Vulnerable Seafloor Ecosystems


633px-PS1376-2_surface_hgBenthos organisms (sponge, bryozoans, ophiuroids) settling on the surface sediment of the ocean floor in 289 m water depth, Antarctic shelf (Weddell Sea). Sample was taken with a giant box corer. Photographed by Hannes Grobe/AWI Oceans are one of the last great wilderness frontiers left on the planet and despite decades of research, scientists still know very little about what exists beneath the water. Oceans encompass around 70 percent of the earth’s surface. Despite the lack of knowledge, it is increasingly evident that there are numerous seafloor-dwelling or benthic species and complex benthic ecosystems.

Some sea floors consist of awe-inspiring landscapes of mountains, hills, ridges and troughs teeming with perhaps millions of species of undiscovered life. These astonishing landscapes are known as ‘seamounts’ and can consist of huge mountains that can be hundreds of meters above the seafloor. The nutrient-rich waters around seamounts are known to support extraordinary and diverse ecosystems.

1024px-Underwater_mcmurdo_soundUnderwater photo of the ocean floor at Explorer's Cover, New Harbor, McMurdo Sound. Main visible species include; the antarctic scallop (Adamussium colbecki) the common antarctic sea urchin (Sterechinus neumayeri) a stalk-like bush sponge (Homaxinella balfourensis) a brittlestar (Ophionotus victoriae) seaspiders (Colossendeis sp.). Photographed by NSF/USAP Steve Clabuesch

Although few have been properly explored or documented, scientists estimate that there are between 30,000 and 100,000 seamounts across the world's oceans. Amazingly, the earth's longest mountain range is not on land but under the sea. The Mid-Oceanic Ridge winds around the globe from the Arctic Ocean to the Atlantic and is four times longer than the Andes, Rockies and Himalayas combined.

There are many seamount formations in the Southern Ocean, including several concentrated on the Kerguelen Plateau.



Despite the magnificence of these underwater habitats they are under threat from a highly destructive fishing method known as bottom trawling. Bottom trawling denudes the targeted area of all living species and leaves the ocean floor habitat pulverized and lifeless, a 'clear-filled' landscape unable to support life for many years.

Bottom trawling leaves scientists unable to document or study unusual benthic species. There is concern that fishing methods destructive to the seafloor could eradicate species before they are studied by scientists. Conservation aside, since compounds derived from marine species are used in a variety of pharmaceutical applications, bottom trawling could harm our chances of discovering promising treatments for serious diseases.

ASOC strongly supports the decision of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) to set a moratorium on bottom-trawl fishing in the CCAMLR Area until the Scientific Committee has had the opportunity to assess the extent of vulnerable biodiversity and ecosystems in the Southern Ocean.

The next step is for CCAMLR to decide how to deal with other methods of fishing that might damage the seafloor, including the bottom longlining methods that, while not as destructive as bottom trawling, could still damage fragile species. Click here for ASOC's Seamounts Paper. (.pdf)

However, bottom trawling remains a threat to benthic habitats outside of the Southern Ocean. The industrial fishing industry continues to use bottom trawling methods, particularly on seamounts due to their concentrated populations of commercial fish species.

According to studies by the Deep Sea Conservation Coalition, the use of large metal plates, heavy nets and rubber wheels attached to the nets have already caused significant damage to seamounts off both coasts of North America, off Europe from Scandinavia to north Spain, and on seamounts near Australia and New Zealand.

As part of the Deep Sea Conservation Coalition, the Antarctic and Southern Ocean Coalition is campaigning for an immediate halt to bottom trawling in the world’s high seas.

ASOC is calling on the United Nations General Assembly to 'adopt a resolution declaring an immediate moratorium on high seas bottom trawling and to simultaneously initiate a process under the auspices of the UN General Assembly'.

There are an estimated 100-200 fishing vessels currently operating full-time and year-round on the high seas, and a few hundred part-time vessels. The catch is mainly sold to the European Union, United States and Japanese markets. Despite the destruction bottom trawling causes the catch is less than 0.5 percent of the worldwide fish catch.

It’s important to stop bottom trawling now before the industry grows and these key ecosystems are destroyed.

What you can do

Avoid eating species caught by bottom trawling methods, particularly those which are at low population levels. Some fish to avoid are:

Orange roughy

Atlantic cod

Shrimp (from outside the U.S.)

Atlantic flatfish such as flounder, sole, and halibut

Learn more at Blue Ocean


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