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New Fish Farms Move from Ocean to Warehouse
Ben Block, 29 Apr 08


Earlier this week, on a spring day in April, John Stubblefield walked past the blue tanks of striped bass, Atlantic sea bream, and cobia stored inside a Baltimore, Maryland, laboratory. "In this tank, it's spring in May. This tank it's spring in September," he said.

At the University of Maryland Biotechnology Institute's Center for Marine Biotechnology, Stubblefield and his fellow researchers are not only altering nature, they are creating what may be the next generation of seafood.

The experiment uses city-supplied water and a complex microbial filtration system to raise a few hundred fish completely indoors. Yonathan Zohar, the center's director and the study's leader, said it is the first indoor marine aquaculture system that can re-circulate nearly all of its water and expel zero waste. "I'm a strong believer that in 20 years from now, most seafood will be grown on land," Zohar said. "It can go to the Midwest, it can go into the inner city, it can go wherever."

If Zohar's team proves the system could become economically competitive with current marine fish farming techniques, Zohar says he may have found a sustainable answer to the world's growing fishery crisis.

Some estimates say as much as 90 percent of edible marine fish may disappear by 2048. The most common alternative is through fish farms that raise ocean-captured fish in coastal nets called net pens . Marine aquaculture expanded about 10 percent each year between 2000 and 2004, according to the U.N. Food and Agriculture Organization, with recent growth especially in the Mediterranean Sea around Greece and Turkey. However, net pens pollute coastal environments with waste and antibiotics, fish escapees pose a threat to the diversity of wild fish populations, and diseases can spread easily through net-pen fisheries.

Some nations are responding to net-pen pollution by closing troublesome operations. In Israel, for example, the government has called for the removal of 2,700 tons of Red Sea net pens by June due to damage to nearby coral reefs. Zohar spent a decade developing those same net pens when he worked for the Israeli National Center for Mariculture before relocating to Baltimore in 1990. He says his land-based fish farming system is an improved alternative. "They are disease free, pathogen free; they are contaminant free; they are toxin free," he said. "We tested them. They're as clean as you can get."

Aquaculture Cobia

Zohar's team is primarily raising cobia, a highly priced fish found off the eastern coast of North America and in the western Pacific Ocean. Cobia do not swim in schools, making them difficult to catch in large amounts, but when raised in an aquaculture operation they become a valuable food product. The lab is growing the cobia faster and more efficiently than if they were in a net pen, researchers say. "They grow like crazy-about one pound per month! That's double most species," said Stubblefield, the lab manager.

Most fish do not reproduce in captivity due to the absence of environmental clues, so forcing reproduction was the team's first hurdle. In addition to altering the water temperature, lighting, and salinity levels, Zohar invented a pellet that mimics the hormone necessary to spur a fish's natural reproduction process. The pellet is now being used in aquaculture and conservation efforts for various global fish species.

From the start, Zohar's lab committed to creating a sustainable, low-impact aquaculture system. They say that 99 percent of their water is recycled, with the only losses due to evaporation. An open-air system filled with microbe-covered, honeycomb-shaped plastic first detoxifies ammonia from the water. The water then flows into an oxygen-free system where different bacteria absorb the nitrogen. For the solid fish waste, a separate filter uses microbes to convert the sludge into methane, creating a clean-burning biofuel. The goal is for 10 percent of the aquaculture's energy needs to be offset by the methane byproduct, Zohar said.

Environmental Defense senior scientist Rebecca Goldburg visited Zohar's lab several years ago while serving on the Pew Oceans Commission. She said that while the system offers potential, it still has trade-offs. "When you grow fish in an indoor tank, it takes a fair amount of infrastructure and it can take a fair amount of energy," said Goldburg, an ecologist who specializes in aquaculture systems. "I'm hesitant to advocate a one-size-fits-all solution."

Also, the fish being raised are carnivorous, so feeding them requires the input of other fish that are caught or farmed, likely in a less sustainable manner. Several research efforts around the world, including Zohar's lab, are studying whether an algae-based food can replace the food pellets currently used, which are about 40 percent fish meat.

So far, investors have been hesitant to replicate Zohar's aquaculture due to fears that the system cannot compete with net pens. But as seafood demand increases and supply dwindles, Zohar remains confident. "Once the first couple are up and running, this thing is going to spread like fire," he said.

Ben Block is a staff writer with the Worldwatch Institute who covers everything environmental for Eye on Earth. He can be reached at

Stay Tuned! Worldwatch will be releasing a comprehensive report Farming Fish for the Future in August 2008, written by senior researcher and food expert Brian Halweil.

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Waterfield Farms in Amherst, MA has been doing this for years Their system has the advantage of raising vegetarian fish (tilapia) and using a combined hydroponics system (growing basil & other herbs) for water filtration.

Posted by: Garth on 1 May 08

Any effort to remove Atlantic salmon feedlots from the marine coastal environment is welcome. These feedlots (called "fish farms" to soften their image) threaten the entire coastal ecosystem by damaging wild fish populations and destroying coastal habitats. In Canada we are no longer protecting wild fish populations and we are allowing our marine wilderness areas to be destroyed for the sake of higher profits for one industry. When the wild salmon are gone what will happen to the orcas, what will happen to the tourism industry? We need to learn to value those things that we cannot sell.

Posted by: Paul Rideout on 1 May 08

Thanks for the article.

Indoor aquaculture has huge potential, if done right. Feeding the fish with other fish that have been caught, processed and transported unsustainably is not "doing it right." Indoor aquaculture can be a very productive and multifunctional part of a permaculture-based society. It can play a role as a treatment stage in living machines. Let's turn our turds into fish and useful plants! Much more research and cultural adjustment is needed in this area.

Posted by: greensolutions on 1 May 08

This is interesting but I'm also a little concerned about where the fish's food and energy will come from. We are pushing unsustainable operations from the sea to the land. Hopefully they can develop new ways to feed the fish without drawing on existing food supplies. Grain is already in short supply for humans partly because of rerouting grain supplies to feed other land animals and power vehicles. It also takes huge amounts of energy to heat large volumes of water so the fact that they could offset that by 10% might not be so encouraging.

So, great concept, but its hard to tell what the actual impact of this will be. Can they say if the carbon footprint or environmental impact of these fish is any better, or is it just different?

Posted by: Jarrett on 1 May 08

It is true that it takes a lot of energy to raise the temperature of water but solar thermal panels are 70-90% efficient. That is perhaps the easiest challenge involved in this whole proposition. The energy from methane would help at night and on cloudy days. Of course, the whole system would benefit greatly by being housed in a well-built strawbale with passive solar design elements.

Posted by: greensolutions on 1 May 08

It is true that it takes a lot of energy to raise the temperature of water but solar thermal panels are 70-90% efficient. That is perhaps the easiest challenge involved in this whole proposition. The energy from methane would help at night and on cloudy days. Of course, the whole system would benefit greatly by being housed in a well-built strawbale with passive solar design elements.

Posted by: greensolutions on 1 May 08

I strongly dispute Yonathan Zohar comments, Barramundi Blue Aquaculture has been doing this for 5 years in Australia ( freshwater) plus now in South Korea( marine environment and building the worlds largest re-circulative marine environment recirculative systems under roof(2000 tons) in Vietnam and next month commence a 1000 ton marine farm in Southern China, Mr Yonathan Zohar is just trying to re - invent the wheel, where BBA created it 5 years ago. ( refer Barramnundi Blue Aquaculture and or Barrablue on Google) Barrablue has received both international and Australian Government endorsements, awards and commendations over the last 5 years.
Mr Yonathan Zohar would apprear to have just copied the barrablue methodlogy and others using base technologies and is promoting what really is not his to promote.
For futher information please contact Geoff Orpin or Cynthia Taylor at
Geoff Orpin /Cynthia Taylor

Posted by: Geoff Orpin on 2 May 08

Hey thanks for the great blog, love this stuff. I think fish farms are very proactive. On a diffrent green note Do you have any idea of what celebrities are going green these days? I know there is a ton of them but I interested to find some that I haven’t seen before. I saw Ed Begley Jr. on ( ) Leo DiCaprio is on their site too. Any other good places to find ‘ecolebrities’? (Besides ecorazzi)

Thanks for all your info and drop me a link if you guys see anything worth my time.

Posted by: alex on 2 May 08

Waterfield Farms in Amherst, MA went under in 2005 due to a financial crisis at the bank which was funding the construction of the plant. (long story there) The plant operated at half capacity for ten years and eventually failed due to undercapitalization issues. The plant itself is still intact, waiting to be restarted. If you're interested in the details of this and/or seeing this plant restarted please contact me at

Posted by: Dave on 5 May 08



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