turtle populations

The first cause is overexploitation: poaching for meat, collecting shells for jewelry, and trafficking of live animals, which particularly targets the genera Cuora, Testudo and Astrochelys. Next, accidental bycatch in industrial fisheries traps turtles in gillnets, causing mass drownings. The third pressure is habitat loss: coastal urbanization, wetland drainage and fragmentation of riverside forests. Climate change acts as a multiplier: rising sea levels shrink nesting sites and warming sand causes feminization, since sex is determined by incubation temperature. Finally, plastic pollutants clog the intestines, oil spills impair buoyancy, while eutrophication promotes fibropapillomatosis virus, a tumor disease that impairs vision and swimming.

Ecological role of turtles in ecosystems

Through their methodical grazing, green turtles keep seagrass beds in a young growth stage, which increases carbon sequestration. Leatherback turtles, predators of jellyfish, regulate blooms that would otherwise impact bluefish fishing and coastal tourism. Nesting also plays a fertilizing role: each female carries hundreds of grams of phosphorus and nitrogen from the ocean to the beaches, later enriching the dunes when the eggs hatch or are preyed upon. In tropical forests, land tortoises such as Geochelone denticulata disperse the seeds of thick-shelled fruits. Burrowing species, such as the gopher tortoise, dig burrows up to ten meters long used by more than 350 other species, from snakes to arthropods, making it a keystone species. Finally, the shells of dead turtles serve as micro-habitats for mosses, invertebrates and small mammals.

What can be done to help turtles?

On an individual level, banning single-use plastics limits ingestion and entanglement; opt for reusable bottles, reusable bags and bulk products. During coastal stays, turn off nighttime lighting facing the beach: hatchlings orient themselves using the brightness of the sea horizon, and lights disorient them. At markets, look for labels such as "MSC sustainable fishing - turtle exclusion device" or "Friend of the Sea" for shrimp and tuna. Take part in beach or river clean-ups; removing 50 kg of waste from a nesting area is equivalent to protecting 100 nests during the season. Finally, avoid releasing exotic turtles into the wild; instead, contact a licensed shelter.