At least 47 blue whales, the largest animals on earth, converged around the Farallon Islands last Saturday to feed. They were spotted by scientists for Point Blue Conservation Science stationed on the island, who immediately reported the rare sight and record tally to the Greater Farallones Marine Sanctuary, which in turn alerted the shipping industry to take precautions. The blues belong to an estimated population of 1,647 that breeds off the coast of Costa Rica and are seen as far north as Washington State. They are often documented feeding in California, though sanctuary spokeswoman Mary Jane Schramm said she thinks the right ocean conditions this year drew them to the area in high numbers. “It’s a combination of windy days followed by more restful conditions,” she said. “The wind helps stir up all the nutrients that are down in the lower layers of the ocean and, when sunlight hits them, it triggers photosynthesis in phytoplankton. When those start to produce in large quantities, zooplankton—tiny ocean animals—and everything else up the food web, move in to feed.” High numbers of krill, which sustain blue whales almost exclusively, were already suspected by Point Blue scientists, who noted the increased activity of a small sea bird, the Cassin’s auklet, which also relies on them. Typically, the sanctuary would have its own boat on the water to investigate, but the agency still hasn’t allowed employees to travel together in close proximity due to concern over Covid-19. Nevertheless, with the input from those on the islands, Ms. Schramm said both Greater Farallones and Cordell Bank National Marine Sanctuaries launched an outreach effort immediately in hopes of protecting the whales from nearby shipping lanes. Any large vessel of 300 tons or more was asked to voluntarily slow to a crawl of 10 knots—about 11 miles per hour. The voluntary program launched in 2014, aiming to reduce marine life mortalities caused by ships outside the Golden Gate Bridge. Blue whales were once hunted for their large quantities of bone, blubber and meat. The International Whaling Commission banned commercial whaling in 1966 with the aim of reviving populations, and blues have been protected by the Endangered Species Act since 1973. Yet numbers remain too low. Point Blue estimates that around 18 blue whales in this population die every year due to ship strikes, though that could be just a fraction of the actual deaths. The National Marine Fisheries Service said the population, known as the Eastern North Pacific stock, can accommodate just 1.2 losses to unnatural causes each year without suffering population stagnation or decline.