Greenpeace Builds a Boulder Barrier in the North Sea to Stop Industrial Fishing in a Porpoise Sanctuary
Greenpeace activists have dropped giant boulders on the seabed of a marine protected area in the North Sea to snag the nets of industrial trawlers. The action aims to prevent bottom trawling in the protected area and conserve harbour porpoise populations.
From the Greenpeace ship Arctic Sunrise, activists dropped the stones to form an underwater barrier around the Southern North Sea marine protected area (MPA) — which Greenpeace UK describes as the UK's most bottom-trawled MPA.
The Southern North Sea is an area of importance for harbour porpoises, supporting nearly 20% of the UK North Sea population. But despite its MPA status, there are no restrictions on fishing in most of it, and bottom trawlers, dredgers and other industrial fishing vessels scour it daily.
Greenpeace UK said bottom trawlers logged more than 37,200 fishing hours in the protected zone in 2025 — an act it likened to 'a bulldozer tearing through a treasured national park'.
'Hulking great ships prowl the sea day after day, stripping it of fish and killing precious wildlife like porpoises, sharks and sea birds,' said Will McCallum, the campaign organisation's co-executive director. 'With our ship and a movement behind us, we're doing what the government isn't: protecting our seas.'
Greenpeace UK said the 'boulder barrier' has effectively closed 116 sq km (about 45 sq miles) of the Southern North Sea MPA to bottom trawling. Over the coming days, the Arctic Sunrise will patrol the area to deter other kinds of industrial fishing too, and the activists have declared the zone an 'ocean park', in the spirit of Britain's national parks.
The Southern North Sea MPA lies along the east coast of England, from north of Dogger Bank to the Strait of Dover in the south. It is intended to protect porpoise populations, partly by ensuring the availability of prey is maintained — an objective that, the activists say, intensive fishing in the area contradicts.
'We announced in June that if the government didn't act soon, Greenpeace UK would take direct action,' McCallum said. The action coincided with the nationwide premiere of Blue Planet III, the latest BBC wildlife documentary narrated by David Attenborough to focus on the oceans and the human-made threats they face.
According to a Greenpeace analysis, in 2025 bottom trawlers and dredgers tore through a cumulative 55,600 sq km of MPA seabeds — an area 58 times the size of Dartmoor national park.
