300kg of angry bluefin caught in your pen? The Norwegian government has produced a handy guide on what to do next…

Matthew Wilcox

“When it comes to euthanizing the tuna, the recommended method is to use a firearm…” 

In a bid to address the increasingly common problem of bluefin tuna getting caught in salmon pens, the Norwegian government has issued a four-page guide detailing the correct response and handling procedures.

Tuna have become a relatively common sight in North Atlantic waters in recent years. And, inevitably, their migrations sometimes overlap with areas where salmon farming is taking place.

So what are you supposed to actually do when you have 700lbs of angry bluefin thrashing away in your net pen?

Read more: Attack by giant tuna? “Everything is insurable”

Atlantic bluefin tuna migration routes. Map: The Pew Charitable Trusts

Action time

When a tuna is detected in a pen, the first concern should be the repair of any damage caused by the fish to the net and the deployment of recapture nets.

The next step should only be attempted once the authorities have been contacted and a permit acquired.

The best method to safely secure the tuna is by using a fishing net; when appropriately restrained, the tuna is less likely to struggle.

The theory goes that a tuna that can’t swim freely is more likely to lie on its side, making it easier to handle.

When it comes time to “euthanise” the tuna, the recommended method is via a firearm aimed directly at the fish’s brain to guarantee its immediate unconsciousness.

“Harpoons or the like must not be used,” warns the guide.

Read more: 250 kg bluefin tuna caught in fish cage: Here is Lingalaks’ big catch

Tuna revival

In 2015, bluefin went from ‘endangered’ to ‘near threatened’, reflecting an improvement in stocks.

Following “catch and release” trials, in 2023 the UK Government was authorised by the International Commission for the Conservation of Atlantic Tuna to use 39 metric tons of its quota to trial a new small-scale commercial fishery for the giant fish.

Ten licences have since been issued around the UK.

Read more: Salmon farm finds massive 270kg Bluefin tuna in the pen


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