Aquaculture and food system: earthworms from waste biorefinery to eel feeding and conservation

The last 20 years have seen a dramatic decline in the number of eels (Anguilla anguilla) reaching European river systems. The European eel is listed as “critically endangered” under the IUCN Red List of Threatened Species. One of the strategies to counteract this decline is to improve the aquacultural system, allowing a reduction in wild elvers and juvenile eel harvesting. Using natural food to grow captive eels for restocking will increase their fitness and survival. The study seeks to evaluate the feasibility of earthworms as feed components for elvers and eels, to be used for restocking and to produce a stock of juvenile eels to be released in vocated areas. Earthworms will be reared on wastes of different origins (fruit and vegetable, household/catering waste, and sewage sludge), and their safety for eel and humans as final consumers will be evaluated. Different feeding trials will be conducted, and wastes, earthworms, vermicompost, and eels will be characterized in terms of food safety. The performance will be evaluated and compared among the different diets used. Expected results include validation of the three different waste biotransformation by earthworms (bioconversion efficiency and LCA), safety characterization of earthworms as a novel feed ingredient for eel, and derived food for human consumption (as by EU legislation); production of high-fitness juvenile eels to be used for restocking; contribution to eel conservation by releasing batches of juvenile eel to the wild. Because of the study structure (short duration, involvement of network of earthworm farmers interested in the production of earthworms from waste biorefinery and of eel farmers and fishermen associations), the expected results of the project may contribute not only to advances of knowledge of farmed eel restocking and conservation and the realistic possibility to boost the development of a circular economy valorizing organic substrates while reducing partially their adverse environmental impacts and their management costs, immediately applicable. This also scopes in line with PNRR mission. AQUAFEEL will develop an innovative approach to create a standardized model of research-based skill competence and technology to be implemented, as shared innovation, into the traditional extensive eels farming system of national marginal areas (Po-valley) with relevant value in terms of cultural landscape interest, where the eel is one of the most important species critically endangered by a dramatic decline in the number of eels reaching this area. The study will promote scientific and technological advances by exploiting the current knowledge combined with a joined-up approach involving multi-actors as co-creators of innovations. The proposed approach addresses challenges in line with the “farm-to-fork” strategies for a transition into fair, healthy, and resilient eels’ conservation and food production systems in the marginal area scenario.