The aquaculture industry faces criticism for its reliance on wild fish as feed, prompting the development of metrics like Fish In: Fish Out (FIFO) to assess the efficiency of fish inputs. However, FIFO fails to account for the retention of essential nutrients, particularly omega-3 long chain polyunsaturated fatty acids (LC-PUFAs), in the final aquaculture products. This document introduces the nutrient FIFO (nFIFO) ratio to better measure nutrient retention from marine ingredients (MIs) in aquaculture, specifically focusing on LC-PUFA retention in farmed salmon, which was found to average 37.4%. The study also explores the economic implications of using processing by-products versus whole fish in feed, revealing that nFIFO improves significantly with the use of by-products and is influenced by fluctuating fish oil prices. Additionally, the research highlights the need for precise feed data due to variability in nutritional content, and provides an Excel tool for stakeholders to calculate nFIFO and FIFO metrics effectively.
Introduction
Aquatic foods, primarily fish, molluscs, and crustaceans, have historically been vital for global food security and nutrition. They are the primary source of n-3 LC-PUFAs, essential for brain and cardiovascular health. Marine phytoplankton synthesize these fatty acids, which accumulate in the marine food web, making small oily fish like anchovies and sardines rich sources for human consumption. Farmed fish, such as salmon, can also provide these nutrients if fed appropriately. However, there is a debate regarding the efficiency of using marine ingredients (MIs) in aquafeed, especially when these ingredients come from species that could be consumed directly by humans. Studies suggest that nutrient retention is more effective when marine resources are consumed directly, but processing is necessary to utilize inedible fish parts.
The marine ingredients industry has existed before modern aquaculture, with significant production peaks in the 1990s. However, the rapid growth of aquaculture has raised sustainability concerns regarding the finite supply of MIs, which are heavily utilized in aquaculture. Issues such as climate variability affecting fish stocks and competition for food-grade fish for export complicate the situation. Although many fisheries are well-managed, the demand for aquatic food is increasing, leading to economic and environmental pressures.
Despite the push for direct consumption of small fish, the marine ingredient sector remains crucial due to its nutritional benefits in livestock feeds. Many fish species directed to MIs are unsuitable for human consumption or have low market appeal. There is potential to increase marine ingredient raw materials from processing by-products, but challenges exist in logistics and market scalability. Ideally, food-grade fish would be consumed directly, with by-products used for animal feeds to maximize nutrient retention.
The paper aims to develop a nutrient retention scoring tool for salmon production, termed nFIFO, based on the Fish In: Fish Out (FIFO) metric. While existing metrics focus on general nutrition efficiency, nFIFO will specifically address nutrient retention from marine ingredients in aquaculture. This tool will help measure the retention of key nutrients like n-3 LC-PUFAs, allowing for strategic adjustments in feed formulations to enhance nutrition for consumers. The nFIFO metric could potentially be applied to various nutrients and cultured species, depending on data availability.
Economic Allocation and Byproducts in Aquaculture
The application of economic allocatio principles in the context of Life Cycle Assessment (LCA) for fish feed production, highlights the significance of byproducts from fish processing, such as trimmings and offal, in enhancing the sustainability and efficiency of aquaculture. The findings suggest that by utilizing these byproducts, the environmental impact of fish feed can be mitigated while still providing essential nutrients to farmed fish.
The application of these principles in assessing fish feed production reveals the potential for byproducts to play a pivotal role in enhancing the sustainability of aquaculture. By utilizing trimmings and offal, the industry can improve the nFIFO ratio, reduce waste, and ensure that farmed fish receive the necessary nutrients for healthy growth. The integration of processing byproducts in aquafeeds as a means to foster a more sustainable aquaculture sector.
Testing the nFIFO Model: The sensitivity analysis
To evaluate the robustness of the nFIFO model in aquaculture, the analysis involved simulating two distinct scenarios: the replacement of whole fish with byproducts and the impact of rising fish oil prices. The results indicate significant insights into how these factors influence nutrient retention and economic viability in aquaculture practices.
The sensitivity analysis demonstrates that both the replacement of whole fish with byproducts and the fluctuations in fish oil prices play crucial roles in determining the nFIFO ratio. These findings can guide future aquaculture practices towards more sustainable and economically viable solutions.
Implications for Aquaculture Sustainability
The implications of the nFIFO ratio in aquaculture, emphasize its role in enhancing nutrient retention, particularly for omega-3 long-chain polyunsaturated fatty acids (LC-PUFA). By shifting the focus from biomass to nutrient flows, the nFIFO ratio provides a comprehensive framework for assessing sustainability in aquaculture. Additionally, the document discusses the significance of utilizing processing byproducts in aquafeeds, which can lead to reduced waste and improved nutrient retention, ultimately supporting the sustainability of wild fish stocks.
Conclusion
The nFIFO ratio marks a significant improvement in measuring aquaculture efficiency by addressing the limitations of the traditional FIFO (First In, First Out) ratios. Unlike FIFO, which often overlooks the complexities of nutrient retention and sustainability, the nFIFO ratio specifically targets the retention of essential nutrients, providing a more precise evaluation of aquaculture systems’ performance in sustainable practices.
Recent studies highlight the potential of utilizing processing byproducts to boost nutrient retention in aquaculture feeds. This strategy not only enhances the nutritional quality of aquaculture products but also minimizes waste and reduces the environmental impact of operations. As global challenges like climate change and food security escalate, tools like the nFIFO ratio are vital for the aquaculture industry to sustainably meet the increasing nutritional demands of the growing population while lessening its ecological footprint.
Source : Newton, R. W., Malcorps, W., Robinson, J. P., Kok, B., Little, D. C., Lofstedt, A., De Roos, B., & Willer, D. F. (2025). Fish as Feed: Using the nutrient Fish In: Fish Out ratio (nFIFO) to enhance nutrient retention in aquaculture. Aquaculture, 602, 742332. https://doi.org/10.1016/j.aquaculture.2025.742332
