Salmon farmer Cermaq has begun a cull of up to 900,000 fish at a site in northern Norway due to bacterial wound infections, the latest worrying development for an industry hit by record mortality and growing concerns around fish welfare.

Cermaq said the removal of fish from six cages at its Olderfjord site in Hammerfest had already begun. The cages would be emptied within a few days, the company said in a statement.

Fish welfare has become a major topic of concern for the salmon farming sector in Norway. The country reported a record 62.7 million salmon deaths in netpens last year and the mortality rate across Norway rose to 16.7 percent, due partly to deadly jellyfish attacks.

Another Norwegian salmon farmer, SalMar, reported this week that more than 700,000 mortalities had occurred in just seven weeks at one of its sites in the north of the country.

Cermaq said on Thursday the situation at its Olderfjord site was “desperate.”

“We have seen increased mortality in these cages since the beginning of January this year, as a result of jellyfish and a period of storms, which have subsequently led to bacterial wound infections," the company said.

Astrid Aam, communications manager at Cermaq, said in the same statement that a decision to “remove, anesthetize and euthanize the fish in six of the cages at the facility” had been taken after a long period of consultation with the Norwegian Food Safety Authority.

The fish at the facility are approximately 500 grams in size on average, the company said, and no treatment would be able to save them. Cermaq said it was concerned that infection from the six cages could spread to the rest of the farm.

"It is a difficult decision,” the company added, “as there are also many individuals in these cages that show normal behavior and appetite.”

In a bid to bring the industry together in tackling high mortality rates, SalMar announced this month that it will invest NOK 500 million ($47 million/€43 million) in what it calls a "Salmon Living Lab". It is seeking partners for the venture, having already brought US agricultural giant Cargill on board.

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