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How to choose the best locations for Integrated Multi-Trophic Aquaculture (IMTA)?

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By Milthon Lujan

Due to environmental concerns associated with aquaculture activities, Integrated Multi-Trophic Aquaculture (IMTA) is considered one of the primary alternatives to reduce negative environmental impacts.

A research project funded by the European Union has been analyzing the feasibility of introducing a more sustainable and potentially more profitable aquaculture method, using three complementary species.

IMTA aims to mitigate the environmental footprint of aquaculture by cultivating multiple species from different trophic levels together. These species work together to remove excess organic and inorganic nutrients, ultimately benefiting the ecosystem while providing a variety of marine products.

In this regard, a study conducted by researchers at Bangor University in the Atlantic region of Europe sheds light on the suitability of IMTA in this region for the cultivation of three species: Atlantic salmon (Salmo salar), blue mussel (Mytilus edulis), and the macroalgae Laminaria digitata. The study’s results offer valuable insights into establishing new and sustainable aquaculture systems.

According to Conchúr Hughes of Bangor University: “One of the issues with the type of single-species aquaculture practiced in Europe is that excess feed and waste can lead to local ecological degradation, while density may require aquaculture companies to use antibiotics and other additives to maintain a healthy fish stock.”

Identifying suitable locations for IMTA

The feasibility study carried out by Bangor University has identified locations on the Atlantic coast that would be most suitable for IMTA, based on the rearing of salmon, blue mussels, and common kelp along temperate Atlantic coasts.

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The research considered the natural distribution of the three species, whether suitable locations conflicted with busy maritime routes or protected marine areas, and whether there was nearby access to sizable ports to reach markets.

“Mussels are filter feeders and can be responsible for removing up to 54% of salmon waste from the water column, using it as energy to grow, while the oarweed removes soluble nutrients from the water column. Then, the oarweed can be cultivated for use in a variety of products, from human dietary supplements to aquaculture fertilizers or pharmaceutical ingredients,” emphasized Hughes.

To identify the most suitable locations for establishing a new IMTA system, researchers employed advanced habitat suitability models. These models were created using spatial jackknife tests in MaxEnt software and analyzed using ArcGIS (ArcMap 10.8.1).

The results demonstrated a high level of predictive capability, with AUC values of 0.889 for S. salar, 0.876 for M. edulis, and 0.901 for L. digitata.

Key variables in IMTA suitability

Jackknife tests helped identify the two most critical variables in the model for each target species: Chlorophyll A (mg m−3) and Salinity (PSS).

These factors reflect the complex relationships between nutrient availability and water conditions, underscoring the importance of water quality in successful integrated multi-trophic aquaculture systems.

Highlighted locations in Europe

The study identified coastal areas in the UK, Ireland, and northern France as highly suitable for IMTA systems. According to the study’s results, the west coast of Lewis in the Outer Hebrides, Scotland; Lough Swilly in County Donegal, Ireland; and the west coast of Brittany in northwestern France were the best locations for further developing integrated multi-trophic aquaculture.

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As one moves south, suitability gradually decreases. The research also considered additional factors, such as the density of local vessels, whether potential IMTA sites were within Marine Protected Areas (MPAs), and site accessibility from nearby ports.

The validation process

To validate the suitability of these areas for IMTA purposes, the study compared environmental conditions in these locations with known Atlantic salmon aquaculture sites in Scotland.

This additional step reinforced the findings, ensuring that the proposed areas met the necessary criteria for large-scale aquaculture systems.

The research, therefore, provides a scientifically based and robust foundation for the implementation of IMTA.

Promoting sustainable squaculture

The results of this study are of great significance for the future of aquaculture in Europe and the world. By identifying optimal conditions for each species and pinpointing suitable areas for IMTA, the research provides aquaculture companies with crucial information for preliminary site selection.

It also paves the way for further integration of integrated multi-trophic aquaculture systems in the European market in a sustainable and environmentally responsible manner.

IMTA systems represent a promising path to address the growing demand for marine products while simultaneously reducing the environmental impact of aquaculture.

Conclusion

As our world continues to face the challenges of population growth and resource scarcity, innovative solutions like Integrated Multi-Trophic Aquaculture offer a glimmer of hope.

This study in the Atlantic region of Europe highlights the potential of IMTA to transform aquaculture into a sustainable and environmentally responsible industry. With a focus on suitability and optimal conditions, it lays the groundwork for a more eco-friendly and productive future in food production.

By embracing the principles of IMTA, we can simultaneously meet the global demand for marine products and safeguard the health of our oceans. As we move forward, it is imperative that we continue to support and invest in research that promotes sustainable practices, ensuring a better and more resilient future for both our planet and our plates.

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Contacto
Conchúr Hughes
School of Ocean Sciences, Bangor University
Menai Bridge, Anglesey, LL59 5AB, UK
Email: conchur_h@hotmail.com

Reference (open access)
Conchúr Hughes, Jonathan W. King. Habitat suitability modelling for an integrated multi-trophic aquaculture (IMTA) system along Europe’s Atlantic coast, Ecological Modelling, Volume 484, 2023, 110459, ISSN 0304-3800, https://doi.org/10.1016/j.ecolmodel.2023.110459.

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