The life-cycle of the European eel has yet to be successfully closed in captivity, giving limited possibility for stocking programmes. Major bottlenecks concern the blockade of puberty, alternative treatments to induce full maturation, high quality gametes, and larval food. All eel-related activities (fisheries, aquaculture, industries), are fully dependent on wild stocks that have dramatically declined during the last decades.
Further, there is intense fishing pressure on all life-history stages of the eel, especially glass eels which are caught to sustain the European eel aquaculture industry (capture-based aquaculture). Moreover, due to their unique life-cycle, eels accumulate during their long continental growth phase, not only metabolites and energy stores, but also contaminants which will be acutely mobilized during the prolonged oceanic migration, and subsequent spawning. Eel reproductive capacity is therefore especially sensitive to pollutants and endocrine disruptors. Gaining new basic knowledge on eel reproductive endocrinology is crucial for future development of eel conservation.