By: Elise Hansen In Partnership With: Amy Westman, Oceanographer
What is a Benthic Trawl? Benthic, or bottom trawling is dragging an enormous fishing net across the ocean floor, to collect and catch marine organisms. The net is held down with heavy steel trawl doors and imbedded weights, up to 5 metric tons each, (11,023 lbs) at the base of the net. Floats line the trawl edge for the opposite purpose, to keep the upper portion afloat. Trawling is a popular way of fishing, however has devastating effects on the ocean environment. Over time, trawling has gradually been and is being banned in a growing number of places.
Benthic Zone The word benthic refers to the benthic zone, the floor of a body of water. The organisms that live in this zone are referred to as benthos, and are the focus of bottom trawling. Several primary species of benthos are cod, shrimp, sole, haddock, rockfish and flounder. The net of the trawl drags across coral reefs and tears them out of the ground, snagging any hidden benthos in the process. The different samples of each snared organism broadens our understanding of the ocean, and also supplies seafood.
Collected Data Benthic trawls have increased knowledge in marine biology by a hundredfold. Through a trawl, oceanographers have evaluated differences between sexes with species of crab and lobster. Litter from the sea floor can be caught in a trawl, and biologists sort and analyze the trash and devise new ways to prevent garbage. Furthermore, the depth of the benthic zone can be calculated according to benthic trawl results. The following hyperlink leads to a PDF of the Manual for the International Bottom Trawling Surveys: ices.dkices.dk
Impact However, the heavy steel doors and weights don’t just hold the net down. When dragged across the benthic zone, they can destroy century-old reefs in mere seconds, leaving a trail of barren sea bed and mud behind. Not only does this destroy the habitat of many benthos organisms, but also depletes them of their source of food and shelter. Every year, twice the area of the 3.806 million square mile United States, (9.857 million km 2 ) is destroyed through bottom trawling. With such extensive damage, repair is not easy and occasionally cannot occur. Percentage of fishing methods used throughout the world:
Organizations and Efforts Many organizations throughout the world are attempting to ban benthic trawls. The Marine Conservation Institute avoids the devastating impact of trawls by using other, more friendly fishing methods. Oceana is working with scientists, lawyers, and fishermen to protect the benthic zone from trawling. Efforts to keep the sea bed safe are gradually becoming more efficient as trawling is being banned in more and more areas. The chart to the right illustrated countries whom trawl and what percentage of income consists of trawled fish.
Summary Benthic trawls had and have an enormous effect on science, both beneficial and not so. From trawling more knowledge about the ocean been gained, but has lead to terrible and sometimes unredeemable results. Trawling is a popular way of fishing throughout the world, especially for organisms living on the sea bed. Several aquatic research organizations are working at finding better, less destructive ways of fishing and collecting data. In the next few years, hope that trawling will be completely banned and old coral reefs and benthos organisms will return is strong.
Bibliography; 1 Banerjee, Gargi. "Tourism (Pollution): Not so Incredible!" Follow Green Living. Follow Green Living, 12 May 2014. Web. 23 Dec. 2014. "Benthic Zone." Wikipedia. Wikimedia Foundation, n.d. Web. 23 Dec. 2014. "Bottom Trawling." Bottom Trawling. N.p., n.d. Web. 22 Dec. 2014. "Bottom Trawling Impacts On Ocean, Clearly Visible From Space." ScienceDaily. ScienceDaily, n.d. Web. 23 Dec. 2014. "Destructive Fishing." Marine Conservation Institute. Marine Conservation Institute, n.d. Web. 22 Dec. 2014. "The Fishing Industry and Our Oceans." Middle School Science at Synergy School. Middle School Science at Synergy School, 16 May 2012. Web. 23 Dec. 2014.
Bibliography; 2 "Gulf Coast Preservation Society- Bottom Trawlers." Gulf Coast Preservation Society- Bottom Trawlers. Gulf Coast Preservation Society, n.d. Web. 23 Dec. 2014. "I Love Coastal Living." : Ryby świata. Najbrzydsza I Najsmutniejsza Ryba świata, Blobfish. N.p., n.d. Web. 23 Dec. 2014. "The Impact of Trawling." Institute of Marine Research. Institute of Marine Research, n.d. Web. 23 Dec. 2014. "Infographic: What Is Trawling?" Oceana. Oceana, n.d. Web. 22 Dec. 2014. "Manual of the International Bottom Trawling Surveys." Series of ICES Survey Protocols (n.d.): 1-68. Ices.dk. Web. "Pelagic Environment Animals." Images & Pictures. N.p., n.d. Web. 23 Dec. 2014. Special thanks to Amy Westman, for the information she provided!