Overview
- A peer-reviewed analysis released Monday in Frontiers in Marine Science reports a minimum 18% death rate for gray whales that entered San Francisco Bay from 2018 to 2025.
- Researchers identified 114 individual whales from photos and matched 21 of them to carcasses among 70 documented, with only four whales seen in more than one year.
- Necropsies point to vessel strikes as the leading cause, with 30 of 70 carcasses and nine of 21 identified whales showing fatal collision injuries, and others dying from starvation.
- San Francisco Bay is especially risky because all ships and whales must pass through the narrow Golden Gate Strait, where heavy traffic, frequent fog, and the whales’ low profile make them hard to spot.
- The study notes the 18% figure is a floor since many carcasses sink or decompose fast, and after a spate of local deaths in March, officials are promoting a voluntary 10‑knot slowdown starting April 22 along with calls for route changes, crew training, and more monitoring.