Following the Tohoku Earthquake and Tsunami on March 11 and the resulting nuclear power plant disaster in Fukushima, radiation released into the environment and contamination of food has been a major concern among the Japanese public.
This report on the levels of iodine (I-131), cesium-134 (Cs-134) and cesium-137 (Cs-137) in Hokkaido marine life (such as pink salmon, chum/dog salmon, saury, etc.) was released by the Prefectural Government of Hokkaido and the Ministry of Health, Labor and Welfare back at the end of July.
The report finds that cesium radition was detected in marine life in Hokkaido from April through July, while no iodine radition has been found. The levels of cesium per kilogram, however, are well under the government's restrictions of 500 becquerels per kilogram.
Although I cannot speak with expertise in this area, the fact that raditation levels have been detected is a cause for concern as it raises questions about its impact on the Ainu community (salmon plays a major role in both traditional and modern Ainu life), and to the Japanese public in general (that the radiation has travelled all the way to Hokkaido and also because it is a major producer of food).