Using fish waste in new ways

Judging by its environmental footprint, aquaculture is one of the most sustainable sources of food. Yet the sector still has its challenges, with one of the biggest being fish waste.

Uneaten food and fecal matter tend to accumulate under fish cages during production, which can have a negative impact on local ecosystems. Farmers are also banned from restocking the site before conditions on the seafloor return to normal.

Luckily, one major seafood company based in Bergen has found out how to turn this problem into an opportunity.

Lerøy Seafood Group, together with environmental organization Bellona, is using excess resources in order to grow both mussels and seaweed around its fish farms.

These species use the phosphorous and nitrogen coming from the fish cages as vital nutrients. They can even contribute to absorbing carbon dioxide from the air.

The two organizations have formed a new company, Ocean Forest AS, and are aiming to develop this sustainable method of farming seaweed and blue mussels on an industrial scale.

The seaweed harvested by Lerøy and Bellona can be turned into a range of useful products, including food additives and animal feed. Photo © Lerøy

Growing underwater forests

The team at Ocean Forest begin by placing seaweed sticklings (1mm large seaweed plants that have been grown in tanks on land) on special frames next to Lerøy’s fish farms.

The sugar kelp grows through the winter months, reaching a length of up to 1.5 metres.

The dripping, dark-brown fronds are then harvested and sent to the processing plant, where they can be turned into a range of useful products.

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This includes spices and food additives, although Ocean Harvest’s CEO Harald Sveier mentions that they are also exploring other areas including animal feed.

Kelp is often referred to as a “superfood”, rich in Vitamin A and calcium, but it turns out that it also holds surprising benefits for livestock.  

“We have shown that if fermented seaweed is added to the diets of cows, it can help to reduce methane production, thereby cutting down on greenhouse gases,” Sveier explains.
 

Reaching mass production

Last year, Ocean Forest managed to gather 130 tonnes of sugar kelp, making the company by far the largest producer of seaweed in Norway.

Sveier wants to go further than this, and is eventually aiming to produce more than 1,000 tonnes of the versatile crop every year.

However, getting to this stage won’t be easy. “We have a very long way to go before we have a really efficient industrial production of seaweed,” he notes.

“We manage today, but there is a huge room for optimization in how to grow, seed, harvest and process these plants.”

He adds that so far, the company have been relying on a solid base of research, as well as good old‑fashioned trial and error and hands-on experience from many years of fish farming, in order to make progress.

“We wouldn’t have come this far without the work of many smart, hard-working colleagues who have helped to drive this forwards. In a way, I think of myself and my team as pioneers.”

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This new way of farming could help the aquaculture industry to become much more sustainable. Photo © Sjømat Norge / Ingun Mæhlum.

A better way of farming

If Lerøy can succeed in showing that large‑scale seaweed farming is not only possible, but profitable, it won’t just be the company that benefits from this.

We all stand to gain from a world where food is grown in a more sustainable way.

As Sveier notes, “Seaweed, mussels and other bottom fauna need almost no inputs with respect to fresh water, pesticides, and land area.”

“As a result, these crops have an extremely low environmental footprint.”

It appears that Lerøy and Bellona are now well on the way to making this new method of farming a reality.

Find out more about Greater Bergen’s aquaculture industry

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