For a second year, seafood taken from Alaska waters has tested negative for radiation from Japan's 2011 Fukushima tsunami and nuclear disaster, state officials say.
The Department of Environmental Conservation said Monday that the tests show no appreciable iodine-131, cesium-137 or cesium-134 in samples of cod, halibut, herring, pollock, sablefish and king, chum, sockeye and pink salmon. The fish were collected from the Aleutian Islands and the Bering Sea, the Gulf of Alaska, Bristol Bay and Southeast Alaska, following negative test results on Alaska seafood last year. Scientists had suggested that Fukushima radiation in water might peak in 2015.
"The testing in 2015 continues to confirm that the quality of Alaska seafood has not been impacted, with all tests showing 'non-detect' for radionuclides associated with the Fukushima nuclear disaster," DEC officials wrote.
Marlena Brewer, a risk management specialist with the department, said a number of fish -- between four and 10, according to DEC's website -- were gathered by the state for each of the 23 samples collected across the four regions of this year's testing.
"There's no significant difference in the sampling sizes," Brewer said. "It's a composite of multiple fish of the same species."
The samples were taken to the federal Food and Drug Administration's Winchester Engineering Analytical Center in Massachusetts for examination. Brewer said this year's testing system didn't differ significantly from 2014's.
"We used the same statistical sampling method the FDA uses for all of their analyses, and the lab used the same analytical method," Brewer said.
None of the samples triggered the detection threshold per kilogram of 2 becquerels, an international unit of radiation measurement. The FDA's official levels of concern, by contrast, are 170 becquerels per kilogram for iodine-131 and 1,200 becquerels per kilogram for the cesium isotopes.
In April, the Woods Hole Oceanographic Institute collected samples that showed trace elements of Fukushima radiation off the coast of British Columbia. DEC described the radiation levels as "thousands of times lower than what the U.S. Environmental Protection Agency considers safe for drinking water."
DEC said the Alaska environmental organization Cook Inletkeeper also ran a 2014 test on water taken from the Inlet, which generated a "non-detect" result for radiation from the Fukushima disaster.
According to Brewer, the test findings bear out DEC's theories about why contamination hasn't spread to Alaska fish, few of which travel to the Japanese side of the Pacific Ocean.
"It's just that the levels are so low in our waters that it's just not getting picked up by the fish," Brewer said. "And then there's also the great amount of dilution that's occurred from Japan to Alaska."
With state officials unaware of further word from scientists of future peaks in Fukushima radiation, the department has no plans to continue testing in 2016 -- but will be following test results from Woods Hole and other groups.
"There are continuous monitoring efforts from a multitude of agencies and organizations," Brewer said.