Assessment of the eel stock in Sweden, spring 2021 : fourth post-evaluation of the Swedish eel management

For decades, the population of the European eel has been in severe decline. In 2007, the European Union decided on a Regulation establishing measures for the recovery of the stock, which obliged Member States to implement a national Eel Management Plan by 2009. Sweden submitted its plan in 2008. According to the Regulation, Member States shall report regularly to the EU-Commission, on the implementation of their Eel Management Plans and the progress achieved in protection and restoration. The current report provides an assessment of the eel stock in Sweden as of spring 2021, intending to feed into the national reporting to the EU later this year. This report updates and extends the reports by Dekker (2012, 2015) and Dekker et al. (2018). In this report, the impacts on the stock - of fishing, restocking and mortality related to hydropower generation - are assessed. Other anthropogenic impacts (climate change, pollution, increased impacts of predators, spread of parasites, disruption of migration due to disorientation after transport, and so forth) probably have an impact on the stock too, but these factors are hardly quantifiable and no management targets have been set. For that reason, and because most factors were not included in the EU Eel Regulation, these other factors are not included in this technical evaluation. Our focus is on the quantification of biomass of silver eel escaping from continental waters towards the ocean (current, current potential and pristine) and mortality risks endured by those eels during their whole lifetime. The assessment is broken down on a geographical basis, with different impacts dominating in different areas (west coast, inland waters, Baltic coast). In 2011, a break in the downward trend of the number of glass eel was observed throughout Europe, the trend since being upward, but erratic. Whether that relates to recent protective actions, or is due to other factors, is yet unclear. This report contributes to the required international assessment, but does not discuss the causing factors behind that recent trend and the overall status of the stock across Europe.