Bottom fishing has operated for over a century on heavily fished grounds such as the North Sea and Grand Banks. While overfishing has long been recognised as causing major ecological changes to the fish community on the Grand Banks, concern has been raised more recently about the damage which benthic trawling inflicts upon seabed communities. A species of particular concern is the slow growing, deep water coral Lophelia pertusa. This species is home to a diverse community of deep sea organisms, but is easily damaged by fishing gear. On November 17, 2004 the United Nations General Assembly urged nations to consider temporary bans on high seas bottom trawling.
Resuspension
Bottom trawling stirs up the sediment at the bottom of the sea. The suspended solid plumes can drift with the current for tens of kilometres from the source of the trawling. These plumes introduce a turbidity which decreases light levels at the bottom and can affect kelp reproduction.[citation needed]
Ocean sediments are the sink for many persistent organic pollutants, usually lipophilic pollutants like DDT, PCB and PAH. Bottom trawling mixes these pollutants into the plankton ecology where they can move back up the food chain and into our food supply.[citation needed]
Phosphorus is often found in high concentration in soft shallow sediments. Resuspending nutrient solids like these can introduce oxygen demand into the water column, and result in oxygen deficient dead zones.[citation needed]
Even in areas where the bottom sediments are ancient, bottom trawling, by reintroducing the sediment into the water column, can create harmful algae blooms. More suspended solids are introduced into the oceans from bottom trawling than any other man-made source.
Deep sea impacts
The UN Secretary General reported in 2006 that 95 percent of damage to seamount ecosystems worldwide is caused by deep sea bottom trawling.
Current restrictions
Today, some countries regulate bottom trawling within their jurisdictions:
• The United States National Oceanic and Atmospheric Administration banned bottom trawling off most of its Pacific coast in early 2006 and has restricted the practice severely off its other coasts as well. Federal regulation affects areas between 3–300 miles from the coast (areas within 3 miles (4.8 km) of the coast are State regulated).
• The Council of the European Union in 2004 applied "a precautionary approach" and closed the sensitive Darwin Mounds off Scotland to bottom trawling.
• In 2005, the FAO’s General Fisheries Commission for the Mediterranean (GFCM) banned bottom trawling below 1000 metres and, in January 2006, completely closed ecologically sensitive areas off Italy, Cyprus, and Egypt to all bottom trawling.
• Norway first recognized in 1999 that trawling had caused significant damage to its cold-water lophelia corals. Norway has since established a program to determine the location of cold-water corals within its EEZ so as to quickly close those areas to bottom trawling.
• Canada has acted to protect vulnerable coral reef ecosystems from bottom trawling off Nova Scotia. The Northeast Channel was protected by a fisheries closure in 2002, and the Gully area was protected by its designation as a Marine Protected Area (MPA) in 2004.
• Australia in 1999 established the Tasmanian Seamounts Marine Reserve to prohibit bottom trawling in the south Tasman Sea. Australia also prohibits bottom trawling in The Great Australian Bight Marine Park near Ceduna off South Australia. In 2004, Australia established the world’s largest marine protected area in the Great Barrier Reef Marine Park where fishing and other extractive activities are prohibited.
• New Zealand in 2001 closed 19 seamounts within its EEZ to bottom trawling, including in the Chatham Rise, sub-Antarctic waters, and off the east and west coasts of the North Island. New Zealand Fisheries Minister Jim Anderton announced on 14 February 2006 that a draft agreement had been reached with fishing companies to ban bottom trawling in 30 percent of New Zealand's exclusive economic zone, an area of about 1.2 million km² reaching from sub-Antarctic waters to sub-tropical ones. only a small fraction of the area proposed for protection will cover areas actually vulnerable to bottom trawling.
• Palau has banned all bottom trawling within its jurisdiction and by any Palauan or Palauan corporation anywhere in the world.
• The President of Kiribati, Anote Tong, announced in early 2006 the formation of the world’s first deep sea marine reserve area. This measure— the Phoenix Islands Protected Area— creates the world's third largest marine protected area and may protect deep sea corals, fish, and seamounts from bottom trawling., the actual boundaries of this reserve and what harvest limitations may occur therein have not been detailed. Moreover, Kiribati currently has only 1 patrol boat to monitor this proposed region.
Lack of regulation
Beyond national jurisdictions, most bottom trawling is unregulated either because there is no Regional Fisheries Management Organization (RFMO) with competence to regulate, or else what RFMOs that do exist have not actually regulated. The major exception to this is in the Antarctic region, where the Convention for the Conservation of Antarctic Marine Living Resources regime has instituted extensive bottom trawling restrictions. The North East Atlantic Fisheries Commission (NEAFC) also recently closed four seamounts and part of the mid-Atlantic Ridge from all fishing, including bottom trawling, for three years. This still leaves most of international waters completely without bottom trawl regulation.
As of May 2007 the area managed under the South Pacific Regional Fisheries Management Organisation (SPRFMO) has gained a new level of protection. All countries fishing in the region (accounting for about 25 percent of the global ocean) agreed to exclude bottom trawling on high seas areas where vulnerable ecosystems are likely or known to occur until a specific impact assessment is undertaken and precautionary measures have been are implemented. Also observers will be required on all high seas bottom trawlers to ensure enforcement of the regulations.
Failed United Nations ban
Palau President Tommy Remengesau has called for a ban on destructive and unregulated bottom trawling beyond national jurisdictions and Palau has led the effort at the United Nations and in the Pacific to achieve a consensus by countries to take this action at an international level. Palau has been joined by the Federated States of Micronesia, the Republic of the Marshall Islands, and Tuvalu in supporting an interim bottom trawling ban at the United Nations. The proposal for this ban did not result in any actual legislation and was blocked.
In 2006, New Zealand Fisheries Minister Jim Anderton promised to support a global ban on bottom trawling if there was sufficient support to make that a practical option. Bottom Trawling has been banned in 1/3 of New Zealand's waters (although a large percentage of these areas were not viable for bottom trawling in the first place