For the past few years, the sharp rise in gray whale deaths along the west coast of North America has largely been understood as a story of starvation. That was not without reason. NOAA’s investigation into the 2019–2023 unusual mortality event found malnutrition to be a common cause of death, linked to ecosystem changes in Arctic and sub-Arctic feeding grounds that left many whales in poor body condition.
But new research suggests that this is no longer the whole story.
A study published this month in Frontiers in Marine Science found that gray whales entering San Francisco Bay are facing strikingly high mortality, with at least 18% of identified individuals later found dead in the local area. Of the 70 gray whale carcasses examined between 2018 and 2025, blunt and/or sharp force trauma consistent with vessel strike was identified as the cause of death in 30 cases. For matched whales where a cause of death could be determined, vessel strike was the leading cause.
This matters because it changes the conservation picture. It suggests that some gray whales may first be pushed into difficulty by changing ocean conditions and reduced prey availability, but then die not only because they are hungry, but because they are being forced into dangerous places. San Francisco Bay is a heavily trafficked waterway with a narrow bottleneck at the Golden Gate through which both whales and vessels must pass. In other words, environmental stress may be driving whales into the path of another major threat: ships.
That is a vital lesson far beyond California. Around the world, whales are increasingly having to adapt to changing oceans. As prey shifts, temperatures rise and feeding patterns alter, whales may begin using habitats they have not relied on before. But adaptation is not the same as safety. If those new habitats overlap with busy shipping lanes, ports or coastal bottlenecks, the result can be deadly.
For ORCA, this speaks directly to one of the most urgent priorities in whale conservation today: preventing ship strikes before they happen. We already know what works best. Reducing vessel speeds and avoiding the most important whale habitats remain the most effective proven measures for lowering collision risk. In California, the voluntary vessel speed reduction programme has been expanded again this month in response to growing concern about whale deaths, with ships encouraged to slow to 10 knots or less along much more of the coast.
The gray whale story is a reminder that ship strike is not a secondary issue to be tackled later. It is already a major cause of mortality for large whales, and in a rapidly changing ocean that risk may grow as whales alter their movements in search of food. If we want whales to survive the pressures of climate change, we must also make the seas safer for them to move through.
Because a whale that escapes starvation, only to be killed by a ship, is still a whale whose death we could have prevented.