(UPDATE) Additional info from the person who watched the program is as follows:
Radioactive silver (Ag-110m) was ND level in the seawater where abalones were found with radioactive silver. So there is no way of telling whether Ag-110m exists in marine life just by analyzing the water.
That was one piece of new information from NHK's ETV (Educational TV) program aired on November 27 at 10PM in Japan, "Mapping the Radiation Contamination - Marine Contamination", 4th in the series.
I'm sure I can still view the video at a third party site, until NHK finds out and takes down the video as it almost always does. While I look for the video, here's what the Japanese viewers are tweeting:
NHK's own survey off the coast of Fukushima Prefecture on September 11, 2011.
Radiation on the ship: 0.14 microsievert/hr, in the water 0.025 microsievert/hour. The number increases as it gets deeper. On the rock [at the bottom of the ocean] 1 microsievert/hour. Maximum number at the bottom of the ocean 1.74 microsievert/hour. Fine-grained sands at the bottom. The radiation level at the bottom of the ocean was max 70 times that of the ocean surface. (from this tweet)
Bioconcentration of radioactive cesium seen 10 to 20 kilometers off the coast of Fukushima. At the bottom of the ocean, 200 to 300 becquerels/kg [of cesium in the ocean soil]. The radiation level at the bottom 1 microsievert/hour. The area is an abalone fishery. 40 becquerels/kg in the sea water, 420 becquerels/kg in arame (type of seaweed that abalones eat), 2000 becquerels/kg in abalone. 50-fold concentration [from seawater to abalone].
Radioactive silver (Ag-110m) in abalone 410 becquerels/kg, in abalone liver 1800 becquerels/kg. (these two points from this tweet)
Effect of ocean currents is not what you may think. The Kuroshio Current, which comes up from south, may generally prevent the contaminated water from Fukushima from spreading further south. But the coastal current behaves totally different, and radioactive cesium has actually being transported south from Fukushima along the coast. In addition, as rivers reach the Pacific Ocean and discharge water, that creates their own micro-currents. As it turned out, a location off Ibaraki (Kajima) measured lower in radiation of the ocean soil than a location off Chiba (Inubozaki), which is much further south from Fukushima than the Ibaraki location. (from this and this tweets)
Abalone liver is a gourmet food in Japan.
And a Fukushima fisherman, with anger and sadness:
It's all fine idea, this "decontamination". But where will radioactive materials go after they are decontaminated? Into the river and in the end, into the ocean!