Dear EarthTalk: Recent news reports have revealed the discovery of previously unknown species inhabiting the deepest parts of our oceans. Is anything being done to protect this habitat before humans have a chance to fish it to death or otherwise destroy it?—Matthew Polk, Gary, Ind.

Unfortunately it may already be too late for some of the deep sea’s undiscovered life forms. Advances in so-called “bottom trawling” technology in recent years has meant that fishing boats now have unprecedented access to deep ocean habitats and the sea floor itself where untold numbers of unknown species have been making a living for eons. Scientists speculate that upwards of 10 million different species may inhabit the deep sea. This is biodiversity comparable to the world’s richest tropical rainforests.

The Deep Sea Conservation Coalition (DSCC), a group of more than 50 environmental and other groups dedicated to protecting cold-water corals and vulnerable deep-sea ecosystems, reports that trawlers today are capable of fishing deep sea canyons and rough seafloors that were once avoided for fear of damaging nets. “To capture one or two target commercial species, deep-sea bottom trawl fishing vessels drag huge nets armed with steel plates and heavy rollers across the seabed, plowing up and pulverizing everything in their path,” the coalition reports. In addition, adds DSCC, large quantities of coral and unwanted fish species are hauled up only to be thrown back dead or dying. Indeed, the result of a few hours of trawling can be the destruction of fragile deep-sea habitats, such as delicate coral and sponge communities, that may have taken centuries to grow and thrive.

Bottom trawling also stirs up the sediment at the bottom of the sea. The resulting undersea plumes of “suspended solids” can drift with the current for tens of miles from the source of the trawling, introducing turbidity throughout the water that inhibits the transfer of light down to the depths where it is needed for photosynthesis in plankton, sea kelp and other undersea plants that serve as the basis for the marine food chain. Also, ocean sediments serve as natural safe resting places for many persistent organic pollutants (such as DDT and PCBs). Dredging these sediments up effectively reintroduces such toxins into the water where they are unwittingly absorbed and consumed by the fish we eat and other marine life already trying to cope with otherwise compromised undersea habitats. The sediment plumes also reintroduce nutrient solids from agricultural and other practices, increasing demand for oxygen in the water (causing algae blooms) and contributing to the outbreak of ocean “dead zones” devoid of marine life.

What can be done? For its part, the United States has banned bottom trawling in its offshore jurisdictions, but the practice continues mostly unabated throughout Europe and out on the world’s high seas. DSCC has gotten upwards of 1,400 marine scientists from 69 different countries to sign onto a statement expressing profound concern “that human activities, particularly bottom trawling, are causing unprecedented damage to the deep-sea coral and sponge communities on continental plateaus and slopes, and on seamounts and mid-ocean ridges.” The statement calls on governments and the United Nations to adopt a short-term global moratorium on deep sea bottom trawling to try to provide immediate protection to the mostly undiscovered biodiversity of deep sea ecosystems while governments hash out longer term conservation and management regimes. In the meantime, bottom trawling continues unabated in sensitive areas of the North Atlantic and elsewhere, harvesting now for us what our grandchildren may never know.

CONTACT: DSCC, www.savethehighseas.org.

2 Comments

1. 1. Wayne Williamson 04:47 PM 3/25/11

   As far as I can see(in other articles) the depth of deep sea trawling is at depths of less than 100 meters...why is the article talking about over a thousand meters...
   
   That being said, I agree with the rest of the article on the destruction of environment that occurs with this method of harvesting...how long will it take for them to become productive again....
   

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2. 2. scientific earthling in reply to Wayne Williamson 09:01 PM 3/25/11

   Wayne: Forget about them becoming productive again...
   
   The use of the word productive, suggests you believe all life exists to aid and assist Homo sapiens. This is not so; we exist because of all the life that went before, most of the current base lifeforms can exist without us, but we can not exist without them. We even need the 10G bacteria and viruses that live in and on our bodies. Yes a small minority of them assist us attain our end.
   
   We are living in interesting times, the sixth extinction is rapidly accelerating to its ultimate end, when it is done most of the mega species will be gone, we are a mega species.
   
   Natural selection works in wondrous ways, we might even convince ourself the biosphere has some form of collective intelligence. The Gaia hypothesis is based on this assumption. I use the word Hypothesis because no one has established that this is so, people who refer to it as a theory are using the wrong scientific descriptor. A Theory in science is a proved fact, it explains the past history, current events and predicts successfully future outcomes. In loose everyday English it is often used to imply a postulate or hypothesis. All the idiots who come back at you, but it is only a theory are using the non scientific meaning of the word.
   
   Don't worry yourself too much about the loss of species as a result of human activity. In a few thousand years life will be abundant again, and new lifeforms will start occupying the space vacated by the mega lifeforms lost. Historic record indicates every extinction was followed by more advanced species replacing the ones lost. We can not be sure this will happen again, but that is immaterial. The fact that we have never encountered lifeforms more advanced than ourselves might hint at the possibility that when lifeforms advance on this path they inevitably exterminate themselves. No this is an hypothesis I am advancing, not a theory.

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