Giant snake-like fish washed up onto Californian beaches in recent days may have died a result of the seismic activity under the seabed that occurs days or weeks before an earthquake, scientists said.
At least two oarfish, which grow up to 15 metres long and live in the deep ocean, have been sighted on beaches in California without any visible signs of injury or disease, leading to speculation that they have been affected by some kind of deep underwater disturbance.
Rachel Grant, a lecturer in animal biology at Anglia Ruskin University in Cambridge, said there might be some truth in the ancient Japanese legend that the appearance of oarfish precedes an earthquake. She has begun a study to test the idea.
“It’s theoretically possible because when an earthquake occurs there can be a build-up of pressure in the rocks which can lead to electrostatic charges that cause electrically-charged ions to be released into the water,” Dr Grant said.
“This can lead to the formation of hydrogen peroxide, which is a toxic compound. The charged ions can also oxidise organic matter which could either kill the fish or force them to leave the deep ocean and rise to the surface,” she said.
Another possibility is that prior to an earthquake there is a release of large quantities of carbon monoxide gas, which could also affect oarfish and other deep-see creatures, Dr Grant said.
“The geophysical processes behind these kinds of sighting can happen before an earthquake. I will be watching California closely over the next couple of weeks,” she added.
A 4.3 metre oarfish was found on a beach near the city of Oceanside this week, while a larger specimen was washed up on Santa Catalina Island a few days earlier. Tests on the fish failed to find any obvious reason for the stranding.
Dr Grant said that she has built up a database of several hundred oarfish sightings over the past two and a half years and will now see if there are links between the sightings and any earthquakes reported by the US Geological Survey within a 500 mile radius.
“We do know that there’s not an earthquake after every oarfish sighting, but we are going to see if there is an increased probability of oarfish being seen prior to an earthquake,” Dr Grant said.
“It may be due to seismic activity or it may be due to other factors unconnected with earthquakes, such as infrasound caused by underwater activities, such as military submarines, or pollution,” she said
Japanese legend has linked oarfish sightings to earthquakes. It is one of several myths surrounding unusual animal behaviour or observations prior to earthquakes, which have been used anecdotally to predict impending disasters.
However, Dr Grant has shown in earlier research that there was no link between reports of mass migrations of young frogs and earthquakes – a connection that had been made in Chinese folklore.