A Japanese company has started exporting what it calls sustainably grown bluefin tuna, which it says allows sushi lovers to keep eating the species without driving down ocean stocks.
Bluefin tuna is either caught in the open seas or farmed from baby fish caught in nets, but marine products company Burimy says it is the first to sell bluefin grown from artificially hatched eggs.
"Our tuna won't affect the ecological system so that we can help stop draining marine resources," said Takahiro Hama, a director of the company based in the southern Japanese city of Amakusa.
"We have just begun full shipments to the United States," he said. "We hope to provide our sustainable tuna for Japanese sushi bars and restaurants which are concerned about protests from environmental activists."
Atlantic bluefin tuna stocks have crashed in recent decades due to industrial-scale fishing, mostly for the Japanese market.
Burimy has teamed up with Japan's Kinki University, which has succeeded in hatching eggs, nurturing baby fish and breeding them into fat adults in what the company says is the world's first complete cultivation cycle.
Burimy first bought 1,500 artificially hatched baby bluefin tuna from the university's A-marine Kindai laboratory in December 2007 and over the next two years grew them into 1.2-metre (four-foot) adults.
A baby bluefin tuna. (Photo: A-marine Kindai Co)
"This complete cultivation will help meet the demand of tuna-loving people without damaging the ecological balance," said Osamu Murata, chief of the project at A-marine Kindai.
"It may help the vision of bringing nature and humans into balance."
Since January, Burimy has shipped 20 fish a week to the United States.
Small amounts of fully farmed bluefin tuna, dubbed Kindai tuna, have also been sold at Japanese department stores and shops, priced at JPY 2,000 to JPY 4,000 (USD 22 to USD 44) per kilo (USD 10 to USD 20 per pound).
Burimy has set up five tanks measuring 40 by 40 metres that are 20 metres deep and filled with murky water to make the fast predator fish swim more slowly and avoid crashing into each other.
The company expects to ship 7,000 to 10,000 of the fish a year by 2012, targeting annual sales of JPY 1 billion (USD 11 million).