A single sock-eyed salmon found in a Canadian lake in 2015 did test positive for trace amounts of Fukushima radiation, but this is not a demonstrable health concern.
A single salmon found in the Osoyoos Lake in British Columbia in 2015 (first reported in November 2016) had low but detectable levels of the radioactive isotope cesium-134, universally acknowledged as a marker for Fukushima radiation.
This single fish, whose radiation levels were well below any metric used by any government agency to gauge exposure risk, remains the only salmon specimen to test positive for Fukushima radiation in North America; the actual amount of radiation you would be exposed to from this fish — should more exist — would be roughly equal to the amount you would get from eating any salmon as a result of naturally occurring radioisotopes.
On 10 February 2017, OrganicAndHealthy.org published a story with the frightening headline “Fukushima: First Images Emerge Of Radioactive Salmon In Canada”. While this post did, in fact, come with a stock image of Canadian salmon, it did not deliver on its promise of visual evidence of radioactive salmon, instead providing lazily researched, error-riddled assertions based entirely on others’ flawed reporting.
Cesium-134 is a radioactive isotope formed principally by man-made activity, whose only plausible source on Earth, currently, is the Fukushima disaster. It decays at a relatively fast rate and therefore cannot be tied previous nuclear disasters or atomic testing.
The narrative presented by OrganicAndHealthy.org conflates two issues: the presence of cesium-134 in marine waters off of the coast of western North America, and the presence of cesium-134 in North American salmon. Becquerels per cubic meter, cited above, are used to assess the concentration of radioactive isotopes in a volume of liquid, while becquerels per kilogram would be the appropriate for measuring its presence in fish.
Read more at Radioactive Canadian Salmon Tied to Fukushima Disaster?