This appears to be just another baseless media-scare, like the mercury-in-fish hype. I checked with a physicist on allexperts.com who pointed out that the Fukushima radiation was far less than the levels found in Czernobyl, and the latter also turned out to be  a fraudulent scare.

There is a bigger issue as regards Alaskan so-called "wild" salmon:-

http://blogfishx.blogspot.co.at/2008/09/alaskas-half-farmed-salmon.html

Geoff.