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Salmon Says: Should you Worry about Radiation in your Wild Pacific Fish?

Posted: 05/30/2012 2:44 pm

Buck and Upton warned us. They're the two U.S. scientists who told the U.S. government early this year that there might be a problem with some migratory fish. Possible culprits: your salmon and tuna.

How correct were they? How will history's largest accidental deposit of radiation in the ocean affect our Pacific fish?

Despite the decades of nuclear testing in the Pacific Ocean, most experts agree that up to now, Pacific fish have been quite clean, when it comes to radiation. The reason: Pacific Ocean currents are so strong and waters so vast that radiation gets extremely diluted.

What are researchers finding post-Fukushima?
Dr. Ken Buesseler, a world expert in marine radioactivity with the Woods Hole Oceanographic Institution in Massachusetts, is leading an international research team tracking Fukushima's trails in the Pacific. He -- and other scientists -- have found radiation up to 600 km off Japan's coast. The amount they've found thus far does not pose a risk to humans or marine life, they say, although a few scientific voices are raising doubts.

But Buesseler warns there is a problem: The reactors are still leaking, and the radioactivity levels in the ocean at the power plant have not been declining in recent months. "Levels of radioactivity found in fish are not decreasing and there appear to be hot spots on the seafloor that are not well mapped," he said. He calls the trend worrisome and is encouraging scientists worldwide to work together in order to understand Fukushima's full impact.

"We still don't know the answers to many important questions concerning the impacts of Fukushima radionuclides on the oceans. For example, we still don't have a good handle on how much radioactivity was released, and we don't fully understand where it has ended up, and that holds for the ocean waters, seafloor sediments, and for marine biota, such as tuna," he explained in an email interview.

And what are the specific concerns?
When it comes to radiation in the waters, cesium- 134 and 137 are among the key elements. They stick around much longer than the short lived radioactive iodine you've heard about -- 134 for about two decades; 137 for about 300 years. (A general rule of thumb: radionuclides remain in the environment for about 10 times their physical half lives.) These elements travel in water, with the currents, and in air, thus getting deposited in rain; and cesium-137, along with strontium-90, can both accumulate in fish.

Then there's plutonium, which can stick to particles that settle on the sea floor or to sediments directly. Plutonium is highly reactive. (Buesseler has also detected radioactive silver from Fukushima. Results of tests for plutonium and strontium are pending.)

Understandably, experts are much more worried about the poor Japanese than those of us sitting comfortably across the Pacific. "I am very concerned...for those Japanese who may consume contaminated food from the areas surrounding Fukushima," said Jarvis Caffrey in an email. Caffrey is a radiation health specialist at the University of Oregon and a member of Buesseler's research team. "I am still not worried about us here in North America."

And what are the Japanese finding?
Fortunately, the Japanese are being somewhat transparent, testing the marine life in the affected area -- both fish life and plants -- and posting results regularly on the Internet. As they readily admit, they've detected levels of radiation higher than their own standards in many seaweed and fish located near the reactor.

The sand lance, for example, which lives on the coastal surface and is used to make fish feed, was among the first organisms in which excess radiation was detected. The seabass -- a species that dwells in the mid-level waters -- also revealed high levels.

Scientists agree, however, and the Japanese numbers suggest, that the biggest concern at this point are the fish that feed on sediments at the bottom of the sea along with filter feeders such as mussels and clams that take in food by filtering water and accumulate toxins.

"Many of the bottom dwelling fish off Fukushima have levels of radioactive cesium that remain above the limits considered safe for seafood consumption in Japan," said Buesseler. "I worry primarily about the near-shore crab, flounder, mussel/clam and seaweed pathways over there," Caffrey added in an email interview.

Will any of these contaminated plants or fish work their way up the food chain or directly onto our North American plates?

What seafoods are the Japanese selling?
Fortunately, the Japanese have shut down fishing in the immediate area and banned the selling of contaminated species. They appear to be engaged in intensive surveillance -- inspecting fish from offshore nearby prefectures as well. And effective April 1, 2012, their standards for acceptable levels of radiation became much stricter -- in the case of cesium-137, 10 times as strict as U.S. and Canadian standards.

But Japan is still exporting some fish. From where? It's hard to know. Japan's ban on fishing only covers an area 30 km from the site, and nobody seems to know much more than that about exactly where the fish are coming from. Both Canada and the U.S. are still importing Japanese foods, including fish from their seas.

What are the U.S. and Canadian governments doing to protect us?
This we know for sure: they're not inspecting all Japanese imports. Right after the incident, the Canadian Food Inspection Agency (CFIA) launched an emergency plan -- a sampling and testing strategy to monitor radiation in Japanese products. All food products they tested were "well below Health Canada's actionable levels for radioactive material," they said. In June 2011, they discontinued that plan. Since then, products from Japan have been getting the same scrutiny as products from elsewhere. The government still monitors radiation in imported foods to the same degree it did prior to the disaster; at this point, they have no plans for extensive testing of foods from Japan.

And the FDA? Since March 2011, the FDA has tested 199 samples of seafood coming in from Japan and performed field exams, using radiation detectors, on 40 per cent of the seafood products entering the U.S. To date, nothing has been of concern.

Almost 200 samples in 14 months, amid reports that radiation levels are not declining? Does that put you at ease? The FDA's post-Fukushima seafood statement still proclaims loudly and clearly that the Japanese sandlance is "the only Japanese fish with levels of radiation exceeding standards," and it buries the truth -- that many other fish exceed standards -- in fine print hidden elsewhere on its site.

Beyond Japan: Tuna and salmon and other migratory fish

At the start of the crisis and in spring 2012, the Canadian government tested a few samples of domestic migratory fish. Again, results were "well below the actionable level for radionuclides. ... At the present time, the CFIA is not planning further testing of domestic fish from the Pacific region for radionuclides," said a spokesperson in an email. Health Canada, however, will be examining the Vancouver food supply in the upcoming year, including fish caught off its shores.

Does the FDA have plans to test domestic migratory fish? They won't tell us unless and until they implement a program, said a spokesperson. Well, should they be testing?

"Radioactive contamination from the nuclear disaster in Japan has not emerged as a food safety problem for consumers in the United States," concluded natural resources policy experts Eugene H. Buck and Harold F. Upton in a report they prepared for the U.S. Congress.

Neither the radiation carried through ocean currents nor the radiation carried through atmospheric currents and deposited via rainfall in North America and the Pacific is a problem, they conclude. (The report is dated January 2012; much of the evidence it relies on is from the early days of the disaster.)

But the authors raise this possibility: migratory fish from Japan or from elsewhere in the Pacific could feed in contaminated waters and then swim to U.S. or Canadian waters and get caught. Albacore tuna and salmon, they suggest, are two potential culprits.

So what about our tuna?
Tuna, we know, do migrate across the Pacific. And now comes a report from Dr. Nicholas S. Fisher, a professor at the School of Marine and Atmospheric Sciences at State University of New York, that bluefin tuna caught off the San Diego coast just 4 months after the disaster are carrying Fukushima's footprint. Not to worry, however, Fisher tells us. The levels are low, he says, and "there is little evidence that these radioactivity levels would pose a risk to public health." He'll better understand any risks after measuring radioactivity in tuna arriving from Japan this summer, he said in an email interview. "But we do not expect serious risks from these newly arriving fish."

"This new article is a clear example of how a contaminant release on one side of the Pacific can quickly reach the other side and be detected, here in tuna," said Buesseler. I wonder what will happen to those tuna as toxins build up over their long lives.

What about our salmon? Is that a problem?
With wild Pacific salmon caught off the U.S. and Canadian coasts, you have nothing to worry about, says Dr. David Welch, a world expert on salmon migratory patterns. Salmon from Japan do not migrate as far as the North American coast, he says, and likewise, our North American species do not migrate as far west as Japan's coastal waters.

Mackerel, another migratory species, also don't cross the Pacific, he says. Instead, they travel up and down the coast.

But look what's coming our way -- the Kuroshio Current
You have to see this map -- a moving projection of the Kuroshio, a strong ocean current that flows eastward off the coast of Japan and could be carrying many of the longer-lived radioactive elements.

The current moves toward the U.S. Pacific coast (in fact, it kept the radiation from travelling southwards), then mixes with another current and moves up to Alaska. The elements in the current are projected to arrive near the U.S. west coast in about four years. (Don't confuse this with the debris you've seen; that gets pushed along faster by the wind. In fact some of it has already arrived, but many experts say it probably doesn't present a radiation problem. The tsunami pushed the debris offshore before most of the radiation was released.)

By the time any Fukushima elements arrive here in that current, most experts say, they will be so diluted as to have no effect. Meanwhile, could our fish become contaminated by feeding in that current -- or by feeding on fish that have fed there? Again, Welch is not concerned about our salmon. "Nothing we currently know about salmon suggests that any North American salmon go anywhere close to the areas of higher radiation levels," he said.

But what about your beloved tuna? We'll have to wait for those answers. Personally, I've been avoiding it for years because much of it is laden with mercury. Most tuna live longer than salmon and thus have more time to accumulate pollutants. As Salmon Says, wild Pacific salmon's a healthier choice.

 

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