Integrated multi-trophic aquaculture (IMTA) is both conceptually a simple idea and also highly appealing to regulators: the waste products from one food production process (in this case, fin-fish production) is acquired and assimilated by other organisms and converted into valuable products. This process both eliminates waste and increases the productivity of the food production system (Troell et al. 2003, Neori et al. 2004, Chopin et al. 2006).
This win/win situation has its roots deeply buried in the eco-efficiency philosophy that aims to simultaneously increase both the economic and environmental performances of an industry or business (Ehrenfeld 2005).
Alternately, IMTA can be thought of in terms of eco-intensification, where the productivity per unit input is increased (Amano & Ebihara 2005).
In Europe, the model for fed fin-fish aquaculture has been very linear, in line with a fast replacement economy where the inputs to the industry lead to consumption of natural resources with high energy and water consumption, with externalised wastes.
This is in contrast to the principles of IMTA, which aim to create an industry-based spiral or loop system (now termed the circular economy) that minimises energy flows, losses, and environmental deterioration, without restricting economic growth or social progress (Boulding 1966, Stahel 1982).
The win/win that IMTA represents has been cited a number of times as a solution to some of the problems that are facing the European fin-fish aquaculture industry, such as ecological damage, economic stability, and dependence on commercial feed (Klinger & Naylor 2012, Chopin et al. 2013, Granada et al. 2015).
Despite a strong tradition in Asia (Chan 1993) and the fact that the IMTA concept in various guises has been in the scientific literature for at least 40 yr, since the early 1970s (Ryther et al. 1972, 1975, Ahn et al. 1998, Buschmann et al. 2001), there is almost no commercial uptake of IMTA in Europe. This is against an increasing academic interest in Europe in the concept of IMTA (OECD 2010).
Given the significant up - take of the concept of the circular economy within Europe as a whole (World Economic Forum 2014) and the eco-efficiency potential of IMTA technology, this lack of uptake is, on the face of it, hard to understand.
Several studies have elucidated possible reasons why there has not been a transition from academic promise to commercial reality (Troell et al. 2003, 2009) and have included reasons such as the performance of the extractive organisms or the economic performance of the systems. However, most previous studies have identified gaps in the scientific knowledge, but it will not be scientists who implement IMTA at a commercial scale, but rather companies and individuals within those countries.
Therefore, this paper attempts to better understand the commercial motivation for the adoption of IMTA. The question is even more pertinent given the fact that aquaculture production in Europe is stagnating, with growth over the last decade only around 1% per annum (Anon 2009, 2015). This is in stark contrast to the picture in Asia, where aquaculture is the fastestgrowing food production sector (FAO 2012) and IMTA is commonplace.
Here, we argue that there is a need to move past this win/win conceptual framework and its view that IMTA is a solution: this framework is flawed or at best is unhelpful. If we move beyond a solution-based mind-set, we may explain the contrasting implementation of IMTA in Europe and Asia.
Instead of considering IMTA as a ‘solution’ for European aquaculture, it is perhaps better to quantify the trade-offs involved in its adoption. Sowell (1995) argued that in social systems, there are no solutions, there are just trade-offs between different conditions, situations or states. Thus, instead of thinking ‘What will remove particular negative features in an existing situation to create a solution?’, it is more useful to frame the question as ‘What must be sacrificed to achieve this particular improvement?’ (Sowell 1995).
Instead of thinking of IMTA as a solution and wondering why there is no industry adoption of the technology, we consider the trade-offs between the benefits and costs of adopting IMTA at the level of an existing fin-fish farmer or company.
Applying this analysis to regions where IMTA is more common, we can try to understand what needs to shift in that balance of trade-offs to foster the adoption of IMTA in Europe. For the sake of this thought experiment, we will assume the scenario of an existing European (including Norway) fin-fish farmer wishing to develop a simple system of IMTA consisting of fish, mussels, and seaweed in a temperate openwater system.
