Progress in hatchery development for European eel .

Abstract

European eel, Anguilla anguilla, is critically endangered and hatchery technology for commercial production of glass eels is fundamental to sustainable eel aquaculture, as wild-caught glass eels is still basis of eels cultured to marketable sizes. During the past 15 years, DTU researchers have engaged in the development of captive breeding technology for European eel aiming at a closed life cycle in culture (Tomkiewicz et al., 2019). As reproduction and early life history in nature is uncharted, experimental research is pre-requisite to fill gaps in knowledge. Thus, on the one hand research has targeted broodstock nutrition and reproduction, while on the other the establishment of larval culture systems, rearing conditions and diets. Encouraging for this research is the progress of hatchery technology for Japanese eel (A. japonica), now approaching commercialization. To date, European eel research has successively improved assisted reproduction methodologies leading to enhanced broodstock responsiveness, quantity, and quality of gametes as well as viability of offspring, now entering the first feeding stages. Broodstock involve captive-raised and wild-caught females using the latter as benchmark, while targeting a closed-cycle production, also aiming at benefits regarding lower disease risks and better performance in culture systems (low stress). Here, we present progress made during the innovation project ITS-EEL (2018-2021) focussed on upscaling viable egg production and establishing the technology for feeding larval culture. This involved tailoring broodstock feeds and refining hormonal treatments, while progressing larval survival through custom-designed culture systems and novel diets for feeding larval culture.