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Aquaculture AdvantageUQ: Fisheries = BrinkGlobal fish shortage is comingAlex Salkever 9, Senior Writer at AOL DailyFinance covering technology and greentech, “Sushi salvation: Startup sees future of fish farms in giant Kevlar spheres,” 11-4-9, http://www.dailyfinance.com/2009/11/04/sushi-salvation-startup-sees-future-of-fish-farms-in-giant-kevl/ DOA: 6-24-14, y2k That luscious ahi tuna roll you chowed down on at your local sushi joint? It's the same as eating an endangered Siberian tiger. Well, not quite. But scientists are increasingly worried that ahi, the blood-red belle of the raw-fish ball, is being quickly fished to extinction courtesy of the never-ending quest for superior sushi. But now, a small startup in Hawaii has an ambitious goal to save the ahi. Its secret weapon? A giant, self-powered, Kevlar-coated ball that could prove a perfect way to raise tuna in captivity and supply discerning fish fiends with their piscine fix without further depleting wild stocks. The company, Hawaii Oceanic Technology, was founded by Paul Troy, a former professor of oceanography at the University of Hawaii. A tinkerer and inventor, Troy had long followed the plight of marine fisheries. Three years ago, he began to sketch a plan for a radical new form of fish farming that would appease hard-core environmentalists and provide restaurants and fish markets with a reliable supply of ahi and, potentially, numerous other forms of seafood favored by homo sapiens. Troy envisioned giant floating balls that could circulate and move up and down in the water column. He laid out a formal design for the system, filed patents, and started work on a prototype. Dubbed Oceanspheres, these balls will be constructed with an aluminum frame sheathed in Kevlar embedded with nanoscale anti-fouling particles. Kevlar was selected because water slips through it very easily, reducing drag on the cages, but the material is strong enough that sharks and other predators can't chew through it. As Reliance on Fish Farms Grows, So Does Environmental Cost Troy's timing is impeccable. No doubt, the world needs more righteous fish. Demand for seafood is rising at double the rate of population growth, according to the United Nation's Fisheries and Aquaculture Organization. But many wild fisheries have showed significant signs of strain and even collapse, including the Pacific salmon and the Atlantic cod and bluefin tuna populations. Much of the growing demand is being met through aquaculture, which provides 43 percent of the world's seafood according to the FAO. However, environmentalists and scientists have long held significant environmental and health concerns about current aquaculture methods. Most of the industry remains unregulated and practices vary widely from country to country. Onshore and near shore practitioners often use high doses of antibiotics to keep their fish alive and allow them to grow quickly in environments that could not normally sustain dense fish populations. Instances of fish farmers in Asia using chemicals toxic to humans in order to boost yields have caused significant reputational damage to the industry. And discharges of fecal matter from high-density farms have concerned health advocates and recreational fishermen alike. Additionally, many fish farms in coastal waters use species that are not endemic to the area. Often bred for rapid growth and weight gain, these farmed fish have the potential to cause problems for native species and potentially out-compete local populations if they escape from their pens or cages, a regular occurrence on many fish farms. The presence of farms in near-shore and coastal areas also creates conflicts with boaters and recreational fishermen. Great High-Tech Balls of Fish Troy believes his system can address all these concerns. Each Oceansphere will have a volume of 82,500 cubic meters and a diameter of roughly 50 meters, large enough to comfortably hold over 1,000 tons of seafood at densities that are very low compared to those found in traditional aquaculture. Unlike existing open-water aquaculture cage systems, Troy's system would require no tethers. The tops of the spheres would float roughly 25 meters below the surface most of the time. The spheres could be raised to the waterline for replenishment of feed pellets and restocking or harvest, and can drop well below the 25 meter mark to grow fish species more accustomed to deeper depths. Attached to the spheres will be small thrusters powered by ocean thermal energy conversion (OTEC). This is a system harvests the unlimited thermal energy of the ocean by sucking up colder water from below the sphere as well as warm water from above the sphere. The warm and cold water go into a type of heat exchanger, which converts the thermal differential into electricity to power the directional motors, telemetry, automated fish feed dispensers and other onboard systems. Similar systems are already used to power submarines and other submersible vehicles. The OTEC units allow the Oceanspheres to travel independently on predetermined courses, a capability that could alleviate concerns about fish feces by allowing for waste dispersal over wide areas. The self-propulsion and navigational capabilities also allow for Oceanspheres to be located in much deeper waters, where tethered cages can't be used. 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