Fish caught in coastal waters of Ibaraki Prefecture were found to have 526 becquerels of radioactive cesium per one kilogram. That’s higher than the allowable amount of 500 becquerels per kilogram.

Cesium, which has a half-life of 30 years, is likely to have accumulated inside the fish’s body after the fish consumed smaller organisms.

The recent development comes after sand eels caught in coastal waters of Ibaraki Prefecture were found to have four-thousand-80 becquerels of radioactive iodine per one kilogram.

Following that discovery, the Japanese government decided to apply its first radiation safety measure on fish by using the same standard of allowable radioactive iodine for vegetables. The amount of radioactive iodine allowed by Tokyo for vegetables is two-thousand becquerels per kilogram.