From the report of NRA (Nuclear Regulation Authority), Cesium-134/137 was detected from 32 of 32 marine soil samples taken this May.
The sampling locations are offshore of Miyagi, Fukushima, Ibaraki and Chiba Prefecture. The report was published on 7/13/2015.
The report says the samples were taken from 30m depth to 660m and collected by Marine Ecology Research Institute (MERI) and analyzed by Japan Atomic Energy Agency (JAEA).
Cs-134 was not detected from only one sample. Cs-134 was measured from all the rest of the samples.
The highest reading was 164 Bq/Kg in total of Cs-134/137. The sampling location was approx. in 40km South East of Fukushima nuclear plant.
Other nuclides such as Sr-90 and U-235 were not even tested. They did not collect samples from Tokyo Bay either.