Oarfish Sightings Don't Predict Earthquakes, Study Says

MEXICO - JANUARY 11: People look at Dead Oarfish 'Sea Serpent' that washed ashore on a beach in Mexico. Oarfish dive more than 3,000 feet deep, sighting of the creatures are rare. Oarfish 'Sea Serpent'. Oarfish dive more than 3,000 feet deep, sighting of the creatures are rare. in Mexico January 11, 2006

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Oarfish washing ashore on Pacific beaches probably aren't warning of an impending earthquake after all, according to a new study.

Japanese folklore says that when these long, serpentlike silver fish emerge from the depths, an major earthquake is imminent. But Japanese researchers who pored over newspaper reports, aquarium records, and academic papers dating back to 1928 couldn't find any correlation between oarfish sightings and major earthquakes. "One can hardly confirm the association between the two phenomena," wrote seismologist Yoshiaki Orihara and his colleagues in a recent paper in the Bulletin of the Seismological Society of America.

Oarfish attracted attention after the devastating March 2011 Tohoku earthquake, which (along with the tsunami it triggered) killed more than 19,000 people and caused meltdowns at three nuclear reactors at the Fukushima Diaiichi Nuclear Power Plant. At least a dozen of the rarely-seen deepwater fish had washed ashore in Japan in late 2009 and 2010, and observers retrospectively connected those sightings with the March 2011 quake, based on the oarfish's role in Japanese earthquake lore. Called Ryugu no Tsukai, or Messenger from the Palace of the Sea God, oarfish -- especially one of the smaller species, the slender oarfish -- supposedly visit Japan's shores to warn of impending earthquakes and tsunami.

"If this folklore is proved to be true, the appearance of deep‐sea fish could be useful information for disaster mitigation," wrote Orihara and his colleagues. Previously, some scientists have tried to explain the legends by suggesting that the movement of tectonic plates could generate electromagnetic currents which drive oarfish and other deep sea swellers, such as dealfish, ribbonfish, and unicorn creshfish, into the shallows. Oarfish live around 200 meters (650 feet) deep in the northern Pacific and Indian Oceans, and scientists believe they migrate to the Sea of Japan on the Tsushima Current. A few research teams have captured video of live oarfish in recent years, but otherwise we've been limited to the sporadic beached carcasses or accidental catches in fishing nets. Because they live at such depths and rarely venture into shallower waters, we know very little about their habits at home, which makes it hard to try and explain their behavior.

The largest members of the largest oarfish species, aptly named the giant oarfish, can grow up to 11m (36 feet) long, and it's easy to see why they've been linked with early reports of sea serpents; they definitely fit the bill. But Orihara and his colleagues say these sea serpents don't predict earthquakes. The team combed aquarium reports (since local aquariums often get called to investigate when an oarfish or other seldom-seen sea creature washes ashore) and academic journals for oarfish sightings, along with other deep-sea species, but they also turned to local newspapers dating back to 1928.

"In Japanese domestic local newspapers, such appearances have often been reported because rare appearances might attract readers," they wrote. Altogether, Orihara and his colleagues found 336 deep-sea fish sightings in Japan between November 1928 and March 2011. But none of those sightings happened within 30 days of an earthquake with a 7.0 or greater magnitude. Orihara and his colleagues also couldn't find any reports of a 6.0 or greater magnitude quake happening within 10 days of a deep-sea fish sighting.

So although the oarfish legend is really compelling, as stories go, there's no scientific reason to think we can actually use oarfish as an earthquake warning system. And that leaves scientists still looking for a detailed explanation of occasional oarfish sightings in shallow water, especially since they seem to come in clusters or waves. A 2018 study found a correlation between oarfish sightings an El Niño years, when the water of the central and eastern equatorial Pacific Ocean is much warmer than usual. El Niño affects the ocean depths differently than the surface, so the oarfish's pelagic home turns cooler at the same time surface waters warm up. Some scientists have suggested that the cooler depths might prompt the oarfish to swim to the shallows in pursuit of plankton.

Officials at the Uozu Aquarium suggested seawater temperatures, or some other change in deep-sea ecosystems, might be responsible for the spate of oarfish sightings off the Japanese coast earlier in 2019, Japan Times reported. Until we know more about the behavior and ecology of the oarfish and its ecosystem, it will be hard to answer that question in much more detail.

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