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Recently, copper alloys have become important netting materials in aquaculture (the farming of aquatic organisms including fish farming). Various other materials including nylon, polyester, polypropylene, polyethylene, plastic-coated welded wire, rubber, patented twine products (Spectra, Dyneema), and galvanized steel are also used for netting in aquaculture fish enclosures around the world.〔Offshore Aquaculture in the United States: Economic considerations, implications, and opportunities, U.S. Department of Commerce, National Oceanic & Atmospheric Administration, July 2008, p. 53〕〔(【引用サイトリンク】title=Commercial and research fish farming and aquaculture netting and supplies )〕〔(【引用サイトリンク】title=Aquaculture Netting by Industrial Netting )〕〔Southern Regional Aquaculture Center at http://aquanic.org/publicat/usda_rac/efs/srac/162fs.pdf〕 All of these materials are selected for a variety of reasons, including design feasibility, material strength, cost, and corrosion resistance. What sets copper alloys apart from the other materials used in fish farming is that copper alloys are antimicrobial, that is, they destroy bacteria, viruses, fungi, algae, and other microbes. (For information about the antimicrobial properties of copper and its alloys, see Antimicrobial properties of copper and Antimicrobial copper alloy touch surfaces). In the marine environment, the antimicrobial/algaecidal properties of copper alloys prevent biofouling, which can briefly be described as the undesirable accumulation, adhesion, and growth of microorganisms, plants, algae, tube worms, barnacles, mollusks, and other organisms on man-made marine structures.〔Marine Fouling and its Prevention, Wood Hole Oceanographic Institution, 1952, United States Naval Institute, Annapolis, Maryland, USA〕 By inhibiting microbial growth, copper alloy aquaculture pens avoid the need for costly net changes that are necessary with other materials. The resistance of organism growth on copper alloy nets also provides a cleaner and healthier environment for farmed fish to grow and thrive. In addition to their antifouling benefits, copper alloys have strong structural and corrosion-resistant properties in marine environments. It is the combination of all of these properties – antifouling, high strength, and corrosion resistance – that has made copper alloys a desirable material for such marine applications as condenser tubing, water intake screens, ship hulls, offshore structure, and sheathing. In the past 25 years or so, the benefits of copper alloys have caught the attention of the marine aquaculture industry. The industry is now actively deploying copper alloy netting and structural materials in commercial large-scale fish farming operations around the world. ==Importance of aquaculture== Much has been written about the degradation and depletion of natural fish stocks in rivers, estuaries, and the oceans (see also Overfishing).〔(The State of World Fisheries and Aquaculture (SOFIA), Biennial Report, 2005 ), as summarized in Food and Agriculture Organization of the United Nations〕 Because industrial fishing has become extremely efficient, ocean stocks of large fish, such as tuna, cod, and halibut have declined by 90% in the past 50 years.〔The Next Seafood Frontier: The Ocean, April 28, 2009, references article by Myers in Nature〕〔Tietenberg, T.H. (2006), Environmental and Natural Resource Economics: A Contemporary Approach, p. 28, Pearson/Addison Wesley. ISBN 0-321-30504-3〕 Aquaculture, an industry that has emerged only in recent decades, has become one of the fastest growing sectors of the world food economy.〔 Aquaculture already supplies more than half of the world’s demand for fish.〔Half Of Fish Consumed Globally Is Now Raised On Farms, Study Finds Science Daily, September 8, 2009〕 This percentage is predicted to increase dramatically over the next few decades. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Copper alloys in aquaculture」の詳細全文を読む スポンサード リンク
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