By Jill Marshall
Alvin's Guide To Good Business, BBC World News, Japan
A billion people depend on eating fish, while 200 million workers survive by catching it.
Cod stocks are in peril worldwide
But the oceans are under extreme pressure and many fear we are running out of fish.
The experience of the Grand Banks Cod Fishery, off the east coast of Canada, serves as a grim warning.
It had been landing tens of thousands of tonnes of cod every year for centuries.
But, in the early 1990s, one of the world's most abundant populations of the fish suddenly collapsed, leading to a total fishing moratorium.
"Forty thousand fishermen lost their livelihoods," says Rupert Howes, chief executive of the Marine Stewardship Council (MSC). "This was the wake-up call."
Over the last 50 years, the amount of fish caught around the world has increased five times. We used to think the oceans were limitless: now we know this isn't true.
The MSC was established 10 years ago to help transform fishing. A partnership of businesses, scientists and environmentalists, it certifies seafood that has been caught in a sustainable way.
At the moment, 10% of seafood is certified by the MSC as sustainable. Now it is moving into one of the biggest and most challenging markets - Japan.
Although Japan has just 2% of the world's population, it eats 10% of its fish. It's a national obsession.
Fisheries certified by the MSC as sustainable: 63
MSC-certified or under assessment: 10% of seafood
MSC-certified products are available in 41 countries
MSC logo appears on 2,500 products
In Tokyo's Tsukiji market - the world's largest - they trade more than 400 different types of seafood, from wriggling eels to 300kg tuna.
Before World War II, the vast majority of Japan's fish came from local waters. But now, because of depleted stocks, 40% of this fish is actually imported.
If this market is to have a future, it is essential that all these fish are caught using sustainable methods.
This will not happen unless customers understand the importance of sustainability and demand MSC-certified fish.
But few Japanese people know anything about the MSC.
"Is it to protect whales?" asked one woman.
"I've only heard the name," said another. "I don't know what they do."
The solution may lie in the small port of Yaizu. Here, some fishermen still use the traditional pole-and-line method to catch skipjack tuna, rather than nets.
This is more sustainable because young, small fish, that have not yet reproduced, can be thrown back. But fewer than 30% of Yaizu's fish are caught this way.
Hiroyuki Myojin, the president of a local fish processing factory, is determined to change this.
His ambition is to get his processing company MSC-certified, not only to ensure his own future but also as a marketing tool.
He only buys pole and line-caught fish. But winning certification is a rigorous process. To be successful, not only does the fishery have to become certified, but the entire supply chain.
Every step is checked, from fishery to processor, distributor, right up to the ultimate retailer, whether a supermarket or restaurant.
It will take many months.
"Given the choice," he says, "99% of Japanese consumers would choose tuna caught by pole and line. Unfortunately, the fact that the MSC logo proves the fish is sustainable is not commonly known among Japanese consumers."
And that's the problem. Without consumer awareness, there is little incentive for fisheries to take the time or make the necessary investment to become MSC-certified.
To tackle this, the MSC is now forming alliances with big retailers to market the benefits of sustainable fish.
At an eco-fair in Tokyo, the MSC's Rupert Howes proudly displays the results of months of planning.
THE FISH TRADE
Between 90 and 93 million tonnes of fish are caught each year
The export value of world trade in fish was $63bn in 2003
A quarter of the world's fish stocks are over-exploited, depleted or in recovery
Source: UN FAO report, 2005
Aeon, the biggest supermarket chain in Japan with more than 1,200 stores, has dedicated a third of its stand to displaying its MSC-certified products.
"In Japan, we've seen the growth in MSC-labelled products go from none three years ago to 160 individual labelled products now," says Rupert.
"Aeon is carrying over 20 products just on their own."
Right now, 8% of Japanese consumers recognise the MSC logo. To improve that, the council has made some changes.
The logo now spells out that the fish symbol stands for "Certified, Sustainable Seafood".
And this tag line is translated into the appropriate local language in every market where certified seafood is sold.
Back in Yaizu, after six months, Mr Myojin has triumphed. His factory has just gained its MSC certificate.
A huge MSC logo adorns the exterior of the factory. The certificate itself is proudly displayed inside.
Mr Myojin is already discovering that it's not just good for fish, it's good for business.
"We've had around 30 inquiries from overseas," he says. "So we are currently exploring doing business with these contacts."
Fish has been fundamental to life in Japan for hundreds of years.
Mr Myojin invites Rupert Howes to accompany him to a local 2,000-year-old Shinto shrine. Dedicated to agriculture and fisheries, it's where local people have always come to pray for bountiful harvests, big catches and the safety of their fishermen.
Rupert pays his respects. "My prayer was for the world's oceans," he says, "and a hope that one day the Marine Stewardship Council can deliver its mission.
"And that in the future we can have plentiful bountiful supplies of sea food for future generations. It's as simple as that."
The MSC's work in Japan programme was featured in the series Alvin's Guide To Good Business, transmitted on BBC World on 27 and 28 February 2010.