Back in August I posted about how some Fukushima seafood (whelks and octopus, not fish) was being sold in Tokyo fish markets and at premium prices. My post ran with the unfortunately misleading title of “Fukushima fish: It’s back on the menu”. The fact is that fish from the beleaguered area is definitely not on the menu and hasn’t been since the disaster.

Export of Fukushima beef to the US has recently started again after a ban which began due to a foot and mouth outbreak in 2010, not the meltdown of three nuclear reactors at Fukushima-Daiichi power plant in March 2011. For the area’s fish, however, it’s still a life of freedom, albeit a freedom rich in radioactive caesium-134 and 137.

From Australia’s The Age:

In the wake of the incident, the Japanese government sought to calm public fears by lowering the levels of radioactivity that would mean a fish was deemed unsafe for human consumption. As of April 2012, fish can only be sold in Japan if it contains less than 100 becquerels of caesium 134 and 137 in seafood per kilogram of wet weight, down from a previous limit of 500 becquerels.

a pre-accident Fukushima power plant, pic: Kawamoto Takuo (Flickr CC)

Surprisingly, caesium levels in Fukushima fish have not decreased since the accident, some 18 months ago. Dr Ken Buesseler, of the Woods Hole Oceanographic Institution in Massachusetts believes this is due to continued caesium contamination of sea water from the sea floor or because of contaminated ground water from under Fukushima leaking into the sea.

He is quoted by the Associated Press:

The [radioactivity] numbers aren’t going down. Oceans usually cause the concentrations to decrease if the spigot is turned off. There has to be somewhere they’re picking up the caesium. Option one is the sea floor as the source of the continued contamination. The other source could be the reactors themselves.

Though contamination levels vary greatly from fish to fish and from day to day, under Japanese regulations around 40% of fish that are caught in the area are considered unfit for human consumption. Bottom-dwelling species like flounder, cod, pollock, halibut, skate and sole have the most consistently high caesium levels. Members of these species which live near Fukushima and surrounding prefectures are likely to be off the menu for another 10 years.

However, a BBC News report points out that Japan’s standards for radioactivity levels in fish are far more strict than, for example, those in the US – just 100 becquerels (units of radioactivity) per kilo when wet for the former compared to 1,200 Bq/kg for the latter. Still, since Japan consumes more fish per capita than most nations in the world, they have significant cause to be more stringent.

Fukushima fishing boat, pic: Kunimasa Kawabe (Flickr CC)