Crabs die immediately in boiling water

Animal welfare"You can stun lobsters"

Ulli Blumenthal: New rules for the preparation of crustaceans: In future, lobsters will no longer be allowed to be thrown consciously into boiling water in Swiss restaurants. As of March 1st, the crustaceans must be anesthetized before they can be prepared, as the Swiss government decided last week. In the future, live lobsters in Switzerland will no longer be allowed to be transported on ice or in ice-cold water.

I'll talk to Ulf Bickmeyer about it. He is a zoologist and cell biologist at the Alfred Wegener Institute and has carried out a comparative study on the animal-friendly stunning or killing of crustaceans.

How much pain does a lobster get when thrown into boiling water?

Ulf Bickmeyer: Just the question of how much pain it becomes very difficult, because pain is clearly cognitive or is influenced by consciousness. We feel pain when we are distracted, for example much, much less than when we are not distracted. So pain is obviously very strongly linked to consciousness, and that is why we did not even make the distinction in our study between pain, which possibly only higher organisms, however, can actually feel. And the nocezftive reflex, that is, it is a reflex to protect the organism, all living beings in this world obviously have such protective mechanisms. And we said and also wrote that we make no distinction between pain and this nozzesive reflex, because in that case pain is, I would say, quite simply not the right term.

"Difficult to judge whether an organism feels pain"

Blumenthal: You have carried out a comparative study on the appropriate stunning or killing of crustaceans. How did you go about setting up the experiment? How did you conduct this investigation?

Bickmeyer: It is very difficult for us to judge from the outside whether an organism feels pain or whatever. But a mechanism is natural if one derives the nerve activity electrophysiologically at the moment by being very clear that when the nerves no longer respond, no signal is transmitted. And then we decided to use such a method that we introduced very tiny electrodes into these animals - that is, they have such a decentralized nervous system - with which they could move wonderfully, do everything, move everything, and have them then tries to stimulate them, for example with a small sponge, with such a small brush, or with a small electrical stimulus. If this transmission of stimuli to the central nervous system could no longer be measured, we said, then the animals are anesthetized.

Blumenthal: How did you go about it? What different procedures did you then use? Have you taken animals and examined what? Boiling water only, or other processes?

Bickmeyer: The question was whether these animals can be anesthetized so that they can no longer perceive this treatment. And then we applied several parameters. The classic thing is to put them on ice. We took fresh water ice, also salt water ice. We anesthetize various organisms with magnesium. This is very easy with mollusks, for example, magnesium chloride. They are instantly relaxed and relaxed and numb. And we used CO2 fumigation because experience shows that it works relatively well with different organisms. If you bubbled the water with CO2, so to speak, that the organisms are anesthetized. And we used a method, this electrical stunning, because it is also used in different organisms, i.e. higher animals, in mammals and so on, and tried to carry out the various treatments and see whether the stimulus transmission is still present.

"Very different results"

Blumenthal: And how different were the results?

Bickmeyer: Very different. For example, ice-water ice does not help, the animals are only very slow, everything is slow, but the stimulus responses are just as there, only in slow motion. It is the same with sea ice, everything is slowed down, slower and slower, and it actually goes so seamlessly into death. So this is not a classic anesthetic procedure. Magnesium chloride has no effect on these decapods, i.e. decapods. And then, CO2, amazingly, I did not expect so much, CO2 is a very quick method to stun these animals. After that, no further stimulus transmission was actually detectable. We did the electrophysiological experiments and put the animals between electrodes - that is, we put electrodes in the water and gave them a current surge, so to speak. And then something really amazing happened because the central nervous system becomes highly active, but the animals look phenotypically almost dead. They are completely paralyzed, but the nervous system is extremely active. And in this state you can of course no longer discriminate whether a stimulus from the outside is still coming in, because everything is active.

Animals showed no reaction when heated slowly

Blumenthal: Then what would your recommendation to the Swiss Confederates be if they have now forbidden to just throw lobsters and other crustaceans into boiling water and ultimately kill them? Which method would you say would be an alternative?

Bickmeyer: We once thought what would happen if the water was heated very slowly. And there these animals showed no reaction at all, were completely relaxed, at least with the electrophysiological recordings, so there were no particularly active recordings to be measured. And if you increased the temperature so slowly, one degree per minute, at 30 to 35 degrees the activity stopped completely.

In other words, they slipped over very slowly, and the water is still heated. If you would ask me that is an alternative. Of course, does not correspond to anesthesia, because it is definitely not reversible.

But it is also not this throwing into hot water, where of course we do not know how the lobster reacts to it. It may be that because of this sudden shock, he does not even know what is happening and therefore sits still. But with the slow heating it seems that he is sitting there perfectly still and showing no reactions.

And that was also shown in the electrophysiological measurements. You can find signal responses and they just disappear over 30 degrees. Therefore, really recommending such procedures is extremely difficult. Everyone has a couple of horse feet. But you can at least anesthetize lobsters, we now know that because we used this procedure to have the electrodes directly in the nervous system.

Statements by our interlocutors reflect their own views. Deutschlandfunk does not adopt statements made by its interlocutors in interviews and discussions as its own.