Researchers find increase in whale deaths in the Bay, largely because of collisions with vessels on busy shipping route
Gray whales have historically been a rare sight in the San Francisco Bay. They trek from the warm lagoons of Mexico’s Baja California over 10,000 miles north to the Arctic region to feast on shrimp-like animals during the summers, seldom stopping in the busy shipping corridor for prolonged periods.
But in recent years, that story has changed in a dire way. A new study, published this week in the journal Frontiers in Marine Science, has found that gray whales in the Bay have been dying at alarming rates, largely due to collisions with vessels.
Eastern North Pacific (ENP) gray whales began to show up with more frequency in the well-trafficked maritime core around 2018. According to researchers, at least 18% of gray whales that entered the Bay between 2018 and 2025 have died. They determined that for over 40% of the whale carcasses, the cause of death was blunt force trauma consistent with vessel strikes, prompting calls for renewed efforts to help avoid more fatal collisions.
“It was historically very unusual for them to enter the Bay, especially for longer amounts of time or consistently year after year,” said Josie Slaathaug, lead author of the study.
