If you care about the welfare and quality of fish, you should stun the fish with a blow to the head as soon as it is caught.
If you care about the welfare and quality of fish, you should stun the fish with a blow to the head as soon as it is caught. Photo: Private

Thou shalt kill (the fish)!

Most of us do not eat fish that are alive, it is therefore obvious that fish need to be killed. However, did you know that the way the fish dies determines the quality of the fillets?

Blogger
Portrettbilde av Ragnhild Aven Svalheim

I remember a fishing trip from my childhood very well. We caught a huge cod that was put in a tub in the boat.

“You have to hit the fish on the head!”, I remember saying. But I was told that the fish will just die because it is out of water, so doing something else other than just leaving it there wouldn’t make a difference.

As a little girl, I thought that it wasn’t good for the fish to just lie there and die like that. As a big girl, I know it’s not good.

Fishing from the rocks along Sognefjord – that’s summer for me.

Fishing from the rocks along Sognefjord – that’s summer for me. Photo: Private

Stressful dying out of water

Yes, it’s true, fish die when they are out of the water – Fish gills aren’t good at allowing fish to breathe the oxygen from the air, therefore, the fish suffocates when not in water, but it takes a long time. Firstly, carbon dioxide accumulates in the fish’s blood and tissues and the pH drops. In addition, the fish will attempt to acquire energy without the use of oxygen, something which leads to the production of lactic acid and waste materials. Without oxygen, cells and tissues will begin to die and after a while, the fish will lose consciousness and eventually die. However, it takes a long time. A cod can actually show brain activity for up to two hours while out of the water.

It might be unnecessary to point this out, but I still think it needs to be mentioned that choking for two hours is pretty stressful for the fish.

Over the last few years, I have been investigating what happens to fish when they become stressed when being caught and how this stress affects quality. Maybe It was the fishing trip I remembered from my childhood, where I sat looking at the fish the tub. Maybe that is what inspired me to go on and research what exactly happens when fish are stressed in such a dramatic way.

As part of my doctorate work, I conducted many different measurements to assess the levels of stress in cod.

As part of my doctorate work, I conducted many different measurements to assess the levels of stress in cod. Photo: Lidunn M. Boge © Nofima

A cod fillet full of blood

For many, stress is a negative word. However, stress is really a way for fish and other animals to cope with a situation that requires extra energy. The senses are sharpened in situations of acute stress, the heartbeat and breathing increases and the muscles become tense. Blood is distributed to the larger muscles to allow the fish to swim quickly. So, in the short term, stress is a good thing – it prepares the body for “fight or flight”, stay and fight, or get away.

Back to the cod that is in a tub without access to vital oxygen. It becomes stressed. The body tries to obtain oxygen by opening the gill covers more and more, but no water passes through, only air and very little oxygen gets into the body. The muscles become tense and the blood gets distributed to the large white muscles (what later become cod fillets).

There is a lot of power in these muscles. By distributing the blood that contains oxygen and energy to these muscles, the cod “wishes” to escape from the situation it is in, but it can’t move enough. When in water, the fish can be described as being weightless, whereas on land, it becomes very heavy. When the fish is unable to move, the blood can’t flow efficiently back to the large veins that run along the length of its body. Instead, the blood remains in the large white muscles. This blood doesn’t drain out when the fish is bled.

It results in a cod fillet full of blood that can smell and taste differently than if the fish hadn’t been exposed to the air.

Better welfare – better quality

So how can this be avoided? The answer is quite simple. You have to beat the fish to death!

The fish should be stunned into unconsciousness or death, for example by two powerful blows to the head followed by cutting its throat and letting it bleed out.

A lot of the stress response is stopped by employing this method, the blood isn’t distributed to the large white muscles, the heart stops after a while and the fish doesn’t lie around gasping for air. This results in a nice white fillet, better welfare for the fish and perhaps a clearer conscience for the person catching it.

It’s something to keep in mind during this year’s fishing season. I’ll see you there. I’ll be the one shouting that you need to beat your fish to death.

Related content

  • Blog