TROMSOE, Norway (AFP) - After perfecting the art of salmon farming, Norwegians now hope to repeat the success with the trickier cod, which has been fished to near extinction in some parts of the world. "The success of the farmed salmon is part of the reason for the optimism we see in cod farming today," says Jens Oestli of the Norwegian Institute of Fisheries and Aquaculture Research in Tromsoe in northern Norway.This Scandinavian nation began salmon farming in the 1960s. It now exports three times more farmed salmon than wild salmon, attaining 383,085 tonnes in 2005. Cod farmers are now gambling on a similar boom.In parts of Canada and the United States, restrictions have been placed on cod fishing for more than 10 years due to the depletion of stocks. In December the European Union slashed cod quotas by up to 20 percent due to fears that overfishing would lead to extinction.While Norway is not a member of the EU and its cod stocks are not threatened, its fish farmers are keen to supply a hungry market, after overcoming initial fears about high production costs."With the drop in total allowable catches we have seen the last years, this convinced investors that there is a market for much more cod than what is available," explains Oestli.But cod -- a staple in Britain's much-loved fish and chips or dried and salted as in many traditional southern European dishes -- is much more complex to breed than salmon."Salmon is very simple compared to cod. It has a larva 100 times bigger. For cod we have to have live feed, and that is a science in itself," says Atle Mortensen, the head of the centre's breeding programme.Cod farms began popping up along Norway's west coast in 2000, and while the country is the most important player on the market the industry is still in the early stages."We are in the beginning of the cod farm. We do not know everything ... there is much to learn and study," says Margrethe Esaiassen, a researcher at the Tromsoe centre says, noting that the death rate of codlings remains high. "But we are advancing fast," she adds.About 20 kilometers (12 miles) from Tromsoe, nestled at the foot of a lush snow-covered fjord beyond the Arctic Circle, a large hangar houses one of the institute's production facilities.Inside is a typical laboratory with microscopes, a bevy of centrifuges and basins of different sizes. The unmistakable odour is the only indication of what actually goes on here."These are the lucky ones, the survivors," says Mortensen as he points with pride at the adult cod splashing around in a greenish basin."The juveniles, that's really our main problem," he says as if he were talking about a bunch of delinquents."The mortality rate is tremendous, about 90 percent just for the larva. But it may not be very different from nature," he explains, noting that there is a bit of margin as each female produces millions of eggs at a time.Researchers stumbled to find the best nutritional diet for the codlings after a 20-day incubation period. The breakthrough came with a mix of rotifer, a microscopic plankton, for the first three weeks and then artemia, a small crustacean. The diet has done wonders. "We had to adjust the protocols and we are still experimenting but we are improving every year," according to Mortensen. In 2003, the Tromsoe centre successfully produced the first "family" of cod, a cycle which takes three years. But other problems remain to be resolved: some fish are deformed with pointy backs, some become cannibals if they are underfed and some yield an unpleasant mushy texture rather than the usual prized firm, white flesh. Another hitch according to researcher Torbjoern Tobiassen is that farmed males become sexually active too early -- at the age of one year instead of three years in the wild. "We're aiming to slow down this process because a fish that spawns is not suitable for sale, it is too slim because he spends a lot of energy," he says. One aspect that has not been an issue is the taste -- consumers cannot tell the difference between farmed and wild cod. "People will have a different perception when they know in advance if it is a farmed fish or a wild fish. But during blind testing, people cannot tell the difference," insists Oestli. Mortensen is convinced that cod farming will flourish in coming years, and has the numbers to back him up. In 2000, 1,000 tonnes of farmed cod were produced in Norway, a number that surged to 7,000 in 2005 and which, according to forecasts, could total 10,000 tonnes in 2006. "This is going to explode. Production could be limitless and it will be up to the market to see how much it can swallow," he says.