Fish farming — or aquaculture — holds vast potential in feeding the world, scientists believe.
However, a new study by the University of Miami’s Rosenstiel School has found that global fish farming relies on larger quantities of wild-caught ocean fish than previously believed, according to a news release by the university. These wild-caught fish end up in feed for carnivorous farmed species, such as salmon, trout and eel.
The study was part of a special issue focused on expanding contributions from the aquaculture industry to food systems with an aim toward sustainability.
“These findings call into question long-held assumptions about the sustainability of the rapidly growing aquaculture industry and provide a range of plausible estimates for its impact on wild fish populations,” the October 17 news release stated.
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The research was led by an international team of scientists from Rosenstiel, Peru’s Oceana, and New York University. It provided a reassessment of the “fish-in:fish-out” (FI:FO) ratio for global fed aquaculture—a key metric used to evaluate the efficiency and sustainability of aquaculture.
The findings indicate that the ratio of wild fish inputs to farmed fish outputs is 27% to 30% higher than previous estimates. For carnivorous farmed species, wild fish inputs likely exceeded twice the farmed fish biomass produced.
“Our study reveals that the aquaculture industry relies more heavily on wild fish extraction than previous research has suggested,” said Spencer Roberts, a Rosenstiel doctoral student and lead author of the study. “This demonstrates the scale at which aquaculture could be impacting marine ecosystems.”
The research team’s approach included accounting for previously overlooked sources of wild fish in aquaculture feed, such as trimmings and byproducts from wild-caught fish.
“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 Jennifer Jacquet, a co-author of the study and a Rosenstiel professor.
The study also examined the environmental trade-offs involved in reducing wild fish use in aquaculture feed.
“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,” said Patricia Majluf, a senior scientist with Oceana.
Peru is home to the largest fishmeal fishery in the world.
The findings have significant implications for policy-makers, investors, and consumers, the news release stated. The study called for more comprehensive and transparent reporting of feed ingredients in the aquaculture industry.
