"Just because you haven't read about it in the news" lately, he added, "doesn't mean it has gone away."
Because the Japanese rank among the most voracious consumers of seafood in the world, the country's Ministry of Agriculture, Forestry and Fisheries has been closely monitoring radiation levels in coastal fish since the Fukushima disaster in March of 2011.
To play it extra safe, Japan has also tightened restrictions on two radioactive forms of cesium so that fisheries must be closed if levels in fish exceed a limit of 100 units of a measurement called becquerels per kilogram of wet weight. Consuming levels of cesium above that much every day for a year, Buesseler said, would start to constitute a safety risk.
The fisheries agency has been releasing data regularly, including an annual report on more than 8,500 samples of fish, shellfish and seaweed taken from the coastal areas near Fukushima. Even though the data is freely accessible to the public, it can be hard to interpret so much information. So, Buesseler analyzed the numbers to see what kind of patterns they might reveal.