Radioactive Bluefin Tuna: Japan Nuclear Plant Contaminated Fish Found Off California Coast

[MyLittlePony 340]

LOS ANGELES -- Across the vast Pacific, the mighty bluefin tuna carried radioactive contamination that leaked from Japan's crippled nuclear plant to the shores of the United States 6,000 miles away – the first time a huge migrating fish has been shown to carry radioactivity such a distance.

"We were frankly kind of startled," said Nicholas Fisher, one of the researchers reporting the findings online Monday in the Proceedings of the National Academy of Sciences.

The levels of radioactive cesium were 10 times higher than the amount measured in tuna off the California coast in previous years. But even so, that's still far below safe-to-eat limits set by the U.S. and Japanese governments.

Previously, smaller fish and plankton were found with elevated levels of radiation in Japanese waters after a magnitude-9 earthquake in March 2011 triggered a tsunami that badly damaged the Fukushima Dai-ichi reactors.

But scientists did not expect the nuclear fallout to linger in huge fish that sail the world because such fish can metabolize and shed radioactive substances.

One of the largest and speediest fish, Pacific bluefin tuna can grow to 10 feet and weigh more than 1,000 pounds. They spawn off the Japan coast and swim east at breakneck speed to school in waters off California and the tip of Baja California, Mexico.

Five months after the Fukushima disaster, Fisher of Stony Brook University in New York and a team decided to test Pacific bluefin that were caught off the coast of San Diego. To their surprise, tissue samples from all 15 tuna captured contained levels of two radioactive substances – ceisum-134 and cesium-137 – that were higher than in previous catches.

To rule out the possibility that the radiation was carried by ocean currents or deposited in the sea through the atmosphere, the team also analyzed yellowfin tuna, found in the eastern Pacific, and bluefin that migrated to Southern California before the nuclear crisis. They found no trace of cesium-134 and only background levels of cesium-137 left over from nuclear weapons testing in the 1960s.

The results "are unequivocal. Fukushima was the source," said Ken Buesseler of the Woods Hole Oceanographic Institution, who had no role in the research.

Bluefin tuna absorbed radioactive cesium from swimming in contaminated waters and feeding on contaminated prey such as krill and squid, the scientists said. As the predators made the journey east, they shed some of the radiation through metabolism and as they grew larger. Even so, they weren't able to completely flush out all the contamination from their system.

"That's a big ocean. To swim across it and still retain these radionuclides is pretty amazing," Fisher said.

Pacific bluefin tuna are prized in Japan where a thin slice of the tender red meat prepared as sushi can fetch $24 per piece at top Tokyo restaurants. Japanese consume 80 percent of the world's Pacific and Atlantic bluefin tuna.

The real test of how radioactivity affects tuna populations comes this summer when researchers planned to repeat the study with a larger number of samples. Bluefin tuna that journeyed last year were exposed to radiation for about a month. The upcoming travelers have been swimming in radioactive waters for a longer period. How this will affect concentrations of contamination remains to be seen.

Now that scientists know that bluefin tuna can transport radiation, they also want to track the movements of other migratory species including sea turtles, sharks and seabirds.

[Darnell 8,478]

come to Texas. We Have Catfish Farms.

Is some nice meat

[Hilarious Clinton 452]

"That's a big ocean. To swim across it and still retain these radionuclides is pretty amazing," Fisher said.

Really? What a stupid statement.

The biological half-life of cesium for humans is 70 days. I'm not sure what is for tuna. But since tuna always swim I don't think distance is an issue...... only time. It's just math.

FWIW biological half-life is the time it takes the body to remove half of an isotope from the body. It's different than radioactive half-life.

[mawilson 2,133]

Really? What a stupid statement.

The guy's name is Fisher. He knows stuff about fish.

[I AM NOT THAT GUY 5,715]

I was in the Marshalls around 1980. Apex predators, like sharks, still had sufficient byproducts from the fusion testing in the decade between 1948 and 1958, to cause heavy metal poisoning in the islanders, if you ate the cartilage along the back strap, a favorite delicacy, chucked and deep fried.

Edited May 29, 2012 by ☼

[I AM NOT THAT GUY 5,715]

Really? What a stupid statement.

The biological half-life of cesium for humans is 70 days. I'm not sure what is for tuna. But since tuna always swim I don't think distance is an issue...... only time. It's just math.

FWIW biological half-life is the time it takes the body to remove half of an isotope from the body. It's different than radioactive half-life.

I heard, and I don't remember the correct number, that it only takes months, at the most a few years, to replace every single atom and molecule in your entire body. I wonder if that includes the enamel in your teeth.

Edited May 29, 2012 by ☼

[Mr. Big Dog 10,747]

We just need less regulation. That would take care of testing fish for contamination. And nobody would know what's happening. Sure, people would die but who gives a ** if we get to pretend in return that nuclear energy is a good idea?

Edited May 30, 2012 by Mr. Big Dog

[unlockingsky 94]

there goes all my sashimi

[mawilson 2,133]

there goes all my sashimi

Tastes the same, radioactive or not.

[Mr. Big Dog 10,747]

Tastes the same, radioactive or not.

Yep, it will just have a little glow to it, that's all. Could replace the candle light.

[mawilson 2,133]

Yep, it will just have a little glow to it, that's all. Could replace the candle light.

What doesn't kill you makes you stronger. Or gives you cancer which will eventually kill you. Whatever.