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Dependence on Wild Fish in Global Aquaculture Raises Concerns

A recent study published in Science Advances reveals a troubling trend in the global aquaculture industry: an increasing reliance on wild fish populations. Contrary to claims made by the aquaculture sector, these findings suggest that the burgeoning demand for high-end farmed salmon is making it difficult for coastal communities to access affordable local fish such as sardines and anchovies.

Instead of being used for direct human consumption, these smaller pelagic fish are often harvested, processed, and turned into fishmeal and fish oil. Astonishingly, these reduction fisheries account for 26% of the total global fish catch.

Dr. Kathryn Matthews, Oceana Chief Scientist and co-author of the study, emphasized, “As the aquaculture industry grows, so does its dependence on wild fish. The rapid expansion of this sector will require an increasing amount of fishmeal and fish oil, even if feed efficiency improves.” This dependence poses significant challenges not only for the ecosystem but also for communities relying on these fish for their livelihood.

The research team, which includes notable scholars such as Dr. Patricia Majluf from Cayetano Heredia University, and Dr. Daniel Pauly from the Sea Around Us project, critiques the industry’s use of the “Fish-in-Fish-out” (FIFO) ratio, a standard metric aimed at estimating the quantity of wild fish utilized in producing farmed fish.

Historically, the FIFO ratio has been employed as a yardstick to evaluate aquaculture’s impact on wild fish stocks. However, the authors highlight several misleading methodologies associated with its calculation. For example, combining the fishmeal and fish oil inputs of both carnivorous and herbivorous fish often obscures the substantial feed requirements of carnivorous species, resulting in a falsely favorable FIFO ratio for the aquaculture industry.

This manipulation allows the sector to assert that its reliance on fish oil and fishmeal is decreasing. However, the reality is stark; fish oil is becoming a scarce resource, increasingly sought after by salmon farms, which currently account for 70% of the global salmon supply. According to the authors, farmed Atlantic salmon alone constituted 60% of fish oil usage in 2020.

“The salmon industry does not merely serve as a food production system; it represents a food reduction system,” Dr. Matthews argued. “It benefits a select few who can afford it while depriving those in need of nutritious fish.” This sentiment is reinforced by evidence from West Africa, where processing facilities are extracting large quantities of highly nutritious sardinella, primarily for export as fishmeal and fish oil, further disadvantaging local communities.

Moreover, the authors forewarn about the precarious future looming over fishmeal and fish oil production, particularly influenced by climate change, which adversely affects fish populations globally. One of the primary sources for fishmeal and fish oil, the Peruvian anchoveta, is particularly vulnerable as warming waters reduce its oil content.

The ongoing mismanagement of these fisheries exacerbates the situation, leading to increased catches of juvenile fish, which inherently contain less oil. “These combined challenges are pushing feed manufacturers to seek alternative sources of oil, including fish typically intended for human consumption,” Dr. Majluf added.

Given these complications, the authors strongly encourage the aquaculture industry to explore viable substitutes for both fishmeal and fish oil in their feeding practices. This report constitutes a crucial piece of a broader special issue on aquaculture published in Science Advances, which also highlights the necessity for enhanced transparency in aquaculture subsidy reporting, as discussed by Dr. Rashid Sumaila, a fisheries economist and Oceana Board Member.

More information: Patricia Majluf, A review of the global use of fishmeal and fish oil and the Fish In:Fish Out metric, Science Advances (2024). DOI: 10.1126/sciadv.adn5650. www.science.org/doi/10.1126/sciadv.adn5650

Citation: Global north’s growing appetite for farmed salmon imperils communities’ access to local fish, study warns (2024, October 16) retrieved 16 October 2024 from https://phys.org/news/2024-10-global-north-appetite-farmed-salmon.html

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