Nearly 1 in 5 Gray Whales Die in San Francisco Bay

Vessel strikes a major cause of deaths among this dwindling population, researchers find

Apr. 13, 2026 at 5:59pm by

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A highly structured abstract painting in muted tones of blue, green, and gray, depicting sweeping geometric arcs, concentric circles, and precise spirals that conceptually represent the complex interplay of ocean forces, whale migration patterns, and ship traffic in San Francisco Bay.An abstract visualization of the perilous intersection of gray whale migration, ocean currents, and vessel traffic in San Francisco Bay, where nearly 1 in 5 whales have perished in recent years.San Francisco Today

Researchers tracking gray whales in San Francisco Bay between 2018 and 2025 found that at least 18% of the individual gray whales photographed in the bay failed to escape alive, with many struck by vessels. The work links more than 40% of examined local gray whale deaths to collisions with boats, and scientists say more monitoring, ship-speed limits, route changes, and outreach to commercial operators could help address the issue.

Why it matters

Gray whale populations have fallen by more than half since 2016 as Arctic feeding grounds shift with the climate, and the San Francisco Bay has become an increasingly dangerous migration route for the whales. Addressing the high rate of vessel strikes is crucial to protecting this dwindling species.

The details

Researchers from the Marine Mammal Center and California Academy of Sciences tracked gray whales in San Francisco Bay between 2018 and 2025 and found that at least 18% of the individual gray whales photographed in the bay failed to escape alive. More than 40% of the examined local gray whale deaths were linked to collisions with boats. Undernourished whales may have a harder time evading boat traffic, and the busy Golden Gate Strait bottleneck puts the whales at high risk of strikes.

  • Researchers tracked gray whales in San Francisco Bay between 2018 and 2025.
  • At least 5 whales have been found dead in the last few weeks.

The players

Marine Mammal Center

A research organization that tracks and studies marine mammals, including gray whales.

California Academy of Sciences

A natural history museum and research institution that collaborated with the Marine Mammal Center on the gray whale study.

Josephine Slaathaug

The lead author of the study published in Frontiers in Marine Science.

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What they’re saying

“These are just minimums that we were fully able to confirm.”

— Josephine Slaathaug, Lead author of the study

What’s next

Scientists say more monitoring, ship-speed limits, route changes, and outreach to commercial operators could help address the high rate of vessel strikes on gray whales in San Francisco Bay.

The takeaway

The high rate of gray whale deaths due to vessel strikes in San Francisco Bay highlights the urgent need to protect this dwindling species as their migration patterns shift with climate change. Implementing measures to reduce collisions, such as speed limits and rerouting, could be crucial to the survival of the local gray whale population.