(Update: Checked the corporate site of Maruha Nichiro. It is "pink salmon" or "humpback salmon", in northern Pacific Ocean, Bering Sea, Sea of Okhotsk, Japan Sea, Iwate Prefecture, and Hokkaido.)
Seikatsu Club is a co-op that has been publishing the results of its own analysis of food items it sells.
In the latest results on March 30, 2012, there are several items with radioactive cesium including a can of salmon from a major seafood company (Maruha Nichiro):
30 Bq/kg from lemon
32 Bq/kg from Kiyomi tangor (hybrid of satsuma mandarin orange and regular orange)
18 Bq/kg from a can of boiled salmon
For people trying to eliminate as much radioactive cesium as possible from the food they eat everyday, it's not getting any easier after one year.