National Geographic News
A photo of fish seized from two Chinese ships for bottom trawling.

A giant haul of fish were seized from two Chinese ships in 2007 after they were caught bottom trawling.

PHOTOGRAPH BY KAMBOU SIA, AFP/GETTY

Dan Vergano

National Geographic

Published May 19, 2014

Deep-sea trawling may have "devastating consequences" for marine life, suggests a study of a Mediterranean sea canyon. (Related: "Clear Cutting the Seafloor.")

Trawling—dragging nets behind boats to catch fish—dates back to the 1300s. But with coastal fisheries' stock increasingly depleted, industrial trawlers have traveled farther out on the world's continental shelves, with ships now trawling below 650-foot depths (200 meters).

What happens when those nets are dragged along the deep-sea floor, where they disrupt slow-growing sea life? Nothing good, says the new Proceedings of the National Academy of Sciences report led by Antonio Pusceddu of Italy's Polytechnic University of Marche, in Ancona.

The study compared trawled areas with pristine portions of a Mediterranean sea canyon off the Spanish coast, about 25 miles (40 kilometers) long and 7,220 feet (2,200 meters) deep.

The researchers found trawled canyon sediments contained 52 percent less organic matter than the undisturbed seafloor. There were 80 percent fewer sea worms in the trawled region as well. And there was only half as much diversity of species in the trawled seafloor. (Related: "Trawlers Destroying Deep-Sea Reefs, Scientists Say.")

"Ultimately, intensive and chronic bottom trawling," the authors say, will  "transform large portions of the continental slope into faunal deserts and highly degraded seascapes."

Follow Dan Vergano on Twitter.

7 comments
Linda Mount
Linda Mount

Humans are ruining this earth...we need to change what we eat.

Arthur Hendriks
Arthur Hendriks

 But these guys on the picture aren't doing Deep-sea trailing with those nets. If i'm correct


James Lucier
James Lucier

I've been hearing about this and I saw documentaries decrying the practice a decade ago.  Lots of talk and nothing changes.  It's like the tusk hunting, only Nations are doing it to the oceans.

Maggie P.
Maggie P.

What makes me especially angry about this brutality against ocean habitat is that we knew about it a long, long time ago!  Even had evidence! 

I watched a PBS special *years* ago - maybe as long as 15 years - that documented this kind of devastation.  Since then, the relevant "power corp technology" has only become more grand!  The PBS special had before/after film of ocean floor.  I think a groper was featured as a  engaging 'character', giving audience a place to focus empathy --- and that's important, given our psychology!
 

I also get angry on behalf of fishermen, families, and villages represented by those in the photo - whose 'crime' is nothing at all compared to 'factory fishing' ships. My anger on this theme brings Somalian piracy into focus - industrial fishing by large corporate owned ships was decimating Somalian 'family sized' fishing operations for years.  Appeal was made to the UN, etc, etc - to no avail. When piracy first began to appear, 'modern world-owning nations' took absolutely no responsibility, (not to mention 'modern world-owning nations' also inserting themselves unhelpfully into Somalian politics 'back when'.) Instead, the 'comfortable of the world' were encouraged to cheer massive wealthy-nation power brought against the pirates. (I'm not approving the piracy - but - development of desperate action by Somali fisherpeople could easily have been predicted if "the industrial world" had actually cared!


As I post this a line from Shakespeare pops to mind - a line that lays out of my attention for years at a time, but after this post will stick around for awhile:  "You blocks, you stones, you worse than senseless things"!  

(Could be aptly directed at large industrial oceanic fishing, could fit "modern world-owning national leaders", ... could be fairly directed many places these days!)

"We" are the whole world and all its life - inextricably intertangled and interdependent.  ... grr ... blocks and stones .. grr...

Oedhel Setren
Oedhel Setren

@Arthur Hendriks  

Deep sea or not, drag nets damage ocean ecosystems. We've lost entire coral shelves to drag netting, as well as put many species on or near the endangered limit. One could even make the case that shallow water drag nets are worse due to the amount of species that can live in a coral reef.

Oedhel Setren
Oedhel Setren

@James Lucier  

I agree. Nat Geo is quite late to this party. I've been sea food free for about 5 years because of this.

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