Fishing companies in Asia and Norway may benefit from an increase in demand from Japan, where radiation being released by the crippled Fukushima No. 1 nuclear plant is showing up in the ocean and food supply.

Hong Kong's Pacific Andes International Holdings Ltd. and Norway's Marine Harvest ASA, Cermaq ASA and Salmar ASA may see higher demand for their fish to make up for the drop in Japan's seafood production.

Five kinds of radioactive material released by damaged fuel rods from the Fukushima plant were detected in the nearby sea, including iodine-131, cesium-134 and cobalt, according to operator Tokyo Electric Power Co.

Chief Cabinet Secretary Yukio Edano said Wednesday the government instructed regulators to implement maximum monitoring on Japan's seafood. The prefectures nearest the nuclear plant — Miyagi, Iwate and Fukushima — produce 707,500 tons of seafood, accounting for 13 percent of Japan's 5.6 million tons of annual production, according to Statistics Japan.

"The fishing industry in Japan is actually badly destroyed or harmed by the earthquake and nuclear plant crisis," said Katie Tsui, head of investor relations at Pacific Andes International. "It's possible, in the longer term, demand for fish from Japan will increase."

The nation consumes about 9 million metric tons of seafood a year, second behind China, according to the website of the Sea Around Us Project, a collaboration between the University of British Columbia and the Pew Environment Group.

Pacific Andes Resources, a Singapore-based trading company 65 percent owned by Pacific Andes International, operates a fish-processing plant in Qingdao, China, and is China's largest importer of frozen fish, Tsui said.

Sales to Japan account for 8.5 percent of group revenue, with its No. 1 export being Alaska pollock roe, a Japanese delicacy, Tsui said. Pacific Andes also supplies McDonald's Corp. with pollock for its restaurants.

"Japan will have to increase the import of fish from other regions," Tsui said.

Japan is the world's largest importer of food and the second-largest buyer of seafood, according to the U.N. Food and Agriculture Organization.

Norway is the world's second-largest exporter of seafood after China, according to the FAO. The industry there may see "a positive benefit" because of the potential drop in Japanese seafood production, said Dag Sletmo, an analyst at ABG Sundal Collier Holding ASA in Oslo.

Japan accounts for 4 percent of Norway's salmon exports, he said. Marine Harvest, Cermaq and Salmar could benefit "as salmon is a high-value fish which can defend high transportation costs," he wrote.

Japan exported ¥195 billion in seafood last year, accounting for 0.3 percent of total exports, according to data on the website of the Agriculture, Forestry and Fisheries Ministry.

Edano assured consumers Wednesday that contamination levels in Japanese food, including milk and vegetables, were not harmful, yet that hasn't stopped foreign companies from taking precautions.

Sushi restaurants and hotels, including Shangri-La Asia's luxury chain and London's Zuma and Roka Japanese restaurants, said last week they stopped buying fresh produce from Japan because of fears of possible contamination.

Mandarin Oriental International Ltd.'s Hong Kong flagship stopped buying Japanese food, and Shangri-La Asia Ltd. withdrew Japanese fresh food from its kitchens. Tesco's Korean unit planned to halt sales of some fish from Japan.