The global demand for EPA and DHA, crucial omega-3 fatty acids, significantly exceeds the current supply. While marine sources are typically highlighted, the EPA + DHA density varies across aquatic foods depending on trophic level and species. Farmed fish represent half of the global aquatic food supply, but inland aquaculture in land-locked regions like Central Europe (CE) remains underdeveloped, leading to high reliance on imported marine fish. CE, particularly Czechia, exhibits low fish consumption and low blood EPA + DHA levels. The study focuses on Czechia as a case study, analyzing the nutrient footprints, eco-services, and resource use efficiency of different EPA + DHA sources (marine fish, farmed salmon, pond-farmed carp, and fish oil capsules) to determine sustainable strategies for improving EPA + DHA security in the region.

Existing literature emphasizes the global EPA + DHA supply gap and explores alternative sources like transgenic plants and microalgae. The environmental footprint of different aquatic foods varies significantly depending on the farming system and species. While aquaculture is a major food production sector, inland aquaculture in CE hasn't developed sufficiently to meet local demands, resulting in reliance on imports. Studies on the environmental impact of various EPA+DHA sources remain limited, highlighting a gap in existing research. Previous clinical trials show the low omega-3 index in CE populations, especially Czechia, and the positive health effects of increased fish consumption.

The study used Czechia as a representative of land-locked CE. Data on fish consumption patterns, EPA + DHA content of various fish products, and fish oil capsule consumption were compiled from various sources, including previously published research and unpublished datasets. The study focused on three primary EPA + DHA sources: pond-farmed carp, intensively farmed salmon, and fish oil capsules. Greenhouse gas emissions, nutrient effluents (nitrogen and phosphorus), and ecosystem services were calculated for each source. Resource use efficiency (RUE) was evaluated using EPA + DHA conversion ratios and concentration factors. Two experiments were conducted with carp: one on EPA + DHA digestibility from natural food sources in a controlled laboratory setting, and another on fatty acid balances from food to flesh in traditionally farmed carp. The study used data from various sources including FAO assessments, Norwegian industrial assessments, EU assessments, and published research on carp farming and fish oil production.

Czechia's daily per capita EPA + DHA intake is 217.8 mg, only 87% of the recommended intake. Marine fish, fish oil capsules, and farmed salmonids are the highest contributors to EPA + DHA supply. Terrestrial animal products have significantly higher GHG emissions per mg of EPA + DHA than aquatic sources. Intensively farmed salmon has lower GHG emissions per mg of EPA + DHA than traditionally farmed carp, but carp's lower production footprint and potential for positive ecosystem services need to be considered. Increasing EPA + DHA intake with minimal environmental impact requires pond-farmed carp with a finishing feeding strategy using local fish oil, as this approach could lower GHG emissions to levels comparable to or lower than fish oil capsules. Carp's EPA + DHA content can be significantly improved by finishing feeding strategies, reducing the differences in nutrient effluent and GHG emission per mg EPA+DHA compared to salmon. Pond carp systems demonstrate high resource use efficiency for EPA + DHA production compared to salmon, largely due to EPA + DHA accumulation from the pond food web. Experiments showed high EPA + DHA bioavailability from natural food and endogenous DHA synthesis in carp.

The findings highlight the need for a balanced approach to achieving EPA + DHA security in land-locked regions. While increasing consumption of oily marine fish could meet minimum intake requirements, relying solely on imports would be unsustainable. Pond-farmed carp, with improved production practices, offers a more environmentally sustainable and resource-efficient option to complement imported fish and fish oil capsules. The high resource use efficiency of pond carp, combined with its potential for positive ecosystem services, makes it a valuable addition to the regional food system. The synergistic health benefits of consuming whole fish, including fish protein peptides, should also be considered.

This study demonstrates that a combination of sustainably produced pond-farmed carp and imported marine fish or fish oil capsules is the most effective strategy for ensuring EPA+DHA security in land-locked regions like Central Europe. Future research should focus on optimizing pond-carp farming techniques to further enhance EPA+DHA content and reduce environmental impact. Investigating the potential of circular fish oil from local waste streams for use in finishing feeds is also warranted.

The study primarily focuses on Czechia, which may not fully represent the entire land-locked CE region. The data on fish oil capsule consumption in Czechia relied on extrapolation from a clinical trial, potentially introducing some uncertainty. The assessment of ecosystem services primarily focused on pond carp systems; a comprehensive comparison with other aquaculture systems would provide more context. Future studies could improve the accuracy of GHG emissions accounting by considering factors such as feed production emissions and transportation.