For nine months, a scientific expedition searched for blue whales in the waters around the Galápagos Islands and found none, Live Science reported. Between October 2025 and July 2026, researchers surveyed areas of the Ecuadorian archipelago where the animals had historically been recorded, hoping to attach satellite tags and learn more about their migratory routes. The search ended without a single whale being tagged. The absence coincided with unusually warm ocean conditions during an El Niño event. Sea surface temperatures were as high as 82 degrees Fahrenheit (28 degrees Celsius), and at a depth of 330 feet (100 meters) the water was 66 to 67 F (18.9 to 19.4 C), up to 9 F (5 C) warmer than usual for that time of year.
"The hypothesis is that the whales are staying in areas with greater productivity [more food] farther south, in waters with slightly cooler temperatures," said Daniela Alarcón, the expedition's leader and a researcher at the Universidad San Francisco de Quito's Galápagos campus and the Galápagos Science Center. Possible destinations include waters off Peru and offshore areas where the animals could go undetected. In that scenario, the warm water around the islands would act as a "temperature barrier," she said. Blue whales can consume up to 12,100 pounds (5,500 kilograms) of krill a day, so they have to keep moving to where food is. It is not yet clear whether this year's El Niño caused a krill shortage around the Galápagos, but some indirect evidence points that way. Past work suggested the whales tend to feed in water layers around 71 F, which this season was found at about 197 feet (92 meters). Peak chlorophyll, an indirect sign of the phytoplankton that krill eat, was recorded much higher in the water column, between 39 and 121 feet (12 to 37 meters). Because krill were not measured directly, that suggests, but does not prove, a mismatch between the preferred feeding layer and the food. "Honestly, we had never encountered such unusual conditions before," said Juan Pablo Muñoz, a marine biologist at the same university who was also on the expedition.
The absence was not a complete surprise. Citizen-science reports through Cetácea Galápagos had already begun to dwindle between August and September 2025. There were two isolated reports in May and June 2026, but the team could not confirm either one. "We searched, and searched, and searched — and found nothing," Alarcón said. Fernando Félix, a marine biologist at the Pontifical Catholic University of Ecuador who was not on the expedition, was unsurprised. During the 1982-1983 El Niño, he noted, blue whales, fin whales, and Bryde's whales were recorded shifting southward. "I don't think the whales have died," he told Live Science. "They simply didn't go to the Galápagos region. They went elsewhere, where conditions were better."
El Niño's effects will likely persist for months. "Between January and May 2027, we'll have warm water coming from the north and warm water coming from the west," Félix warned. He and Muñoz expect blue whales, humpbacks, and some fish to return once colder, nutrient-rich water rises again. Muñoz noted that more whale sightings were recorded in the years after the 2015 and 2023 El Niño events, and suggested 2028 could be a promising year if cold water returns. Félix said, "I can guarantee that there will be large numbers of blue whales at this time in 2028." That is a prediction based on past rebounds, not a count already in hand. The verified result of this expedition is simpler: no tags, no confirmed sightings, and a strong suspicion that the whales swam around the warm water rather than dying in it.