Oarfish catch that revives memories of sea monsters

It's believed oarfish can jettison sections of their bodies, much the way lizards shed their tails

It was a big day for marine biologists: On Oct. 13, the body of an 18-foot oarfish was dragged from the water onto Santa Catalina Island off the California coast, presenting a rare opportunity for local scientists to study one of the world’s most elusive and awe-inspiring big fish. Five days later, it was a big day again: Another oarfish washed up 50 miles away, this one 14 feet with 6-foot-long ovaries full of eggs.

Pairs of oarfish have appeared within days of each other before, deepening the mystique that surrounds the animal. But the twin discoveries nevertheless sent a wave of excitement through a scientific community more used to reading about oarfish than handling them in the lab. “These are unpredictable fish,” said Dr Milton Love, a research biologist at the Marine Science Institute of the University of California, Santa Barbara. “And it’s hard to study unpredictable fish.”Oarfish, which are long and eel-like in appearance, can grow to stupendous lengths - though ancient rumours of 55-foot specimens are probably exaggerated - and have inspired tales of sea monsters since ancient times. Scientists know very little about them because they are “virtually never caught in nets or by hooks, and they’ve only been observed under water a handful of times,” Love said. “So you’re kind of left with these not random but rare events, and that’s the only way you can study them.”

It is known that oarfish are notoriously bad swimmers; their long bodies remain still while their undulating fins handle most of the propulsion, yet they have apparently learned to avoid nets, Love said. Precisely what will be learned from the two newfound fish, which were dissected and divvied up among a handful of research institutions, remains to be seen. “You can only learn so much from a dead fish,” Love said. But by last week, a coterie of researchers, including a comparative ophthalmologist and a gill expert, were lining up to study them.

Early observations revealed that the second fish, found in Oceanside, was apparently ready to spawn. “There were probably hundreds of thousands of eggs in those ovaries,” said Dr H J Walker, the marine biologist at the Scripps Institution of Oceanography who extracted the eggs. Its stomach was nearly empty, supporting the theory that a strong current, possibly the northeast-flowing Kuroshio, had carried it and the other oarfish, a male, away from their preferred environment and food sources.

A variety of parasites, including large larval tapeworms and a spiny-headed worm, were found in the intestines of the male, potentially giving a clue about where these particular oarfish lived and fed. Their species, Regalecus russelii, is most populous in the Western Pacific. 

Oarfish fans noted with excitement that the male was missing some of the posterior part of its body, colloquially known as the tail. Dr. Tyson Roberts, an ichthyologist with the Smithsonian Tropical Research Institute who is widely regarded as the world’s leading oarfish expert, has long hypothesized that oarfish can jettison sections of their bodies below the abdomen, much the way lizards can shed their tails.

Energetic benefits

As the world’s largest bony fish, oarfish have no known natural predator, so unlike with lizards, any shedding of the body is probably not done in self-defence, Roberts said. Such behaviour is more likely meant to make swimming more efficient, among other reasons. “There may also be energetic benefits in shedding the posterior part of the body if it does not have much survival value, as apparently is the case in oarfishes,” he added.

Even oarfish experts disagree on some basic facts. Most refer to them as deep-sea creatures, contending that they live 500 to 1,000 feet below the surface. Roberts says that is not so. “Mostly they spend their time quite near the surface, suspended vertically with their heads up, just passively floating,” said Roberts who championed the idea that there was more than one species of oarfish. He also believes that they have the capacity to change gender. “It may be that all individuals pass through a stage in which they are males and then pass through a stage in which they’re females,” he said.

Just how deep the oarfish resides may become clearer in the coming months as researchers study the eyes of the new specimens, possibly learning whether they are designed to see in the low light of the deep ocean. “There’s not much information on the oarfish eye, which is unusually large,” Walker said.

At California State University, Fullerton, Misty Paig-Tran, a biomechanist, will use CT scans to make a three-dimensional model of the female specimen, most of which she now possesses (the head will soon be delivered to Walker). Her preliminary X-rays gave researchers a closer look at the structures that support the dorsal fin, which may help explain the animal’s unusual way of swimming.

Oarfish have been a source of fascination for centuries. With long bodies, toothless jaws and giant red dorsal fins that protrude from their heads, they are often mistaken for monsters. “Most biologists will tell you it probably is the species responsible for the sea serpent legend,” Walker said.

An ancient Japanese myth holds that washed-up oarfish are a sign of an impending earthquake, a theory that regained popularity after about 20 oarfish beached themselves in Japan before the 2011 earthquake and tsunami. In Japan, the oarfish is known as ryugu no tsukai, or “messenger from the sea god’s palace.” In California, the one-two arrival of the latest oarfish brought feverish speculation that an earthquake was imminent. But researchers said there was little science behind the myth.

“If something about tectonic movement is killing these fish, why aren’t the other fish in the environment doing the same thing?” Love said. The Catalina specimen might still be under water had Jasmine Santana, 26, a marine science instructor at the Catalina Island Marine Institute, not spotted it about 15 feet down while snorkeling on her day off.

“I recognised it because my colleague had shown me pictures of it,” she said. After dragging the fish to land, she and some of her co-workers placed it on ice in a ditch outside the institute.

“We wanted the kids to see it,” said Dr. Jeff Chace, a programme director at the institute. “We dissected it after we found it, then packed up all the organs, tissue samples, skin samples and eyeball samples and sent them off to various institutions.” Chace has put the rest of the carcass in deep freeze until he can find someone who can clean and mount the skeleton.