SAUSALITO, Calif. (KRON) — The Marine Mammal Center has determined what killed at least one of the four gray whales found dead in the Bay Area in the past week.

One of the gray whales died from a ship strike, the center said on Friday.

“It’s alarming to respond to four dead gray whales in just over a week because it really puts into perspective the current challenges faced by this species,” says Dr. Pádraig Duignan, Director of Pathology at The Marine Mammal Center. “These necropsies are critical to provide insights into gray whale population health and that of their ocean home, including how human activity impacts them.”

The deaths of the other three are still under investigation.

However, the center claims malnutrition, entanglement, and ship strikes as the most common causes of death – based on what they have found in recent years.

This is what brought them to the conclusion of a ship strike for one of the whales:

“During the necropsy at Muir Beach, scientists discovered significant bruising and hemorrhaging to muscle around the whale’s jaw and neck vertebrae consistent with blunt force trauma due to ship strike. The team identified the gray whale as a 41-foot adult female that was minimally decomposed based on the quality of the internal organs. Experts also noted the whale was in good body condition based on the blubber layer and internal fat levels.

Marine Mammal Center

For another gray whale so far, scientists ruled out trauma and infectious disease as its cause of death based on initial evidence. They said they plan to reexamine the whale’s skeleton to completely rule out human interaction.

It has been concerning for experts to find this many dead whales in the Bay Area in such a short time span.

“Our team hasn’t responded to this number of dead gray whales in such a short span since 2019 when we performed a startling 13 necropsies in the San Francisco Bay Area,” says Duignan.

However, regular whale sightings in the Bay Area have recently increased as they migrate north for better Arctic waters, the center says.

To report a dead whale or whale in distress, call the Center’s rescue hotline at 415-289-SEAL (7325).