The Role of Mediterranean Lagoons in the European Eel (Anguilla anguilla) Stock Recovery Process

We performed a comprehensive stock assessment of the European eel in Mediterranean coastal (MC) lagoons (so far a missing gap in European eel stock assessment) and estimated pristine and current escapement. Through an extensive review of both peer-reviewed and grey literature spanning the period 1950-2012, we collected yield, climatic, geographical and other environmental and fishery data for 82 MC lagoons corresponding to roughly 80% of the overall lagoon area in the Mediterranean. Our analysis showed that eel catch declined by over 80% over the entire distributional range, while total catch across all fisheries including species other than eel also declined but less sharply. We used linear mixed-effect models to determine that variability in productivity per hectare was partially explained by latitude, longitude, lagoon area, and salinity type in addition to the temporal trend. Using an age-structured model to simulate eel population dynamics, we estimated that current escapement is <3,000 metric tons per year, corresponding to only 10% of the estimated escapement under pristine conditions. Our analysis showed that the MC lagoons contribute a small but significant fraction of total spawning stock, and effective restoration of the Mediterranean sub-population will substantially contribute to the recovery of the overall Anguilla population.