A recent study indicates that fish farming globally, known as aquaculture, may depend on much larger amounts of wild-caught fish from oceans than earlier estimates suggested. This research falls under a special issue aimed at exploring how aquaculture can more effectively contribute to sustainable food systems.
A recent study published in Science Advances indicates that fish farming globally, commonly referred to as aquaculture, might heavily depend on wild-caught ocean fish in significantly higher volumes than previously thought. This research is part of a broader initiative aimed at enhancing the role of aquaculture in sustainable food systems.
These new findings challenge long-standing beliefs regarding the sustainability of the rapidly developing aquaculture sector and offer various reasonable estimates for its effects on wild fish stocks.
Led 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 study re-evaluates the “fish-in:fish-out” (FI:FO) ratio for globally fed aquaculture, a critical measure to assess the practice’s efficiency and sustainability.
The research reveals that the ratio of wild fish used in producing farmed fish is between 27% and 307% higher than earlier figures, sitting between 0.36 and 1.15, compared to a previous estimate of only 0.28. When accounting for fish deaths during capture and excluding systems that do not use feed, this ratio can increase to between 0.57 and 1.78. Specifically for carnivorous species like salmon, trout, and eel, the amount of wild fish used could be more than double the biomass of farmed fish produced.
Spencer Roberts, a Ph.D. candidate at the Rosenstiel School and the study’s lead author, commented, “Our study shows that the aquaculture sector depends more on the extraction of wild fish than past research has indicated. This highlights the significant impact aquaculture might have on marine ecosystems.”
The researchers took into account previously missed sources of wild fish in aquaculture feed, including fish trimmings and byproducts. They also considered collateral fishing deaths from practices like “slipping,” where unwanted catch is returned but many do not survive. By analyzing several datasets reported by the industry, the team offered a range of estimates and highlighted the uncertainties in current reporting methods.
“This research reveals that our assumptions about carnivorous aquaculture have been overly optimistic and emphasizes the need for strategic consideration regarding which aquatic species are most viable for mass production,” said Jennifer Jacquet, a co-author of the study and a professor at the Rosenstiel School.
The study also assessed the environmental compromises involved in decreasing the use of wild fish in aquaculture feed. The researchers found that commonly referenced drops in wild fish usage from 1997 to 2017 would necessitate over a five-fold rise in the use of land-based crops during the same timeframe.
Patricia Majluf, Ph.D., a senior scientist with Oceana in Peru, which hosts the world’s largest fishmeal fishery, remarked that even with the increasing use of by-products and trimmings, the capture and consumption of whole wild fish for aquaculture feed has not declined. “The rapidly expanding offshore aquaculture industry is not replacing wild-caught fish in their feed. Instead, they are adding alternative feed sources to the wild fish usage,” noted Majluf.
The implications of these findings are significant for policy-makers, investors, and consumers alike. The study calls for a more thorough and transparent reporting system of feed components within the aquaculture sector and suggests a reevaluation of policies that promote aquaculture expansion based on sustainability claims.
Matthew Hayek, an assistant professor in the Department of Environmental Studies at New York University and the study’s corresponding author, emphasized, “It’s essential to gain a fuller understanding of the industry’s effects on marine and terrestrial ecosystems and to mitigate these uncertainties.” He pointed out that even with the broad uncertainty ranges identified, the impacts are greater than previously recorded, and “most offshore finfish aquaculture operations raise carnivorous fish, hence they are extracting far more fish from the ocean than they can produce.”
The researchers highlight that while their study offers a deeper understanding of aquaculture’s environmental impacts, additional research is vital to fully comprehend the sector’s effects on issues like nutrient pollution, habitat loss, and the transmission of diseases to wild fish populations.
As global seafood demand continues to rise, these findings stress the urgent need for increased transparency in fish farming practices.
Support for this research was contributed to Spencer Roberts and Matthew Hayek by the Grace Communications Foundation.
