The creation of the world’s biggest ocean sanctuary, protecting a huge tract of remote seas around Antarctica, has come a step closer after major fishing companies came out in favour of the plan.

A global campaign – spearheaded by Greenpeace and backed by 1.7 million people – had put massive pressure on the krill fishing industry and retailers amid fears it was endangering one of the world’s last great wildernesses, undermining the global fight against climate change.

On Monday evening that pressure appeared to have paid off when companies responsible for 85% of krill fishing in Antarctic waters announced a “voluntarily permanent stop” to their operations in key areas, including the proposed sanctuary and “buffer zones” around penguin breeding grounds.

“The momentum for protection of the Antarctic’s waters and wildlife is snowballing,” said Frida Bengtsson, of Greenpeace’s Protect the Antarctic campaign. “This is a bold and progressive move from these krill fishing companies, and we hope to see the remainder of the krill industry follow suit.”

Krill are small crustaceans that play a key part in the delicate Antarctic food chain. They feed on marine algae and are a key source of food for whales, penguins and seals. They are also important in removing the greenhouse gas carbon dioxide from the atmosphere by eating carbon-rich food near the surface and excreting it when they sink to lower, colder water. Campaigners have warned that industrial fishing and climate change is driving a sharp decrease in their numbers.

The Guardian has been investigating the threat posed to the Antarctic ecosystems by the krill fishing industry for the past six months, with the articles widely shared by readers and supporters.

In February, the Guardian visited the region to highlight how the delicate eco-system was under threat with potentially dire consequences, not just for wildlife, but for the wider fight against climate change.

On Monday, ocean experts described the move by the krill fishing industry as “visionary”, adding they now expected governments to back the sanctuary proposals at a meeting in October.

Andrea Kavanagh, director of Antarctic and Southern Ocean conservation with Pew Charitable Trusts, said: “The Association of Responsible Krill harvesting companies’ [ARK] support for the creation of a network of marine protected areas, including large no-fishing zones, is a truly visionary step that more commercial fishing interests in Antarctica and around the world should follow.”

She said that cooperation among scientists, governments, industry, and conservation groups was “the surest bet to protecting the 30% of the ocean that scientists tell us is needed to maintain global ocean health”.

Kristine Hartmann, from Aker BioMarine, the largest krill fishing company in the world, explained the decision to agree a voluntary halt to fishing, saying that “safeguarding the Antarctic ecosystem in which we operate is part of who we are”.

She added: “Our ongoing dialogue with ARK members, scientists and the community of environmental NGOs, including Greenpeace, is what makes additional efforts like this possible. We are positive that ARK’s commitment will help ensure krill as a sustainable and stable source of healthy omega-3s for the future.”

The companies which have made the announcement are all members of ARK and represent 85% of the krill fishing industry in the Antarctic.

The campaign for the sanctuary had seen people target krill products in stores around the world and had already led to some leading retailers – including Holland and Barrett – removing krill-based supplements from the shelves.

Greenpeace said Monday’s decision meant there would be no Antarctic krill fished near critical ecosystems in any products sold in the UK.

The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), whose members include 24 national governments and the EU, manage the seas around Antarctica and will decide on the sanctuary proposal at a conference in Australia in October. The move is being put forward by the EU and is being backed by the UK.