The bespectacled third-generation angler has heard the warnings that milk, spinach and other vegetables grown around the plant have been found to contain traces of the radioactive isotopes iodine-131 and cesium-137.
Now Kondou and others in Kesennuma worry that radiation from the seaside nuclear plant might also affect the region's long-bustling fishing industry, which provides tuna, oysters, shark, squid and seaweed to restaurants and supermarkets throughout Japan and around the world.
Photos: Japan's earthquake, tsunami and nuclear crisis
Japanese officials this week said they have detected higher than normal radiation levels in samples of seawater around the power complex. Kondou is concerned that dangerous isotopes might soon sicken the huge schools of tuna he reels onto his trawler, the 31 Kohei Maru.
"I worry the radiation might move up the food chain," says Kondou, 40, who was more than 300 miles from shore searching for fish when the quake struck March 11 . "At first, the smaller fish will become infected and then will get eaten by the bigger fish."
While the alarm is understandable, the science of radiation contamination suggests the health risks are less scary. Andrew Maidment, associate professor of radiology at the Hospital of the University of Pennsylvania, says radiation will be very heavily diluted in the large expanse of seawater off Japan's northeastern coast, though inland fisheries such as shallow-water fish farms might face a slightly higher risk of contamination.
"These radioactive materials are highly soluble and are going to dissolve," says Maidment, who is a consultant to the International Atomic Energy Agency.
But that may not damp ongoing fears both here and abroad, which can affect sales with the same force as reality.
At the Tsukiji fish market in Tokyo, which ships Kesennuma's catch to ports across the globe, wholesalers say that overseas orders have been slashed and prices on some fresh fish have fallen by half due to radioactivity concerns.
In recent days, the market's sushi bars, which usually are packed with tourists who wait more than two hours for service, have been half-empty.
At one stall, exporter Yasuhiro Yamazaki has a cellphone pressed to his ear as he fields calls from customers in the U.S., Australia, Taiwan, Hong Kong and Indonesia. They all want to know the same thing: Are Japan's fish contaminated?
Says Yamazaki: "We are up against an invisible enemy."
The growing concerns could cause his company, Tsukiji's largest exporter, to lose $10 million, roughly 20% of his annual revenue.
It is unclear how much of the radioactive isotope seepage has flowed into the sea at Fukushima through sources ranging from windblown smoke settling atop the water to the possibly tens of thousands of gallons of water that have been pumped into the stricken nuclear reactors or dumped from above by helicopter. Water pumped into the reactors to cool the fuel rods is usually protected from contamination by a zirconium casing, but casings have melted in overheated reactors, exposing any water moving past to high levels of radiation. As workers seek to repair the Fukushima Daiichi nuclear plant, the impact of radioactivity on comestibles produced here is intensifying. Officials have now urged consumers not to eat a dozen types of vegetables from Fukushima prefecture after traces of iodine-131 and cesium-137 were found in the region. The U.S. Food and Drug Administration has banned imports of milk, fresh fruit and vegetables from four areas near the nuclear plant.
On Wednesday, government officials in Tokyo and five nearby cities announced that infants should no longer consume tap water because elevated levels of radioactive iodine were found at a water treatment plant.
This week's report on seawater has heightened fishermen's concerns about their wares, the nation's signature export, even though the government has said the seafood is safe to eat.
The northeast, where the quake and tsunami hit, plays a vital role in Japan's $16.5-billion annual fishing industry and harbor towns such as Kesennuma already are reeling from nature's devastation.
"I wonder whether this town can survive," says Kondou, who has gone to sea since he was 15 and now fills the shiny hip boots of his father and grandfather before him. "I hope it can, but I'm not sure."