On Sal, one of ten islands in the Cape Verdean archipelago in the Atlantic, biologists with Project Biodiversity counted exactly 35,507 nests of hawksbill sea turtles in 2020. Twelve years earlier, there were 506. This 70-fold increase ranks among the most remarkable conservation successes in recent marine biology. What drives it is not a paper-based protected zone alone, but a social transformation: an archipelago that ate its turtles into the 2000s has made them the foundation of a protection model now cited worldwide.
From 506 to 35,507: The Numbers of Change
Until well into the 2000s, sea turtle meat was ordinary food on Cape Verde. The Turtle Foundation documented 1,253 illegally hunted females on Boa Vista's beaches in 2007 alone. Animals that came ashore to lay eggs were killed there. In 2005, sea turtle fishing became illegal on Cape Verde. In 2018 came a ban on consuming even frozen meat from pre-ban stocks. By 2024, the number of illegally killed females on Boa Vista had fallen to 20.
On the primary nesting island of Sal, nest numbers rose from 506 to 35,507 in the same period. The 2024 season recorded 36,745 nests by Project Biodiversity, the second-highest ever measured. After Florida and Oman, Cape Verde has traditionally been the world's third-largest nesting population for this species. Current data from the 2026 SWOT Report (State of World's Turtles) suggest Cape Verde may now lead this ranking.
Former Poachers as Rangers: The Social Key
A fishing ban alone would not have achieved this. The decisive factor was integrating former poachers as paid rangers and community guardians. The Turtle Foundation on Boa Vista and Project Biodiversity on Sal hired men from local families who knew beach routes for decades. Their task: mark nests, protect females while laying, and document hatch sequences. Since 2018, thermal imaging drones patrol nesting beaches at night on some islands. Mongabay magazine documented in 2025 how profound this change is in affected families.
NOAA Fisheries described the Cape Verde model in a 2024 global overview as one of few examples where state fishing bans, community-based protection, and economic integration of former poachers all worked simultaneously. Most of the seven sea turtle species show recovery trends globally. Cape Verde leads as a flagship case.
In Comparison: Lynx and Humpback Whales Show What's Possible
The Cape Verde example stands alone. After the 1986 international moratorium on commercial whaling, humpback whales recovered from an estimated 5,000 to over 80,000 today, a recovery that also took roughly three decades and required active enforcement. The Iberian lynx, by the IUCN's account, represents the fastest conservation comeback in modern wildlife science: in 2002, fewer than 100 remained on the Iberian Peninsula; by 2024, over 2,000, through breeding programs in Spain and Portugal that worked with individual animals.
The scale difference is crucial: with lynx, biologists worked with dozens of individuals in controlled breeding facilities. Sea turtle nesting involves tens of thousands of animals across entire coastal kilometres, often in countries with limited enforcement capacity. That Cape Verde achieved both prohibition and social integration is the true core of the success.
The Next Threat Doesn't Come with a Knife
Scientists with Springer Nature documented in 2025 a troubling climate signal in their long-term study of the Cape Verde population: females arrive at beaches earlier than in the 1990s, lay fewer eggs per clutch, and extend the interval between breeding seasons from an average of two years to four. If sand temperatures rise further, this threatens sex determination of embryos. Extremely hot nests produce nearly all females, undermining long-term population stability.
The success of the last twelve years has an expiration date if unchecked climate change continues. Project Biodiversity is testing natural vegetation shade on parts of Sal as a countermeasure. The population has recovered. The next test is not a legal one but a physical one: whether nesting beaches stay cool enough to maintain balanced sex ratios.