Gray whales, a signature of the Washington coast, are dying by the thousands, victims of declines in Arctic sea ice.
Boom-and-bust cycles of gray whale populations are normal. But for the first time since the Eastern North Pacific population has been monitored over the past five decades, scientists are seeing not a cycle of loss and recovery, but continued decline in the population by more than 40% over the past 10 years.
Steven Swartz and his partners at the Gray Whale Research in Mexico program began monitoring gray whale calving beginning in 2006. In 2025, in the winter breeding and calving lagoons of Baja California, researchers reported the lowest recorded counts of female-calf pairs in some areas.
The problem appears to be starvation. Global warming is upending food webs in the Bering and Chukchi seas of the Pacific and Arctic oceans, leaving an animal that undertakes one of the longest migrations in nature without enough to eat. Females should be leaving their Arctic grounds fat and happy at the end of the summer, ready for the journey south to give birth in Mexico. Instead they are dying en route or can’t conceive or carry their calves to term.
A long-distance journey turned fatal
Gray whales must fatten in the summer on food found in Arctic waters. But melting sea ice means gray whales were underfed last year as they began their annual journey south to calving lagoons. A record low number of calves were seen by scientists last winter and many whales were skinny. Mortalities are already high as the northbound migration gets underway.
Now, gray whales are washing ashore as they struggle north to their feeding grounds. Gray whales are being seen eating in unusual places and eating substances they don’t usually eat — even trying to harvest food from barren sand they are so hungry. “We are seeing them at the southern end of their range, they should be fat, and they are skinny, they are behaving unusually,” Swartz said.
As with any animal, the biology of the gray whale relies on its environment: the places where it can rest, breed and feed. For the gray whale, for thousands of years, that has been the West Coast of the U.S. and Mexico. Gray whales shuttle between their birthing lagoons in Mexico and the shallow, food-rich Arctic waters they return to each summer to fatten up.
The sea ice is the platter for their feast: algae grows on its underside as Arctic summers bring brilliant sunshine around the clock. The algae blooms and dies, falling to the bottom, where it fertilizes fine sediments perfect for growing amphipods. Those are tiny, fat-rich crustaceans that whales filter through their baleen, which are plates in their mouth that strain the food out of mud they suck into their mouths.
But melting sea ice changes all that.
At first, scientists thought melting sea ice might be good for the whales because they could reach their feeding grounds earlier. But that’s not what’s happening, because of the interconnection between the ice and growth of the food the whales need.
With less sea ice, there is less surface on which the algae can grow. Also, what algae is produced doesn’t make it to the seafloor because less sea ice means more sunlight penetrates the water column, boosting the growth of algae, which in turn is eaten by zooplankton. That leaves little food for the tiny beasties in the benthos that the whales and other animals thrive on. Retreating sea ice also means more open water, which is more energetic. Currents are washing away the fine sediments in which the crustaceans live.
These changes add up to a wholesale regime shift in this food web.
That one of the largest animals on the planet would be susceptible to relatively minor changes — such as the grain size of sand where it feeds, thousands of miles from where it reproduces — is perhaps a surprise. But examination by the paper’s authors of a 50-year database on gray whale population estimates showed clear evidence of rapid population increases and declines, coupled to changes in available prey, which in turn linked to changes in ice cover, and all the rest.
The gray whale recovered from near extinction after people nearly killed it off in a signature success of policies to end commercial whaling and protect an endangered species. It was delisted in 1994. But now the mighty gray is declining again because of human-caused starvation.
John Calambokidis, senior research biologist and a founder of the Cascadia Research Collective, is concerned for these whales, even as tough and adaptable as they are. A subpopulation has taught itself to feed along the Northwest coast, not even bothering to make the long migration between the Arctic and Mexico. Others, called Sounders, tuck into Puget Sound to snuffle up snacks in the mud around Whidbey Island, fattening up a bit for the long trip north from the calving lagoons.
But the shift in the Arctic food chain means that the big numbers of gray whales seen since they recovered from whaling — a population some 27,000 strong — probably will not be seen again. Recent counts reported by the National Oceanic and Atmospheric Administration document a crash of 46% from 2016 to 2023, to just 14,526 grays, and the numbers are expected to be even lower when counts are finalized this year, marking a continued year-over-year decline.
A changed Arctic just can’t support as many gray whales as it could even 10years ago. Few places are changing as fast as the Arctic because of global warming.
“It’s hard to watch,” said Joshua Stewart, assistant professor in the Marine Mammal Institute at Oregon State University, and lead author on a paper published in 2023 that spotlighted the whale’s unraveling food web.
The link between human inaction on climate change and dead whales is clear, Stewart said.
“We know the link,” Stewart said. “We know that these populations are fluctuating in response to Arctic conditions and prey availability, and we know that that’s in decline because of warming, and we know that that warming is caused by humans.
“So how many dots do you need to connect?”
