Whale's Death Remains a Mystery Days After Washing up in San Francisco

Experts have so far been unable to determine the cause of a death for a 45ft-long gray whale that washed ashore at San Francisco's Ocean Beach on Sunday.

Researchers from The Marine Mammal Center, based in the city of Sausalito, and the California Academy of Sciences investigated the animal's carcass on Monday, taking a variety of samples for testing that could potentially provide insights into its death.

During the investigations on Monday, experts identified the 45ft-long whale as an adult female with a body in average condition. They found multiple fractured spinal vertebrae but the lack of bruising and hemorrhaging to nearby tissue indicated that the animal was possibly hit by a ship after it had already died of other causes.

Pádraig Duignan, director of pathology at the Center, said in a press release: "Gray whales are sentinels for ocean health so performing these investigations is essential to better understand how human activity and changing environmental trends are impacting this species."

This is the 17th dead whale that experts from the Center—the world's largest marine mammal hospital—have responded to in the San Francisco Bay Area this year. The dead have included 14 gray whales—all of which were found from April onwards—one pygmy sperm whale and two fin whales.

Many of the these whales were killed by vessel strikes, officials from the Center said in a press release, while the cause of death for several others has yet to be determined.

The Center said the 14 dead gray whales found since April marks the highest total deaths—more than the entire years of 2019 and 2020—in the Bay Area since the National Oceanic and Atmospheric Administration (NOAA) declared an Unusual Mortality Event (UME) for the species in early 2019.

The NOAA declared the UME, which is still ongoing, due to the occurrence of elevated gray whale strandings along the west coast of North America—from Mexico through Alaska—since January, 2019.

NOAA figures show there were 465 dead gray whale strandings in the U.S., Canada, and Mexico between January 1, 2019 and June 4, 2021. While some whale standings are to be expected, these figures are far above the 18-year average for 2001 to 2018.

Researchers are still investigating the causes of the UME, but investigations of the whale carcasses have revealed some clues. Experts say several of the whales have been found emaciated.

Kathi George, the director of field operations and response at the Center, previously told Newsweek: "This suggests potential ecosystem changes that may be impacting their habitat and food availability. Climate change affects water temperatures and prey availability, leading to shifting food sources for marine mammal populations and other marine species."

However, not all the dead whales have been found emaciated. Some appear to have been killed by vessel strikes, entanglement in fishing gear, while in other cases, the deaths remain unexplained.

Update 6/28/21 9:30 a.m. ET: This article was updated to include a different picture.

Dead gray whale at Ocean Beach
Experts from The Marine Mammal Center and the California Academy of Sciences were unable to confirm a cause of death for a 45-foot adult female gray whale that washed ashore on Sunday, June 20, at Ocean Beach in San Francisco. Katie D’Innocenzo © The Marine Mammal Center