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Higher percentage of plant-based ingredients in feed
could alter levels of healthy fatty acids and
environmental footprint in farm-raised fish.
The fish-farming
industry is increasing its use of plant-based
ingredients in its feed and moving away from
traditional feed made from fish, which could impact
some of the health benefits of eating certain types
of seafood, suggests a new analysis from the Johns
Hopkins Center for a Livable Future (CLF) at the
Johns Hopkins Bloomberg School of Public Health.
The findings are
published March 11 in the journal Environment
International.
Half of the seafood
consumed by Americans is farmed. Fish farming, also
known as aquaculture, is the fastest-growing food
animal sector, outpacing the beef and poultry
industries. While wild fish find their own food –
which includes smaller fish for carnivorous species
– intensively farmed fish are fed a manufactured
aquaculture feed.
Until recently, this manufactured feed was typically
composed of high levels of fishmeal and fish oil
derived from wild fish — but it has become
unsustainable to catch more wild fish to feed
growing numbers of farmed fish, so the industry has
shifted the makeup of the feed. For example, twice
as much soybean meal was used in commercial
aquaculture feed in 2008 as compared to fishmeal,
and the use of crop-based ingredients is projected
to increase 124 percent between 2008 and 2020.
“Farmed fish get their
health-promoting omega-3 fatty acids, EPA and DHA,
from their feed, and specifically from fish oil,”
says study leader Jillian Fry, PhD, director of
CLF’s Public Health and Sustainable Aquaculture
Project and a faculty member at the Bloomberg
School. “Our review found that increasing
plant-based ingredients can change the fatty acid
content in farmed fish, which can affect human
nutrition.”
The new study details
the industry shift to crop-based feed ingredients,
such as soy, corn, and wheat, to replace wild fish
as a key ingredient in manufactured feed. The
researchers—in collaboration with colleagues from
the University of Minnesota’s Institute on the
Environment and McGill University - reviewed
aquaculture and public health literature, and
conducted a new analysis to estimate the
environmental footprint for the top five crops used
in commercial aquaculture feed.
The shift has been
hailed by some as a positive change in light of the
increasingly depleted oceans and the rapidly
expanding aquaculture industry. But the shift may
have some unintended consequences as well.
Using vegetable oils
instead of fish oil changes the fatty acid content
of fish and nutritional value for human consumption,
the researchers say. Considering Americans are
encouraged to consume seafood high in omega-3 fatty
acids, which promote improved cardiovascular health
and neurodevelopment, this has large implications
for dietary recommendations and the aquaculture
industry. More research is needed, they say, to
better understand the impact of this shift in feed
on the health benefits of consuming farmed fish.
While fish-based
ingredients are seen as acutely limited, so are the
resources such as land, water and fertilizer used to
produce feed crops.
Aquaculture’s environmental footprint likely now
includes increased nutrient and pesticide runoff
from the industrial crop production needed to supply
fish food. This runoff is a key driver of water
pollution globally, and can negatively impact public
health.
Depending on where and how feed crops are produced,
plant-based fish feed could be indirectly linked to
negative health outcomes for agricultural workers
and nearby communities due to exposure to air, water
or soil contaminated by nutrients and/or pesticides.
Fry says that these new
findings may raise more questions than they answer.
“The nutritional content
of farmed fish should be monitored,” Fry says. “The
aquaculture industry should assess the environmental
footprint and public health impacts of their
crop-based feed ingredients and seek those produced
using sustainable methods.”
For more information
“Environmental Health Impacts of Feeding Crops to
Farmed Fish” was written by Jillian P. Fry, David C.
Love, Graham K. MacDonald, Paul C. West, Peder M.
Engstrom, Keeve E. Nachman, and Robert S. Lawrence.
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Johns Hopkins University
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University of Minnesota’s Institute on the
Environment
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McGill University
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