land-based recirculating aquaculture systems: a more sustainable approach to aquaculture

8/14/2019 Land-Based Recirculating Aquaculture Systems: A More Sustainable Approach to Aquaculture

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About Food & Water WatchFood & Water Watch is a nonprot consumer organization that works to ensure clean water and safe food. We chal-

lenge the corporate control and abuse of our food and water resources by empowering people to take action and by

transforming the public consciousness about what we eat and drink. Food & Water Watch works with grassroots or-

ganizations around the world to create an economically and environmentally viable future. Through research, public

and policymaker education, media and lobbying, we advocate policies that guarantee safe, wholesome food produced

in a humane and sustainable manner, and public, rather than private, control of water resources including oceans,

rivers and groundwater.

Main Ofce1616 P St. NW, Suite 300

Washington, DC 20036tel: (202) 683-2500fax: (202) [email protected]

www.foodandwaterwatch.org

Copyright September 2009 by Food & Water Watch. All rights reserved. This report can be viewed or downloaded atwww.foodandwaterwatch.org.

About the Alliance for Sustainable AquacultureAlliance for Sustainable Aquaculture (ASA) is a collaborative group of researchers, business owners, non-prot

organizations and interested members of the public working to further Recirculating Aquaculture Systems (RAS) in

the United States through research, education, legislative work and advocacy. We believe that RAS, closed-looped

and biosecure aquaculture operations, are the best option to meet our countrys need for a clean, green, sustainable,

healthy seafood source to supplement our wild sheries.

1616 P St. NW, Suite 300Washington, DC 20036tel: (202) 683-2500fax: (202) [email protected]

www.foodandwaterwatch.org/asa

On the Cover

California Ofce25 Stillman Street, Suite 200San Francisco, CA 94107tel: (415) 293-9900fax: (415) [email protected]

Images rom let to right

Methane fame generated rom waste captured by RAS.Photo courtesy o Dr. Yonathan Zohar at UMBI Center O Marine Biotechnology

Lettuce and other vegetables growing in RAS aquaponic tanks at UVI.Photo courtesy o Dr. James Rakocy at the University o the Virgin Islands in St. Croix.

Shrimp produced in a RAS acility at Blue Ridge Aquaculture.Photo courtesy o Mr. Martin Gardner rom Blue Ridge Aquaculture in Martinsville, VA.

Nile tilapia, a species oten produced in RAS.

RAS tanks or raising tilapia.

Photo courtesy o Dr. Martin Schreibman at Brooklyn College, CUNY, Aquatic ResearchEnvironmental ssessment Center (AREAC)

This report is a joint project of the Alliance for Sustainable Aquaculture and Food & Water Watch.


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Land-Based ReciRcuLating

aquacuLtuRe systems

a more sustainable approach to aquaculture

Table of Contentsiv Executive Summary

1 Introduction

1 What Is RAS?

2 Types of RAS: Freshwater and Saltwater

3 Why RAS Can Be an Important Fish Production Method for the United States

4 RAS Factors

8 Research and Development

10 Future Improvements

12 Specifc Commercial Case Studies

13 Conclusion

14 Endnotes


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Executive Summary

This report,Land-Based Recirculating Aquaculture Systems, provides an introduction to Recirculating Aquaculture

Systems (RAS). RAS are closed-loop sh farming facilities that retain and treat water within the systems. This form

of land-based aquaculture is quickly gaining popularity in the United States.Land-Based Recirculating Aquaculture

Systems addresses why RAS could be an important method of producing more sh for the United States; highlights

research, development and technical innovations in RAS; and discusses concerns and recommendations for thefuture of these systems.Land-Based Recirculating Aquaculture Systems also provides commercial case studies of

existing successful RAS operations in the United States.

Consumer demand for cleaner, greener, safer seafood is on the rise. Many popular sh, like tuna, cod and certain

snapper are depleted in the wild from many years of poor management, overshing and other ecological problems

like pollution and damage to key habitat areas. There is a need to supplement wild-caught sh to meet consumer

demand for seafood. One method to produce more sh is known broadly as aquaculturethe rearing of aquatic

animals in captivity. Aquaculture is also often called sh farming, as it can be likened to the farming of other food

animals, like chickens, pigs and cattle. Aquaculture is increasing worldwide; between 2004 and 2006 the annual

growth rate of this industry was 6.1 percent in volume and 11 percent in value.

Widespread open-water sh farming methods, such as coastal ponds and open-ocean aquaculture (OOA), can seri-ously damage marine ecosystems and are far from providing the safe and sustainable seafood many consumers want

In particular, OOAthe mass production of sh in huge oating net pens or cages in open ocean watersraises

concerns about consumer safety, pollution of the marine environment and conicts with other ocean uses.

Fortunately, RAS can likely provide a cleaner, greener, safer alternative to open-water farms that does not compete

with other ocean uses. These systems are usually land-based and reuse virtually all of the water initially put into the

system. As a result, RAS can reduce the discharge of waste and the need for antibiotics or chemicals used to combat

disease and sh and parasite escapesall serious concerns raised with open-water aquaculture.

RAS provide a diversity of production options. Tilapia, catsh, black seabass, salmon, shrimp, clams and oysters are

just a few examples of what can be raised in these systems. RAS can also be operated in tandem with aquaponics

the practice of growing plants using water rather than soil to produce a variety of herbs, fruits and vegetables suchas basil, okra, lettuce, tomatoes and melons. RAS range from small-scale urban aquaculture systems in individual

homes to larger, commercial-scale farms that can produce sh and produce equaling millions of dollars in sales each

year.

Currently, research and development is being conducted at academic, government and business facilities across the

country to continuously improve the techniques and methods used in RAS. With innovations in waste management

systems, sh feeds and energy usage, RAS has the potential to be a truly safe and sustainable aquaculture industry.

In recent years, the U.S. government has been shockingly insistent that development of open-water aquaculture,

in particular ocean aquaculture, is the best way to have an increased seafood supply in the United States. Given the

many ecological concerns associated with OOA, rather, the United States should be looking to explore more sus-

tainable sh production, such as RAS. This report challenges natural resource managers and consumers to be moreactive in helping to promote a cleaner, greener, safer domestic seafood supply by learning more about RAS and re-

questing grocery stores and restaurants carry RAS products rather than those from open-water aquaculture systems.


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Alliance for Sustainable Aquaculture and Food & Water Watch

1

What Is RAS?

Recirculating aquaculture systems (RAS) are closed-

loop facilities that retain and treat the water within the

system. The water in RAS ows from a sh tank through

a treatment process and is then returned to the tank,hence the term recirculating aquaculture systems.4 RAS

can be designed to be very environmentally sustainable,

using 90-99 percent less water than other aquaculture

systems.5 RAS can reduce the discharge of waste, the

need for antibiotics or chemicals used to combat disease,

and sh and parasite escapes. RAS have been under

development for the over 30 years, rening techniques

and methods to increase production, protability and

environmental sustainability.6

Various methods can be used to clean the water from the

sh tanks and make it reusable. Some RAS sh farms

incorporate aquaponics the practice of growing herbs

and vegetables in water into their system. Plants need13 elements to grow; the wastewater from the sh tanks

naturally provides 10 of these elements.7 The plants

thrive in the nutrient-rich system water, and they actu-

ally help to purify it for reuse the plants absorb the

nutrients and the cleaned water can go back to the sh

tanks!

Consumer demand for cleaner, greener, safer seafood is on the rise. Popular speciesof wild sh are depleted,1 leaving many people looking to aquaculture to help meetthe demand for seafood. Aquaculture production the rearing of aquatic plants andanimals in captivity is increasing worldwide; between 2004 and 2006 the annualgrowth rate was 6.1 percent in volume and 11 percent in value.2 There are many formsof aquaculture; recirculating aquaculture systems (RAS), coastal ponds and open-

water net pens are a few major types. Open-water aquaculture systems are, as theysound, open to air and water, and can therefore have a risk of air- or water-bornecontaminants.3 RAS are closed, controlled, bio-secure systems that retain and treat

water within the system, reducing the risk of contamination from air- and water-bornecontaminants.

Introduction

Lettuce and other vegetables growing in RAS aquaponic tanks at UVPhoto courtesy o Dr. James Rakocy at the University o the Virgin Islands in St. Croi


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Land-Based Recirculating Aquaculture: A More Sustainable Approach to Aquaculture

2

Types of RAS: Freshwater andSaltwater

Recirculating aquaculture systems can be divided into

two main categories: freshwater and saltwater opera-

tions. Each of these can be paired with specic technolo-

gies designed to maximize efciency within the system,

minimize efuent discharge and occasionally to work in

a symbiotic relationship with other technologies, re-

viewed in brief below.

Freshwater RAS

Freshwater RAS can include the production of such

sh as tilapia, catsh, eel or striped bass, among oth-

ers. One innovative method explored in conjunction

with freshwater RAS is aquaponics, as described above.

Aquaponics works by allowing for the growth of plants,

sh and nitrifying bacteria simultaneously each of

which feed off of the waste of the others to create a sys-

tem that requires very little maintenance, aside from pH

monitoring, to ensure optimal growth.8 A major concern

of most aquaculture systems is the buildup of ammonia

(NH3) and its derivatives from sh waste, which can be

fatal to sh even at very small concentrations as little

as .08 mg/L. Aquaponic systems work by introducing

nitrifying bacteria, which feed on the ammonia in sh

waste to convert it into nitrate, which is non-toxic to the

sh and benecial for the plants.9 Another innovation in

freshwater RAS involves the use of microalgae to reduce

the prevalence of carbon dioxide within these systems

and provide a food source to developing sh.

Saltwater RAS

Saltwater RAS can take several forms as well, and are

sometimes referred to as marine RAS. One type of sys-

tem that has been researched extensively in recent yearsis the high-rate algal pond, or HRAP. HRAPs make

use of macroalgae seaweed in order to reduce the

amount of waste in RAS. In fully recirculating systems,

nitrate and phosphate levels accumulate at a rate that is

proportional to sh density; thus, the larger the produc-

tion scale, the more efuents will appear in the system

and need treatment in order to ensure the continued

growth of the sh.10 Macroalgae can accomplish this be-

cause they absorb the nutrients that are in sh waste for

their own growth, the same way that aquaponics produce

plant growth from these nutrients. The difference in ma-

rine RAS is that the seaweed is generally not intended for

consumption, and the seaweed will thrive in high-salin-

ity environments, whereas land-based plants would not.

Macroalgae HRAPs have been found to be even more

productive in the removal of wastes than the microalgae

that are used in freshwater systems, so this is considered

a very viable route for marine RAS.11 One factor that is

holding back more extensive use of the HRAP system is

that seasonality can affect the productivity of micro- and

An example o a small-scale RASPhoto by Eileen Flyn


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3

macroalgae alike with higher productivity rates in the

warmer, brighter summer months.

Why RAS Could Be an Important FishProduction Method for the United

States

How RAS Function

A key feature of RAS is that it re-uses water; the water is

recirculated continuously throughout the system. All of

the tanks and various components in RAS are connected

by pipes. Water ows from the sh tank to the mechani-

cal lter where solid waste is removed. The water then

ows into a biological lter that converts ammonia to

nitrate. Some RAS incorporate plant tanks as a biologi-

cal lter plants absorb nutrients, thus cleaning the

water. Other systems use special tanks that are designedto promote good bacteria growth the bacteria act as

a lter. After being treated in the mechanical and

bioltration components, the water ows back to the sh

tank.

Biosecurity

RAS sh farms are often fully closed and entirely con-

trolled, making them mostly biosecure diseases and

parasites cannot often get in. Biosecurity means RAS

can frequently operate without any chemicals, drugs or

antibiotics, making a more natural product for consum-ers. Water supply is a regular route of pathogen entry,

so RAS water is often rst disinfected or the water is

obtained from a source that does not contain sh or in-

vertebrates that could be pathogen carriers (rain, spring

or well water are common sources).12 Biosecurity in RAS

requires that the systems be designed for easy clean-

ing, completely and frequently, to reduce pathogens.13

Being self-contained and cleaner also means RAS can be

located near markets or within land-locked communi-

ties that will use the sh, rather than by natural water

sources like oceans or rivers RAS does not need to be

located on water to supply the system or for drainage.Locating RAS by the markets or communities they serve

means they can have a smaller carbon footprint due to

reduced shipping distance and provide a fresher product

to the consumer.

Water Reuse

RAS are completely contained systems that reuse most

of the water from the sh holding tanks. Wastes are

removed; water is treated and then recycled back to the

tanks. Ideally, RAS only replace very small percentages

of the total water volume, due to some loss during waste

removal and/or evaporation (less than 1 percent daily

water exchange).14 This low replacement volume is espe-

cially important in saltwater systems since salt water can

be more expensive and more difcult to make or obtain

than fresh water.

Space and Production Efciency

RAS production levels are often higher than those in oth-

er forms of aquaculture. RAS control the environmental

conditions in which products are raised, thus allowing

for optimal year-round growth.16 Some RAS can produce

market-sized sh in just nine months, compared to the

15 to 18 months it often takes for the sh raised in other

Open-Water Aquaculture

Open-water aquaculture, (when in the ocean, also known

as oshore aquaculture, ocean sh arming, open-ocean

aquaculture and other, similar terms), is the mass production o

sh in coastal ponds, or large foating pens or cages in ocean

waters. Just one arm is a large-scale operation.

While open-water sh arming is a airly common practiceworldwide (we dont do it large-scale in U.S. waters currently) it

can pose real threats to human health and the environment:

Fragile habitat can be permanently damaged rom clearing

out space to site the arm or rom anchors to hold down

cages.

Fish in cages can spread diseases to wild sh, or escape

and intermix with wild sh, interering with or even

overtaking natural populations.

Open-water sh arms allow ree fow o water between

the sh enclosures and the ocean. Concentrated amounts

o sh ood, wastes, diseases and any chemicals orantibiotics that may be used in arms can fow straight into

open waters, polluting habitat and wildlie and impeding

recreational water uses like swimming and diving.

Chemicals used in production may remain in the sh and be

transerred to people who consume them later.

Because there are so many potential problems with open-water

arms, the United States should explore other options, like RAS.


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systems to grow to market size.17 It takes 197.6 acres of

open ponds to produce the same amount of shrimp that

a RAS farm can raise on just 6.1 acres.18 Tilapia, cobia,

black sea bass, branzini, salmon, trout and shrimp are

among the many seafood products being raised in RAS.

Aquaponic RAS produce a large array of herbs, vegeta-

bles, fruits, owering plants and seaweeds as well.

RAS Factors

Water Quality and Waste Management

The critical water quality parameters in RAS are dis-

solved oxygen, temperature, pH, alkalinity, suspended

solids, ammonia, nitrite and carbon dioxide (CO2).19

These parameters are interrelated in a complex series of

physical, biological and chemical reactions.20 Monitoring

and making adjustments in the system to keep the levels

of these parameters within acceptable ranges is very

important to maintain the viability of the total system.

The components that address these parameters can vary

from system to system.

Dissolved Oxygen

Oxygen that is dissolved in the water is called dissolved

oxygen or DO. Fish take in DO from the water through

their gills. The amount of DO that a sh needs to stay

alive and grow depends on the species and size of sh,

as well as the effects of the other water quality param-

eters.21 A sh with a higher metabolic rate will consume

DO at a higher rate. 22 Oxygen is also critical to the meta-

bolic processes of the bacteria living in the system that

break down ammonia and solid waste.23

Low levels of DO in the system can reduce productivity

of the sh and bacteria, ultimately resulting in mortali-

ties. DO levels are monitored as water is leaving the

sh tank or the biological lter (where a large amount of

bacteria lives) to accurately access the level of DO that is

available to sh and bacteria respectively.24

DO can be maintained in RAS through aeration, either

with atmospheric oxygen (air) or pure oxygen. Standard

sources of air in aquaculture are blowers, air pumps or

compressors. The primary differences between theseoptions are the water and DO pressure requirements

and volume discharged.25 Airstones, pieces of limewood

or porous rock, are often used to release the air into the

water.26 Pure oxygen sources are used when diffusing

atmospheric oxygen (air) into the system cannot keep

up with the consumption of DO by the sh and bacte-

ria. Three sources of pure oxygen often used for RAS

are high-pressure oxygen gas, liquid oxygen and on-site

Oxygen dissolving into a RASPhoto by Eileen Flyn


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5

generators.27 U-tube aerators, packed columns, low

head oxygenators and down-ow bubble contactors are

component options for diffusing pure oxygen into the

system water. These components are all designed to use

a counter-ow of water and oxygen to enhance the gas-

liquid interface forcing more oxygen to dissolve into the

water.28 In general, warm-water sh grow best when DOconcentrations are above 5 mg/L.29

Temperature

Fish are cold-blooded; the temperature of the water in

which they live controls their body temperature. Water

temperature directly affects the physiological processes

of sh such as respiration rate, efciency of feeding and

assimilation, growth, behavior and reproduction.30 Fish

are often grouped into three categories based on pre-

ferred temperature ranges: cold-water species below 60

degrees Fahrenheit, cool-water species between 60 F to68 F and warm-water species above 68 F.31 To ensure

maximum growth and minimize stress, temperatures

need to be maintained in the species optimal range.

Indoor RAS allows the farm to have greater control over

the temperature of the ambient air that can impact the

water temperature. Heaters and chillers can be added to

RAS to maintain temperature, though this is not ideal in

terms of energy efciency.

At Skidaway Institute of Oceanography, Dr. Richard Lee,

an emeritus professor of oceanography, uses geothermal

chilling and solar heating to regulate the temperature ofhis RAS. The geothermal chilling is conducted through

a closed-loop pipe running down into the groundwa-

ter and back up to the surface (no water is exchanged

between the facility and the groundwater). The ground-

water is approximately 64.5 F and the contact of the cool

water on the outside of the pipe transfers the heat so that

the tank can maintain its temperature between approxi-

mately 79 F and 82.5 F during a Georgia summer.32 The

solar heating is conducted by running pipes carrying

system water through sheets of black plastic that trans-

fer the heat they absorb from the sun to the water in the

pipes. Using this method the RAS system had tempera-

tures between approximately 70 F and 77 F in the winter

when air temperature was not above 60 F in the same

time period.33

pH and Alkalinity

Monitoring of the pH level is among the most im-

portant tasks in RAS. The pH is directly affected by

concentrations of ammonia from sh wastes. When sh

waste is produced, most of it eventually breaks down

into nitrate, and nitrate accumulation tends to produce a

drop in pH and alkalinity, which can be harmful to sh if

it is not monitored properly.

34

The scale of pH ranges from 0 to 14, with lower numbers

demonstrating increased acidity and higher numbers

showing greater basicity. Seven is considered the equi-

librium point of freshwater, where it is neither acidic nor

basic. In freshwater RAS, pH is generally maintained

around 6 to 7.5. In aquaponic systems, pH may be main-

tained at a slightly lower level (around 5.5 to 6.5), where

the slightly higher acidity level helps plants to obtain nu-

trients. Some studies have been done in aquaponics sys-

tems to reconcile the lower optimal pH of plants with the

higher optimal pH of sh, and it has been found that apH as high as 7 can be maintained without reducing the

productivity of plants.35 Marine RAS needs to maintain

a slightly higher pH, as the average pH of ocean saltwa-

ter is around 8, which makes it somewhat basic. People

who work with recirculating systems need to monitor

pH carefully in order to keep levels within an accept-

able range for health and growth of the sh. Some of

the aforementioned technologies, such as high rate algal

ponds, can act as a counterbalance to the accumulation

pH testersPhoto by Eileen Flyn


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of certain chemicals within an RAS and can help to bal-

ance pH levels naturally.

Alkalinity is a measure of the pH-buffering capacity

of water.36 The principle ions that contribute to alka-

linity are carbonate (CO3-) and bicarbonate (HCO

3-).

Supplements may be added to water to adjust the alka-linity. Alkalinity of fresh water ranges from less than

5mg/L to more than 500mg/L and salt water is about

120mg/L CaCO3.37

Waste Removal: Ammonia, Nitrite,Nitrate, Solid and Suspended Waste(Without Aquaponics)

One major benet of RAS over other forms of aquacul-

ture is the ability to capture, treat and/or utilize waste

from the system. In general, solid wastes, including

feces and uneaten feed, are ltered and removed from

the system. Once removed, these solids can be treated

or utilized in a secondary function (converted to energy,

fertilizer and possibly even feed). Systems that do not

effectively and quickly remove sh fecal matter, uneaten

food and other solids from the water will never produce

sh economically.38

Nitrogen is required in small amounts by sh for good

health and growth. Nitrogen that is not utilized by sh

becomes nitrogenous waste in the system and needs to

be removed. There are several sources of nitrogenouswaste including: feces, urine, excretions from gill dif-

fusion, uneaten food and dead and dying sh.39 The

decomposition of these nitrogenous compounds is par-

ticularly important because of the toxicity of ammonia,

nitrite and to some extent nitrate to sh.40 Ammonia

exists in two forms: non-ionized NH3

and ionized NH4+.

Non-ionized ammonia is the most toxic form, due to its

ability to move across cell membranes.41 An increase

in pH, temperature or salinity increases the propor-

tion of the non-ionized form of ammonia.42 Nitrite is

the intermediate product in the process of nitrication

of ammonia to nitrate and is toxic because it affects thebloods ability to carry oxygen.43 In RAS, efuent water

is passed through a biolter containing bacteria that

converts ammonia to nitrite and nally to nitrate.44 This

conversion from ammonia and nitrite to nitrate is called

nitrication; the bacteria in this process require ample

amounts of oxygen.45 Plants in an aquaponic system will

act as the biolter converting ammonia and nitrates. In

RAS facilities without plants in the system (aquaponics),

the bioltration component consists of media with living

benecial bacteria that converts harmful ammonia and

nitrite to nitrate. Algae and bacteria oating in the water

column can also convert ammonia to nitrate.46 Nitrateis the end product of nitrication and is the least toxic; it

can be removed from the system by daily water changes

or denitrication.47 Denitrication is the process of

converting nitrate to nitrogen gas; the bacteria in this

process do not require oxygen.48Treatment processes or recycling water at the USDA ARS National Cold Water

Marine Aquaculture Center, Franklin, ME.Photo courtesy o Dr. Steve Summerelt o the Freshwater Institute, Shepherdstown, WV.


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7

Carbon dioxide

Dissolved carbon dioxide is another product that can

accumulate in high-density RAS. Large-scale RASsystems must supplement their tanks with pure oxygen

for a greater quantity of sh to be bred, but this results

in insufcient natural removal of the carbon dioxide

(CO2) that is then produced.49 (In lower-density systems,

oxygenation is generally unnecessary, as sufcient water

exchange and aeration occurs to naturally balance levels

of both oxygen and CO2.)

Excessive levels of CO2

can result in changes in pH

towards acidication, which can be detrimental to sh

if the pH level drops too low. Various technologies have

been tested to reduce the amount of carbon dioxide inthe water of these high-density systems. One method of

addressing excessive carbon dioxide is the use of chemi-

cals, which can balance pH levels and thereby eliminate

the CO2

in RAS.50 Sodium hydroxide and sodium bicar-

bonate are two chemicals commonly used in aquaculture

for this purpose. Both function by increasing alkalinity

in the water, resulting in a series of chemical reactions

which break down carbon dioxide and reformulate it into

lesser molecules.

Another process for carbon dioxide elimination is calledaeration stripping, a process in which water is forced

through a series of cascading stripping columns that

expose the water to air and result in the release of dis-

solved CO2

into the atmosphere. Experiments have been

done to determine the optimal ratio of air to water as it

cascades through the stripping columns, and for now,

experiments suggest that higher ratios of air to water

implying a slower ltration process improve the

efciency of carbon dioxide stripping from a recirculat-

ing system.51

Similar to aeration stripping, a third type of carbon

dioxide removal is performed by vacuum degassing, a

process that vents excessive gasses through a vacuum or

pump system. The process of carbon dioxide elimination

is similar to the manner in which it is eliminated in the

aeration stripping process.52

Basil grown in a RAS aquaponics tank at UVI.Photo by Eileen Flynn


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8

The overall waste-capture efciency of a full RAS facility

can be 100 percent.53

Researchers and industry experts are developing a vari-

ety of resourceful ways to deal with the waste produced

by RAS sh farms, such as creating fertilizer for crops

and plants. Some RAS farms turn the waste into pelletsto create a feed ingredient for other sh or shrimp. Still

other RAS turn the waste into methane gas, which can be

used to help power generators. 54

Research and Development

Currently, research and development is being conducted

at academic, government and business facilities across

the country to continuously improve the techniques and

methods used in RAS to offer consumers cleaner, green-

er and safer products.

Urban Aquaculture as a Community-Based Option

Dr. Martin Schreibman, founder and director of the

Aquatic Research and Environmental Assessment Center

at the City University of New Yorks Brooklyn College,

is conducting research on RAS he calls urban aquacul-

ture. Dr. Schreibman is working with RAS of various

sizes that can be run virtually anywhere, in warehouses,

on browneld sites or right in your own home, utilizing

the hydroponic component of aquaponics to clean the

water. One aspect of his research involves aeropon-

ics, in which plants are suspended above the tanksand sprayed with system water every 10 to 15 minutes

instead of being submerged in the water.55 This process

reduces the horizontal space needed to run the system

when compared to other aquaponic systems. Urban

aquaculture can be located in or near populated areas,

so it can provide positive socio-economic benets like

jobs as well as fresh, safe seafood and produce to local

markets.56

Larger-Scale Aquaponics

Dr. James Rakocy, director of the University of theVirgin Islands Agricultural Experimental Station, con-

ducts RAS aquaponic research in a large-scale system

with plants growing on oating rafts. Foam rafts oat on

the surface of large water-lled hydroponic tanks. Plants

develop and expand atop the rafts, basked in sunlight,

while roots get maximum exposure to water by growing

This is an urban aquaculture/aquaponics system (it grows both fsh and plants) in a small setting in act it is in a part o a classroom at Brooklyn CollegePhoto courtesy o Dr. Martin Schreibman at Brooklyn College, CUNY, Aquatic Research Environmental Assessment Center (AREA


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9

beneath. Raft tanks have no size limitations. A disad-

vantage of raft culture exposing the roots to zooplank-

ton and snails that may grow in the tanks is addressed

through the addition of ornamental sh (tetras) and

red ear sunsh to consume these pests.57 Additional

research has been done rening waste management

components and water quality needs for optimal plantand sh growth. Dr. Rakocys research shows the tech-

nology UVI uses can be applied for an individual family

subsistence or commercial scale, while conserving water

and recycling nutrients. Researchers at the UVI facility

grow tilapia and continue to experiment with basil, okra,

lettuce, watermelon, mint, chives, tomatoes, cantaloupe,

cucumber, owers, squash, bok choy, collard greens and

sorrel (a locally grown plant used in a popular drink) and

other crops. The UVI commercial-scale aquaponic sys-

tem can annually produce up to 35,570 pounds of tilapia

and vegetables on 1/8 an acre of land.58

Various Species Grown in RAS

The list of aquatic species being researched and grown

in RAS is constantly broadening to include: oysters,

blue crabs, sea bream, branzini, cobia, red drum, black

seabass, bivalves, soft corals, horseshoe crabs, assorted

atsh, lobster, nautilus, tilapia, rainbow trout, striped

bass, salmon and assorted shrimp.

The list of plants that are grown in conjunction with

these aquatic species is also growing rapidly, including:

algae, seaweeds, basil, okra, lettuce, watermelon, mint,chives, tomatoes, cantaloupe, cucumber, owers, squash,

bok choy, collard greens, sorrel, arugula, peas and vari-

ous pharmaceutical plants

Fish Feed

Existing RAS farms and researchers are working to feed

their sh a more environmentally sustainable diet while

remaining nutritionally appropriate. One of the biggest

and most crucial hurdles faced by aquaculture has been

to decrease the amount of wild sh used as an ingredient

in sh feed. Traditionally, large amounts of wild sh areused to produce the pellet feed for farmed sh. Taking

prey sh from the oceans to feed farmed sh can deplete

ocean food chains and disrupt ecological balance. Work

is being done at various RAS farms to improve feed,

including reducing the amount of sh needed to be put

into feed; nding alternative feed ingredients (includ-

ing worms and algae);59 and even using waste to create a

healthy feed source.

Dr Richard Lee at Skidaway Institute of Oceanography

has found a unique solution to raising carnivorous sh

without taking wild sh. At the Skidaway RAS facility Dr

Lee grows black seabass to a market size of two poundsin one year by feeding them whole tank-raised tilapia.

The feed conversion rate is ve pounds of tilapia to one

pound of black seabass. The seabass grow twice as fast

when they are fed tilapia, when compared to being fed

the traditional shmeal pellet. Feeding a tank-raised

freshwater sh to a saltwater RAS raised sh also reduc-

es the chance of pathogen introduction.

A majority of commercial feeds use soybean as a com-

mon protein replacement for shmeal and sh oil. There

are some concerns with using soybean, a terrestrial

protein, in sh feed. In 2009, 91 percent of soybeansgrown in the United States were genetically modied.60

Another concern is that soybeans are high in estrogen

and do not occur naturally in the aquatic environment.61

In addition, soy protein is quite expensive. Many re-

searchers are looking to replace soybeans in feed with

other proteins that occur naturally in the aquatic en-

vironment, like algae, that could increase the nancial

sustainability of RAS.

Fish eed pelletsPhoto by Eileen Flyn


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Future Improvements

RAS is not yet perfect, but the benets of a controlled,

closed system with waste management should not be

overlooked. Additional research is being done to devel-

op new techniques and methods to continually improve

RAS.

Chemical Usage

Water supply is a common means of pathogen entry.

Water for RAS is often disinfected, or obtained from a

source that does not contain sh or invertebrates that

could be pathogen carriers (rain, spring or well water are

common sources).62 Biosecurity in RAS requires that the

systems be designed to be cleaned easily, completely and

frequently to reduce pathogens.63

When diseases do appear, a veterinarian and diagnos-

tic laboratory should be involved in determining the

specic disease and treatment, using chemicals that are

approved for use in food sh production.64 Many RAS

can operate without any chemicals, drugs or antibiotics,

making a more natural product for consumers.65

Energy Usage

RAS facilities require varying amounts of energy to run

the machinery that moves the water through the system

and treatment processes. Some producers using aqua-

ponics and facilities raising shrimp may be able to usefewer pieces of machinery to run the systems therefore

having reduced energy demands. Research is being

done by Dr. Timothy Pfeiffer at the U.S. Department

of Agricultures Agricultural Research Service to de-

termine the specic energy requirements for different

aspects of the treatment processes and how to get the

most efcient water treatment with the least amount of

energy.66 Dr. Yonathan Zohar, Director at University

of Maryland Biotechnology Institutes Center of Marine

Biotechnology (COMB), is using waste captured from

RAS to produce energy in the form of methane that

can be fed straight into a generator.67 Dr. Zohar andresearchers at COMB are also working to convert algae

biomass, produced in RAS, into bio-fuel.

Both freshwater and marine RAS have been the sub-

ject of experiments to enhance energy efciency.

Implementing solar heating for the maintenance of

proper temperature within the sh basin has been found

to reduce conventional energy requirements by 66 per-

cent to 87 percent, depending on the regional climate

where the RAS are located.68 Wind energy has also been

tested as a means to power reverse-osmosis membrane

ltration, which separates puried water from a concen-

trated brine of sh efuent, with some success.69 Many

of these technologies have been proven viable at a small-

scale, and implementation on large-scale (high-density)

RAS are ongoing.

Feed Efciency

In the production of farm-raised sh, the feed plays a

large role in determining sustainability and quality of

farmed sh. Farmed sh are often fed wild forage sh,

such as anchovies, sardines and herring, after being

processed into shmeal or oil. These prey sh are a

crucial part of the marine ecosystem, serving as food for

marine mammals, birds and large predatory sh. Since

Lettuce and other vegetables growing in RAS aquaponic tanks at UVPhoto courtesy o Dr. James Rakocy at the University o the Virgin Islands in St. Croi


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taking these sh from the oceans can disrupt food chains

and ecosystem balance, feed conversion rate is always

a concern with farm-raised sh. The ideal feed conver-

sion is one pound or less of wild sh to raise one pound

of farmed sh. Although existing feed sources do not

always have completely efcient 1:1 conversion rates,

RAS farms and scientists are conducting research anddeveloping techniques that can improve feed quality and

reduce the need for wild sh. Examples of innovations

in RAS feed efciency include nding alternative feed

ingredients, such as worms and algae, improving feed

quality by using algae to increase protein content and

raising prey sh in RAS, instead of harvesting wild for-

age sh, to feed larger predatory sh.70

Organic?

Organic foods are produced under conditions in which

all inputs are controlled. RAS is the only method ofraising sh that can completely control the production

environment. Being a closed-loop system, RAS can

better ensure sh and plants are not being exposed to

synthetic fertilizers or pesticides, growth hormones,

sewage sludge, antibiotics or any other articial feed or

treatments. Other forms of aquaculture that allow water

to ow freely in and out of the holding ponds or cages

can not control what chemicals and pollutants are being

carried with the water. Some RAS/aquaponic facilities

have been certied organic for the plants produced.

Not a Natural Environment, but Still aHealthy One

To achieve economic viability, RAS farms run their sys-

tems with a higher density of sh per tank than would be

found in the wild. Density depends primarily on water

quality, sh species and size.71 Overcrowding of younger

sh is avoided to allow them optimal room to grow dur-

ing their rapid growth stage.72 As sh grow they may

be moved to reduce densities to maintain good water

quality and to optimize sh health and growth until they

reach market size. RAS sh farmers avoid keeping sh

at densities that can be detrimental to sh health; for ex-ample, trout raised at high densities can develop eroded

ns.73 Researchers regularly experiment with densities to

ensure optimum health and productivity.

Algae growing in tubes in RAS at COMB acilityPhoto courtesy o Dr. Yonathan Zohar at UMBI Center O Marine Biotechnolog


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Specifc Commercial Case Studies

Premier Organic Farms

Premier Organic Farms combines organic growing prac-

tices in controlled ecological environments as the basis

for their state-of-the-art, eco-friendly aquaponics farm-

ing operation, which can run anywhere in the world.74

The company has done extensive research and develop-

ment over the past three years on its design known as

the Pod Growing Unit.75 Premier raises tilapia in RAS

facilities that are linked to plant tanks producing but-

ter and Boston lettuce, herbs, peppers and tomatoes as

its core products.76 Premier Tilapia is fed an all-natural,

nutritionally balanced diet of organic grain and pro-

tein.77 Premier Organic Farms does not use antibiotics

or chemicals.78 Nor does it use hormones.79 Other farms

use certain hormones to convert female sh to males (to

avoid unintentional breeding in grow out tanks beforethe sex of each sh can be identied).80 Premier plans

to build commercial Pod Growing Units near strategic

markets across the United States over the next ve years,

with further expansion worldwide as demand dictates.

One Pod is predicted to produce $43 million in rev-

enue annually from all segments (tilapia and mixed

organic produce).81

Premiers growing system uses 80 percent less water

than conventional agriculture.82 The companys goals

are to produce high quality, safe food while achieving a

carbon neutral footprint.

Marvesta Shrimp Farms

Marvesta Shrimp Farms, located in Hurlock, Maryland,

is growing saltwater shrimp miles away from the coast.

Water from the Atlantic is brought in and ltered down

to below 50 microns and run through an ultraviolet lter

(which removes unwanted bacteria, algae and viruses).83

Co-founder Scott Fritze says that the water is 100 per-

cent recirculating and completely bio-secure, with no

efuent and little waste. The nitrication system that

they have in place now is entirely indoors and producessome feed for the shrimp within the tanks. The small

amount of waste produced by the system is composed of

undigested protein, and can be easily dried out and dis-

posed of.84 Marvesta does not use antibiotics, hormones,

pesticides or chemicals of any kind.

Blue Ridge Aquaculture

Blue Ridge Aquaculture, established in 1993, pro-

duces RAS tilapia at their headquarters in Martinsville,

Virginia. The 80,000 square foot facility produces four

million pounds of tilapia a year. 85 An estimated 75,000

pounds of live tilapia are shipped to market each week

from the facility, making Blue Ridge the worlds largest

indoor producer of tilapia.86 Blue Ridge Aquaculture as-

serts that its products are free of growth hormones, pes-

ticides, antibiotics, and synthetic chemicals.87 According

to the companys president, Bill Martin, Blue Ridge

Aquaculture is one of few tilapia farms that hand select

broodstock for desirable characteristics, rather than us-

ing hormones.88

Blue Ridge is partnering with feed production com-

pany Marical and Virginia Tech to research low-salinity

technology and feed options for cobia in RAS.89

Thecompany hopes to research other marine species once

they have brought the cobia production up to commer-

cial levels.90 Blue Ridge is also partnering with Virginia

Tech on a 30,000-square-foot RAS facility dedicated to

shrimp production.91 The aim is to bring shrimp produc-

tion up to 325 million pounds per year.92 In 2007, Blue

Ridge began a joint venture with aquaculture company

West Virginia Aqua, to produce over 300,000 pounds of

Atlantic salmon and rainbow trout in RAS.93

Computer rendering o the 4,800 L/min water recirculating system at th

Conservation Fund Freshwater InstituteSummerelt, S.T., Sharrer, M.J., Hollis, J., Gleason, L.E., Summere

S. R. 2004. Dissolved ozone destruction using ultraviolet irradiation

a recirculating salmonid culture system. Aquacultural Engineering 3

209-224. Drawing courtesy o Marine Biotech Inc. (Beverly, MA


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13

Conclusion

Consumers love seafood, and with wild sh stocks de-

pleted, aquaculture is likely to be supplying increasing

amounts of sh for food. However, not all sh farming

methods are equal. In order to ensure safer and more

sustainable seafood, consumers are more regularly ask-

ing about how their sh was produced before making

seafood choices. Common forms of aquaculture, such

as open-water systems, can pollute the marine environ-ment with chemicals and waste, and may produce sea-

food contaminated with pesticides and antibiotics. These

are not acceptable factors for most consumers seeking

greener, more healthful options.

RAS, on the other hand, are closed, controlled, bio-

secure systems. Since RAS retain and treat water within

the system, they reduce waste discharges and the need

for chemicals and antibiotics. RAS can be efcient in

production and space usage and can range from small-

scale to commercial operations growing a variety of

different sh and plants.

RAS are currently operating in the United States. In

fact, RAS have been under development for over 30

years, rening techniques and methods to increase pro-

duction, protability and environmental sustainability. 94

Academic, government and business facilities across the

country are conducting research and further improving

and expanding RAS. Premier Organic Farms, Marvesta

Shrimp Farms and Blue Ridge Aquaculture, highlighted

in this report, are just a few examples of successful com-

panies that are producing RAS seafood.

Technical innovations are essential for the continued

growth of the aquaculture sector. Instead of pushing

OOA, which can damage the marine environment and

may pose a threat to consumer health, the U.S. govern-

ment needs to play a vital role in promoting opportuni-

ties to develop cleaner, greener, safer aquaculture in the

United States,such as RAS. 95

Recommendations

Federal and State governments should increase funding

to RAS researchers to help provide consumers with a

cleaner, greener, safer seafood aquaculture option.

If standards must be set for an organic label for sh, RAS

raised sh should viewed as the only true option, due to

the controlled, closed-loop nature of RAS.

Consumers should ask grocery stores and restaurant

managers whether the seafood they sell comes from

domestic RAS farms. If not, they should request U.S.

RAS-produced seafood as an alternative to imported,

open-water farmed sh.

Fish waste being distributed by a manure spreadeSummerelt, S.T. and B.J. Vinci. (2008). Better management practices or recirculating systems. Pages 389-426 in C.S. Tucke

and J.A. Hargreaves (editors), Environmental Best Management Practices or Aquaculture. Blackwell Publishing: Ames, Iow


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Endnotes

1 Fishwatch.gov

2 FAO Fisheries and Aquaculture Department, Food andAgriculture Organization of the United Nations. The State ofWorld Fisheries and Aquaculture 2008 Rome, Italy. 2009 at 16.

3 Timmons, M.B. and J.M. Ebeling. (2007) Recirculating

Aquaculture. Cayuga Aqua Ventures at 3.4 Timmons at 30.

5 Timmons at 6.

6 Timmons at 1.

7 Rakocy, James. The UVI Aquaponic System. Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.

8 Tyson, R.V. et al, Effect of Water pH on Yield and NutritionalStatus of Greenhouse Cucumber Grown in RecirculatingHydroponics. Journal of Plant Nutrition 31.11 (2008): 2019

9 Ibid.

10 Metaxa, E., et al, High rate algal pond treatment for water reusein a marine sh recirculation system: Water purication and shhealth. Aquaculture 252 (2005).

11 Pagand, P. et al, The use of high rate algal ponds for the treat-

ment of marine efuent from a recirculating sh rearing system.Aquaculture Research 31 (2000).

12 Timmons at 621

13 Timmons at 620.

14 Torsten, E.I. Wik, et al. Integrated dynamic aquaculture andwastewater treatment modeling for recirculating aquaculturesystems. Aquaculture. 287. 2009 at 361-370.

16 Timmons at 7.

17 Zohar, Yonathan. Environmentally compatible, recirculatedmarine aquaculture: addressing the critical issues. Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.

18 Conversion of information from hectares to acres by Food &Water Watch from: Moss, Shawn. An integrated approachto sustainable shrimp aquaculture in the U.S. Clean, Green,

Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009. Samocha,Tzachi. Overview of some sustainable, super-intensive micro-bial biooc-rich shrimp production systems used by Gulf CoastResearch Lab, Waddell Mariculture Center and AgriLife ResearchMariculture Lab. Clean, Green, Sustainable RecirculatingAquaculture Summit. Washington D.C.: hosted by Food andWater Watch. January 2009.

19 Timmons at 39.

20 Timmons at 47.

21 Timmons at 88.

22 Timmons at 88.

23 Timmons at 90.

24 Timmons at 89.

25 Timmons at 412.

26 Timmons at 413.27 Timmons at 413.

28 Timmons at 413-426.

29 Timmons at 50.

30 Timmons at 51.

31 Timmons at 51.

32 Lee, Richard. Rapid growth of black sea bass Centropristis stria-ta in recirculating systems with geothermal cooling, solar heating,tilapia diet and microbial mat/seaweed lter. Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.

33 Lee, Richard. Rapid growth of black sea bass Centropristis stria-ta in recirculating systems with geothermal cooling, solar heatingtilapia diet and microbial mat/seaweed lter. Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.

34 Neori, Amir, et al, Biogeochemical processes in intensivezero-efuent marine shculture with recirculating aerobic andanaerobic biolters. Journal of Experimental Marine Biologyand Ecology 349 (2007): 241.

35 Tyson, et al, Effect of Water pH on Yield, 2019.

36 Timmons at 56.

37 Timmons at 57.

38 Timmons at 115.

39 Timmons at 53.

40 Timmons at 275.

41 Timmons at 54.

42 Timmons at 54.

43 Timmons at 55.

44 Timmons at 275.

45 Timmons at 277.

46 Timmons at 281-283.47 Timmons at 56.

48 Timmons at 275.

49 Summerfelt, Steven T., et al., Evaluation of full-scale carbondioxide stripping columns in a coldwater recirculating system.Aquacultural Engineering 28 (2003).

50 Summerfelt, Steven T., et al, Oxygenation and carbon dioxidecontrol in water reuse systems. Aquacultural Engineering 22(2000).

51 Summerfelt, et al, Evaluation of full-scale carbon dioxide strip-ping columns, 2003.

52 Summerfelt, et al, Oxygenation and carbon dioxide control,2000.

53 Timmons at 10.


55 Schreibman, Martin. Urban Aquaculture: The promises andconstraints. Clean, Green, Sustainable Recirculating AquacultureSummit. Washington D.C.: hosted by Food and Water Watch.January 2009.

56 Schreibman, Martin. Urban Aquaculture: The promises andconstraints. Clean, Green, Sustainable Recirculating AquacultureSummit. Washington D.C.: hosted by Food and Water Watch.January 2009.

57 Rakocy, James. The UVI Aquaponic System. Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.

58 Food & Water Watch staff email exchange with Dr. James

Rakocy, University of the Virgin Islands. June 22 September 7,2009.

59 Steve Craig and other from the Summit

60 Kidd, Karen. Effects of Synthetic Estrogen on AquaticPopulation: A Whole Ecosystem Study, Freshwater Institute,Fisheries and Oceans Canada.

61 Adoption of Genetically Engineered Crops in the U.S.: SoybeanVarieties. Data Set, Economic Research Service, UnitedStates Department of Agriculture. www.ers.usda.gov/Data/BiotechCrops/ExtentofAdoptionTable3.htm

62 Timmons at 621


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63 Timmons at 620.

64 Timmons at 648-649.

65 General Discussion. Clean, Green, Sustainable RecirculatingAquaculture Summit. Washington D.C.: hosted by Food andWater Watch. January 2009.

66 Pfeiffer, Tim. Utilization of Low-head Technology for InlandMarine Recirculating Aquaculture Systems. Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.


68 Fuller, R.J., Solar heating systems for recirculation aquaculture.Aquacultural Engineering 36 (2007).

69 Qin, Gang., et al, Aquaculture wastewater treatment and reuseby wind-drive reverse osmosis membrane technology: A pilotstudy on Coconut Island, Hawaii. Aquacultural Engineering 32(2005).

70 Lee, Richard. Rapid growth of black sea bass Centropristis stria-ta in recirculating systems with geothermal cooling, solar heating,tilapia diet and microbial mat/seaweed lter. Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.

Craig, Steve. Sustainable Aquafeeds for Cobia Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.

Clean, Green, Sustainable Recirculating Aquaculture Summit.Washington D.C.: hosted by Food and Water Watch. January2009.

71 Timmons at 85.

72 Timmons at 120.

73 Timmons at 120.

74 Susan Bedwell. Premier Organic Farms. Clean, Green,Sustainable Recirculating Aquaculture Summit. WashingtonD.C.: hosted by Food and Water Watch. January 2009.

75 Bedwell, Susan. Personal email. Chief Financial Ofcer ofPremier Organic Farms, May 15, 2009. Email on le at Food &Water Watch.

76 Ibid.

77 Ibid.

78 Ibid.79 Ibid.

80 Ibid.

81 Ibid.

82 Ibid.

83 Process. Marvesta Shrimp Farms. Accessed on May 2, 2009.Available at: http://www.marvesta.com/process.php

84 Fritze, Scott. Personal Interview. Cofounder and owner ofMarvesta Shrimp Farms, March 28, 2008.

85 Gardner, Martin. Personal email. Director of Marketing at BlueRidge Aquaculture, May 22, 2009. Email on le at Food & WaterWatch.Nicholls, Walter. Two sides to every tilapia. WashingtonPost, August 8, 2007.

86 Ibid.

87 Tilapia. BlueRidge Aquaculture. Accessed on May 13,

2009. Available at: www.blueridgeaquaculture.com/tilapia.cfmTilapia. Op. cit.

88 Martin, Bill. Personal Interview. President of BlueRidgeAquaculture, March 26, 2008. On le at Food & Water Watch

89 Gardner, Martin. Op cit.





94 Timmons, M.B. and J.M. Ebeling. Recirculating Aquaculture. Aat 1.

95 FAO Fisheries and Aquaculture Department, Food andAgriculture Organization of the United Nations. The State ofWorld Fisheries and Aquaculture 2008 Rome, Italy. 2009 at 161


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land-based recirculating aquaculture systems: a more sustainable approach to aquaculture

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