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Clear Cutting the Seafloor: Deep-Sea Trawling

A trawl catch of myctophids and glass shrimp from a layer associated with the bottom at greater than 200 meters depth. Photo from Wikimedia Commons.
A trawl catch of myctophids and glass shrimp from a layer associated with the bottom at greater than 200 meters depth. Photo from Wikimedia Commons.

As debate rages in the European Union on how to regulate, and eventually phase out and ban deep-sea trawling, I am reminded of my many deep-sea cruises. Looking for cold-water corals in the depths of the Atlantic, Pacific, and Antarctic, often thousands of meters below the oceans surface, there is almost always a reminder that human influences run deep.

Paint can lying on the seafloor next to a deep-sea coral, at 2000m depth in the North Atlantic. Image courtesy of Rhian Waller, DASS05_URI_IFE_NOAAOE
Paint can lying on the seafloor next to a deep-sea coral, at 2000m depth in the North Atlantic. Image courtesy of Rhian Waller and the DASS05 team, DASS05_URI_IFE_NOAAOE

Trash is common – paint cans, bottles, bolts, and shackles – i’ve even seen house numbers laying barren at thousands of meters depth. I always wonder where they came from, what period in time and how they came to be many thousands of meters below the surface and many hundreds of miles from the nearest land.

Maybe saying we're the Number 1 ROV exploration team? This sign lay on the seafloor at around 1000m depth in the North Atlantic. Image courtesy of Rhian Waller, DASS05_URI_IFE_NOAOE
Maybe saying we’re the Number 1 ROV exploration team? This sign lay on the seafloor at around 1000m depth in the North Atlantic. Image courtesy of Rhian Waller and the DASS05 team, DASS05_URI_IFE_NOAOE

One of my most memorable “trash” moments was on a cruise in 2005 with an ROV. As we were flying over the seafloor, looking for cold-water corals, one came into view, only something was not quite right. A foil balloon, wrapped tight around a soft coral at 3000 m depth in one of the remotest parts of the North Atlantic. This image is firmly etched in my mind as I see them being handed out at children’s parties.

A foil balloon wrapped around a coral at 3000m depth in the North Atlantic. Image courtesy of Rhian Waller, DASS05_URI_IFE_NOAOE
A foil balloon wrapped around a coral at 3000 m depth in the North Atlantic. Image courtesy of Rhian Waller and the DASS05 team, DASS05_URI_IFE_NOAOE

Much more pervasive however is deep-sea trawling. As traditional, shallow water pelagic fisheries have been running low, many have been moving into deeper waters, utilizing new species of fish, and new populations. Unlike traditional pelagic (or open water) trawls however, these deep-sea trawlers often use bottom nets to gain fish living close to the seafloor. Fish using ecosystems such as deep-water corals and sponges for feeding and protection of themselves and their young.

A net filters into view on Manning Seamount, in the North Atlantic. Image courtesy of Rhian Waller and the DASS05 team; DASS05_URI_IFE_NOAOE
A net filters into view on Manning Seamount, in the North Atlantic. Image courtesy of Rhian Waller and the DASS05 team; DASS05_URI_IFE_NOAOE

Bottom trawling is by far the most destructive method of fishing out there. Running nets sometimes larger than football fields along the seafloor, often with large “rollers” of metal or hard plastics, specifically made to crush anything in their way to protect the nets. The path of these trawlers can be clearly seen, even in thousands of meters of water. Very little, sometimes nothing, is left in their path, except the scars on the rocks to show you where they’d been.

An example of deep-sea trawling scars on the seafloor, at 800m depth in the North Atlantic. Image courtesy of Rhian Waller, DASS05_URI_IFE_NOAOE
An example of deep-sea trawling scars on the seafloor, at 800 m depth in the North Atlantic. Image courtesy of Rhian Waller and the DASS05 team, DASS05_URI_IFE_NOAOE

For deep-sea corals, and other deep-sea habitat forming organisms, trawling means destruction, they can’t move out of the way, they’re attached to the bottom. For corals that live 200 m and below, life is hard – they get little food so they grow really slowly (some are up to thousands of years old) and so recolonization of areas wiped clean by trawlers may take decades to hundreds, maybe even thousands, of years. These corals form habitats in the deep-ocean, supporting thousands of species of fish (including commercial fish), crabs, sea stars and more. So it’s not just the corals that get taken away, it’s the whole ecosystem.

Searching for deep-sea corals with an ROV. Image courtesy of Rhian Waller and the DASS05 team, DASS05_URI_IFE_NOAAOE
Searching for deep-sea corals with an ROV. Image courtesy of Rhian Waller, DASS05_URI_IFE_NOAAOE

“Out of sight out of mind” is a phrase we often use to describe these ecosystems, and the impacts happening every day. Although there are a handful of researchers like myself exploring, researching, and publishing data on these deep-sea ecosystems, these fragile organisms may be lost in many areas before we can really understand their importance to the whole ocean ecosystem.

What can you do? Be informed, know where your seafood comes from (if it’s from the deep-sea, it’s unlikely to be sustainable), know what fisheries are in your area, sign petitions to help ban deep-sea trawling, and most of all, spread awareness. No one would trawl in the Great Barrier Reef – so let’s stop trawling the reefs of the deep!

 

Comments

  1. romain
    December 17, 2013, 6:45 am

    Bloom association fights for ocean conservation via several action. Like awareness event, jural action, research, and consumer protection.

    So please help them to save our planet ! Supoort them !!
    https://www.facebook.com/deepseabottomtrawling/info
    https://www.leetchi.com/c/association-de-bloom-association

  2. A Smith
    U.S.
    June 26, 2013, 8:02 pm

    That’s just sad.