Kelp dredging in Scotland 'would destroy the marine ecosystem'

Kelp and a sea snail
Permitting Marine Biopolymers to mechanically dredge kelp could set a dangerous precedent that would be detrimental for pristine marine ecosystem, argues AILSA McLELLAN

Marine Biopolymers want to tow a large-toothed dredge in strips through kelp beds ripping the entire plant up by the holdfast (killing it), then throw the holdfast over the side to ‘facilitate survival’ of invertebrates.

Kelp dredging is currently not allowed in Scotland. This could change as the biochemical company Marine Biopolymers has submitted a scoping report to Marine Scotland outlining plans to dredge for the kelp Laminaria hyperborea over a huge area of Scotland’s West Coast. 

This type of dredging already takes place in other countries such as Norway, North America, and Iceland. The potential devastating impacts on the environment and coastal communities are just starting to be understood. 

Marine Biopolymers describe the kelp habitat as a ‘monoculture’;  it is more commonly thought of as one of the most ecologically dynamic and biologically diverse habitats on the planet. L. hyperborea supports more life than the other kelp species in Scottish waters.  Kelp is a ‘Keystone species’ at the bottom of the food chain: to remove it is ‘fishing down the food chain’ at its very worst.  

Marine ecocide

Currently kelp can only be hand-cut with a license from the Crown Estate, with strict guidelines on preserving the plant. The hand harvester must cut the kelp above the meristem ensuring that the holdfast, stipe, and a large part of the frond remain intact to allow the kelp to regenerate.  They must record invertebrate by-catch, and community structure must be monitored to ensure no changes in assemblage of structure.

Marine Biopolymers want to tow a large-toothed dredge in strips through kelp beds ripping the entire plant up by the holdfast (killing it), then throw the holdfast over the side to ‘facilitate survival’ of invertebrates. 

Assuming any invertebrates survive this treatment, where are they meant to go when chucked back over the side? Their habitat is gone, the other invertebrates are not going to ‘budge up’ and make room for them, that’s not how biology works.   

Marine Biopolymers want to tow a large-toothed dredge in strips through kelp beds ripping the entire plant up by the holdfast (killing it), then throw the holdfast over the side to ‘facilitate survival’ of invertebrates.

Kelp is long-lived and the holdfast and stipe are a vital part of the habitat, supporting other seaweeds, and hundreds of species of invertebrate that feed fish, including cod, seatrout, and wrasse, lobster, crab, otters, birds, seals, and us.  

So much employment of coastal Scotland is reliant upon a healthy coastal ecosystem: fisheries and eco-tourism would all be jeopardised by the destruction of kelp beds. We can’t peddle Scotland to tourists as a beautiful pristine environment, whilst committing ecocide under the waves at the same time.

Moreover, climate change is happening.  Its effects, such as increasing acidity and rougher seas are already being measured in our oceans.  Kelp sequesters significant amounts of carbon, buffers acidity, and acts as a storm barrier for coasts.   

Endangering biodiversity

The Scottish Governments ‘Wild Seaweed Harvesting Consultation’ from November 2017 references papers which highlight the many unknowns associated with kelp dredging. 

L.hyperborea is only classed as having a ‘moderate’ recovery potential. One study showed that it did not re-grow at all, whilst another tells of places where sea urchins have taken over due to the absence of predators (they went with the kelp) allowing them to over graze and inhibit kelp regeneration.

The only thing we know for a fact is that removing the kelp would most definitely reduce an incredible habitat along with everything that relies on it, and it would remove one of the few barriers to ocean acidification.

Virgin kelp beds can be looked on in the same way as virgin terrestrial forest. At the moment the beds are pristine, they have been evolving for thousands of years; that is not the sort of habitat that can recover in the short term.

Even if the L. hyperboreais dredged and returns to harvestable size within 5 or 6 years (which is not a given) there is no evidence that original communities ever return, and of course they never well if the area is re dredged every time it gets big enough to make it worth the dredgers time. The new habitat would be more homogeneous than before with plants of the same age. Homogeneity is the enemy of biodiversity.  Biodiversity is what supports our coastal fisheries and life. 

Sustainable solutions

There is a growing demand for seaweed products, but it doesn’t need to be from dredged kelp. 

Scottish waters are an ideal environment for farming kelp which could create real sustainable employment in coastal communities without jeopardising the ecosystem.  The Scottish Association for Marine Science have proven that kelp can be farmed at their test sites near Oban, and there are successful kelp farms in the Faeroes, and Rathlin Island between Scotland and Ireland.  

There are an increasing numbers of successful small businesses doing well selling seaweed as food where the emphasis is on sustainability.  

If alginate companies are finding it hard to farm the kelp that they need, then work needs to be done to identify how to overcome whatever obstacles they are encountering. Marine Biopolymers may be able to get more alginate more quickly by ripping up wild L.hyperborea, but so what?  It is not theirs to take. 

The importance of this habitat is so great that allowing dredging at any level is to set a dangerous precedent where short term profit comes above a healthy coastal environment.  The kelp forests and the life that they support belong to all of us and should never be dredged up for a fast profit for one company.  

To open the door to this proposal would normalise dredging. Businesses always want to expand, and other alginate companies would want a slice of the pie.  The door to kelp dredging must be slammed shut now.

This Author 

Ailsa McLellan has a background in marine science and over 18 years of experience working in inshore fisheries management.  She currently runs an oyster farm with her husband, and has been diversifying into seaweed. She is a member of the Scottish Seaweed Industry Association. Find her on Twitter @AilsaMcL. For more information see the report by Ecology and Evolution, and visit the 'Stop Mechanical Kelp Dredging' Facebook page