Seaweed Harvesting in The Netherlands I Ask the Expert

Jan Kruijsse harvests seaweed for a living. He sells it to restaurants, fishmongers and food companies. We went seaweed harvesting with Jan in the Eastern Scheldt – a former estuary in the south of the Netherlands that was closed off to the ocean in the 1980s – and asked him whether seaweed really is the food of the future.

How do you harvest seaweed?

I don't cultivate it myself, but together with a company called Seaweed Harvest Holland, I'm looking into this possibility. In a protected corner of the Eastern Scheldt, we have several long cables that are suspended in the water, with young seaweed plants attached to them. That seaweed grows, and we can then easily harvest it by reeling in the cables. As we go along, we're gradually adjusting our method and learning from our mistakes.

Learn how seaweed is cultivated.

How did you come up with the idea of becoming a seaweed harvester?

Nine years ago, I took over my uncle's company. He supplied seaweed to oyster traders as decoration, to display shellfish on. I believed in the potential of seaweed as food, so I expanded the business to include edible wild seaweeds.

Photo Credit: Kim Verhaeghe

Can anyone just go and harvest seaweed?

No. In the Netherlands, you need a licence. Anyone can go out and harvest up to 10kg of mussels, for instance, but you can't harvest any seaweed at all without a licence.

Read about shellfish poisoning.

Does it take a chef to prepare seaweed?

Well, my main customer base is mostly chefs, but really anyone can use seaweed in the kitchen. I do think a lot more could be done to make seaweed more appealing to consumers. It needs to be made more easily accessible, and pretty much ready to eat. I have a company that makes seaweed crisps for me, for example, and you can also get seaweed croquettes. We're always thinking of new things. I often discuss with food companies how we can get seaweed to consumers more easily.

What are the advantages of seaweed over traditional vegetables?

I collect seaweeds at low tide at various places in the Eastern Scheldt, based out of the fishing village of Yerseke.

I cut off only one-third of the plant with a hand-held knife, leaving the rest so it can grow back. The seaweeds I collect grow in different places, and I spend a lot of time going from one place to the next to collect from different plants. I also have to take the tides into account. That means no two days are the same for me - sometimes I start as early as half past four in the morning. 

I recently bought a mussel boat and renovated it so I can use it to harvest seaweeds at greater depths. It has a steel net that trawls the riverbed, and there's a blade mounted on it that cuts off the weeds about 10cm up.

Photo Credit: Kim Verhaeghe

Seaweed is rich in protein, vitamins A, B, C and E, and minerals, including calcium, sodium, iron and iodine. And the fibre-rich parts of the seaweed that are not broken down by the body can help regulate intestinal function. Seaweed is also much more sustainable than food grown on land. It absorbs carbon dioxide, so it’s useful in the fight against ocean acidification and climate change.

Why isn't seaweed readily available in stores yet?

Photo Credit: Kim Verhaeghe

We still have a few hurdles to overcome. We need to increase shelf life. Unless you dry it – in which case you can store it for up to 2 years – seaweed only stays fresh for about 6 days. That needs to be extended to at least 9 days to make it interesting for supermarkets. Many tests are currently underway to find out how we can preserve seaweed longer – without adding preservatives, of course.

Consumers also need to get used to seaweed, and that takes time. About 10 years ago, chefs suddenly started incorporating glasswort and sea lavender into their creations. This was a novelty for consumers at the time, but since then, these sea vegetables have become almost as commonplace as lettuce and tomatoes. I think it's going to be a similar story for seaweed.

The author originally wrote this piece for Belgian outlet Eos Tracé. Read the piece in Dutch here.

Salty and nutty. Firm, but softens when heated. Can be eaten as crisps (baked in the oven), mixed with mashed potatoes, or used as a powder to marinate vegetables, meat or fish.

Full flavour, one of the best algae. This seaweed can be used to make ice cream or pressed for oil.

Nutty aroma, mineral taste. Perfect for wrapping fish and then cooking it in the oven.

Tender and soft, somewhat salty. The taste is reminiscent of spinach or white cabbage. Can be braised, blanched, or served raw with a drizzle of olive oil. Can also be used to wrap fish. Dried sea lettuce is also used as a flavour enhancer.

Works well blanched, braised, or in tempura dishes. The strong flavour is best combined and balanced with other strong flavours.

Type of red algae with a fruity flavour. Tastes great raw, braised, or fried in tempura dishes. The structure is reminiscent of glasswort. Dried gracilaria is used as a salt substitute.

How much seaweed do you collect in a day?

A few hundred kilograms - it largely depends on which type I'm harvesting. The fishmongers place their orders earlier than 6 a.m. The restaurants order a little later. By noon, the harvest is already delivered to the customers. I also have a basin I can use to keep seaweed fresh for a few days, but I try not to harvest too much in advance.

Is all seaweed edible?

There are 153 species of seaweed in the Eastern Scheldt. They're all edible, but I only harvest 6 types. The rest of them are only found in small quantities, so I prefer to leave them alone. 

Some types grow in summer, others in winter. Summer seaweeds – like gracilaria, felty fingers, or sea lettuce – tend to be softer and sweeter. In winter, I harvest wakamé and Japanese wireweed. Those are harder and tougher to chew. Then there's wrack, which grows year-round. 

Each type of seaweed has a specific flavour and way of preparation (see image below). Does it taste good? I think so. More and more chefs are exploring the possibilities and taste variations that seaweed has to offer. I'm truly amazed at the dishes they create with it.

Different types of edible seaweed

Does harvesting seaweed impact marine life?

No. There's an abundance of seaweed in the Eastern Scheldt. After a storm, the banks are full of washed-up seaweeds. I also never harvest an entire plant, so it can grow back. That's why I only harvest sea lettuce at the same spot 2-3 times a year, and wrack only once, maybe twice a year. I also have to go along with nature. I can't make adjustments, like a farmer in a field. I don't use fertiliser or pesticides. I'm completely dependent on the wind, currents, temperatures, and the seasons.

Can seaweed be cultivated instead of being harvested in the wild?