The fish had lost its tail somehow while alive and it had disc-shaped wounds from cookiecutter sharks, but those injuries wouldn't have been deadly, Walker said.
In fact, it's unclear why the creature died, although Walker said it was possible the deep-water fish came too close to the surface, where it may have been knocked around by waves.
The oarfish washed up on a beach in the San Diego County coastal city of Oceanside on Friday. Several days earlier, a snorkeler found the carcass of an 18-foot oarfish off Catalina Island and dragged it to shore with some help.
The cause of death for the larger fish also remains a mystery.
The rarely seen deep sea-dwelling creatures, which can grow to more than 50 feet, may be the inspiration of sea monsters found in literature and throughout history. Photos of the oarfish have circulated widely online, spurring general interest in the mysterious creature but contributing little to scientists' knowledge of the fish.