European aquaculture will need offsets to reach net zero by 2050, says study

Aquaculture is expected to supply a growing share of Europe’s seafood, but increasing production while reducing greenhouse gas emissions presents a complex challenge to producers, explored in a new European Commission-funded study.

The report, EU Aquaculture: Greenhouse Gas Reduction Costs and Pathways to Net Zero by 2050, examines how EU aquaculture could move towards carbon neutrality by 2050 – and what the transition might cost.

While farms can tackle some carbon emissions by installing renewable energy, improving feeding efficiency, modernising equipment and reducing fuel use, a large part of aquaculture’s carbon footprint is generated elsewhere in the supply chain.

The report thus covers the full farming chain, including hatcheries, grow-out operations, feed production and transport, on-farm energy use, vessels, infrastructure and logistics.

It examines five aquaculture production systems: sea cages, non-fed aquaculture, ponds, raceways and recirculating aquaculture systems (RAS).

Rather than proposing a single route to net zero, the researchers designed eight scenarios for 2030, 2040 and 2050, combining measures such as alternative feed ingredients, precision feeding, selective breeding, renewable energy, energy audits, integrated multi-trophic aquaculture (IMTA) and carbon offsets.

Feed was identified as the dominant emissions source in fed aquaculture. The report’s historical analysis found that feed production and transport accounted for 54% of EU aquaculture emissions between 2005 and 2024.

Under the model, feed raises the sector’s projected emissions for 2026 from around 1.8 million tonnes to 2.8 million tonnes of CO2 equivalent.

This presents a difficulty for aquaculture operators because many of these emissions occur outside the farm. Under a strict interpretation of the EU Climate Law, the report authors said, emissions from feed, energy, transport and hatcheries should primarily be reduced by the supplying industries rather than by aquaculture alone.

However, the study nevertheless counts direct emissions, purchased energy and emissions from feed production and transport within aquaculture’s total carbon footprint.

As a result, the report concludes that fed aquaculture could only become carbon neutral if agriculture and fisheries also decarbonised, or if their remaining emissions were offset.

Non-fed systems have a much clearer route towards very low emissions, with modelling suggesting that shellfish and similar production could approach near-zero emissions by 2050.

The report identifies several measures that producers can adopt directly, including improving feed efficiency, using digital systems to reduce waste, replacing fossil energy with renewable sources and upgrading pumps, aeration equipment and other machinery.

“There is a general consensus among stakeholders that tools to increase energy use efficiency and stimulate energy savings are the easiest to implement,” the report states.

It adds that these measures are seen as “a quick way to contribute to GHG emissions reduction” while also reducing companies’ operating costs.

Selective breeding could improve growth and feed conversion, while integrated multi-trophic aquaculture could allow nutrients from fed species to be used by shellfish, seaweed or other organisms.

The study notes, however, that the cost and practicality of these measures will vary between farms, species and production systems.

The study estimates how much each scenario would cost for every tonne of greenhouse gas emissions avoided – the "marginal abatement" cost.

Across the six scenarios, estimates ranged from €46 to €243 per tonne of CO2 equivalent for 2026 to 2030. The range was €65 to €232 by the year 2040, and €69 to €228 by 2050.

The highest figure, €243 per tonne, applied to a scenario based on measures described as relatively low investment. However, those measures produced only limited emissions reductions and the scenario did not include carbon offsets, pushing up the cost of each tonne avoided.

Scenarios that used carbon credits or funded ecosystem restoration appeared cheaper per tonne. This was because the study assumed that compensating for some remaining emissions would cost less than trying to eliminate them through technology alone.

Costs also varied between production systems. The estimated cost was €41 to €52 per tonne for RAS, €60 to €62 for ponds, €65 to €68 for cages and €66 to €72 for raceways.

Non-fed aquaculture, including shellfish, had the highest estimated cost, at €172 to €227 per tonne. The authors said this reflected its already low emissions and the limited number of easy or inexpensive options for further reductions.

The report concludes that the measures it assessed would not be enough on their own to achieve carbon neutrality, meaning carbon offsets would be needed to counteract the emissions from energy, transport and construction on the one hand, and aquafeed on the other.

Even in the scenario that applied all available technological measures without cost restrictions, the total emissions were reduced by only around 50%, according to the study.

The amount of offsetting required varied by production system and over time. In most systems, more offsetting was expected to be needed to meet the 2040 target than the 2050 target, because measures such as renewable energy, AI-based feeding systems and alternative feed ingredients are not expected to be adopted widely until after 2040.

The report thus sets out eight areas for policy action, including supporting energy audits and digitalisation, reducing emissions from feed materials, replacing fossil energy in transport and farm operations, and developing breeding programmes focused on efficiency and resilience.

It also recommends continued support for integrated multi-trophic aquaculture and non-fed species, recognised standards for carbon offsets, stronger markets for low-carbon aquaculture products, and changes to policy and licensing intended to support long-term investment.

"Achieving carbon neutrality in EU aquaculture by 2050 is therefore only possible through a combination of full deployment of available tools, credible offsetting, strong public policy support across the whole value chain, and parallel decarbonisation of indirect, upstream emission sources in feed, energy, transport and their related sectors," the report authors state.

The European Commission said the findings will contribute to its forthcoming roadmap for the energy transition in fisheries and aquaculture.

The study was authored by a consortium led by Wageningen Social & Economic Research, alongside MRAG Europe, AZTI, ABTG, Poland’s National Marine Fisheries Research Institute and the Aquaculture Stewardship Council.