Japan's Fisheries Agency plans to increase tests of marine products from around the Fukushima Daiichi nuclear plant to prevent reputational damage after treated and diluted water from the facility is released into the ocean.

Now, fish are being caught off Fukushima Prefecture except in areas within 10 kilometers of the plant.

Fukushima prefectural officials test the hauled fish every week. If radioactive substances are detected in higher-than-acceptable levels, the national government orders restrictions on the shipment of the same species of fish.

Currently, only black rockfish are subject to shipment restrictions, after they failed tests in January of last year.

Fishers' cooperatives in Fukushima plan to test all species of fish to be shipped, every day a catch is landed. If radioactive substances at levels higher than voluntarily-set standards are detected, the cooperatives will refrain from shipping the fish.

The Fisheries Agency has been testing various species of fish for tritium since June of last year, along the Pacific from Hokkaido in the north down to Chiba Prefecture.

In addition, after the water discharge begins, the state agency will examine fish caught within 10 kilometers of the plant for tritium every day for the time being, including weekends. The test results will be made public a day or two later.

Agency officials say that by disclosing the results of tests near the point of discharge, they hope to dispel consumer concerns and enable them to enjoy Fukushima's seafood without worry.

Water used to cool molten fuel at the plant mixes with rain and groundwater. The accumulated water is treated to remove most radioactive substances, but still contains tritium.

The government plans to dilute the treated water to reduce tritium levels to about one-seventh the World Health Organization's guidelines for drinking water quality before releasing it into the sea.