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• Direct human consumption provides an additional 75% edible protein as compared to aquaculture return. • Aquaculture yields <27% edible biomass from total production. • Even at a feed conversion rate of 0.7, a 57% protein loss is identified. • From an economic perspective, direct consumption is preferred over aquafeed. • More than 7 kg of non-marine ingredients are needed to obtain 1 kg of farmed trout protein. The growing pressure on pelagic resources and the dilemma of redirecting high-nutritional whole fish to aquafeed, underscore the need for quantitative evidence to maximize marine-protein availability for human consumption. This study compares two scenarios with anchovy ( Engraulis spp. ) and tuna ( Thunnus spp .): 1) minimally processed marine biomass for direct human consumption (DHC); and, 2) whole-fish rendered into fishmeal and fish oil (FMFO) for aquafeeds (indirect human consumption), with trout ( Oncorhynchus mykiss ) as farmed specie. A material flow analysis was performed using 1 t of cleaned pelagic-fish ready for DHC as functional unit, with system boundaries spanning from wild landings to fish on the plate. Mass-protein balances were modeled with STAN software. Net relative protein-return, energy-return, and the relative-profitability indicators were calculated for each product-process. Results show that all indicators applied favor DHC, even under optimized feed conversion rates. In protein-efficiency terms, these findings corroborate that DHC of pelagic fish outperforms its use as aquafeed, making it the preferred strategy, especially in contexts of food insecurity and limited supplies of high-biological value protein.
Sousa et al. (Sat,) studied this question.