Mysteries of the Deep: Oarfish Discoveries

Posted by: Kelsey Schueler

Imagine an almost 20 foot deep-sea fish with a bright-orange, ribbon-like dorsal fin along its narrow body that lives in one of the earth’s last largely unexplored ecosystems. Now imagine stumbling into two of these fish in the same week! This is reality for researchers in Southern California. The exciting and puzzling discovery has sparked many to ask why? From Japanese legends that oarfish are harbingers of , to hypotheses on shifting ocean conditions, the cause of death is still unknown.

Catalina Island Marine Institute

In some respects, the oarfish are reminders of how little is known about the ocean. The rarely seen and rarely studied species lives in the mid-ocean mesopelagic zone, which receives almost no sunlight. Compared to the sea surface and floor, researchers have explored very little in the middle of the water column. While many smaller species call the mesopelagic home, the giant oarfish is quite unique. This over 20 foot behemoth floats in place, essentially swimming vertically while slurping up tiny organisms (check out rare footage of a live oarfish swimming). Their unique body shape likely gave rise to the notion of sea serpents.

As a result, samples are in high demand. The first oarfish, measuring 18 feet, was found off Santa Catalina Island. It is the largest oarfish reported in nearly 20 years. Around the world, researchers are anxious for a piece of tissue. Samples will be tested for toxins, including radiation from Fukushima. DNA samples were also collected to shed light on the oarfish’s nearest relatives. The vertebrae, gills, liver, heart and eyes will also be examined. Large parasites (up to six feet long) were discovered in the intestine.

Phil Hastings, Scripps Institution of Oceanography

The second oarfish, a female with eggs, was last week. Researchers found parasites, sand, and a small amount of krill in the stomach. The ear bones, which provide a wealth of information including the age, were not recovered from the damaged head. Scientists did not even attempt to weigh the massive fish, which had to be cut into four pieces for transport.

Many species like , spend more time in the mesoplegaic than was originally thought. While it will take years for research results, it also represents an opportunity to learn more about the entire water column and how the ocean works.

Want to learn more? Check out this fantastic with Russ Vetter, NOAA’s Southwest Fisheries Science Center biologist.

Date Posted: November 4, 2013 @ 2:33 pm Comments Off

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