Los Angeles, CA (KTLA) -- Scientists say that migrating Pacific bluefin tuna off California's coast are carrying radioactive contamination from Japan's Fukushima Daiichi nuclear accident.
According to findings in the Proceedings of the National Academy of Sciences, the levels of radioactivity are 10 times higher than the amounts usually found.
Scientists sampled 15 tuna caught off San Diego and found that they all contained two radioactive substances -- caesium-134 and caesium-137.
The tuna have carried the radioactive contamination 6,000 miles from the waters near Japan's crippled nuclear plant.
It was damaged in a devastating magnitude 9.0 quake and subsequent tsunami in April 2011.
Experts say this is the first time that a huge migrating fish has been shown to carry radioactivity that far.
Previously, smaller fish and plankton in the waters off Japan were found to have higher-than-normal levels of radioactivity.
Scientists say that, even with the increased radioactivity, the levels in the tuna are still within the limits of what is safe to eat.