• Analysis
Greenpeace Boulder Barrier in North Sea Targets Bottom Trawlers
Greenpeace activists aboard the Arctic Sunrise have dropped a boulder barrier in the North Sea, closing off part of the Southern North Sea marine protected area to bottom trawling.
What Greenpeace did in the Southern North Sea
Activists aboard the Greenpeace ship Arctic Sunrise have placed a boulder barrier in the North Sea, lowering stones as an underwater barrier around the Southern North Sea marine protected area (MPA). The stated aim is to snag the dragnets of industrial trawlers working inside the zone, which is the UK's most bottom-trawled MPA. The activists declared the protected stretch an "ocean park", in the spirit of Britain's national parks.
Why the protected area is open to trawlers
The Southern North Sea MPA matters for harbour porpoises, supporting nearly 20% of the UK North Sea population. It runs along England's east coast from north of Dogger Bank to the Strait of Dover and is meant to protect porpoise populations partly by maintaining the availability of prey. Greenpeace activists say intensive fishing there contradicts that objective.
According to the group:
- •Most of the Southern North Sea carries no restrictions on fishing, and bottom trawlers, dredgers and other industrial vessels scour it daily.
- •Bottom trawlers logged more than 37,200 fishing hours in the protected zone in 2025.
- •Greenpeace UK compared that level of trawling to "a bulldozer tearing through a treasured national park".
What Greenpeace and its backers say
Will McCallum, Greenpeace's co-executive director, said heavy ships strip the sea of fish and kill wildlife including porpoises, sharks and sea birds, describing hulking ships that prowl the sea day after day.
With our ship and a movement behind us, we're doing what the government isn't: protecting our seas.
McCallum noted that Greenpeace announced in June it would take direct action if the government did not act soon. The group's wider analysis found bottom trawlers and dredgers tore through a cumulative 55,600 sq km of MPA seabeds in 2025, an area 58 times the size of Dartmoor national park.
Notable figures added their names to boulders tipped from the Arctic Sunrise, among them Labour MP and former climate minister Kerry McCarthy, a member of the all-party parliamentary group for the ocean.
McCarthy said industrialised fishing is having a hugely destructive impact on the marine environment, yet less than 1% of UK seas are protected from it, and that boats can legally tear through supposedly protected areas, wreaking havoc on the seabed, habitats and sea life. Calling progress too slow, she backed a ban on bottom trawling and properly protected ocean sanctuaries in UK waters and across the Atlantic.
Scale of the closure and what comes next
Greenpeace UK said the boulder barrier had effectively closed 116 sq km, about 45 sq miles, of the Southern North Sea MPA to bottom trawling. The action coincided with the nationwide premiere of Blue Planet III, the latest BBC ocean documentary narrated by David Attenborough. The Arctic Sunrise will patrol the area in the coming days to deter other kinds of industrial fishing, and the government has been contacted for comment.
