"TEPCO made the startling admission... at a press conference that the plant is leaking 8 billion bequerels per day. (8 gigabequerels)
5 billion bq of strontium 90
2 billion bq of cesium 137
1 billion bq of tritium..." from SimplyInfo
Worth noting is that the majority of the relases are strontium 90, a radioisotope known to collect in bone and increase the risk of leukemia. Strontium 90, along with tritium, is particularly hard to detect through widely used detection methods.
According to SimplyInfo, 8 billion Bq per day would mean that the total release to the ocean from Fukushima would be well over the assumed release of 11 Terabecquerels over four years' time.