Fishermen in the Okuaizu region of Japan’s Fukushima prefecture were left hopeless after radioactive cesium exceeding the allowable limit detected in some river fish forced them to postpone this year’s fishing season indefinitely.

“This river’s sweetfish is exceptional,” Kiroku Gonoi, 65, the head of a local fisheries cooperative, said as he posted a sign reading “No Fishing ” along the Nojiri River in Okuaizu on March 30. “When I send it to my son and his wife who live far away, they are always pleased.”

The fisheries cooperative of the town of Kaneyama and Showa village near the Nojiri River was forced to postpone this year’s mountain stream fishing season, which was set to begin on April 1, after fish samples caught in the river in mid-March registered 119 to 139 becquerels of radioactive cesium per kilogram.

The readings exceed the new government-imposed provisional limit, which requires that cesium in regular food items not exceed 100 becquerels per kilogram.

The readings left many fishermen stunned, however. Furthermore, the Nojiri River runs some 130 kilometers away from the damaged Fukushima No. 1 nuclear plant.

Just before the opening of the 2011 season, fish samples from the Nojiri River measured only around 50 becquerels of radioactive cesium per kilogram — far lower than the then-allowable limit of 500 becquerels per kilogram. The fishermen were allowed to open the season as usual.

However, due to harmful rumors and other related reasons, the number of visitors to the river — which was popular with anglers for its clean streams — decreased drastically. The local fishermen were counting on a comeback this season.

In the beginning of March this year, in preparation for the opening of the fishing season and in consideration to the new, stricter cesium limits, fishermen submitted iwana (char) samples to be tested for radiation contamination. The results were positive — the fish measured between 45 to 66 becquerels per kilogram, below the new safety level.

Gonoi and other members of the fisheries cooperative were relieved — it had been another confirmation that the Okuaizu fish was safe. However, on March 28, shortly after he began sending fishing tickets to regular customers, he was notified that the most recent fish samples from mid-March measured 19 to 39 becquerels per kilogram over the 100-becquerel limit.

“It was decided by the government so the only thing we can do is accept it,” Gonoi says. “We have to prevent the possibility that children eat the fish and something happens to them.”

The decision to postpone the fishing season, however, was a harsh development that will affect not only fishermen but also local inns targeting visiting anglers.

Aerial radiation doses within the Nojiri River area are not high, and many locals and officials wonder what led to the recent high contamination readings.

“We are not exactly sure why cesium has accumulated in the fish. It could be that they were contaminated through the food chain,” an official with the Fukushima Prefecture’s fisheries division said.

The ban will be lifted if fish samples measure below the allowable limit three consecutive times. For the moment, however, there is no clear prospect of when this may happen.

Meanwhile, the fisheries cooperative is skeptical about the forthcoming sweetfish fishing season, set to begin in June. “As the water temperature rises, so too do the fishes’ metabolic rates. It is possible that the fish will excrete the cesium, ” Gonoi said.

The Mainichi Daily