Dutch algae growers tout their first mechanical harvest at sea

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The site is located about 12 km off the Dutch coast. North Sea Farmers grew kelp on nets suspended under a 50-meter plastic tube that floated on the surface of the water and held in place by buoys and two anchors on the sea floor.

According to BBC, North Sea farmers have converted a fishing boat into a mechanical harvester. The boat positioned itself along the plastic tube, and an 8-meter-high electric cutter arm entered the water. He pulled up the tube and cut the long strands of seaweed from the 2 meter wide net. The seaweed was then automatically bagged and deposited on the deck.

North Sea Farmers has nearly 100 members, including food and consumer goods giant Unilever and energy company Shell. They hope to significantly increase European production of cultivated algae over the next decade.

The seaweed industry is still dominated by China and Indonesia, but Europe is hoping to capitalize on its seaweed farming potential. In 2019, Europe produced 287,033 tonnes of seaweed, around 0.8% of the global total. However, unlike their more established Asian counterparts, European seaweed companies harvest wild stocks. Many makers hope to change this and start cultivating different species of macroalgae on a large scale.

In addition to EU financial support (273 million euros last year, with more funding planned in the future), the Dutch government has offered to set aside 400 km2 of its territorial waters in the North Sea for large-scale algae cultivation.

Although the move has been heralded as a potential climate resilience solution, some researchers and environmental activists remain unconvinced. Marc-Philippe Buckhout of Seas At Risk, a coalition of ocean protection organisations, told the BBC he fears seaweed has become the new green fad. A boom in seaweed farming could have potentially negative repercussions, such as crowding out other marine organisms.

“Large-scale farms might be the industry’s preferred route,” he says, “but we would certainly prefer small farms that are defined in the type of carrying capacity of the area in which they are located.”

Reinier Nauta, an algae researcher at Wageningen University in the Netherlands, shares these concerns. “One of the most important questions is the impact of seaweed farming on the nutrient balance of the sea,” he explains.

There is a risk that large-scale algae cultivation will cause phytoplankton populations to collapse. Since phytoplankton are the building blocks of the marine food web, a decline in these organisms could be disastrous for fish, seals and porpoises higher up the food web.

Eef Brouwers, head of agriculture and technology at North Sea Farmers, admits that to fully determine the environmental impact of seaweed aquaculture will require much larger test farms. “We need to reach a large scale first to be able to understand what’s going on,” he says.

However, he told the BBC that the first successful mechanical harvest is “an important first step” towards the large-scale cultivation of commercial seaweed farms in the North Sea.

Read more about this story on the BBC.

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