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Greenpeace is using boulders in the fight against bottom trawlers - but why?

Greenpeace dropped boulders weighing between 500 and 1,400 kilograms into the Channel.
Greenpeace dropped boulders weighing between 500 and 1,400 kilograms into the Channel. Copyright AFP
Copyright AFP
By Hannah Brown with AFP
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Bottom trawling in marine protected areas is "like ploughing a combine harvester through a national park".


In an effort to prevent "destructive" industrial fishing off the UK coast, Greenpeace dropped 18 large boulders onto the seabed last week.

The giant rocks were dropped on Thursday from the Arctic Sunrise research vessel in an area of the Channel called the South West Deeps (East) Conservation Zone. This Marine Protected Area (MPA) is around 190 kilometres off Land's End, the most westerly point of mainland England.

The Portland limestone boulders, each weighing between 500 and 1,400 kilograms, are intended to make it impossible for trawlers to drag their nets along the seabed.

"Right now, there's an industrial fishing frenzy happening in UK waters, and what's our government doing about it?" asks Greenpeace UK's head of oceans, Will McCallum.

Why is bottom-trawling bad?

MPAs, or marine conservation zones, are protected areas that act as sanctuaries for nationally important, rare or threatened species.

Greenpeace UK says it is "absurd" that bottom-trawling is legal in MPAs.

"MPAs are supposed to be the areas where fish stocks can recover, so that we fish for generations to come,” says McCallum.

"[Bottom trawlers] destroy huge swathes of the marine ecosystem and make a mockery of our so-called 'protection'," he adds.

According to Greenpeace, the 4,600-square-kilometre South West Deeps is "one of the most heavily fished so-called Marine Protected Areas in the UK".

Figures from the Global Fishing Watch monitoring agency indicate that 110 vessels - more than half of them from France - fished for 18,928 hours in the South West Deeps in the 18 months up to July.

Of that, industrial vessels with bottom-towed fishing gear spent 3,376 hours fishing in the zone. That’s the equivalent of over 20 weeks of non-stop trawling.

Neil Whitney, a fisherman from East Sussex in southern England, says bottom-trawling is "like ploughing a combine harvester through a national park".

"[Bottom-trawlers are] able to take out entire ecosystems, and if they cause a fishery to collapse, they just move on to the next one," he adds.

As well as the risk to sea creatures, bottom trawling also disturbs and releases the carbon stored in the seabed.

Will the boulders cause damage to the seabed?

This isn’t the first time Greenpeace has taken this action. And there’s no evidence to suggest the placing of the boulders negatively affects the sealife.

In the UK, boulders were placed in the Dogger Bank MPA in 2020 and the Offshore Brighton MPA in 2021.

It’s proven to be a successful tactic as these actions contributed to bottom trawling equipment being banned in four of the UK’s 76 offshore MPAs, including the Dogger Bank.

Though this is progress, according to McCallum it’s still "outrageous" that bottom-trawlers are allowed to operate on the seabed in protected areas.


Messages of hope and the names of supporters, including celebrities and politicians, were stencilled onto the boulders before they were dropped into the sea.

Inspired by the fossils often found in Portland limestone, artists also created a giant ammonite sculpture from one of the boulders, which was also placed on the seabed.

The action comes after the latest round of UN talks to protect marine life in international waters broke up without agreement.

Watch the video above to learn more about Greenpeace’s campaign.

Video editor • Nathalie Texier

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