Anorwegian striped squid. Photographer: Miguel Bao-Dominguez / Institute of Marine Research (Havforskningsinstituttet)

The Institute of Marine Research Checked 'squid' for Anisakis

“Do not eat them raw,” warns parasitologist.

Norwegian and Spanish researchers have recently examined the presence of Anisakis parasites in ten-armed squid from Norwegian waters, often (and partly incorrectly) referred to colloquially as “akkar.”

They found them — they found them.

“We examined 425 squid from four different species. Anisakis larvae were present in individuals from all species. It is clear that squid are hosts for Anisakis in the North Atlantic, just like fish,” says parasitologist Miguel Bao.

The results have been published in a scientific article.

Like lights on a Christmas tree

The researchers examined the internal organs and used a UV press to illuminate the flesh. Under UV light, Anisakis larvae glow like Christmas lights.

The Anisakis larvae light up under UV light in the flattened pieces of flesh.Anisakis from Loligo forbesii gut exposed to UV light (Photo: Miguel Bao / Institute of Marine Research)

“As expected, most Anisakis were found in the internal organs, but we also found them in the mantle itself,” says Miguel Bao.

You have probably seen the mantle sliced and deep-fried on a plate while on holiday in southern Europe. Fried or grilled squid is extremely popular there. Prepared this way, the food poses no risk — Anisakis is killed by heat and freezing.

Fried squid is a common street food in Southern Europe. (Photo: Erlend A. Lorentzen / HI)

The arms were free of Anisakis

In Japan and other parts of Asia, however, squid are often eaten lightly processed or raw, for example as sashimi.

Raw seafood is trending worldwide. This is what motivates parasitologists to examine ever more species for things one does not want inside the body.

“Interestingly, the tentacles were completely free of Anisakis in all 425 squid. That does not mean Anisakis can never occur there in other squid,” says Bao. “But it is an interesting finding that we would like to investigate further.”

Small squid ( Todaropsis eblanae) are being investigated. Photographer: Miguel Bao-Dominguez / Institute of Marine Research

Freezing is a win-win

He advises freezing all squid that will be eaten without heat treatment. Freezing is also mandatory for restaurant sushi in Norway (see the Norwegian Food Safety Authority for details).

“In addition to killing Anisakis, freezing has a tenderizing effect on squid meat — so it’s a win-win,” says Bao.

The researchers examined the intestines, mantle, and tentacles. Photographer: Miguel Bao-Dominguez / Institute of Marine Research

The number of larvae varied by species and size

On average, between 0 and 5 Anisakis larvae were found per squid. The number correlated with squid size, which is logical.

“The more a squid eats, the more exposed it is to infection. Anisakis enters the host through food. For squid, this comes from crustaceans and small fish,” the researcher explains.

There were also differences among species. Deep-water species such as European flying squid (Todarodes sagittatus), lesser flying squid (Todaropsis eblanae), and shortfin squid (Illex coindetii) had higher infection levels than European squid (Loligo forbesii), which lives in shallower waters with access to different prey.

A total of 425 squids were examined. Photographer: Miguel Bao-Dominguez / Institute of Marine Research

Low levels compared to many fish species

The number of Anisakis larvae is low compared with some fish species. The record holder, hake, was shown in another study to carry an average of 840 Anisakis larvae.

<-- Research technician Rebeca Garcia Perez with squid. Photographer: Miguel Bao-Dominguez / Institute of Marine Research

“Hake live much longer than squid. They are apex predators that eat almost anything they encounter. This is therefore also an effect of diet and age,” says Bao.

The researcher emphasizes that Anisakis is a natural part of the ecosystem.

“But it is important to map how widespread the parasite is in different raw materials. That way, we understand the risk and can take the necessary precautions,” he says.

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