. Deep-sea biodiversity and ecosystems - a scoping report on their socio-economy, management and governance. UNEP-WCMC Biodiversity Series 28. . Bottom trawling for deep sea red fish [Sebastes marinus) at depths of 650 metres in the North Atlantic Ocean. Top: Trawl scars across a destroyed coral reef, offshore Norway. Bottom: A giant piece of 500-year-old gorgonian coral being hoisted out of a trawl net. and leaving ground for opportunistic species such as scavengers. The removal of ecosystem-building species such as corals might lead to a temporal or permanent change in fauna composition. In
. Deep-sea biodiversity and ecosystems - a scoping report on their socio-economy, management and governance. UNEP-WCMC Biodiversity Series 28. . Bottom trawling for deep sea red fish [Sebastes marinus) at depths of 650 metres in the North Atlantic Ocean. Top: Trawl scars across a destroyed coral reef, offshore Norway. Bottom: A giant piece of 500-year-old gorgonian coral being hoisted out of a trawl net. and leaving ground for opportunistic species such as scavengers. The removal of ecosystem-building species such as corals might lead to a temporal or permanent change in fauna composition. In general, the impact depends on four factors: the type of gear (weight and size), the towing speed and length of the line, the nature of the seabed substrate (sand, sediments, rocksl and tidal conditions or currents (Linnane ef at, 20001. Depending on local conditions, sediments suspended by the trawl may impact neighbouring ecosystems over considerable distances. Water column species are also affected by the cloud of suspended particles churned up by the bottom gear. While most deep-sea ecosystems are threatened by demersal trawling, the risk is particularly acute for seamounts and cold-water coral reef communities. The benthic biomass from unfished seamounts has been measured at 106 per cent more than that of fished ones (Koslow era/.. 2001], Suspension feeders such as cold-water corals and deep-sea sponge fields are particularly at risk from physical impact and smothering by sediments. Evidence of impact on cold-water corals from bottom trawling includes images of devastated reefs and large amounts of coral bycatch (both reef-forming and solitary species]. Thirty to fifty per cent of cold-water corals in Norwegian waters are severely damaged or dead, and their extremely slow growth threatens recovery (Fossa ef at, 2002]. In 1999, Norway was the first country to protect and conserve cold-water coral reefs within its Exclusive Economic Zone (EEZI under the Norwegian Nature Cons
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