Why Are Gray Whales Dying in San Francisco Bay?

Scientists are investigating a rise in gray whale deaths in San Francisco Bay, as growing numbers of the animals are found undernourished and increasingly vulnerable.

In 2025, a record 21 gray whales were discovered dead in the broader bay area, and at least seven have already died in 2026.

Researchers say many of the whales entering the bay appear thinner than expected, likely due to declining food sources in the Arctic, where they typically feed before migrating.

Gray whales undertake one of the longest migrations of any mammal, traveling up to 20,000 kilometers annually between breeding grounds in Mexico and feeding areas in the Arctic. In recent years, some whales have begun stopping in San Francisco Bay, a shift scientists believe may be driven by hunger and changing environmental conditions.

However, while food shortages may be drawing whales into the bay, many of the deaths are linked to human activity.

Researchers say ship strikes in the bay’s busy waters are a leading cause, with nearly one in five whales entering the area dying there.

The trend has raised concerns among scientists, who say these deaths may reflect broader changes in ocean ecosystems and highlight the need for improved conservation efforts.