Environmental Benefits of Novel Nonhuman Food Inputs to Salmon Feeds

Global population growth and changing
diets increase the importance,
and challenges, of reducing the environmental impacts of food production.
Farmed seafood is a relatively efficient way to produce protein and
has already overtaken wild fisheries. The use of protein-rich food
crops, such as soy, instead of fishmeal in aquaculture feed diverts
these important protein sources away from direct human consumption
and creates new environmental challenges. Single cell proteins (SCPs),
including bacteria and yeast, have recently emerged as replacements
for plant-based proteins in salmon feeds. Attributional life cycle
assessment is used to compare salmon feeds based on protein from soy,
methanotrophic bacteria, and yeast ingredients. All ingredients are
modeled at the industrial production scale and compared based on seven
resource use and emissions indicators. Yeast protein concentrate showed
drastically lower impacts in all categories compared to soy protein
concentrate. Bacteria meal also had lower impacts than soy protein
concentrate for five of the seven indicators. When these target meals
were incorporated into complete feeds the relative trends remain fairly
constant, but benefits of the novel ingredients are dampened by high
impacts from the nontarget ingredients. Particularly, primary production
requirements (PPR) are about equal and constant across all feeds for
both analyses since PPR was driven by fishmeal and oil. The bacteria-based
feed has the highest climate change impacts due to the use of methane
to feed the bacteria who then release carbon dioxide. Overall, the
results of this study suggest that incorporating SCP ingredients into
salmon feeds can help reduce the environmental impacts of salmon production.
Continued improvements in SCP production would further increase the
sustainability of salmon farming.