Public Education / Sea Grant News

Second “sea serpent” carcass was female with cookiecutter shark bites

NOAA Fisheries scientists dissect the oarfish's head to look for ear-bone structures that can help age the fish. Credit: C. Johnson

NOAA Fisheries scientists dissect the oarfish’s head to look for ear-bone structures that can help age the fish. Credit: C. Johnson

Two giant, sea serpent-like oarfish have been found dead in Southern California in the last week, and now the question is why?

Searching for clues about the rare find, NOAA Southwest Fisheries Science Center scientists on Monday performed a necropsy on the 14-foot specimen that washed up in northern San Diego County on Friday. The other specimen, discovered dead off Catalina, last week, is being dissected and analyzed by University of California researchers.

As of mid-day, NOAA scientists had learned that the rarely seen eel-like fish was female and had been actively oozing eggs from her massively long ovary. Her skin bore the tell-tale round scars of encounters with cookiecutter sharks.

Scientists had removed the stomach and examined its contents. “There was not much in the stomach: some parasites and sand and some krill,” said feeding ecologist Antonella Preti with NOAA Southwest Fisheries Science Center in La Jolla.

The dark round scar on the skin of the oarfish is from a cookiecutter shark. Credit: C. Johnson

The dark, round scar on the skin of the oarfish is the bite-mark from a cookiecutter shark. Credit: C. Johnson

Although parts of the animal’s mouth and head were missing and damaged, scientists were in the process of dissecting the brain, trying to recover ear-bone structures, known as otoliths, that can be used to estimate the animal’s age and growth rates over time.

While not as exciting as some of the theories put forth by the press, the female oarfish could have died from plain old age.

“I don’t have a good guess as to what might be the cause of death,” said Suzanne Kohin, a NOAA Southwest Fisheries Science Center fish ecologist, who recovered the carcass over the weekend. “We are considering everything.”

“Everything” includes testing tissue for radiation, algal toxins, PCBs and mercury.

oarfish ovary with eggs

A close-up of the oarfish’s ovary. The little round balls are oarfish eggs. Credit: C. Johnson

The press has been particularly curious about whether earthquakes might have killed the oarfish, said Milton Love, a biologist at UC Santa Barbara, who said he spent the day talking to media. After the Fukushima nuclear disaster, there were accounts of several of the animals washing ashore.

Love speculates that ocean currents or internal waves could have pushed the oarfish, the world’s largest bony fish, to shallower waters near the coast.

“These fish live at depths of a thousand meters where there is not much current,” he said. Though large, they are fragile. If caught in an internal wave or by a current, they could be propelled out of their normal territory.

According to NOAA Fisheries, oarfish “probably only come to the surface when injured or dying.”

The oarfish's stomach. Credit: C. Johnson

The oarfish’s stomach. Credit: C. Johnson

“The question is what could bring them up to the surface,” California Sea Grant Director James Eckman said. “You can speculate. We know that the eastern Pacific Ocean is notorious for having low-oxygen waters at depth and that these low-oxygen waters are starting to shoal more frequently and could drive animals to shallower waters. Animals that live in perpetual cold are not very tolerant to different temperature conditions.”

“One dead oarfish is odd,” Eckman said. “Two is a pattern.”

Written by Christina S. Johnson, csjohnson@ucsd.edu, 858-822-5334.

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3 thoughts on “Second “sea serpent” carcass was female with cookiecutter shark bites

    • Good question! Many scientists will be studying the fish so the findings will likely be published in academic journals. When those nuggets of news come out, we will share it here on the Our Ocean blog.

  1. A scientist from NOAA Southwest Fishery Science Center just contacted me about the dissection and she further confirmed that not all the test results would be available immediately. Her guess is that some basic information on the morphological (body) measurements could be posted fairly quickly, maybe on a website. But some results could take months or longer.

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