Open‐water integrated multi‐trophic aquaculture: environmental biomitigation and economic diversification of fed aquaculture by extractive aquaculture

Abstract

Integrated multi‐trophic aquaculture (IMTA) seeks to biodiversify fed aquaculture (e.g. finfish or shrimps) with extractive aquaculture, recapturing the inorganic (e.g. seaweeds) and organic (e.g. suspension‐ and deposit‐feeders) nutrients from fed aquaculture for their growth. The combination fed/extractive aquaculture aims to engineer food production systems providing both biomitigative services to the ecosystem and improved economic farm output through the co‐cultivation of complementary species. Major rethinking is needed regarding the definition of an ‘aquaculture farm’ and how it works within an ecosystem. The economic values of the environmental/societal services of extractive species should be recognized and accounted for in the evaluation of the full value of these IMTA components. Seaweeds and invertebrates produced in IMTA systems should be considered as candidates for nutrient/carbon trading credits. While organic loading from aquaculture has been associated with localized benthic impacts, there have also been occurrences of increased biodiversity and abundance of wild species in response to moderate nutrient enrichment and the use of infrastructures as substrates. To develop efficient food production systems, it will be important to understand and use the duality of nutrients (essential when limiting/polluting when in excess) to engineer systems producing them in moderation so that they can be partially recaptured while maintaining their concentrations optimal for healthy and productive ecosystems. Measures of species diversity, colonization rates, abundance, growth and ecosystem functions with respect to nutrient partitioning and recycling, species interactions and control of diseases could represent valid indicators for the development of robust performance metrics.

Seaweed aquaculture in Norway: recent industrial developments and future perspectives

“…Whereas, evidence from IMTA sites elsewhere indicates many benefits, both on conceptual, practical, environmental and economic levels (Barrington et al 2008;Chopin et al 2012), potential risks associated with integrated fish and seaweed production need to be evaluated and assessed in the context of specific geography, production systems (regarding both fish and seaweed), scales of production and associated technology. Such issues are also addressed in on-going research projects in Norway.…”

“…in proximity to fish farms, function as extractive components within a cultivation food web. In addition to reducing the environmental impact of intensive fish aquaculture, IMTA systems add value to the investment in finfish aquaculture by increasing the yield of total biomass produced on a single site (Chopin et al 2001;Neori et al 2004;Troell et al 2009;Chopin et al 2012).…”

Offshore and Multi-Use Aquaculture with Extractive Species: Seaweeds and Bivalves

“…The recognition of the ecosystem services provided by extractive species and the implementation of NTCs would give a fair price to extractive aquaculture (Chopin et al 2010(Chopin et al , 2012. They could be used as financial and regulatory incentive tools to encourage single-species aquaculturists to contemplate IMTA as a viable option to their current practices.…”

Accounting for inventory data and methodological choice uncertainty in a comparative life cycle assessment: the case of integrated multi-trophic aquaculture in an offshore Mediterranean enterprise

“…However, this indicator cannot yet be translated into impacts that are accountable throughout the life cycle of marine offshore aquaculture systems within the LCA methodology (see Rico et al 2013 for other types of aquaculture), and this is an area where IMTA can have a positive impact (Ford et al 2012). The presence of shellfish, filtering significant quantities of water to remove particulates, can have beneficial effects in potentially removing parasites, such as sea lice (Chopin et al 2012), thus reducing infection potential. Moreover, for monoculture and IMTA, there is often a lack of evidence of environmental improvement in the nutrient discharges because of difficulty in directly measuring changes in the environment (Pecorino et al 2016).…”