Why do gray whales keep dying in San Francisco waters?

With an area of ​​4,140 square kilometers, this bay is the largest estuary on the West Coast of the United States. Josephine Slaathaug, who led a recent study of gray whale mortality in the bay, said that before 2018, the whales were not known to stay in the bay seasonally or continuously, but instead circled the bay on their migratory route back to Baja California and back to the Arctic.