Fishermen are back on the water along the coast of Fukushima after operations were suspended last month after large amounts of contaminated water from the crippled Dai-ichi nuclear power station were found leaking into the Pacific Ocean.

Kyodo news agency reported that 20 fishing vessels set sail Wednesday from a port in the city of Soma, 45 kilometers north of the beleaguered nuclear campus. The expedition is said to be a trial to check if radiation levels in seafood caught off Japan's northeastern coast are within the government's safety limits.

Similar trials have previously taken place in the past, but various interruptions have stalled the process.

Commercial fishing off the Fukushima coast was suspended for 15 months following the March 2011 earthquake and tsunami that caused the meltdown of three nuclear reactors. After trail fishing operations were restarted in June 2012, they were halted again last month, Kyodo reported.

The nuclear plant's operator, Tokyo Electric Power Co. (Tepco), has faced an onslaught of criticism for its handling of the situation. Tepco faces the challenge of running out of room to store the hundreds of thousand of gallons of contaminated water produced in an effort to keep the broken reactor cores cool, as well as keeping water contaminated by the nuclear reactors from spilling into the sea.

After a string of tests on seafood caught off the Fukushima coast did not show radiation levels above the Japan government's 100 becquerels per kilogram safety limit for food products, the Soma fishing cooperative was given the green light to resume fishing trials. Of the 100 fish and seafood specimens tested, 95 had no radioactive material and and the other five contained less than one-tenth of the government limit, Kyodo reported.

The fishermen were at sea for 12 hours, attempting to catch 18 species of fish and seafood, including octopus and squid.

"We must carry out this trial operation to demonstrate to Tepco, the government and society that we are determined to act with an eye to starting full-fledged operations," said Hiroyuki Sato, chief of the Soma fisheries co-op.

The catch will be put on sale if radiation readings are below 50 becquerels per kilogram, Kyodo reported.

Two other fishing cooperatives from Iwaki and Onahama will begin fishing trials next week, the first time since the 2011 disaster, Bloomberg News reported from Tokyo.