Aquaculture’s wild fish use far higher than previously estimated
A new study published in Science Advances shows that the global aquaculture, including salmon farming, may rely on far more wild-caught fish than previously estimated.
Scientists from the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science challenged previous information about the sustainability of fish farming and suggested that the impact on wild fish populations is significantly higher than reported.
The research revises the "fish-in" (FI) ratio—a key metric for measuring the efficiency of aquaculture. The study found that wild fish inputs into aquaculture are between 27% and 307% higher than previous estimates. For carnivorous species like salmon, the wild fish inputs often exceeded double the amount of farmed fish biomass produced.
"Our study shows that the aquaculture industry relies more heavily on wild fish extraction than previously thought," said Spencer Roberts, the study's lead author and a doctoral student at the Rosenstiel School.
In contrast to previously-available information, the researchers included wild fish trimmings and byproducts, and also highlighted the practice of "slipping," where unwanted catch is released but often does not survive. In other words, they calculated the weight of wild fish caught, not just the weight included after processing for fishmeal.
The study calls for greater transparency and comprehensive reporting of feed ingredients used in aquaculture, warning that policies promoting aquaculture expansion on sustainability grounds may need reconsideration.
Jennifer Jacquet, a co-author of the study, emphasized that earlier assumptions about the sustainability of carnivorous aquaculture were overly optimistic. "This study highlights the need to rethink which aquatic species are most suitable for mass production," she said.