Down Deep, An Unexpected Fish Boom
RENEE MONTAGNE, host:
Most of the stories you hear about wild fish involve their disappearance, usually because of over-fishing. Now for a fish tale that's more upbeat. Marine biologists working in the Pacific Ocean say they found a tasty deep-sea fish that is unexpectedly thriving. NPR's John Nielsen has more.
JOHN NIELSEN reporting:
If Iraq were to fall out of the sky onto a random part of the earth, odds are good that it would plunk into the ocean, sink for at least two miles and then settle into a seemingly endless mudflat called the abyssal plain. Marine biologist David Black(ph) of the Scripps Institution of Oceanography says the abyssal plain is at once the most common and least studied habitat in the world.
Dr. DAVID BLACK (Marine Biologist, Scripps Institution of Oceanography): About 50 percent of the earth's surface is made up of these big, flat plains of mud we know so little about.
NIELSEN: It's pitch-black down there in the mudflats and very, very cold but there's plenty of life including lots of weird looking fish. Boris Worm, a marine biologist at Dalhousie University in Halifax, Canada says the weirdest fish of all is the one they call the rattail.
Dr. BORIS WORM (Assistant Professor, Marine Conservation Biology, Biology Department, Dalhousie University, Halifax, Canada): They have a huge head, a big mouth with which they can engulf their prey and then the rest of their body is a long tapering tail. They look as a cross between a snake and a frog and some alien creature.
NIELSEN: David Black of Scripps is part of a team that's been counting rattails for 15 years now about 200 miles off the California coast. Basically, he rides around in a research boat that tows a sled across the mudflats 13,000 feet below him. The sled is equipped with a spotlight and an underwater camera.
Dr. BLACK: It takes photographs every couple of seconds so we end up with a strip of images about 1500 meters long and it's using those images to count the fish swimming above the sea floor.
NIELSEN: Black says the rattails barely notice the sled. Some swim straight into the camera. These collisions have seemed a bit more common in recent years he says. That hunch was confirmed when he went back and reviewed his records.
Dr. BLACK: And sure enough there was this long-term increase in the numbers of fish followed by a, you know, pretty rapid increase towards the end of the time series. We were very excited about that.
NIELSEN: Black was excited because deep-sea fish stocks aren't supposed to grow this quickly. Rattails, in particular, are notoriously slow to reproduce. Black's team says it's not sure what sparked the rattail boom. Boris Worm says that's not surprising given how little we know about the abyssal plain.
Dr. WORM: This is only the first long-term look that anybody had at the abyssal plains that I'm aware of. And so, it's like looking at the back of the moon for the first time--everything is a discovery basically.
NIELSEN: Worm says scientists may not have much time to make sense of this discovery partly because the rattail is a fish that people like to eat. In restaurants they're known as grenadier, they taste a lot like cod. Fishermen have already wiped out rattails living in the relatively shallow mudflats found in the Atlantic Ocean. Biologist Boris Worm says these fish should be safer in the deeper waters of the Pacific, but he also says he's been wrong before.
Dr. WORM: I thought jellyfish were safe. I thought sea cucumbers were safe. I thought sea urchins were safe, but we seem to be incredibly inventive in finding new resources and exploiting them very quickly.
NIELSEN: David Black of Scripps says he's yet to turn up evidence of fishing in his study area, but he has seen lots of beer cans sticking up out of the mud. John Nielsen, NPR News, Washington.
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