Integrated Multitrophic Aquaculture: An Overview 243
management of large-scale IMTA areas still needs improvement, requiring a deeper understanding of
the interactions between the different components and between species and the environment, in order to
ensure sustainable development (Shi et al. 2013; Fang et al. 2016).
Although commercial IMTA is not yet widely applied in western countries, some companies are
already using this concept to produce seaweed, since the nutrients produced by fed aquaculture are a
valuable resource, increasing yields and productivity. Examples are AlgaPlus, in Portugal, a land-based
seaweed aquaculture company that is established in association with a semi-intensive fish aquaculture,
receiving water from the fish earthen tanks (www.algaplus.pt) and Hjarno Havbrug (www.havbrug.dk), in
Denmark, which produces sugar kelp in open water with organic certification, and also mussels, to reduce
the nitrogen in the water originated by fish aquaculture.
In fact, a driver for IMTA development in western countries is the growing interest in seaweed
aquaculture, both for their contribution to nutrient reduction and for the multiple high value applications
of their biomass, from high quality healthy food to source of bioactive compounds for the cosmetic and
pharmaceutical industries (Hafting et al. 2015). Nevertheless, for the seaweed component of IMTA to
fulfill its role in nutrient mitigation, and to supply the market for the above mentioned applications,
biomass production must be up-scaled, and the logistics for processing and marketing must be developed
for this increased biomass. Thus, besides the need to resolve the regulatory constraints, the economic
stability is still to be demonstrated, especially over the long term (Chopin 2017), in order to attract
investment for IMTA development and move IMTA from a research concept to a mainstream commercial
activity.
Challenges and opportunities
Policy and regulation are, as stated above, the main challenges that IMTA has to meet to reach a
commercial level. In order to inform licensing and regulatory authorities, it is fundamental to establish
clear definitions for IMTA systems and products. Once this is established, added value will be placed
on IMTA products, based on their quality as well as their sustainable way of production. Consumers
are increasingly willing to support environmentally sustainable production of food and other goods,
if properly demonstrated, including IMTA originated food products (Barrington et al. 2010), allowing
the development of markets for differentiated premium IMTA products. Thus, it is important to declare
this differenciation to the consumers, informing them about the environmental sustainability of IMTA
products through organic certification or environmental labelling.
In order to meet the demand of those markets, and support the environmental sustainability claim,
upscaling the production of extractive species (e.g., mussels or oysters and seaweed) is needed. In the
case of mussels or oysters, their value is already recognized and the market and supply chain are already
in place. In the case of seaweed, the interest in seaweed based products has pushed the market forward
with the demand and prices rising in the last years, currently for food, food ingredients, cosmetics,
fertilizers, and hydrocolloids industries (Nayar and Bott 2014). Besides these established uses, promising
new markets for seaweed based products include the bioactive extracts for incorporation in food products
(nutraceuticals), premium feed products, soil conditioners and biofertilizers, and even biofuels. Seaweed
processing for these applications is being considered under the cascade biorefinery concept, which allows
for a more efficient use of seaweed biomass by sequentially extracting different compounds such as
protein, carbohydrates, and minerals (Francavilla et al. 2015; Bikker et al. 2017).
The establishment of larger markets for IMTA products, including seaweed, implies increasing
biomass production, which raises another issue, marine space availability for farm expansion. Coastal
areas are used by very different and sometimes conflicting activities, such as fisheries, navigation, and
recreation, demanding development of spatial planning strategies that accommodate these different
interests. Factors to be considered include physical characteristics such as temperature and hydrodynamics,
water transparency, and distance to harbor infrastructures. An important issue to account for is the
carrying capacity of the site, which is an opportunity for IMTA. For the IMTA concept to work, balanced
production must be achieved, through careful management, which is a recognized challenge for IMTA
implementation. The need for a balanced production, in terms of cultivated organisms, underlying the
management of large-scale IMTA areas still needs improvement, requiring a deeper understanding of
the interactions between the different components and between species and the environment, in order to
ensure sustainable development (Shi et al. 2013; Fang et al. 2016).
Although commercial IMTA is not yet widely applied in western countries, some companies are
already using this concept to produce seaweed, since the nutrients produced by fed aquaculture are a
valuable resource, increasing yields and productivity. Examples are AlgaPlus, in Portugal, a land-based
seaweed aquaculture company that is established in association with a semi-intensive fish aquaculture,
receiving water from the fish earthen tanks (www.algaplus.pt) and Hjarno Havbrug (www.havbrug.dk), in
Denmark, which produces sugar kelp in open water with organic certification, and also mussels, to reduce
the nitrogen in the water originated by fish aquaculture.
In fact, a driver for IMTA development in western countries is the growing interest in seaweed
aquaculture, both for their contribution to nutrient reduction and for the multiple high value applications
of their biomass, from high quality healthy food to source of bioactive compounds for the cosmetic and
pharmaceutical industries (Hafting et al. 2015). Nevertheless, for the seaweed component of IMTA to
fulfill its role in nutrient mitigation, and to supply the market for the above mentioned applications,
biomass production must be up-scaled, and the logistics for processing and marketing must be developed
for this increased biomass. Thus, besides the need to resolve the regulatory constraints, the economic
stability is still to be demonstrated, especially over the long term (Chopin 2017), in order to attract
investment for IMTA development and move IMTA from a research concept to a mainstream commercial
activity.
Challenges and opportunities
Policy and regulation are, as stated above, the main challenges that IMTA has to meet to reach a
commercial level. In order to inform licensing and regulatory authorities, it is fundamental to establish
clear definitions for IMTA systems and products. Once this is established, added value will be placed
on IMTA products, based on their quality as well as their sustainable way of production. Consumers
are increasingly willing to support environmentally sustainable production of food and other goods,
if properly demonstrated, including IMTA originated food products (Barrington et al. 2010), allowing
the development of markets for differentiated premium IMTA products. Thus, it is important to declare
this differenciation to the consumers, informing them about the environmental sustainability of IMTA
products through organic certification or environmental labelling.
In order to meet the demand of those markets, and support the environmental sustainability claim,
upscaling the production of extractive species (e.g., mussels or oysters and seaweed) is needed. In the
case of mussels or oysters, their value is already recognized and the market and supply chain are already
in place. In the case of seaweed, the interest in seaweed based products has pushed the market forward
with the demand and prices rising in the last years, currently for food, food ingredients, cosmetics,
fertilizers, and hydrocolloids industries (Nayar and Bott 2014). Besides these established uses, promising
new markets for seaweed based products include the bioactive extracts for incorporation in food products
(nutraceuticals), premium feed products, soil conditioners and biofertilizers, and even biofuels. Seaweed
processing for these applications is being considered under the cascade biorefinery concept, which allows
for a more efficient use of seaweed biomass by sequentially extracting different compounds such as
protein, carbohydrates, and minerals (Francavilla et al. 2015; Bikker et al. 2017).
The establishment of larger markets for IMTA products, including seaweed, implies increasing
biomass production, which raises another issue, marine space availability for farm expansion. Coastal
areas are used by very different and sometimes conflicting activities, such as fisheries, navigation, and
recreation, demanding development of spatial planning strategies that accommodate these different
interests. Factors to be considered include physical characteristics such as temperature and hydrodynamics,
water transparency, and distance to harbor infrastructures. An important issue to account for is the
carrying capacity of the site, which is an opportunity for IMTA. For the IMTA concept to work, balanced
production must be achieved, through careful management, which is a recognized challenge for IMTA
implementation. The need for a balanced production, in terms of cultivated organisms, underlying the