Marine ingredients are still regarded as a vital constituent of aquaculture feed. Yet, they are often associated with being not sustainable. “But nuance is required here. Currently, there is simply not a lot of detailed information on the environmental impact of all the different marine ingredients (derived from different fish species) we have available, including all the different production systems and regions considered. So, we should not measure them by the same standards,” says Dr. Richard Newton from the Institute of Aquaculture at the University of Stirling in the UK.
One process, multiple fish (co)-products
Newton explains that Life Cycle Assessment (LCA) calculations are increasingly used – and a great tool – to assess the environmental impact of general feed ingredients but may not always give the complete picture for marine ingredients. “This is because standard LCAs are not always equipped to deal with single processes that produce multiple products, as we see in aquaculture. From fish, we produce premium filets, but also trimmings/co-products that are further rendered into fishmeal and fish oil. This means that environmental impact also has to be divided between the different (co)-products that come out of the same process. This can be done by mass allocation (simply dividing the impact based on the weight of each co-product) or it can be done by using the so-called economic allocation. The latter looks at the value of each co-product. Fillets have a higher value than by-products, so they would take a bigger proportion of the environmental impact when the economic allocation is used.”
Unique inventory of available data
To get a better picture of the environmental impact of different marine ingredients, Newton and his team delved into the available information to date. The results were published in the February issue of Aquaculture. “In our ‘Life Cycle Inventory’, we included the broadest range of fish species and geographies to date. We did an extensive analysis of relevant literature complemented with 1) fisheries data (LCA, environmental impact, and energy and fuel consumption studies), 2) processing data from a mixture of primary data collection and literature resources, and 3) rendering data sourced from literature sources. This library was then demonstrated based on economic allocation. We also added two more impact categories that are important to consider, but often not considered in the standard LCA software and hence calculated separately: FIFO and BRU. The FIFO (Fish In:Fish Out) ratio measures the efficiency of fishmeal and fish oil that is used to produce one weight equivalent of farmed fish from wild fish weight equivalents. BRU (Biotic Resource Use) is the impact of fisheries on biotic resources from Net Primary Production appropriation through food webs, typically applied to marine organisms (it has not been applied to terrestrial organisms yet). Adding these metrics to the LCA is important to allow comparison between trade-offs of different marine ingredients against the environmental impact of other types of ingredients used in fish diets,” Newton explains.
Large differences between products
Demonstration of the inventory using an economically allocated LCA showed that marine ingredients are very variable in their impact between, and even within species, mostly depending on the fuel intensity of the fishery from which they are sourced. “I was quite surprised by this huge variety. Within our data set, Danish herring and mackerel meals were highly impacting compared to the same species from other countries (as much as three times higher than Icelandic and Spanish meals). This was due to higher fuel use across all fishery types, including high fuel-intensity demersal and mixed fisheries that contribute to the overall herring and mackerel national catch. Norwegian herring and mackerel are also derived from mixed fisheries in different amounts, but generally have lower fuel intensities than similar Danish fisheries. By-product meals generally had lower impacts than whole fishmeals using economic allocation, although white fish by-product meal impacts were higher because of the fuel intensity of demersal fisheries and the low yields from rendering. The data shows that there is a large range of impacts related to different sources of marine ingredients and they should not be treated as a single entity, but rather looked at individually,” Newton explains.
Driving circular economy principles
Newton sees potential to expand the use of sustainable marine ingredient supplies if we can better valorize underutilized seafood by-product resources. And this starts with having more data on rendering and connecting more data (such as LCA and FIFO ratios) with each other. Newton addresses: “Driving by-product use also depends on which type of allocation you implement: mass allocation or economic allocation. I personally think that economic allocation in LCAs gives more realistic outcomes because you divide the environmental impact according to the value of each product that is derived from the fish. The lower allocation of environmental impact to by-products (marine ingredients) encourages its use and drives circular economic principles. But there are different views on this in the aquaculture community. The fact is that there will always be some uncertainties in LCAs, independent of which software or allocation you use. But to encourage positive change, the value we give to by-products is important. Giving them a high carbon impact figure (as done in mass allocation LCAs) is not driving its use.”
Bridging further data gaps
Newton believes that sustainable marine ingredient supplies should remain part of the growing pool of aquafeed ingredients available. “This is important to meet the growing demand for fish products for human consumption. Yet, we should use marine ingredients in the most strategic and sustainable way, and where they are most effective. This requires more inputs for LCAs and incorporates more metrics (such as FIFO). We also ‘simply’ need more data. In our inventory, we used (Western) information that represents an estimated 48% of global supplies. But we need better primary data on African and Asian fisheries as well, considering the huge growth of African aquaculture and the fact that Chinese, Thai, Vietnamese, and Japanese fisheries constitute a further 26% of global marine ingredient supplies. In addition, more and better data on rendering the raw materials into fishmeal and oil is needed to be able to improve the quantification of marine ingredient environmental impact and do a more holistic sustainability assessment and better value chain analysis. In future studies we will try to bridge more of these knowledge gaps,” Newton concludes.
