Aquaculture impacts wild fish much more than we thought

A recent study on aquaculture reveals that the journey from ocean to oven might be more complex and increasingly unsustainable.

Do you ever wonder how salmon or trout makes it to your dinner plate? While you might be thinking of a quaint fishing boat bobbing peacefully in the ocean, the reality could be quite different.

Hidden side of aquaculture

The study reveals that our global aquaculture industry, commonly known as fish farming, potentially relies on much more wild-caught fish than we had previously anticipated.

This revelation shakes the long-standing belief of a sustainable aquaculture industry and proposes a range of plausible estimates on its actual impact on wild fish populations.

The new insights are the result of rigorous research conducted by an international team of scientists from the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, Oceana, and New York University.

The team has reconsidered the “fish-in:fish-out” (FI:FO) ratio – a significant metric used to judge the efficiency and sustainability of aquaculture.

Ratio of wild-caught fish

The study suggests that the ratio of wild-caught fish used as input to farmed fish yielded as output is somewhere between 27% and 307% higher than previous estimates.

This could mean that for every farmed fish reaching our tables, up to 1.78 wild fish might have been used in the process, a far cry from the earlier estimate of only 0.28. Particularly for carnivorous farmed species like salmon, trout, and eel, the wild fish used might be double the farmed fish produced.

“Our study reveals that the aquaculture industry relies more heavily on wild fish extraction than previous research has suggested,” said lead author Spencer Roberts, a doctoral student at the Rosenstiel School in the Department of Environmental Science and Policy.

“This demonstrates the scale at which aquaculture could be impacting marine ecosystems.”

Overlooked reliance on wild fish

The research team dug deep and brought to light previously overlooked sources of wild fish in aquaculture feed, such as trimmings and by-products from wild-caught fish.

The experts also factored in collateral fishing mortality, like the practice of “slipping” where unwanted catch is released, but most don’t survive.

Jennifer Jacquet is a co-author of the study and a professor in the Department of Environmental Science and Policy at the Rosenstiel School.

“This research shows that the assumptions we have made about carnivorous aquaculture have been too optimistic, and is another reason to think strategically about the kinds of aquatic species it makes the most sense to mass produce,” said Professor Jacquet.

Trade-offs in the aquaculture industry

The study also casts light on the environmental trade-offs made in attempts to reduce wild fish use in aquaculture feed. The decline in wild fish use would require a five-fold increase in the use of terrestrial crops instead.

The study ominously suggests that the aquaculture industry’s rapidly increasing reliance on by-products and trimmings hasn’t phased out the capture and use of whole wild fish for feed.

Dr. Patricia Majluf is a senior scientist with Oceana in Peru, home to the world’s largest fishmeal fishery.

“The offshore aquaculture industry is growing so rapidly that the wild-caught fish are not being replaced in their feed. Instead, other feed sources are merely supplementing wild fish use,” explained Dr. Majluf.

Dependency of aquaculture on wild fish

The research exposes the need to reevaluate current aquaculture practices under the lens of sustainability.

It’s becoming increasingly clear that merely supplementing diets with terrestrial crops or leveraging by-products will not suffice in mitigating the environmental impacts highlighted by this research.

An interdisciplinary approach involving marine biologists, ecologists, and economists could guide the development of innovative solutions to reduce dependency on wild fish.

We must explore alternatives not only for feed but for the aquaculture production process as a whole to strike a balance between meeting global food demands and preserving marine ecosystems.

Sustainable seafood strategies

As aquaculture remains a critical component of global food security, we must turn our attention towards pioneering technology and sustainable methodologies.

Industry leaders are called to invest in research and development aiming at alternative protein sources, such as insect-based feeds or lab-grown alternatives, which show promise in reducing reliance on wild fish.

Meanwhile, consumer awareness regarding sustainable seafood choices can drive demand for responsibly farmed species.

The future of aquaculture depends on our collective commitment to innovate and comprehensive policies to promote sustainability.

Need for transparency and accountability

This eye-opening study raises important questions for policy-makers, investors, and consumers alike.

The need for comprehensive and transparent reporting of feed ingredients in the aquaculture industry has never been more important.

“It’s crucial that we have a more complete understanding of the industry’s impact on both marine and terrestrial ecosystems and reduce these uncertainties,” said study co-author Professor Matthew Hayek of New York University.

As our global demand for seafood continues to balloon, these findings emphasize the urgent need for more transparency in fish farming.

The study is published in the journal Science Advances.

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