Why do gray whales keep dying in San Francisco’s waters?

The 4,140-sq-km bay is the largest estuary on the west coast of the US. Before 2018, this species of whales wasn’t known to stop seasonally or consistently in the bay, bypassing it on their migration route down to Baja California and back up the Arctic, said Josephine Slaathaug, who led a recent study on gray whale mortality in the bay.