Researchers monitoring dead gray whale calf at Seacliff, but cause of death likely to remain a mystery

Researchers tracking the gray whale carcass that washed up on Seacliff State Beach last week say it’s unlikely that they will be able to perform a necropsy on the 20-plus-foot marine mammal, leaving its cause of death to remain unknown.

The whale calf was first spotted between 5 and 6 p.m. on Oct. 2, at the shore directly in front of the cement ship SS Palo Alto, where the since-demolished Seacliff pier stood for almost a century. By the next day, high tides had swept the corpse back into the ocean, where as of Wednesday it continued to float south.

While large, stranded marine animals typically show signs of an attack, injury or other indications of the cause of death, this one did not. In order to figure out what caused the whale’s death, researchers would need to perform a necropsy — a post-mortem examination of a corpse — for evidence. But at this point, that seems out of the question.

Juli Limon, the lab manager for the Long Marine Lab Marine Mammal Stranding Network, which has led the response, said the whale’s positioning had prevented a necropsy even before it had floated back out into the bay.

She said that the carcass would need to be fully landed on the beach and enough distance away from the waterline so that waves would not be a safety hazard. Since the corpse was within the surf for the majority of the time prior to its drifting back into the ocean, the lab was unable to safely necropsy the whale or get any samples beyond a routine blubber sample, which can provide only basic information about the animal’s life.

Limon added that an internal exam is necessary for a robust necropsy. That would include examining tissues, organs and the skeletal system for signs that could help determine the animal’s cause of death.

Some samples of tissues and organs are then examined for signs of trauma, while others are collected to undergo testing for issues such as viruses, toxins, parasites or bacteria. In this instance, however, it appears that it won’t be possible to perform the procedure. Limon said the carcass is “decomposing rapidly and has had severe scavenging,” and scientists obtain the best information when the body is as fresh as possible.

“This is why we rely heavily on the public to report stranded marine mammals when they first spot them,” she said. “Once they start decomposing, our chances to successfully necropsy these animals decreases.”

According to the National Oceanic and Atmospheric Administration, gray whale strandings reached a recent peak in the U.S. in 2019 at 122, but declined to 39 so far this year.

Limon said the lab is monitoring the carcass as it continues to move south with the tide.

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