Berkshire Hathaway, the trading conglomerate owned by US business tycoon Warren Buffett, has bought a 5 percent stake in each of Japan's five biggest trading houses, each with a firm footprint in the international seafood sector.

The long-term investments in Itochu, Marubeni, Mitsubishi, Mitsui and Sumitomo are together worth more than $6 billion (€5 billion) and could increase to 9.9 percent, marking a departure for Chairman Warren Buffett as he looks beyond the United States to diversify his conglomerate.

"The five major trading companies have many joint ventures throughout the world and are likely to have more," Buffett said in a statement. "I hope that in the future there may be opportunities of mutual benefit."

In August last year, land-based salmon farmer Pure Salmon signed a supply contract with Itochu for the domestic distribution of 10,000 metric tons of locally-grown Atlantic salmon.

The agreement, worth around $200 million (€167.5 million) annually at the retail value, will see Itochu sell all of the salmon produced by Pure Salmon at its Soul of Japan plant, which is currently under construction in Tsue, Mie Perfecture, in central Japan and is expected to be finished by 2021.

In April, Marubeni, along with Nippon Suisan (Nissui) Europe snapped up 66.7 percent of the shares of another land-based salmon producer, Danish Salmon.

The move marked a first step into land-based salmon production by the Japanese giants, who cited the growing demand for seafood and the static production of fisheries as their reason for the move.

Mitsubishi owns both Princes canned seafood company in the United Kingdom and salmon farming giant Cermaq.

Mitsui also has its fingers in several seafood pies. In salmonids, Mitsui is focused not only on conventional production through its collaboration with Chilean salmon farmer Multiexport, but also through its subsidiary Japanese land-based trout project, FRD Japan, now entering the second stage of its production plan.

Shrimp, too, is firmly on the agenda with a $153 million (€137 million) investment in Vietnamese producer Minh Phu in February last year.

Sumitomo meanwhile, is one of the Series A financiers behind cell-based seafood pioneer BlueNalu, through US subsidiary Sumitomo Corporation of Americas (SCOA).

Berkshire Hathaway, the largest company in the United States as measured by shareholders’ equity, has a long history of substantial, passive holdings in successful businesses. For instance, Berkshire Hathaway has held major stakes in Coca-Cola for 32 years, American Express for 29 years and Moody’s for 20 years.

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