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.
While the Oceansphere could accommodate any number of sea life species, as well as multiple types of sea life co-existing simultaneously inside the enclosure, Troy and HOT CEO Bill Spencer have chosen bigeye tuna as the first type of fish to raise. Stocks of tuna, which is popular for sashimi, have been in rapid decline due to overfishing. So precipitous has been the drop in both numbers caught and size of fish caught for the Atlantic bluefin that scientists now fear the giant fish may disappear from the ocean. Bigeye populations have not been as hard hit, but have begun to decline. Bigeye has become the most common source of ahi in sushi bars.
The fish is well suited to the Oceansphere model because it moves up and down in the water column often and will be comfortable at any depth where the cage might be deployed. High-grade bigeye costs $10 to $12 per pound in Japan's wholesale fish markets, the premier seafood venue on the planet. HOT can produce the fish for roughly $3 per pound, including fish meal and the costs of maintaining and servicing the giant spheres and their inhabitants. In part, HOT can achieve these lower costs by raising the fish in lower densities and cleaner waters where disease is less of a problem and input costs for medicines or chemicals needed to sustain fish in less beneficial settings are avoided.
HOT's tuna might be able to support even higher prices than the current market sustains because, Troy believes, the tuna will have much lower levels of mercury and PCBs than wild-caught tuna, due to the ability of HOT to closely control what the fish eat and to locate the cages in areas free of these hazardous contaminants. Even attaining an organic designation could be possible, should a program come into existence for seafood. Explains Troy, "Tuna farming today is a billion-dollar business. There are cages you can buy off the shelf that can moored to the bottom that are being used in Mexico. But they have to be moored close to the coastline in shallow depth. The whole idea of making this environmentally friendly is to ensure a lot of flushing of the effluents with clean water to promote oxidation and dispersion. The best way to do that is to be in the open ocean in very deep water."
$120 Million Fish Farmers
Spencer believes the company can derive annual sales of $120 million from a 120-acre site seeded with a handful of Oceanspheres and an initial gross profit margin above 50 percent. That factors in a half-dozen harvests per year of 100 pound fish. Hawaii is the only state in the country that has developed offshore permitting for aquaculture. There are already two other successful open-ocean aquaculture projects in the islands using tethered fish cages. Troy is working with researchers at the University of Hawaii Hill's Pacific Aquaculture Resource Center to develop new hatchery techniques that will allow HOT to harvest eggs from wild tuna, fertilize the eggs and grow the baby fish to fingerling size (in the five-pound range), a process that will take roughly a year. The fingerlings will spend that time in ocean-fed holding tanks before being transported out to the Oceanspheres.
There divers will pump the fingerlings into the Kevlar enclosures using a modified system designed for aquaculture. This stocking technique is different than other tuna breeding operations which scoop up schools of young wild tuna and grow them in fish farms. That stocking technique depletes wild populations; the technique that HOT plans to use will not. The controlled hatching and fertilizing environments, likewise, should help agriculturists keep harmful heavy metals and other contaminants away from the fish at every stage of their life cycle.
Ultimately, the goal is to perfect the sphere and operations required to maintain it and then begin to license the technology to partners in other parts of the world. Troy and Spencer have applications filed for 21 separate process and technology patents to protection the intellectual property of the spheres. Partners in Japan are the most obvious, due to the country's extremely high per capita fish consumption but other potential partners could bring the technology to Australia and the mainland U.S.
Further development of laws regulating open ocean farming ventures will encourage more open-ocean aquaculture in territorial waters. Security will become more of a concern as farms are placed further offshore. To prevent pirates or thieves from stealing the contents of the Oceanspheres, each one will be equipped with a video camera mounted on a warning buoy. The cameras will transmit images via satellite to capture any evidence of wrongdoing, and the warning buoys will serve the dual purpose of warning off divers and fishing vessels. The Oceanspheres will sit deep enough to avoid the propellers and hulls of even the most deep-draft vessels.Spencer and Troy estimate that construction of the first sphere will cost $3 million or more. Already, the company is adding jobs in Hawaii and plans to continue construction and assembly of the spheres in the Hawaiian Islands once the company goes into full production mode. Down the road, Spencer would like to use this technology to reduce the $8 billion American fish buyers spend importing seafood. Already, Hawaii and Florida have set up legal systems to make it easier for open-ocean fish farmers to grow their crops in the deep blue. HOT's tuna: Coming soon to a sushi bar near you.
Alex Salkever is Senior Writer at AOL DailyFinance covering technology and greentech. Follow him on twitter @alexsalkever, read his articles, or email him at firstname.lastname@example.org.