No Fukushima contamination has been found in any of 12 fish sampled and tested by the Alaska Department of Environmental Conservation (DEC) in 2017. Sampled between March and July 2017, the Pollock (Gadus chalcogrammus), Pacific Cod (Gadus macrocephalus), Halibut (Hippoglossus stenolepis), Herring (Clupea pallasii), and salmon (Sockeye (Oncorhynchus nerka), Chinook (O. tshawytscha), and Chum (O. keta)) were sampled from waters off the the Southeast panhandle to the Bering Sea.
These results are consistent with previous DEC testing which began in 2014 and, while 60 fish have been sampled over this period, none have yet tested positive for Fukushima contamination in any of the species tested from any of the regions sampled.
While Fukushima-related cesium was not detected in these samples, it may be present in concentrations below the detection limit. The DEC testing typically has a minimum detectable concentration (MDC) around 3 Becquerels per kilogram. A Becquerel or Bq is a radiation specific unit where 1 Bq = 1 radioactive decay per second. The derived intervention level for cesium (137Cs + 134Cs) is 1,200 Bq per kg in the United States according to the Food and Drug Administration. At these detection levels, any contamination presenting a considerable health risk should be easily detected.
For comparison, InFORM testing of biotic samples from British Columbia and Yukon typically results in an MDC closer to 1 Bq per kg after 6 hours of detection on the gamma spectrometer and samples selected for extended, 2 week testing, have MDCs less than 0.1 Bq per kg. These low thresholds for detection, and a cumulative analysis of all samples from a given year, have taught us that salmon from the NE Pacific have a fairly typical concentration of 0.20 Bq per kg of 137Cs present as a remnant from atmospheric tests of nuclear weapons conducted in the 1950’s and 1960’s.
Similar low levels are likely present in Alaskan fish as well, but detection of such low concentrations is costly and, while informative for scientific purposes, does not change the result that that radiation in these fish poses a negligible health risk when consumed.