This is heartbreaking news on many levels.
Just a few days ago, excitement grew over the unusual presence of numerous gray whales in Cabo San Lucas, Cabo Pulmo, La Paz, and Loreto. This phenomenon was linked to colder waters caused by “La Niña,” pushing the whales further south in search of better temperatures. Initially seen as a positive development, it has now turned into a cause for concern.
Scientists have raised alarms over a decline in gray whale calf births, which could make 2025 the year with the fewest recorded births in Mexico. Meanwhile, mortality rates among juveniles and adults continue to rise in Baja California Sur, where these whales migrate annually from Alaska—a journey spanning more than 9,000 kilometers.
Dr. Jorge Urbán, a leading global expert and head of the Marine Mammal Research Program (PRIMMA) at the Autonomous University of Baja California Sur (UABCS), explained that this shift might be contributing to the increased number of strandings this season.
So far, at least 40 gray whales have died, with most appearing emaciated—likely due to food shortages in their feeding grounds and the additional energy required to reach warmer waters in Mexico.
Although the current mortality rate has not yet reached the peak levels of the Unusual Mortality Event (UME) recorded in 2020—when 88 deaths occurred in Mexico—the numbers are becoming worrisome. These whales still need to conserve enough energy to return to the Bering, Chukchi, and Beaufort seas in Alaska.
Dr. Urbán warned that the mortality event is not over yet, and the number of deaths is expected to rise as migration peaks and the whales begin their northward journey in the coming weeks. By early April, they will be on their way to Alaska.
“I estimate that by the end of March, at least 10 more deaths will be recorded, bringing the total to around 50 in Mexico. Then, we’ll have to see how many die in the United States and Canada along the migration route,” he said.
Dr. Urbán, who is also a member of the International Whaling Commission, is awaiting action from the U.S. National Oceanic and Atmospheric Administration (NOAA) to reactivate the UME alert for gray whales, which had been lifted only in 2024.
Between 2019 and 2023, the Unusual Mortality Event (UME) led to an estimated 40% decline in the Eastern North Pacific gray whale population. Scientists attribute this to ecosystem changes in the subarctic and Arctic feeding areas, which have caused malnutrition, reduced birth rates, and increased mortality.
So far this season, the Whale and Marine Sciences Museum, led by Francisco Gómez, has responded to three gray whale strandings in Baja California Sur—specifically in Margarita Island, La Paz Bay, and La Paz Inlet.
The first case, recorded on January 22, involved an 11.8-meter-long male found dead on Margarita Island at the entrance to Bahía Almejas. No signs of boat collisions, propeller cuts, or fishing net entanglement were observed. The whale’s body was in condition 2 (moderate decomposition) but was already bloated with gases, making it difficult to visually confirm malnutrition. The final assessment will depend on isotope analysis.
The second case, reported on February 24 in La Paz Bay, involved a 13.4-meter-long female in an advanced state of decomposition (grade 3). Although scar marks possibly from fishing nets were observed, the injuries appeared to have occurred earlier in her life.
The third stranding, recorded on March 1 in the Ensenada de La Paz estuary, involved a 13.3-meter-long adult female.
Dr. Urbán emphasized a striking difference this year: the absence of calves among the stranded whales. Typically, calf mortality is more common, but this season, most deaths involve juveniles and adults—a concerning shift for the species.