Biodiversity threat of sea bed trawling

Posted: 12 February 2004

Bottom trawl fishing on the high seas - which consists of dragging heavy chains, nets, and steel plates across the ocean floor - is the single greatest threat to highly vulnerable deep sea environments and the biodiversity they shelter, says a new scientific report.

Three agencies, the WWF, IUCN and the Natural Resources Defense Council (NRDC) released the report at the biodiversity conference in Kuala Lumpur this week. They believe these fragile marine habitats could be protected with little significant economic impact on the global fishing industry. Scientists and conservationists worldwide have been raising the alarm in recent years about the impacts of high sea trawlers on the deep ocean habitats, in which between 500,000 and 100 million species are estimated to live.

The report, High Seas Bottom Fisheries and Their Impact on the Biodiversity of Vulnerable Deep-Sea Ecosystems, stresses that some of these species, such as corals and sponges, are slow-growing and long-lived, which make them particularly sensitive to disturbance.

It also points out that deep sea fish, such Patagonian toothfish and orange roughy, which can live for up to 150 years and sometimes reach reproductive maturity at 30 years of age, are particularly vulnerable to overfishing. Drop in ocean However, according to WWF, IUCN and NRDC, the economic value of the high seas fisheries is not likely to exceed US$300-400 million annually, equivalent to only 0.5 per cent of the estimated value of marine fish caught globally (US$75 billion).

"Compared to the global fishing industry, the high seas bottom trawling industry is a drop in the ocean," said Matthew Gianni, the author of the report. "Protecting deep-sea environments from sea bed trawling would not have a widespread economic impact nor significantly affect fish supplies, prices, or food security." In light of the risks to deep seas biodiversity and sustainable fisheries posed by high seas bottom trawling, the agencies call on the Conference of Parties on the Convention on Biological Diversity (CBD) to:

  • request the UN General Assembly to adopt a resolution calling for immediate protection of seamounts, cold-water corals, and other biodiversity hotspots from high seas bottom trawling until effective international management measures for bottom trawl fisheries in these areas are adopted.

  • facilitate the creation of a global representative network of high seas marine protected areas consistent with international law and based on scientific information, and to ensure its effective management and enforcement.
"Deep sea ecosystems like cold-water coral reefs can be destroyed by a single trawl," added Matthew Gianni. "It is time that the international community takes action before they are completely wiped out."