The blueprint of the European eel life cycle: Does life-history strategy undermine or provide hope for population recovery?

The life cycle of the European eel (Anguilla anguilla) is inherently risky because it relies on the successful migration of larvae and adults across thousands of kilometres of the Atlantic Ocean. In between these migrations, eels need to grow and develop to maximise their potential for successful reproduction. Eels have a number of life-history characteristics at each life stage that minimise mortality, starvation and predation risks and maximise opportunities for growth. In the larval and silver eel phases, eels select specific habitats and adopt efficient swimming behaviours to minimise predation and migration failure risks. In the glass and yellow eel phase, the opposite is the case, and plasticity and adaptability enable occupation of a broad ecological niche that maximises growth opportunities and enables a continent-wide distribution. Under natural conditions, these characteristics enable enough individuals to survive, grow and reproduce so that the population is resilient to natural risks. However, there is increasing evidence of impacts of anthropogenic activities that eels may be particularly sensitive to, resulting in a declining population with reduced resilience. Climate-linked oceanic risk factors are likely to have a significant influence on the recruitment of eels but are not well understood and cannot be easily modified. However, interventions to mitigate known impacts in the growth environment offer hope for population recovery. A greater understanding of the plasticity of the growth phase and the impacts of risks during the oceanic phase is essential to enable management interventions in the Anthropocene to be fully effective.