Mussels in fish feed are not a new idea. Industry and researchers have been working on this for several decades.

The fish feed of the future: Mussels can be an important part of the food package

NORWAY
Friday, May 10, 2024, 07:00 (GMT + 9)

"We need both more and more local raw materials for fish feed than we have today", says researcher Sofie Remø.

Through a five-year project, the researchers have investigated how different low-trophic resources, i.e. organisms far down the food chain, can function as feed ingredients in fish farming. 

"In order to increase the share of Norwegian raw materials, we must also look at what we can grow. Mussels in particular look like they could be a good solution, both for us and the fish", says Remø.

Mussels and kelp can be grown along the coast

During the project, three feeding trials were carried out where the salmon ate feed containing mussels, and one with sugar kelp.

"We realized quite early on that mussels and kelp were the two raw materials that we have the best conditions for growing in Norway", says Remø. 

The only thing sugar kelp and mussels have in common is that they are low trophic and can be grown along the coast in Norway. But what they can be used for is different. A lot of fat and protein are needed in feed for salmon, and there is little of that in kelp. Mussels, on the other hand, have more of the nutrients the salmon need. 

Mussel meal or silage?

Mussels in fish feed are not a new idea. Industry and researchers have been working on this for several decades. 

"We wanted to look at different ways of processing the mussels, so that we can get a good raw material that also has a low climate footprint", says Remø. 

The experiments show that mussel flour works at least as well as fish flour. But what if the mussels are instead ensiled? A process in which acid is added to the mussel meat, so that preservation goes faster.

"The reason why we looked at ensiling was that a lot of energy is required to make mussel meal. To ensile the mussel meat, we use less energy, which in turn makes it more climate-friendly", says Remø and adds:

"In our experiments, we saw that there were very small differences between ensiled mussels and mussel meal in how well the salmon utilized the feed".

During HavExpo, researcher Sofie Remø presented some of the findings from the project. (Photo: Christine Fagerbakke/HI).

More sustainable feed in the future

In 2023, the government launched the "Society mission on sustainable feed" as part of the long-term plan for research and higher education. 

This is an interdisciplinary initiative where research and innovation, management and industry will work together towards the goal of finding new sustainable feed raw materials. Today, the aquaculture industry uses eight percent of Norwegian-produced raw materials in fish feed. The government has set a target for this share to be increased to 25 per cent by 2034.

"Mussels basically have a lower climate footprint, because they grow in the sea. But what is done with the shells when they arrive on land affects the extent to which they can ultimately contribute to reducing the feed's climate footprint", explains Remø. 

Requires large areas

If mussels are to be the solution to obtaining our own local raw materials for fish feed, large areas must also be set aside to cultivate the mussels. 

Marine scientist Tore Strohmeier leads the work package in the same project, which looks at how our ecosystems will be affected by large-scale cultivation of low-trophic organisms in our fjords.

"A modeling experiment shows that up to 180,000 tonnes of shells can be produced in the Hardangerfjord within two years. But such a production size will affect the ecosystem in the fjord, with decline in decline in plant and animal plankton", he says.

Author/Source: Christine Fagerbakke / Havforskningsinstituttet | Norwegian Institute of Marine Research (translated from original in Norwegian)

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