Ikijime slaughter ‘is a waste of time’

Ikijime is often promoted as a Japanese "gold standard" for gentle killing and higher quality fish. There are several methods of ikijime but the most commonly used is to pierce the brain and spinal cord in order to stop the survival signal from the brain to the body.

Ikijime’s proponents say this minimises stress and stops the production of lactic acid. This, in turn, extends the period before the fish goes into rigor mortis, and consequently lengthens its shelf life.

Direct brain spiking is prohibited in Norway but an adapted method of stun-and-bleed followed by spinal cord cutting is used by some Norwegian fish farmers and is frequently promoted as a seal of quality in Michelin restaurants. However, according to scientist Bjørn Roth at research institute Nofima, the method is greatly overrated.

“It sounds nice, but in practice it is a waste of time,” Roth tells Fish Farming Expert’s Norwegian sister site, Kyst.no.

Nofima recently completed a project on halibut harvesting, and according to Roth, the results provided a clear answer: ikijime has no measurable effect, either on meat quality or fish welfare.

No gain in quality

In the project, the researchers compared traditional stun-and-bleed slaughter with and without subsequent cutting of the spinal cord.

“There was no difference. None!,” Roth says clearly.

He emphasises that it is not the killing method itself that determines the quality, but the sum of the handling before slaughter.

“It’s about stress. The crowding, pumping and handling before euthanasia means far more than whether you cut the spinal cord or not.”

Too much risk

Roth is particularly critical of ikijime being marketed as an animal welfare measure.

“Sticking a needle into the brain of a fish is not good animal welfare. The accuracy is too poor, and the risk of error is high.”

He also points to hygiene challenges.

"You're penetrating the shell and drawing bacteria into a fresh product. There's a clear contamination risk, especially in farming," says Roth.

'It's a marketing gimmick'

The researcher's conclusion is therefore clear that percussive or electrical stunning and bleeding are both safer and more robust solutions.

“A correct blow knocks out the entire brain instantly. It is far safer than ikijime. Electricity also works very well for most species,” he says.

According to Roth, there is no scientific reason to prioritise ikijime, either for halibut or other fish species.

“This applies to all fish. We have seen the same thing time and time again. No effect,” he says.

Nevertheless, Roth finds that the method is receiving increasing attention, particularly driven by the market and certification requirements.

“It's a gimmick. A term that sounds good and is used in marketing. But professionally it doesn't hold up,” he says.

No improvements

Børre Erstad, head of R&D and senior biologist at Sterling Halibut, completely agrees with Roth, and tells Kyst.no that ikijime is a waste of time and money.

“It has nothing to do with Norwegian fish farming,” he says.

Erstad says that the company wanted to look at the effect of ikijime and whether this is a killing method that increases the quality of the company's products.

“In this experiment, the use of ikijime has not shown any improvement in either quality or animal welfare in halibut compared to the control groups.”

‘Becomes pointless’

He is clear that industrialising the use of ikijime will lead to increased production costs, which in turn will lead to increased costs for customers without improving quality.

“This becomes pointless. There is also an increased risk of contamination of the inside of the fish by penetration of the skull / bloodstream and therefore an increased risk of the products that go on the market not meeting the strict requirements set for seafood regarding listeria and other unwanted bacteria.”

Erstad is concerned that product quality and animal welfare should go "hand in hand", as handling of fish, gentle pumping, percussive and electric stunning, according to him, define good quality and good animal welfare in the final period of the fish’s life.

“These are the parameters that should be worked on to further increase quality and animal welfare in the future,” he concludes.

See Nofima's summary of research into ikijime here (in English).