More tuna troubles for Norwegian fish farmers

A net pen at a salmon farm in Norway has been broken into by a tuna fish in the latest of a number of increasingly frequent incursions into salmon farms by the large species.

The incident occurred at Lerøy’s Djupevika farm in Tysnes in Vestland County on October 5. The tuna weighted 375 kg and was 2.78 metres long.

Morten E Fjæreide, general manager of Lerøy Sjøtroll, told Fish Farming Expert’s Norwegian sister site Kyst.no that staff saw the tuna on cage camera footage and immediately took measures to seal the hole it had made in the net and have the tuna removed.

“This is unfortunately the second case at Lerøy Sjøtroll this year and this is something we, together with the rest of the players in the industry, are looking into more closely so that we avoid similar incidents,” he said.

The tuna entered the cage at a depth of 22 metres in cage 3 on the site. See sketch below.

In its report to Norway’s fisheries directorate, which Kyst.no has seen, Lerøy wrote that it proved impossible to catch the tuna in a net, and it ended up dying and had to be retrieved by divers.

It is not clear how many fish may have escaped from the site. The fish in the pen had an average weight of approximately 670 grams.

The tuna was the second to break into a pen within the space of a fortnight. At Kobbevik and Furuholmen’s locality Hjartholmosen, a tuna was discovered on Tuesday, September 26.

The company told the fisheries directorate that the hole was very small considering that a tuna had swum through, but said it was the same “type” of hole the company got at its Brattavika location after a tuna invaded a pen there in 2022.