Integrated multi-trophic aquaculture (IMTA) is a type of

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

where the byproducts, including

waste Waste are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor Value (economics), economic value. A wast ...

, from one aquatic species are used as inputs (

fertilizer A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...

food Food is any substance consumed by an organism for Nutrient, nutritional support. Food is usually of plant, animal, or Fungus, fungal origin and contains essential nutrients such as carbohydrates, fats, protein (nutrient), proteins, vitamins, ...

) for another. Farmers combine fed

(e.g.,

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

shrimp A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...

) with inorganic extractive (e.g.,

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

) and organic extractive (e.g.,

shellfish Shellfish, in colloquial and fisheries usage, are exoskeleton-bearing Aquatic animal, aquatic invertebrates used as Human food, food, including various species of Mollusca, molluscs, crustaceans, and echinoderms. Although most kinds of shellfish ...

) aquaculture to create balanced systems for environment remediation ( biomitigation), economic stability (improved output, lower cost, product diversification and risk reduction) and social acceptability (better management practices). Selecting appropriate species and sizing the various populations to provide necessary ecosystem functions allows the biological and chemical processes involved to achieve a stable balance, mutually benefiting the organisms and improving ecosystem health. Ideally, the co-cultured species each yield valuable commercial "crops". IMTA can synergistically increase total output, even if some of the crops yield less than they would, short-term, in a

monoculture In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monocultures increase ease and efficiency in planting, managing, and harvesting crops short-term, often with the help of machinery. However, monocultur ...

.Neori A, Chopin T, Troell M, Buschmann AH, Kraemer GP, Halling C, Shpigel M and Yarish C. 2004. Integrated aquaculture: rationale, evolution and state of the art emphasizing seaweed biofiltration in modern mariculture. Aquaculture 231: 361-391. IMTA is also highly beneficial for reducing the environmental footprint of aquaculture. The growth of farmed Atlantic salmon (''Salmo salar''), provides insight to the rapid growth of aquaculture demand. Output growth rates averaged 25.6% from 1980 to 2004, with the economic value of farmed salmon output exceeding 4 billion U.S. dollars in 2004. IMTA works by creating a closed-loop system where the by-products such as excess nutrients and organic waste from fish farming, are utilized by other species such as shellfish and seaweed. This process can decrease water pollution, minimize the need for chemical fertilizers, and improve overall ecosystem health. Furthermore, by integrating different trophic levels, IMTA can enhance biodiversity and promote more sustainable practices in marine food production.

Terminology and related approaches

"Integrated" refers to intensive and synergistic cultivation, using water-borne nutrient and energy transfer. "Multi-trophic" means that the various species occupy different

trophic level The trophic level of an organism is the position it occupies in a food web. Within a food web, a food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the ...

s, i.e., different (but adjacent) links in the

food chain A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as ...

.Chopin T. 2006. Integrated multi-trophic aquaculture. What it is, and why you should care... and don't confuse it with polyculture. Northern Aquaculture, Vol. 12, No. 4, July/August 2006, pg. 4. IMTA is a specialized form of the age-old practice of aquatic

polyculture In agriculture, polyculture is the practice of growing more than one crop species together in the same place at the same time, in contrast to monoculture, which had become the dominant approach in developed countries by 1950. Traditional example ...

, which was the co-culture of various species, often without regard to trophic level. In this broader case, the organisms may share biological and chemical processes that may be minimally complementary, potentially leading to reduced production of both species due to competition for the same food resource. However, some traditional systems such as polyculture of carps in China employ species that occupy multiple niches within the same pond, or the culture of fish that is integrated with a terrestrial agricultural

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

, can be considered forms of IMTA. The more general term "Integrated Aquaculture" is used to describe the integration of monocultures through water transfer between the culture systems. The terms "IMTA" and "integrated aquaculture" differ primarily in their precision and are sometimes interchanged.

Aquaponics Aquaponics is a food production system that couples aquaculture (raising aquatic animals such as fish, crayfish, snails or prawns in tanks) with hydroponics (cultivating plants in water) whereby the nutrient-rich aquaculture water is fed to h ...

, fractionated aquaculture, integrated agriculture-aquaculture systems, integrated peri-urban-aquaculture systems, and integrated fisheries-aquaculture systems are all variations of the IMTA concept.

Range of approaches

Today, low-intensity traditional/incidental multi-trophic aquaculture is much more common than modern IMTA. Most are relatively simple, such as fish, seaweed or shellfish. True IMTA can be land-based, using

ponds A pond is a small, still, land-based body of water formed by pooling inside a depression, either naturally or artificially. A pond is smaller than a lake and there are no official criteria distinguishing the two, although defining a pond t ...

or tanks, or even open-water marine or

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

systems. Implementations have included species combinations such as shellfish/shrimp,

/seaweed/shellfish, fish/seaweed, fish/shrimp and seaweed/shrimp.Troell M, Halling C, Neori A, Chopin T, Buschmann AH, Kautsky N and Yarish C. 2003. Integrated mariculture: asking the right questions. Aquaculture 226: 69-90. IMTA in open water ( offshore cultivation) can be done by the use of buoys with lines on which the seaweed grows. The buoys/lines are placed next to the fishnets or cages in which the fish grows. In some tropical Asian countries some traditional forms of aquaculture of

finfish Fishery can mean either the Big business, enterprise of Animal husbandry#Aquaculture, raising or Fishing, harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place (wikt:AKA, a.k.a., fishing grounds). ...

in floating cages, nearby fish and shrimp ponds, and

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but no ...

farming integrated with some capture fisheries in estuaries can be considered a form of IMTA. Since 2010, IMTA has been used commercially in Norway, Scotland, and Ireland. In the future, systems with other components for additional functions, or similar functions but different size brackets of particles, are likely. Multiple regulatory issues remain open.Chopin T, Robinson S, Sawhney M, Bastarache S, Belyea E, Shea R, Armstrong W, Stewart and Fitzgerald P. 2004. The AquaNet integrated multi-trophic aquaculture project: rationale of the project and development of kelp cultivation as the inorganic extractive component of the system. Bulletin of the Aquaculture Association of Canada. 104(3): 11-18.

Modern history of land-based systems

Ryther and co-workers created modern, integrated, intensive, land mariculture.Goldman JC, Tenore RK, Ryther HJ and Corwin N. 1974. Inorganic nitrogen removal in a combined tertiary treatment - marine aquaculture system: I. Removal efficiencies. Water Research 8: 45-54.Ryther JH, Goldman JC, Gifford JE, Huguenin JE, Wing AS, Clarner JP, Williams LD andLapointe BE. 1975. Physical models of integrated waste recycling - marine polyculture systems. Aquaculture 5: 163-177. They originated, both theoretically and experimentally, the integrated use of extractive organisms—shellfish,

microalgae Microalgae or microphytes are microscopic scale, microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine life, marine systems, living in both the water column and sediment. They are unicellul ...

and seaweeds—in the treatment of household

effluent Effluent is wastewater from sewers or industrial outfalls that flows directly into surface waters, either untreated or after being treated at a facility. The term has slightly different meanings in certain contexts, and may contain various pol ...

s, descriptively and with quantitative results. A domestic

wastewater Wastewater (or waste water) is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of do ...

effluent, mixed with seawater, was the nutrient source for

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

, which in turn became food for

s and

clam Clam is a common name for several kinds of bivalve mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...

s. They cultivated other organisms in a

rooted in the farm's organic sludge. Dissolved nutrients in the final effluent were filtered by seaweed (mainly Gracilaria and

Ulva Ulva (; ) is a small island in the Inner Hebrides of Scotland, off the west coast of Mull. It is separated from Mull by a narrow strait, and connected to the neighbouring island of Gometra by a bridge. Much of the island is formed from Cen ...

) biofilters. The value of the original organisms grown on human waste effluents was minimal. In 1976, Huguenin proposed adaptations to the treatment of intensive aquaculture effluents in both inland and coastal areas.Huguenin JH. 1976. An examination of problems and potentials for future large-scale intensive seaweed culture systems. Aquaculture 9: 313-342. Tenore followed by integrating with their system of carnivorous fish and the macroalgivore

abalone Abalone ( or ; via Spanish , from Rumsen language, Rumsen ''aulón'') is a common name for any small to very large marine life, marine gastropod mollusc in the family (biology), family Haliotidae, which once contained six genera but now cont ...

.Tenore KR. 1976. Food chain dynamics of abalone in a polyculture system. Aquaculture 8: 23–27. In 1977, Hughes-GamesHughes-Games WL. 1977. Growing the Japanese oyster (Crassostrea gigas) in sub-tropical seawater fishponds: I. Growth rate, survival and quality index. Aquaculture 11: 217-229. described the first practical marine fish/shellfish/phytoplankton culture, followed by Gordin, et al., in 1981.Gordin H, Motzkin F, Hughes-Games A and Porter C. 1981. Seawater mariculture pond - an integrated system. European Aquaculture Society Special Publication 6: 1-13. By 1989, a semi-intensive (1 kg fish/m⁻³)

seabream Sparidae is a Family (biology), family of ray-finned fishes belonging to the Order (biology), order Spariformes, the seabreams and porgies, although they were traditionally classified in the order Perciformes. The over 150 species are found in sh ...

and grey mullet pond system by the Gulf of Aqaba (

Eilat Eilat ( , ; ; ) is Israel's southernmost city, with a population of , a busy port of Eilat, port and popular resort at the northern tip of the Red Sea, on what is known in Israel as the Gulf of Eilat and in Jordan as the Gulf of Aqaba. The c ...

) on the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

supported dense

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

populations, excellent for feeding

oysters Oyster is the common name for a number of different families of Seawater, salt-water bivalve molluscs that live in Marine (ocean), marine or Brackish water, brackish habitats. In some species, the valves are highly Calcification, calcified, a ...

.Neori A, Krom MD, Cohen Y and Gordin H. 1989. Water quality conditions and particulate chlorophyll a of new intensive seawater fishpond in Eilat, Israel: daily and dial variations. Aquaculture 80: 63-78.Erez J, Krom MD and Neuwirth T. 1990. Daily oxygen variations in marine fish ponds, Eilat, Israel. Aquaculture 84: 289-305. Hundreds of kilos of fish and oysters cultured here were sold. Researchers also quantified the water quality parameters and nutrient budgets in (5 kg fish m⁻³) green water seabream ponds.Krom MD and Neori A. 1989. A total nutrient budget for an experimental intensive fishpond with circularly moving seawater. Aquaculture 88: 345-358. The phytoplankton generally maintained reasonable water quality and converted on average over half the waste nitrogen into algal

biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

. Experiments with intensive

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

cultures yielded high bivalve growth rates.Shpigel M and Fridman R. 1990. Propagation of the Manila clam Tapes semidecussatus in the effluent of marine aquaculture ponds in Eilat, Israel. Aquaculture 90: 113-122.Shpigel M and BlaylockRA. 1991. The Pacific oyster, Crassostrea gigas, as a biological filter for a marine fish aquaculture pond. Aquaculture 92: 187-197.Shpigel M, Neori A, Popper DM and Gordin H. 1993a. A proposed model for ''environmentally clean'' landbased culture of fish, bivalves and seaweeds. Aquaculture 117: 115-128.Shpigel M, Lee J, Soohoo B, Fridman R and Gordin H. 1993b. The use of effluent water from fish ponds as a food source for the pacific oyster Crassostrea gigas Tunberg. Aquaculture & Fisheries Management 24: 529-543.Neori A and Shpigel M. 1999. Algae treat effluents and feed invertebrates in sustainable integrated mariculture. World Aquaculture 30: 46-49, 51.Neori A, Shpigel M and Scharfstein B. 2001. Land-based low-pollution integrated mariculture of fish, seaweed and herbivores: principles of development, design, operation and economics. European Aquaculture Society Special Publication 29: 190-191. This technology supported a small farm in southern Israel.

Sustainability

IMTA promotes economic and environmental

sustainability Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...

by converting byproducts and uneaten feed from fed organisms into harvestable crops, thereby reducing

eutrophication Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

, and increasing economic diversification.Tournay B. 2006. IMTA: template for production? Fish Farming International, Vol. 33, No. 5, May 2006, pg. 27. Properly managed multi-trophic aquaculture accelerates growth without detrimental side-effects.Johnson E. 2004. Cleaning up the sea cages. In: Family Jewels. Saltscapes, Vol. 5, No. 3, May/June 2004, 44-48.Lander T, Barrington K, Robinson S, MacDonald B and Martin J. 2004. Dynamics of the blue mussel as an extractive organism in an integrated multi-trophic aquaculture system. Bulletin of the Aquaculture Association of Canada. 104(3): 19-28.Ridler N, Robinson B, Chopin T, Robinson S and Page F. 2006. Development of integrated multi-trophic aquaculture in the Bay of Fundy, Canada: a socio-economic case study. World Aquaculture 37(3): 43-48. This increases the site's ability to assimilate the cultivated organisms, thereby reducing negative environmental impacts. IMTA enables farmers to diversify their output by replacing purchased inputs with byproducts from lower trophic levels, often without new sites. Initial economic research suggests that IMTA can increase profits and can reduce financial risks due to weather, disease and market fluctuations.Ridler N, Wowchuk M, Robinson B, Barrington K, Chopin T, Robinson S, Page F, Reid G and Haya K. 2007. Integrated multi-trophic aquaculture (IMTA): a potential strategic choice for farmers. Aquaculture Economics & Management 11: 99-110. Over a dozen studies have investigated the economics of IMTA systems since 1985. The economic sustainability of IMTA is enhanced through diversification. By cultivating multiple species, farmers can spread their economic risk and gain multiple sources of revenue. For example, if the market demand for one species drops, farmers can rely on the production of other species, such as shellfish or seaweed. This reduces the economic vulnerability that is typically associated with monoculture systems. Additionally, the diverse production of food and raw materials further contributes to the system's long-term economic viability.

Nutrient flow

Typically, carnivorous fish or shrimp occupy IMTA's higher

s. They excrete soluble

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

and

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

(ortho

phosphate Phosphates are the naturally occurring form of the element phosphorus. In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthop ...

). Seaweeds and similar species can extract these inorganic nutrients directly from their environment. Fish and shrimp also release organic nutrients which feed shellfish and deposit feeders.Mazzola A and Sarà G. 2001. The effect of fish farming organic waste on food availability for bivalve molluscs (Gaeta Gulf, Central Tyrrhenian, MED): stable carbon isotopic analysis. Aquaculture 192: 361-379. Species such as shellfish that occupy intermediate trophic levels often play a dual role, both filtering organic bottom-level organisms from the water and generating some ammonia. Waste feed may also provide additional nutrients; either by direct consumption or via

decomposition Decomposition is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is ess ...

into individual nutrients. In some projects, the waste nutrients are also gathered and reused in the food given to the fish in cultivation. This can happen by processing the seaweed grown into food. IMTA systems can significantly improve nutrient recovery efficiency. This is especially crucial in regions where conventional monoculture farming leads to nutrient imbalances, contributing to eutrophication and dead zones. Shellfish, such as mussels and oysters, filter out excess nitrogen and phosphorus from the water, while seaweed absorbs carbon dioxide and releases oxygen, fostering better water quality and a more stable marine environment.

Recovery efficiency

Nutrient recovery efficiency is a function of technology, harvest schedule, management, spatial configuration, production, species selection, trophic level

ratios, natural food availability, particle size, digestibility, season, light, temperature, and water flow. Since these factors significantly vary by site and region, recovery efficiency also varies. In a hypothetical family-scale fish/microalga /bivalve/seaweed farm, based on pilot scale data, at least 60% of nutrient input reached commercial products, nearly three times more than in modern net pen farms. Expected average annual yields of the system for a hypothetical were of seabream, of bivalves and of seaweeds. These results required precise water quality control and attention to suitability for bivalve nutrition, due to the difficulty in maintaining consistent phytoplankton populations.Krom MD, Porter C and Gordin H. 1985. Causes of fish mortalities in the semi-intensively operated seawater ponds in Eilat, Israel. Aquaculture 49: 159-177. Seaweeds' nitrogen uptake efficiency ranges from 2-100% in land-based systems. Uptake efficiency in open-water IMTA is unknown.Reid GK, Robinson S, Chopin T, Lander T, MacDonald B, Haya K, Burridge F, Page F, Ridler N, Justason A, Sewuster J, Powell F and Marvin R. An interdisciplinary approach to the development of integrated multi-trophic aquaculture (IMTA): bioenergetics as a means to quantify the effectiveness of IMTA systems and ecosystem response. World Aquaculture Society. Aquaculture 2007 conference proceedings, pg. 761. (https://www.was.org/Meetings/AbstractData.asp?AbstractId=13933 )

Food safety and quality

Feeding the wastes of one species to another has the potential for

contamination Contamination is the presence of a constituent, impurity, or some other undesirable element that renders something unsuitable, unfit or harmful for the physical body, natural environment, workplace, etc. Types of contamination Within the scien ...

, although this has yet to be observed in IMTA systems.

Mussels Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, whic ...

and

kelp Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...

growing adjacent to

Atlantic salmon The Atlantic salmon (''Salmo salar'') is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae, behind Hucho taimen, Siberian taimen and Pacific Chinook salmon, growing up to a meter in length. Atlan ...

cages in the Bay of Fundy have been monitored since 2001 for contamination by medicines,

heavy metals upright=1.2, Crystals of lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals is a controversial and ambiguous term for metallic elements with relatively h ...

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

, PCBs and

pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...

s. Concentrations are consistently either non-detectable or well below regulatory limits established by the

Canadian Food Inspection Agency The Canadian Food Inspection Agency (CFIA; ) is a regulatory agency that is dedicated to the safeguarding of food, plants, and animals (FPA) in Canada, thus enhancing the health and well-being of Canada's people, environment and economy. The age ...

, the United States

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

and

European Community The European Economic Community (EEC) was a regional organisation created by the Treaty of Rome of 1957,Today the largely rewritten treaty continues in force as the ''Treaty on the functioning of the European Union'', as renamed by the Lisbo ...

Directives.Haya K, Sephton D, Martin J and Chopin T. 2004. Monitoring of therapeutants and phycotoxins in kelps and mussels co-cultured with Atlantic salmon in an integrated multi-trophic aquaculture system. Bulletin of the Aquaculture Association of Canada. 104(3): 29-34.Chopin T, Sawhney M, Shea R, Belyea E, Bastarache S, Armstrong W, Reid GK, Robinson SMC, MacDonald B, Haya K, Burridge L, Page F, Ridler N, Justason A, Sewuster J, Powell F and Marvin R. 2007. An interdisciplinary approach to the development of integrated multi-trophic aquaculture (IMTA): the inorganic extractive component. World Aquaculture Society. Aquaculture 2007 conference proceedings, pg. 177. (https://www.was.org/Meetings/AbstractData.asp?AbstractId=13724 ) Taste testers indicate that these mussels are free of "fishy" taste and aroma and could not distinguish them from "wild" mussels. The mussels' meat yield is significantly higher, reflecting the increase in nutrient availability. Recent findings suggest mussels grown adjacent to salmon farms are advantageous for winter harvest because they maintain high meat weight and condition index (meat to shell ratio). This finding is of particular interest because the Bay of Fundy, where this research was conducted, produces low condition index mussels during winter months in monoculture situations, and seasonal presence of paralytic shellfish poisoning (PSP) typically restricts mussel harvest to the winter months.

Selected projects

Historic and ongoing research projects include:

Asia

Japan, China, South Korea, Thailand, Vietnam, Indonesia, Bangladesh, etc. have co-cultured aquatic species for centuries in marine,

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

and fresh water environments. Fish, shellfish and seaweeds have been cultured together in bays,

lagoons A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into '' coastal lagoons'' (or ''barrier lagoons'') a ...

and ponds. Trial and error has improved integration over time. The proportion of Asian aquaculture production that occurs in IMTA systems is unknown. After the 2004 tsunami, many of the shrimp farmers in Aceh Province of Indonesia and Ranong Province of Thailand were trained in IMTA. This has been especially important as the mono-culture of marine shrimp was widely recognized as unsustainable. Production of tilapia, mud crabs, seaweeds, milkfish, and mussels have been incorporated.
AquaFish Collaborative Research Support Program

Canada

Bay of Fundy

Industry, academia and government are collaborating here to expand production to commercial scale. The current system integrates

, blue mussels and

; deposit feeders are under consideration. AquaNet (one of

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

's Networks of Centres of Excellence) funded phase one. The

Atlantic Canada Atlantic Canada, also called the Atlantic provinces (), is the list of regions of Canada, region of Eastern Canada comprising four provinces: New Brunswick, Newfoundland and Labrador, Nova Scotia, and Prince Edward Island. As of 2021, the landma ...

Opportunities Agency is funding phase two. The project leaders are Thierry Chopin (

University of New Brunswick The University of New Brunswick (UNB) is a public university with two primary campuses in Fredericton and Saint John, New Brunswick. It is the oldest English language, English-language university in Canada, and among the oldest public universiti ...

in Saint John) and Shawn Robinson ( Department of Fisheries and Oceans, St. Andrews Biological Station).Robinson SMC, Lander T, Martin JD, Bennett A, Barrington K, Reid GK, Blair T, Chopin T, MacDonald B, Haya K, Burridge L, Page F, Ridler N, Justason N, Sewuster J, Powell F and Marvin R. 2007. An interdisciplinary approach to the development of integrated multi-trophic aquaculture (IMTA): the organic extractive component. World Aquaculture Society. Aquaculture 2007 conference proceedings, pg.786. (https://www.was.org/Meetings/AbstractData.asp?AbstractId=13764 )

Pacific SEA-lab

Pacific SEA-lab is researching and is licensed for the co-culture of sablefish,

scallops Scallop () is a common name that encompasses various species of marine bivalve molluscs in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related famili ...

, oysters, blue mussels, urchins and kelp. "SEA" stands for Sustainable Ecological Aquaculture. The project aims to balance four species. The project is headed by Stephen Cross under a

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

Innovation Award at the

University of Victoria The University of Victoria (UVic) is a public research university located in the municipalities of Oak Bay, British Columbia, Oak Bay and Saanich, British Columbia, Canada. Established in 1903 as Victoria College, British Columbia, Victoria Col ...

Coastal Aquaculture Research & Training (CART) network.Cross S. 2007. Making the case: quantifying the benefits of integrated multi-trophic aquaculture (IMTA). World Aquaculture Society. Aquaculture 2007 conference proceedings, pg. 209. (https://www.was.org/Meetings/AbstractData.asp?AbstractId=14507 )

Chile

The i-mar Research Center at the Universidad de Los Lagos, in

Puerto Montt Puerto Montt (Mapuche: Meli Pulli) is a port city and commune in southern Chile, located at the northern end of the Reloncaví Sound in the Llanquihue Province, Los Lagos Region, 1,055 km to the south of the capital, Santiago. The commune ...

is working to reduce the environmental impact of intensive salmon culture. Initial research involved trout, oysters and seaweeds. Present research is focusing on open waters with salmon, seaweeds and abalone. The project leader is Alejandro Buschmann.Buschmann AH, Varela DA, Hernández-González MC, Henríquez L, Correa J, Flores R and Gutierrez A. 2007. The development of an integrated multi-trophic activity in Chile: the importance of seaweeds. World Aquaculture Society. Aquaculture 2007 conference proceedings, pg. 136. (https://www.was.org/Meetings/AbstractData.asp?AbstractId=14199 )

Israel

SeaOr Marine Enterprises Ltd.

SeaOr Marine Enterprises Ltd., which operated for several years on the

Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

Mediterranean coast The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eu ...

, north of

Tel Aviv Tel Aviv-Yafo ( or , ; ), sometimes rendered as Tel Aviv-Jaffa, and usually referred to as just Tel Aviv, is the most populous city in the Gush Dan metropolitan area of Israel. Located on the Israeli Mediterranean coastline and with a popula ...

, cultured marine fish ( gilthead seabream), seaweeds (Ulva and Gracilaria) and Japanese

. Its approach leveraged local climate and recycled fish waste products into seaweed biomass, which was fed to the abalone. It also effectively purified the water sufficiently to allow the water to be recycled to the fishponds and to meet point-source effluent environmental regulations.

PGP Ltd.

PGP Ltd. is a small farm in Southern Israel. It cultures marine fish, microalgae, bivalves and

Artemia ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp or '' sea monkeys''. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th cent ...

. Effluents from seabream and seabass collect in

sedimentation Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to th ...

ponds, where dense populations of microalgae—mostly

s—develop.

Clam Clam is a common name for several kinds of bivalve mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...

s, oysters and sometimes Artemia filter the microalgae from the water, producing a clear effluent. The farm sells the fish, bivalves and Artemia.

The Netherlands

In the Netherlands, Willem Brandenburg of UR Wageningen (Plant Sciences Group) has established the first seaweed farm in the Netherlands. The farm is called "De Wierderij" and is used for research.

South Africa

Three farms grow seaweeds for feed in abalone effluents in land-based tanks. Up to 50% of re-circulated water passes through the seaweed tanks.Bolton J, Robertson-Andersson DM, Troell M, and Halling C. 2006. Integrated system incorporates seaweeds in South African abalone culture. Global Aquaculture Advocate, Vol. 9, No. 4, July/August 2006, pg. 54-55. Somewhat uniquely, neither fish nor shrimp comprise the upper trophic species. The motivation is to avoid over-harvesting natural seaweed beds and red tides, rather than nutrient abatement. These commercial successes developed from research collaboration between Irvine and Johnson Cape Abalone and scientists from the

University of Cape Town The University of Cape Town (UCT) (, ) is a public university, public research university in Cape Town, South Africa. Established in 1829 as the South African College, it was granted full university status in 1918, making it the oldest univer ...

and the

Stockholm University Stockholm University (SU) () is a public university, public research university in Stockholm, Sweden, founded as a college in 1878, with university status since 1960. With over 33,000 students at four different faculties: law, humanities, social ...

United Kingdom

The Scottish Association for Marine Science, in

Oban Oban ( ; meaning ''The Little Bay'') is a resort town within the Argyll and Bute council area of Scotland. Despite its small size, it is the largest town between Helensburgh and Fort William, Highland, Fort William. During the tourist seaso ...

is developing co-cultures of salmon, oysters, sea urchins, and brown and red seaweeds via several projects. Research focuses on biological and physical processes, as well as production economics and implications for coastal zone management. Researchers include: M. Kelly, A. Rodger, L. Cook, S. Dworjanyn, and C. Sanderson.Kelly MS, Sanderson C, Cook EJ, Rodger A and Dworjanyn SA. 2007. Integration: enhancing sustainability in open water aquaculture systems. World Aquaculture Society. Aquaculture 2007 conference proceedings, pg. 458. (https://www.was.org/Meetings/AbstractData.asp?AbstractId=14295 )Rodger A, Cromey C and Kelly M. 2007. Open water integrated aquaculture - use of depositional modelling to assist finfish/bivalve integration, for growth optimisation and prediction of waste dispersal. World Aquaculture Society. Aquaculture 2007 conference proceedings, pg. 788. (https://www.was.org/Meetings/AbstractData.asp?AbstractId=14213 )

Bangladesh

Indian carps and stinging catfish are cultured in Bangladesh, but the methods could be more productive. The pond and cage cultures used are based only on the fish. They don't take advantage of the productivity increases that could take place if other trophic levels were included. Expensive artificial feeds are used, partly to supply the fish with protein. These costs could be reduced if freshwater snails, such as ''Viviparus bengalensis'', were simultaneously cultured, thus increasing the available protein. The organic and inorganic wastes produced as a byproduct of culturing could also be minimized by integrating freshwater snail and aquatic plants, such as water spinach, respectively.

Gallery

File:Carp (Catla catla) produced in IMTA pond.JPG, Carp (Labeo rohita) produced in IMTA pond File:Off-bottom snail grown on bamboo split in IMTA.JPG, Off-bottom snail grown on bamboo split in IMTA File:Snail produced on pond bottom of IMTA.JPG, Snail produced on pond bottom of IMTA File:IMTA in Bangladsh.jpg, Collection of water spinach and snail from IMTA pond File:Produced shing in cage in IMTA.JPG, Produced shing in cage in IMTA

Notes

References

* Neori A, Troell M, Chopin T, Yarish C, Critchley A and Buschmann AH. 2007. The need for a balanced ecosystem approach to blue revolution aquaculture. Environment 49(3): 36–43.

External links

AquaNet IMTA

www.sams.ac.ukWorld Aquaculture Conference 2007: IMTA sessionChopin labThe Comparative Roles of Suspension-Feeders in Ecosystems
The use of bivalves as biofilters and valuable product in land based aquaculture systems - review.
Seaweed Resources of the World
Algae: key for sustainable mariculture.
Ecological and Genetic Implications of Aquaculture Activities
Evaluation of macroalgae, microalgae, and bivalves as biofilters in sustainable land-based mariculture systems. {{Commonscat, Integrated multi-trophic aquaculture Hydrography Physical oceanography Aquaculture