CMS Votes to List Scalloped Hammerhead Sharks on Appendix I After Galápagos Migration Study Presented

The Convention on the Conservation of Migratory Species voted in March 2026 to place scalloped hammerhead sharks on Appendix I, requiring signatory countries to enact full legal protection inside their waters. Pelayo Salinas de León, senior marine ecologist at the Charles Darwin Foundation, presented satellite-tag records showing the sharks follow fixed, cyclical routes between the Galápagos Islands and Panama.

The listing decision rested on evidence collected during twice-yearly expeditions to Darwin and Wolf, the northernmost islands inside the Galápagos marine reserve.

During the March 2026 trip, divers recorded dozens of scalloped hammerheads on most dives; in the cold season the local population quadruples, reaching roughly 150 sharks per hectare at peak density. Researchers cannot capture the animals for study because handling stress can prove fatal.

Instead, the team uses underwater cameras to count sharks and chemical analysis of skin biopsies to determine diet.

Carlos Robalino, a junior researcher at the foundation, collected biopsy plugs with a freediving spear during the same expedition, adding samples to a decade-long archive. Satellite tags deployed on the March trip already showed several sharks had left the archipelago and were heading toward Panama while the CMS meeting took place in Brazil.

Eight of every ten previously tagged sharks have followed the same route; most appear to be pregnant females nearing the end of a nine-month gestation.

The data helped meet the criteria for Appendix I status. Illegal longlines remain a direct threat inside the reserve. During the March 2026 expedition the team encountered multiple lines, one tens of metres long that tangled around their research boat and another wrapped around Darwin’s Arch that had hooked two green turtles.

Last year the same group freed a scalloped hammerhead from an artisanal longline within reserve boundaries. After giving birth in Panama’s mangrove nurseries, surviving females turn west, passing the Galápagos and continuing roughly 1,200 miles to the Pacific equatorial front.

Salinas de León said the team plans to extend tagging work into that high-seas region to test whether seasonal closures or gear changes could reduce encounters with industrial fleets.

A single satellite tag costs close to $2,000. The Charles Darwin Foundation is now working with Panamanian authorities to strengthen protections for both newborn sharks and migrating females in the nurseries.