‘Aquafeed 3.0’: creating a more resilient aquaculture industry with a circular bioeconomy framework

As aquaculture continues to grow, so does the requirement for environmentally sustainable and cost-effective aquafeed. With an expected increase in aquafeed demand, it is important (now more than ever) to investigate and utilize new aquafeed ingredients that do not deplete natural resources and, instead, may have positive impacts to help control climate change. Aquaculture has become the largest consumer of global fishmeal (FM) and fish oil (FO) production, accounting for 68% and 89%, respectively (Hua et al. 2019). At the same time, most modern aquafeed are now predominantly composed of terrestrial plant materials and animal by-products [in this issue, you can find a fascinating article describing how aquafeed have evolved and the consequent call for rethinking trophic levels in aquaculture policies (Cottrell et al. 2021)]. This puts heavy reliance on terrestrial agriculture products, which have their own sustainability issues, such as freshwater use, deforestation, areal footprint, pesticide and fertilizer use, irrigation and polluting runoff. Furthermore, the use of terrestrial crops in aquafeed directly compete with human food streams. Besides, many of the terrestrial plant ingredients present certain nutritional challenges for farmed aquatic species. Climate change can exacerbate the situation, hampering the ability to produce crops consistently, in extreme and increasingly unpredictable conditions, and jeopardizing the long-term sustainability of marine products harvesting. The supply, cost, environmental sustainability and social acceptability of raw materials for aquafeed are under threat. The direct consequences for aquafeed, and with a snowball effect, the consequences for global aquaculture economic viability, environmental sustainability and social license to operate are significant. As a result, the industry must develop innovative practices that involve conservation, restoration and/ or remediation. This presents new opportunities for nextgeneration protein and lipid sources for aquafeed that will be more resilient and consistent, in our changing and seemingly unstable world. One such opportunity is the production of nutritional resources that are created through the circular bioeconomy. This encompasses the production of renewable biological resources and converting these resources and their byproducts and waste streams into value-added products, such as food, feed, bio-based products and bioenergy. It is all about valorization – and keeping the value of biomass cascading. The extensive organic biomass and waste streams from agriculture, forestry, fisheries, food and feed and organic processing waste should be integrated into a circular, bioeconomy strategy. It also creates opportunities to link very different industries, which is a unique strength of the bioeconomy concept. This allows for greater diversification and resilience, with the ultimate goal of using renewable natural resources to achieve a sustainable balance in food production and ecological conservation. Of course, this demands innovations, new technologies, knowledgebased processes and new applications, as well as a cultural shift. Efforts towards a climateand ecology-positive economy in aquafeed production will mean moving further away from traditional wild-harvested FM and FO and agricultural crops, shifting towards ingredients produced through the circular bioeconomy. This also has the potential to result in locally sourced aquafeed ingredients, which can reduce transport-related greenhouse gases (GHG) emissions and costs, fuel local economies, create new jobs and overall are more socially accepted and environmentally sustainable. From their infancy, the evolution of aquafeed from being mostly FM and FO-based, to become primarily terrestrialbased, which are the current aquafeed and could be termed ‘Aquafeed 2.0’, has occurred rapidly; essentially within the last 20 years (Cottrell et al. 2021). It is time now to conceive, plan and develop ‘Aquafeed 3.0’. We envisage that Aquafeed 3.0 will use ingredients produced through the circular bioeconomy, which can improve aquaculture’s sustainability by reducing its environmental footprint in terms of water and land use, CO2 conversion, GHG emissions, nutrient recycling and wastewater remediation. Aquafeed 3.0 will be based on raw materials that are nutritionally superior and closer to the natural diet of many carnivorous aquatic species than the terrestrial plant and animal by-products currently being used. There are already several examples of new aquafeed ingredients that are produced through circular bioeconomy frameworks, such as insects, microbial single-celled organisms, seaweeds and fishery and aquaculture processing byproducts. Moreover, we like to think that many others are just waiting to be discovered. Single-celled organisms, such as microalgae, yeasts, bacteria and fungal protists, can utilize environmentally