Deep Sea Trawling Devastates Shipwrecks of “Alien Deep”

“The oceans cover 71 percent of our planet,yet only five percent of it has been explored.” —Dr. Robert Ballard

This Sunday, September 16, 2012, National Geographic Channel will air “Alien Deep” featuring Dr. Bob Ballard, and his expeditions on the E/V Nautilus. We interviewed one of the chief scientists from the show and expedition leader Dr. Mike Brennan to get to the bottom of one of the major threats to the future of ocean exploration: mobil fishing gear or bottom trawls.

What are the effects you are seeing on shipwrecks as a result of bottom trawls?
Unfortunately, on the E/V Nautilus expeditions, we have seen that many of the wrecks in the Aegean and Black Seas are heavily damaged by trawling activity. For example, one shipwreck, Eregli E, is the most trawled shipwreck in the Black Sea based upon scatter and damage to the artifacts and surrounding seabed. When we found it last year we saw that it was really damaged. The site had been so disturbed, it uncovered materials from beneath the sediment, including human bones.  The bones had been preserved in the mud, but then had been ripped out by trawls and that’s why we actually could see them. When we returned this year the artifacts we had seen the year before were either further damaged or gone, including the bones that were completely missing, again due to trawling. (Learn More: Ancient shipwrecks lost to trawlers.)

How exactly do you quantify the damage to sunken shipwrecks?
We can see the intensity of trawl scars using side-scan sonar mapping, and visibly see the dispersal of wooden timbers, and broken ceramic cargo.  We’ve gathered data on where fishing vessels are versus trawl intensity. (See: Quantification of Trawl Damage to Premodern Shipwreck Sites)

What solutions do you recommend for future preservation?
There are some commercial salvage companies using trawling as an excuse and justification for the salvage of these wreck sites, but our research shows that enforcement of certain restrictions to trawl sites can help protect these areas in situ rather than bringing them up. Shipwreck sites have reached an equilibrium with the surrounding environment, and in situ preservation is the best way to keep them intact, as called for by the UNESCO convention for the preservation of underwater cultural heritage. The establishment and protection of more marine protected areas can regulate the trawling and protect the wrecks underwater. Also, the wrecks work as artificial reefs, fish will use ceramics to hide out there. They can’t hide in the muddy sea floor – if you were to rope off the area – you would increase the fisheries.

Alien Deep airs starts tonight, Sunday September 16, 7PM. With cutting-edge tools and amazing new camera technologies, National Geographic embarks on its latest voyage of deep exploration — thousands of feet beneath the waves — to a hidden world of new ecosystems, new species and new wonders never seen before. The episodes are “It’s Alive,” “Wrecks of the Abyss,” “Ocean’s Fury,” “Inner vs. Outer Space” and “Fires of Creation.”

Scene from Alien Deep:

Changing Planet

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Amy Bucci is a web producer for National Geographic. Her projects mainly cover National Geographic explorers, grantees and initiatives.