The devil is in the detail: new aquafeed research reveals hidden environmental trade-offs

Aquaculture plays a crucial role in meeting growing global demand for nutritious seafood. However, feed remains the dominant contributor to the environmental footprint of farmed fish production, accounting for between 50–90% of total impacts in many systems.

Over the past two decades, the aquaculture sector has significantly reduced its reliance on marine ingredients such as fishmeal and fish oil. This shift has often been presented as a key sustainability achievement. Yet new research highlights that the environmental consequences of this transition are more complex than often assumed. You can read the study by Kok et al 2026 here

A shift in environmental pressures

Between 2000 and 2020, European aquaculture production nearly doubled, increasing from 1.15 million tonnes to 2.17 million tonnes of key species including Atlantic salmon, trout, seabream and seabass.

During the same period, the inclusion of marine ingredients in feeds declined sharply and was replaced largely by plant-based ingredients such as soy protein concentrate and rapeseed oil.

The result has been a mixed environmental picture. While the use of wild fish in feed decreased by around 13% overall, other environmental indicators increased significantly. These include:

• Global warming potential: +314%

• Land use: +594%

• Water consumption: +236%

• Marine eutrophication: +630%

• Freshwater eutrophication: +468

Much of this increase is linked to the expansion of aquaculture production itself, but the study shows that changes in feed composition were a major driver, shifting pressures from marine ecosystems toward terrestrial agriculture.

The hidden trade-offs of plant ingredients

Two widely used terrestrial ingredients—soy protein concentrate and rapeseed oil—were identified as having a disproportionate impact on several environmental indicators, including greenhouse gas emissions and land use

These ingredients are often perceived as sustainable alternatives to marine ingredients. However, their production can involve significant agricultural inputs, land occupation, fertilizer use, and water consumption.

This highlights an important point: reducing reliance on marine ingredients does not automatically reduce overall environmental impacts,  it redistributes them across different parts of the food system

The role of marine by-products

One promising pathway identified by the study is the increased use of fisheries and aquaculture processing by-products as raw material for fishmeal and fish oil.

Over the past two decades, greater utilisation of by-products has helped reduce pressure on wild fish resources without creating significant trade-offs in other environmental categories.

Because these by-products often have limited alternative uses for human consumption, their use in aquafeeds represents an efficient way to recover valuable nutrients—particularly long-chain omega-3 fatty acids—while improving overall resource efficiency.

A more balanced sustainability assessment

The findings underline the need for more holistic approaches to evaluating feed sustainability. Focusing solely on reducing marine ingredient inclusion risks overlooking wider environmental trade-offs.

Future feed strategies should therefore consider:

• Efficient use of marine by-products

• Responsible sourcing of terrestrial ingredients

• Development of novel ingredients with demonstrably lower footprints

• Comprehensive assessment tools that capture trade-offs across environmental indicators

Ultimately, sustainable aquaculture will depend not only on replacing ingredients, but on optimising resource use across the entire feed system.