For years, seafood consumers have shared a common, well-intentioned concern about aquaculture: "Are we catching too many wild fish just to feed farmed fish?"
It seems like a straightforward equation. If we reduce the fishmeal and fish oil in aquaculture feeds and replace them with vegetarian alternatives, we protect our wild oceans. Driven by this logic, the global aquaculture sector has spent the last two decades aggressively replacing marine ingredients with terrestrial crop substitutes like soy protein concentrate and rapeseed oil.
However, a groundbreaking study published in the Journal of Cleaner Production, titled "Sustainable aquafeed? The devil is in the detail", reveals that this transition is a massive environmental paradox. Led by sustainability researchers Björn Kok and Dr. Wesley Malcorps from the University of Stirling, the paper shows that focusing blindly on a single headline metric—reducing wild fish use—risks telling an incomplete and deeply misleading story.
By shifting fish diets from the sea to the land, we haven't eliminated environmental pressure; we have simply redistributed it onto a terrestrial agriculture system that is already bucking under global strain. For everyday consumers looking to make ethical food choices, understanding this complex trade-off is absolutely vital.
The Hidden Numbers: Swapping Ocean Pressures for Land Mass
The paper utilizes Index Decomposition Analysis to track the exact footprint of European aquaculture between 2000 and 2020. Over these two decades, aquaculture production nearly doubled—surging from 1.15 million metric tonnes to 2.17 million metric tonnes, heavily driven by Atlantic salmon farming.
On paper, the industry achieved its primary sustainability target: overall wild fish use in feed dropped by 13%, and when looked at as an efficiency metric, wild fish use plummeted by a staggering 59% per kilogram of fish produced. This was possible due to higher inclusions of by-products derived marine ingredients.
But what happened when millions of tonnes of marine ingredients were swapped for land-grown soy protein and rapeseed oil? The terrestrial footprint exploded:
- Land Use skyrocketed by 594% across the industry (an unsustainable +336% increase per kilogram of fish farmed).
- Global Warming Potential rose by 314% (+103% per kilogram of fish).
- Water Consumption increased by 236% (+65% per kilogram).
Most alarmingly for aquatic environments, marine eutrophication soared by 630% (+285% per kilogram), while freshwater eutrophication climbed by 468% (+167% per kilogram). Eutrophication—the runoff of agricultural fertilizers into waterways—triggers massive, suffocating toxic algal blooms that choke out marine life.
In trying to save wild fish stocks from overfishing, the intensive agricultural inputs required to grow fish food on land are now polluting the very aquatic ecosystems we set out to protect.
The Consumer Catch-22: Land Competition and the Omega-3 Dilemma
This data brings two major dilemmas directly to the consumer's dinner plate.
1. The Human Food vs. Fish Feed Land Conflict
As the study highlights, soy protein concentrate and rapeseed oil have a highly disproportionate impact on land occupation. This creates a direct structural conflict with human food security. The more arable agricultural land, freshwater resources, and chemical fertilizers we dedicate to growing feed crops for farmed fish, the less land is available to grow crops directly for human consumption or to preserve native terrestrial biodiversity. Feeding fish a heavily vegetarian diet essentially turns aquaculture into a direct competitor with land-based agriculture.
2. Protecting the Ultimate Health Benefit: Omega-3 Levels
Seafood consumers don't just eat fish for taste; they eat it because marine foods provide long-chain Omega-3 fatty acids (EPA and DHA), which are absolute requirements for human brain function, cardiovascular resilience, and infant cognitive development. Farmed fish cannot magically produce Omega-3s on their own; they accumulate them through what they eat. When an aquaculture feed formula transitions heavily toward vegetable oils and soy protein, the nutritional profile of the harvested fish changes. While alternative terrestrial grains keep the fish alive and growing, they do not provide marine-sourced Omega-3s. Consequently, over-diluting marine ingredients risks lowering the very health benefits that drive consumers to buy seafood in the first place.
Crucially, this nutritional challenge does not mean farmed fish are a lost cause. In fact, a recent 2026 study titled “Fish as Food or Feed? Aligning FIFO with LCA and Food System Objectives” turns the traditional narrative completely on its head. The research reveals that under highly optimized farming conditions, certain aquaculture systems can actually transcend being a net drain on marine resources and become net producers of essential EPA and DHA fatty acids.
Specifically, the study highlights that Atlantic salmon farmed in the Faroe Islands, as well as tilapia farmed in China, are successfully generating more edible long-chain Omega-3s for human consumption than the marine ingredients they consume in their feed. By radically maximizing feed efficiency and nutrient retention, these regions demonstrate a vital proof-of-concept: when managed strategically, aquaculture can shift from a resource-depleting consumer into a powerful, net-positive contributor to global food security and human health.
What is the Solution? Moving Beyond Corporate Silos
If moving completely to plants causes terrestrial degradation, and over-relying on wild whole fish strains forage fish stocks, how do we establish real sustainability?
The University of Stirling study outlines a clear, circular solution: we must optimize and scale the resources we already have.
A key pathway identified by the researchers is the aggressive utilization of fisheries and aquaculture processing by-products—such as heads, frames, and trimmings left over from human seafood processing—to be rendered into clean fishmeal and fish oil. Over the past twenty years, using these nutritional by-products has allowed the industry to reduce its reliance on wild-caught forage fish without triggering any of the negative environmental trade-offs associated with land crops. It captures long-chain Omega-3s that would otherwise be discarded as waste, feeding them back into the loop to keep farmed fish highly nutritious.
Additionally, the development of novel feed ingredients—such as heterotrophic microalgae meals and single-cell proteins—shows massive long-term promise. However, as Dr. Wesley Malcorps notes in the study, these novel ingredients currently face significant commercial bottlenecks, including inefficient supply, high operational costs, and scaling challenges, meaning they have yet to deliver the widespread environmental relief the market expects.
The SCA Verdict: Holistic Transparency is Non-Negotiable
For the Seafood Consumers Association (SCA), this landmark research reinforces why we must stop evaluating sustainability through narrow corporate lenses or simplified marketing badges.
We must refuse to tolerate the blatant misrepresentation passing for 'green' marketing. When an eco-label or restaurant menu aggressively touts a '100% plant-based diet' for farmed salmon, they are passing a fraudulent environmental invoice down to the consumer. This isn't transparency; it's a calculated deception that hides the brutal toll of massive carbon emissions, water depletion, and severe land displacement. The Seafood Consumers Association demands an immediate end to these half-truths: consumers have a right to the unvarnished facts, not corporate fairytales that sell terrestrial destruction as an ecological victory.
True sustainability requires a holistic, honest look at the entire food production network. Consumers have a right to accurate, unassailable packaging information that tracks not just where a fish was farmed, but the transparent footprint of what it was fed. It is time to step out of isolated scientific silos, support local supply chain circularity, and demand consistent, transparent metrics across the entire global seafood system.
What do you think? Does knowing the environmental cost of plant-based fish feed change how you view farmed seafood? Let us know in the comments below and engage with the Seafood Consumers Association today to support our push for total supply chain transparency!
“26 Million Voices. One Seafood Future.”
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