The Queenstown-based company, which has salmon farms at Twizel and Tekapo, received a score of 8.6 out of 10 - the highest-ranking Seafood Watch has given any salmon farm in the world, chief executive David Cole said.
Seafood Watch, operated by United States-based Monterey Bay Aquarium, is a not-for-profit organisation that assesses and ranks sustainable fisheries around the world.
It made its science-based recommendations available to the public via regional pocket guides and a downloadable app.
To be awarded the best choice (green) rating was ''very reassuring'' from a sustainability point of view, Mr Cole said.
''That, for us, is quite pleasing. We spend a lot of time and effort on our sustainability benchmarks.''
Most of the salmon produced by the company was destined for the US market, but it was now also selling fresh fish to Australiaand was due to start selling to the United Arab Emirates.
Producing about 1000 tonnes a year, the company was not necessarily driven by volume, with Mr Cole describing its product as ''like the high-end caviar of salmon''.
English celebrity chef Heston Blumenthal, who is opening a restaurant in Melbourne for six months while he refurbishes his Berkshire restaurant the Fat Duck, has chosen Mt Cook Alpine Salmon to be the only salmon on his menu.
A ballot was held last year to get a seat at the restaurant and meals cost $525. Having its salmon on the menu was a measure of the ''high-end echelon'' the company was achieving with its product, Mr Cole said.
Mt Cook Alpine Salmon opened a $6 million processing factory at Washdyke just over a year ago, which had given it total control over its vertical business model.
There were about 40 staff working in the factory, about 40 staff on the three salmon farms and a ''very small bunch'' in the head office, he said.
