A trawling net can stretch up to 200 meters across a seamount, pulled by metal doors weighing as much as 5 metric tons. As it scrapes the underwater mountain, it can flatten coral and sponge communities that took centuries to grow.
Seamounts are peaks rising from the deep ocean floor. Currents carry cold, nutrient-rich water up their slopes, making many of these places rich habitats in an otherwise vast ocean. Cold-water corals and ancient sponges provide shelter and nursery grounds, while fish, turtles, sharks and whales use the mountains to feed, breed or travel. Some seamounts even rise above the surface, forming parts of places such as the Hawaiian island chain.
Bottom trawling targets valuable fish, including orange roughy and toothfish. But the heavy nets can be 80 to 200 meters wide and are dragged for kilometers over seamount slopes and summits. The toll extends beyond the catch: slow-growing corals and sponges can live for centuries or millennia, and their loss removes habitat that other ocean life depends on. Scientists have found no evidence that a seamount fully recovered after trawling stopped, even after 40 years.
Now, countries are negotiating the United Nations Sustainable Fisheries Resolution, with a proposal to phase out bottom trawling on seamounts in international waters by the end of 2027. These waters are beyond any one nation's exclusive rights. If adopted, the proposal would set a deadline and offer a concrete route toward protection. It comes 20 years after the United Nations first called for safeguards for vulnerable marine ecosystems such as seamounts.
There are examples to build on. Trawling is no longer allowed on seamounts at fishable depths in the Northwest Atlantic, and some seamounts in other parts of the Atlantic and Indian Ocean have also been closed to trawling. Yet these protections cover only 1.5% of known seamounts. In the South Pacific, underwater mountains and ridges such as the Lord Howe Rise, off Australia's east coast, are still trawled.
Efforts to protect the wider ocean have gained ground. In 2022, countries signed the Global Biodiversity Framework, which set a goal of protecting 30% of the oceans by 2030. The U.N. Convention on Migratory Species adopted a resolution on seamount conservation, and the High Seas Treaty, formally known as the BBNJ Agreement, came into effect this year, bringing new tools for protecting marine life in international waters. More than 400 scientists have also signed the Seamounts Proclamation, urging governments to end trawling on these mountains in international waters.
Australia, a major ocean nation with a history of supporting limits on high-seas trawling and a role in South Pacific fisheries management, is among the countries with an opportunity to push for change. The negotiations now put a clear question before governments: will they turn years of calls and evidence into an agreement with a deadline? A phase-out would not undo past damage, but it could help spare more of these deep-ocean habitats from being scraped away.