If Galápagos whales are part of larger, wide-ranging populations, then protecting the archipelago alone is not enough — the same individuals face risks the moment they leave. Understanding connectivity reveals whether local sightings represent a resident, self-sustaining population or occasional visitors passing through, which changes how vulnerable that population really is.

• One individually identified blue whale (BWGaI008) was tracked from the Galápagos (February 2009) to the Costa Rica Dome (January 2014) and back to the Galápagos (May 2016) — direct photographic evidence of a multi-year, cross-border migration (Denkinger et al., 2023).

• Genetic and photo-ID evidence indicates Northern and Southern Pacific blue whale subspecies both use the Galápagos: the Southern subspecies breeds off Peru, Ecuador, and the Galápagos, while the Northern subspecies is more associated with Central America and the Costa Rica Dome (LeDuc et al., 2017).

• Blue whale sightings during the Galápagos austral summer (November–April) suggest Northern and Southern Hemisphere populations overlap here in time and space.

• External researchers reported the first genetic and visual match between a blue whale sampled in southern Chile and one seen in the ETP near the Galápagos (Torres-Flórez et al., 2015).

• Satellite tracking of Chilean Northern Patagonia blue whales recorded the first two complete migratory paths between Chile and the Galápagos (Hucke-Gaete et al., 2018).

• Blue whale song types recorded off Chiloé (Chile), northern Peru, and southern Ecuador match one another, suggesting a shared population across this range (Buchan et al., 2015).

• Of an estimated 8,500 killer whales across the wider ETP (southern California to northern Peru), 64 individuals have been photo-identified in Galápagos waters, with 18 classified as local residents (Denkinger et al., 2020).

• Individual killer whales have been matched between the Galápagos and Peru, Mexico, Costa Rica, and mainland Ecuador, including one non-local Galápagos-identified whale documented across four countries (Pacheco et al., 2019).

• A killer whale photographed off mainland Ecuador in December 2023 was resighted near Wolf Island in the Galápagos in May 2024, directly linking the two populations (Orellana-Vásquez et al., 2025).

• Not every match succeeds: individuals from whale shark predation events in Panama and Mexico did not match any Galápagos-catalogued killer whales, showing connectivity is real but not universal.

Evidence that Galápagos whales travel to Costa Rica, Peru, Chile, Mexico, and mainland Ecuador directly supported the 2022 Eastern Tropical Pacific marine migratory corridor, which connects the Galápagos–Cocos ridge and extends protection along real travel routes. Confirming that Galápagos blue whales belong to genetically distinct, already-endangered subspecies makes every local sighting more significant for global recovery. And because connectivity depends on international data-sharing and matching catalogs across borders, this research only works through cooperation between Ecuador, Peru, Costa Rica, Mexico, and Chile.

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