Aquaculture for all

Britain’s most ambitious seaweed company

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Buoyed by the success of their first seaweed farm, Atlantic Mariculture Limited not only has plans to dramatically increase its own growing capacity but also to catalyse the growth of UK’s entire seaweed sector - by developing transferable technologies and establishing a commercial research hub.

by Senior editor, The Fish Site
Rob Fletcher thumbnail
Seaweed farmers.
Hatch and The Fish Site visit Atlantic Mariculture's farm on Loch Sunart

© Niclas Rieken

Rows of pink buoys bobbing in a fresh easterly breeze brighten an otherwise drab April day on Loch Sunart - one of Scotland’s most spectacular sea lochs - as we approach Atlantic Mariculture's flagship seaweed farm.

Despite its unassuming presence, the East Oronsay site is shaping up to be the most productive in the UK this year, producing several hundred tonnes of macroalgae - mainly sugar kelp (Saccharina latissima), but also Atlantic wakame (Alaria esculenta).

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While the choicest strands are destined to be hand-harvested before being shipped fresh down to restaurants in London, the bulk of the crop will be fermented at the company’s shore base – from where it will emerge as a valuable plant feed and soil restorer - branded Liquid Kelp - that can be used to rejuvenate farmland and promote organic growth in some of the country’s most progressive farms and gardens.

The company, founded as GreenSea Solutions by Amabel and Douglas Hamilton in 2018, has been growing kelp and selling biostimulants for three years, but is now looking to raise substantial investment to take it to the next level.

As we approach the site in the modest aluminium launch that currently serves as the company’s main workboat and harvesting vessel, it’s clear that the crew are excited to see how their crop, sown a few months previously, is progressing.

Seaweed farmers harvesting Scottish seaweed.
The team assessed the growth of their crop, sown months previously

© Niclas Riecken

Dr Adrian MacLeod, the company’s innovation director - whose applied seaweed research while at SAMS has helped to spawn the nascent industry - is clearly very enthusiastic about his recent move away from academia and into the frontline of macroalgal commercialisation and waxes lyrical about the possibilities offered by Loch Sunart, and by seaweed in general.

MacLeod explains that the loch was home to Scotland’s first seaweed farm, which - remarkably - was started by Rodney George 30 years ago, as a means of producing industrial volumes of kelp, a genus that has long been used to fertilise fields along Scotland’s west coast.

The mouth of the loch provides ideal growing conditions, being fairly sheltered, yet containing sufficient tidal flow for the movement of nutrients. Equally, he adds, it maintains close to full salinity sea water, unlike some sea lochs, which can experience periodic drops in salinity after heavy rainfall, which can stress the crop and reduce yields.

While MacLeod brings a biologist’s experience to the company, the engineering perspective is led by Chris Dyer, who has worked extensively both in salmon aquaculture and offshore renewables and has been responsible for the design and deployment of the farm.

As he explains, the East Oronsay site consists of several modular units, each containing custom-made multi-line arrays, and has won a number of admirers – not least Algapelago, which commissioned AML to install the same system at their own site in Devon in December last year.

MacLeod adds that AML is looking to replace the current conventional buoys with oyster baskets, which would not only act as floats, but also be capable of producing up to 70,000 native oysters a year, without the need for any additional infrastructure.

Seaweed farming floats.
Thinking to the future

AML innovation director Dr Adrian MacLeod plans to replace conventional buoys with oyster baskets, diversifying the company's production © Niclas Riecken

While their farm design is working perfectly in the relatively sheltered waters of Loch Sunart, Dyer is itching to test it out in two more sites - one at nearby West Oronsay and the other at Kentra, to the north of Ardnamurchan - which combined would give them up to 130 hectares of growing space. They aim to seed 250 km of lines in these sites, which would put them among Europe’s top seaweed producers and allow them to compete for cost with imports from abroad.

Local support

Unlike some of its English counterparts, which have met with vocal opposition from a variety of coastal stakeholders, social licence for such extensive operations doesn’t seem to be a huge issue for AML. Joss Carnegie, the farm manager, notes that even the local fishermen - who use creels to catch wrasse, lobster, crab and prawn close to the farm - have voiced their backing for AML’s expansion, as they claim that the farm has improved their catches, supporting the seaweed sector’s biodiversity claims.

As Carnegie explains, it also helps that most of AML’s team either lives locally or is on good terms with plenty of local people - from landowners, to business operators, to fish farmers - which has helped to garner support for their plans.

According to MacLeod, the company is aiming to harvest 10 tonnes a day, five days a week. In order to do so they will need to increase the efficiency of seeding and harvesting, as well as increase the yield per metre of rope.

In the longer term, he adds: “it’s important for us to understand local genetic variation and use this knowledge to produce high yielding cultivars from locally sourced parental material, using conventional genetic tools.”

Seaweed farm sugar kelp harvest.
MacLeod aims to harvest up to 50 tonnes of seaweed per week

© Niclas Riecken

The bid for mechanisation

While the AML team welcomes the prospect of upscaling production, they appreciate that it will need to be accompanied by a major programme of mechanisation.

“The seaweed currently requires excessive handling. We are using winches and other mechanically operated lifting tools but this needs to be improved,” points out MacLeod.

“If we didn’t have to touch the seaweed at all that would be ideal,” he adds, given the back-breaking nature of harvesting tonnes of seaweed.

Thankfully, Dyer and his team are in the process of developing a specialist harvesting system which will strip the kelp off the ropes just above the holdfasts. The pilot version, which he later shows us in the work shed, looks both promising and reassuringly simple.

In order to scale up they will also need larger boats for harvesting and managing the varied jobs throughout the site.

A range of applications

Standardisation and modularity are the key means of scaling. It's a question of working out how to create standardised growing modules and not have to rely on producing bespoke systems for every site,” explains David Stewart Howitt, the company’s managing director.

“I feel that we are a bit like the salmon farming sector was in the late 1970s, when farmers were pioneering and having to improvise and innovate to overcome problems they didn’t and couldn’t have anticipated. If design and development of farming systems happens in 15 different ways there will be of no net gain to the industry,” he adds.

Farmed seaweed.
The need for machines

Chris Dyer and his team are developing a system to streamline kelp harvesting © Niclas Riecken

Scaling up will also enable AML to meet the demands of a wider range of markets and is likely to see them shift away from the fickle trends of the food sector – something that they have pre-empted with their early product development.

“The food market won't grow at the rate we need it to grow at, so we have developed biostimulants,” MacLeod explains.

These have recently been certified for use in organic farming systems, and are in demand from progressive farmers and commercial gardeners.

Beyond biostimulants, customers for their raw kelp include several food processors and distributors in Scotland and London. Meanwhile, the country’s largest bioplastic developers have asked them for dried kelp, but Carnegie notes that the cost of drying the kelp using conventional methods would remove any potential profit. However, he adds that they are exploring a collaboration with the local facility which gasifies wood and could provide a reasonably economical means of drying in the future.

“The market is the issue: we've got no problems with the licencing or consent but deep pockets are needed to scale up and reduce production costs in the long run,” Carnegie explains.

The company also has a strong environmental emphasis, which is why they are set on farming, rather than wild harvesting, their raw materials.

“It's an easier route just to harvest wild species but we want to add to the natural capacity of the ecosystem,” MacLeod explains.

A seaweed farmer holding seaweed.
The road less travelled

Harvesting wild seaweeds may be more simple than farming, but Atlantic Mariculture wants to support the surrounding ecosystem through its operations © Peter Green


Forty minutes later, after a quick blast down the loch and a few miles on a single-track road - where the AML team were flagged down for a blether by every other passing car, in true West Highland style - we arrived at the company’s Ardtoe HQ. It’s a location that boasts immaculate golden beaches and, from nearby, spectacular views out to the Sgurr of Eigg and Rum’s Cullin Hills.

Founded in 1966, Ardtoe has had a rich and varied history in marine research. Most recently Benchmark treated it to a multi-million pound refit for growing lumpfish and conducting challenge trials, but - after the multinational consolidated its operations in 2020 - AML decided to try to breathe new life into it. Not only is it conveniently close to their farms, but it also has the space and facilities they need.

As well as having their own workshop and processing facilities, Stewart Howitt believes that Benchmark’s pristine labs could be leased out to commercial seaweed startups.

“We'd like to see it as the point of the spear in terms of the cultured seaweed industry and a centre of excellence for seaweed which can enable others to do it successfully in Scotland,” he reflects.

“We see it as being complementary to SAMS [the epicentre of academic research into seaweed] and would be open to co-developing it with other companies or individuals as a catalyst for learning. We know we can grow good seaweed here and I think we can also add the value to the seaweed here at Ardtoe,” he adds.

While Stewart Howitt notes that their existing investors - “friends and family” - have enough in the bank to acquire Ardtoe, they are currently looking to raise a substantial 7 figure sum to finance the equipment needed to install, harvest and process at scale.

This includes two new boats that have been specially designed for seeding and harvesting multiple seaweed lines simultaneously, further sites, to enable mechanisation by building a processing prototype platform and a refrigerated lorry for transporting fresh seaweed to market.

Stewart Howitt sees the seaweed industry as a once in a generation opportunity for an area where too few opportunities arise.

“The team’s here, we have the site and systems, but we need to have funding in place by September so we can seed the lines in October and then get a second seeding the following January. We need to establish key industrial partnerships and appropriate financing mechanisms over the next three quarters” he emphasises.

AML is clearly facing some of the same key challenges as most players in the West’s nascent seaweed sector - notably that substantial investment is needed to upscale enough to produce seaweed at a cost that allows them to compete with wild harvested and imported farmed species.

Yet, if anyone is going to make the breakthrough they look well placed, having assembled a team with a wide range of practical skills, support for significant expansion, a proven farm design, a product that’s in demand and a state-of-the-art processing and research base.

And, if Atlantic Mariculture succeeds, then it could help to catalyse a generational - and potentially ecologically sound - opportunity for Scotland’s coastal economy.

“Eat seaweed, use seaweed and support our local seaweed production businesses,” MacLeod concludes.


*The author is grateful for the support of WWF UK as this visit was undertaken as a research gathering exercise within the Value of UK Seaweed project, being undertaken in collaboration with Hatch Innovation Services and Macalister Elliot and Partners.

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