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Study Highlights Increased Wild Fish Dependency in Global Aquaculture

A recent study published in Science Advances presents a compelling argument that the global aquaculture sector may be more reliant on wild-caught fish than previously understood. This research is featured in a special issue dedicated to enhancing sustainable practices within the aquaculture industry.

The study’s results challenge existing views on the industry’s sustainability, presenting a broad spectrum of estimates regarding the ecosystem’s strain due to fish farming. Focused on the “fish-in:fish-out” (FI:FO) ratio, a key measure of aquaculture’s efficiency, the findings indicate that the reliance on wild fish may be considerably higher—by 27% to 307% than earlier calculations. Specifically, the revised FI:FO ratios range from 0.36 to 1.15, a stark contrast to the prior estimate of 0.28. When accounting for wild fish mortality associated with capture and excluding systems that do not require feed, this ratio escalates to 0.57 to 1.78. For predators raised in aquaculture, such as salmon and trout, intake of wild fish could exceed twice the biomass produced.

Lead author Spencer Roberts, a doctoral student at the Rosenstiel School of Marine, Atmospheric, and Earth Science, emphasized the implications of the findings: “Our research demonstrates that aquaculture’s dependency on wild fish extraction is more significant than previous studies have indicated, potentially impacting marine ecosystems on a larger scale.”

The research team innovatively factored in previously ignored sources of wild fish in aquaculture feeds, such as fish trimmings and byproducts, while also considering collateral mortality from practices like “slipping,” where non-target species are released but often perish. By analyzing a variety of datasets reported by the industry, the team was able to shed light on uncertainties prevalent in current fisheries reporting.

Co-author Jennifer Jacquet voiced concerns about previous assumptions surrounding carnivorous aquaculture, noting that they had been overly optimistic. This realization further highlights the need to strategically choose species suitable for mass production.

The research delved into the environmental trades-offs of diminishing the use of wild fish in aquaculture feeds. It found that the often-quoted reductions in wild fish usage from 1997-2017 would necessitate a more than fivefold increase in terrestrial crop usage during the same timeframe.

Patricia Majluf from Oceana in Peru, home to the world’s largest fishmeal fishery, remarked on the trend: while there has been an increase in the utilization of by-products and trimmings, the use of whole wild fish remains prevalent in aquaculture feed. “The offshore aquaculture industry is expanding so quickly that the reliance on wild-caught fish is not diminishing—rather, other feed sources are being used to supplement it,” she explained.

The implications of this research are far-reaching for lawmakers, investors, and consumers alike. The study advocates for more robust and transparent reporting regarding aquaculture feed ingredients and suggests that policies promoting aquaculture growth based on sustainability should be thoroughly reassessed.

Matthew Hayek, an assistant professor at New York University and the study’s corresponding author, stated, “A holistic understanding of the sector’s influences on both marine and terrestrial environments is critical in reducing uncertainties.” He reiterated that even allowing for the wide range of uncertainty presented, the impacts remain substantial; many fish farming operations are focused on carnivorous species, which deplete more wild fish from the oceans than they ultimately yield.

While the study provides a comprehensive evaluation of the environmental effects of aquaculture, the researchers emphasize that further investigation is needed to grasp the broader implications related to nutrient pollution, habitat degradation, and the potential transmission of diseases to wild fish populations.

With the global demand for seafood continuing to escalate, this study underscores the pressing need for greater transparency and sustainable practices in fish farming.

More information: Spencer Roberts et al, Feeding Global Aquaculture, Science Advances (2024). DOI: 10.1126/sciadv.adn9698

Citation: Aquaculture uses far more wild fish than previously estimated, study finds (2024, October 16) retrieved 16 October 2024 from phys.org

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