Fish farms saw a peak of 920,000 salmon escapes in 2006, prompting the industry to roll up its sleeves and tackle the problem.

Divers who inspect the cages' nets as well as video cameras helped bring the number of escapes down to just 100,000 last year.

The industry's woes haven't ended with that, though. Fish farmers feeding practices have also landed them in the hot seat.

A recent Swedish documentary created a stir in Scandinavia when it accused Norwegian fish farms of emptying the oceans. In order to produce one kilogramme (2.2 pounds) of farmed fish, the equivalent of 2.5 kilogrammes of wild fish in meal and oil are needed.

Norway's farms, which produced just over 800,000 tonnes of fish last year, consumed 2.0 million tonnes of wild fish.

But professionals say their practices are among the best in the food industry.

"Salmon and trout are very efficient in the use of proteins, much more so than chicken, pork or beef" which require more feed per kilogramme produced, insists Oeyvind Blom, who runs the family farm in Oeygarden.

"So it's very sustainable and environmentally friendly in our view," he says.

But environmentalists, who are generally favourable to fish farming, still want to see an improvement.

"We're not concerned about the ratio between the quantity of feed and the final product. What worries us is what the feed is made of," says Nina Jensen, a marine biologist at World Wide Fund for Nature (WWF) Norway.

She says some of the fish meal and oil are derived from wild fish stocks that are vulnerable, such as sand eel, Icelandic mackerel and Norway pout.

The WWF has therefore called for the feed contents to be traceable so that producers know which fish were used in the process.

"We know it for any other farmed animal, so why not farmed fish," asks Jensen.