"Our study reveals that the aquaculture industry relies more heavily on wild fish extraction than previous research has suggested," said Spencer Roberts, a doctoral student at the Rosenstiel School in the Department of Environmental Science and Policy, and lead author of the study. Pictured: a salmon farm in Norway.
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A new study published in Science Advances has found that global aquaculture is more dependent on wild-caught ocean fish than earlier calculations have suggested.
The research, led by scientists from the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science, ocean advocacy organization Oceana, and New York University, and published on October 16, reassesses the "fish-in-fish-out" (FIFO) ratio, a key metric that evaluates how much wild fish biomass is required to produce farmed fish.
According to the analysis, the updated FIFO ratio spans from 0.36 to 1.15, compared to the previously established ratio of 0.28 - indicating that wild fish inputs into aquaculture range from 27% to an astonishing 307% higher than previously estimated. Furthermore, when accounting for wild fish mortality during capture and excluding "unfed" aquaculture systems, the ratio is even higher, ranging from 0.57 to 1.78, the researchers found.
The research team used multiple industry-reported datasets and the study also included previously overlooked sources of wild fish used in aquaculture feed, such as trimmings and byproducts from wild catches, as well as accounting for discarded bycatch. For certain carnivorous species like salmon and trout, the researchers found that wild fish inputs could be more than double the farmed fish produced.
"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 co-author and Rosenstiel professor Jennifer Jacquet, in a press release.
The study also looked at the "environmental trade-offs" involved in reducing reliance on wild fish in aquaculture feed. According to the analysis, estimated reduction in use of wild fish between 1997-2017 would "require a more than five-fold increase in the use of terrestrial crops over the same period".
Meanwhile, Patricia Majluf, a senior scientist at Oceana Peru and co-author on the study, pointed out that while by-products and trimmings are increasingly used in aquaculture feed, they have not replaced whole wild fish.
"The offshore aquaculture industry is growing so rapidly that the wild-caught fish is not being replaced in their feed. Instead, other feed sources are just supplementing wild fish use," stated Majluf.
The study's findings could have important implications for sustainability policies related to aquaculture, the researchers argue, urging for greater transparency and comprehensive reporting in the aquaculture industry, as well as a reevaluation of policies promoting aquaculture expansion.
The full article can be accessed online at Science Advances here.
