Study: 18% of Gray Whales Entering San Francisco Bay Die

Gray whales, driven by dwindling Arctic food sources amid climate change, are increasingly venturing into the busy waters of San Francisco Bay, where nearly one in five do not survive, according to a new study published this month. Researchers documented 114 individual whales entering the bay between 2018 and 2025, with at least 18 percent later found dead in the area, many from vessel strikes or malnutrition. The findings, based on photographic identifications and necropsy records, highlight a perilous shift in the species' long-established migration patterns along the California coast.

The eastern North Pacific gray whale population, which migrates over 10,000 miles annually from Arctic feeding grounds to Baja California lagoons for breeding, has plummeted by more than half since 2016. Scientists attribute this decline to warming oceans that reduce sea ice and the crustaceans whales rely on for sustenance. Typically, the whales fast during migration, drawing on fat reserves built in the Arctic. But nutritional stress has led some to forage in unfamiliar spots, including San Francisco Bay, which was not part of their historical route until sightings surged in 2018.