I don't have the specific links on this computer (sorry) but one of the major oceanographic research institutes published a fairly detailed report of their own measurements last year.

The general flavor of the report is that the pacific as a whole is in no danger. Despite the toxicity of what's been released, the pacific is very, very, big. They expressed concern for local waters near the plant, but weren't able to study that as freely due to Tepco and the Japanese government. Accumulation of isotopes in predator species is still a very real concern.