Leading the charge is the Dutch food group Nutreco, the world's largest salmon farmer, which boasts of having already carried out a successful first test harvest of cod.

"Cod is one of the most promising new species for fish farming that we have," said Wout Dekker, chief executive of Nutreco, which is also a major meat and poultry producer as well as animal feed maker.

"Demand remains strong, but it's clear that because wild stocks are so low commercial fishing of cod can't go on as it has. There needs to be an alternative. That's the potential for aquaculture."

Cod is one of the world's most important cold water fish, with a large and very well-defined market.

Annual catches, which peaked in 1969 at about four million tonnes, have declined steadily in recent years to about a quarter of that figure now, which is roughly the size of the global farmed salmon market.

Scientists have said repeatedly that stocks of wild cod are so depleted in some areas that a ban on fishing is the only way to prevent its eventual extinction.

Nutreco, citing research by environmental groups, says around 70 percent of the world's oceans are over fished and that hake and sole are other species facing extinction.

DIVING INTO COD

Nutreco, which has struggled in recent years because of low salmon prices -- as well as outbreaks of bird flu and foot and mouth disease -- began to research cod farming in the 1980s.

It was only in 2002 when it finally entered the sector with the purchase of a 56 percent stake in the company Cod Culture Norway and set up a cod hatchery with a capacity of 10 million fry, or infant fish, which was the largest of its kind.

Nutreco is now in the process of taking over the fish farming operations of Norway's Stolt-Nielsen, which will be merged with its own in a stand-alone company it hopes to make a global leader in fish farming.

Salmon as well as cod and other species will play a role there.

Cod farming for the most part is much like farming salmon, something that should give Nutreco -- which also farms halibut, barramundi and yellowtail -- an edge as the industry develops.

But one critical and costly difference is that newly hatched cod larvae are just a fraction of the size of salmon larvae and, unlike larvae of that species, need live feed.

The result was high mortality and costs in the early stages of cod farming and a factor that contributed to the failure in the 1970s of the first attempts to farm the fish.

It proved only a brief obstacle for Nutreco, which eventually became the first to discover cod larvae's nutritional requirements and develop a successful method of feeding them.

Now the firm believes output of farmed cod could expand rapidly, outpacing growth seen in the early years of salmon farming, the start of which some 30 years ago ushered in the era of modern aquaculture.

Nutreco, which produces about 20 percent of the world's farmed salmon, says global production could reach as much as 700,000 tonnes by 2015.

That compares with a starting point of almost zero in 2002 and would nearly equal current output from commercial fishing. Cod production in Norway alone is seen reaching up to 400,000 tonnes within the next decade, about double the country's current annual fishing quota.

WILL CONSUMERS BITE?

But the success of cod farming is not a given.

Nutreco has already felt the pinch of miscalculating the market with poor salmon prices and mistaken estimates of consumer demand has hurt its results in recent years.