The rare oarfish measured more than 9 feet long.

For the second time in less than four months, an incredibly rare fish has washed ashore in the San Diego area, alarming scientists and raising some hard-to-answer questions. The oarfish, which can grow up to 12 feet in length or more, have floated to the coastline in La Jolla and, more recently, Encinitas further north. Experts aren’t sure why — or if more are coming.

The arrival of the two dead oarfish, which were hauled ashore for testing by the Scripps Institution of Oceanography , part of UC San Diego, is puzzling in part because the fish themselves are rarely seen by humans. Oarfish prefer the heavy depths of the deep ocean, surviving between 300 and 3,000 feet below the surface. In fact, according to the San Diego Union-Tribune , last week’s Encinitas oarfish was just the 21st such specimen to have washed up in the state in more than 120 years.

The rare, slender oarfish has often been called a “ doomsday fish” in popular culture, particularly in Japan where historically it have been viewed as a deep sea messenger of disaster or doom. Across Asia, anecdotal accounts of oarfish deaths have preceded earthquakes and other natural disasters.

“Oarfish are encountered all over the world,” Scripps said in an emailed statement to SFGATE, “yet we know relatively little about their life and biology.”

A rare oarfish, often described as a ‘doomsday fish,’ washed ashore in Encinitas, Calif., earlier this month.

The more recent arrival of a 9 ½-foot oarfish at Grandview Beach in Encinitas was preceded in August by an estimated 12-foot-long fish that was pulled to the shore by kayakers down in La Jolla Cove. The Encinitas fish was found by Scripps Ph.D. candidate Alison Laferriere, and both were scooped up by the world-famous Scripps Institution of Oceanography for further testing with the help of NOAA Fisheries .

What killed these two specific California sea serpents remains a mystery. Scientist Ben Frable, who is also the manager of the Scripps Institution of Oceanography’s Marine Vertebrate Collection, said in an email to SFGATE that “changes in ocean conditions” may be playing a role, but it’s not possible to draw firm conclusions at this time. “This wash-up coincided with the recent red tide and Santa Ana winds last week,” Frable said of the Encinitas oarfish’s arrival, “but many variables could lead to these strandings.”