Shifts in the European eel recruitment distribution: the impact of changing environmental conditions?

Abstract

The European eel (Anguilla anguilla) is a facultative catadromous migratory species that spawns in the Sargasso Sea, and grows over a wide continental range from the Barents Sea (72 degrees N) to the southern limit of Morocco (30 degrees N). Recruitment refers to the arrival of glass eels on continental shelves after an oceanic larval drift from the spawning ground. Although recruitment trends used to be quite consistent across European regions, recent modelling exercises have highlighted regional variations. At the European scale, we examined the relative contributions of six regions to overall recruitment over time using trend analysis methods. Variations in these contributions may be related to changes in environmental conditions. We identified the ecological processes preceding recruitment and their associated spatial and temporal scopes (e.g., spawning in the Sargasso Sea from March to May) to propose hypotheses regarding the potential influence of environmental factors on these processes. Using short-and long-term correlation strategies, we examined the relationships between recruitment and selected environmental variables. Our findings support the existence of spatial heterogeneity in recruitment distribution across Europe, which may inform management decisions at both local and broader levels for this species.