4 Whales Have Died in the Bay Area in Less Than 2 Weeks. What's Going on?

A rarely spotted juvenile minke whale that stranded itself on a mudflat in the San Francisco Bay near Emeryville was euthanized on Tuesday, marking the fourth whale death in the area in less than two weeks.

“Our teams have made the difficult decision to humanely euthanize this animal to relieve its suffering,” said Giancarlo Rulli, a spokesperson with the Marine Mammal Center in Sausalito. He noted that the whale had beached itself on several different occasions in recent days and was found almost completely out of the water, suffering from severe sunburns and struggling to breathe.

“If we can relieve an animal of its suffering, from an animal welfare point of view, we take that with incredible sincerity,” he said.

The 20-foot-long whale — only the fifth documented minke whale sighting in the bay since 2009 — was seen stranded on Monday afternoon. The incoming tide helped it move to deeper waters on Tuesday morning, but it got stuck in the mud again, within 20 feet from shore, later in the day.

Alameda County firefighters laid down wooden planks in the mud to reach the animal but were unable to rescue it.

Rulli said the center planned to conduct a necropsy — or animal autopsy — to try to determine why the animal was “showcasing these symptoms and behavioral patterns that are just very abnormal for a live, fully healthy functioning whale.” Results will take several weeks, he said.

It’s been a rough couple of weeks for whales in the Bay Area.

Three dead gray whales were discovered in different locations in and around the bay last week, including an emaciated “subadult” female seen near Alcatraz on April 1 and another floating east of Angel Island State Park the following day. A third was spotted on Friday, off San Francisco’s Fort Point Rock Beach, in the shadow of the Golden Gate Bridge.

It’s unclear what killed the gray whales, Rulli said, noting that two were found in relatively good shape. The third, however, had six fractured vertebrae, suggesting it had been struck by a vessel, he said.

“To have four dead whales in a week and a half is very high,” Rulli said, noting that the center hasn’t responded to a high-mortality event like this since April 2021, when four gray whales were found dead in the Bay Area in the span of eight days. “It’s extremely difficult.”

But he cautioned against drawing correlations between the gray whale and minke whale fatalities.

“These are two very different species,” he said. “The going theory is that … the factors involved are suspected to be quite different.”

Whereas sightings of minke whales are exceedingly rare in the Bay Area, gray whales have, in recent years, become an increasingly common presence between late February and May, using the calm waters of the bay as a resting stop during their vast annual northern migration.

Some ferry services and commercial vessels have even adjusted their routes to avoid hitting the whales, Rulli said.

Another minke whale was found dead on Sunday in Long Beach Harbor in Southern California, where an algal bloom is producing a surge in domoic acid. The naturally occurring marine neurotoxin, which can induce lethargy and erratic behavior, recently poisoned more than 100 sea lions and dozens of dolphins in that region and may have played a role in the whale’s demise.

Rulli said that while the minke whale his organization euthanized on Tuesday would be tested for the neurotoxin, there’s so far been little presence of it in the waters off the coast of Central and Northern California.

KQED’s Katherine Monahan contributed reporting.