“…However, obstacles can have many other consequences (Budy et al, 2002), including stress, disease, injury, increased energy costs, migration delay (Muir et al, 2006;Caudill et al, 2007;Marschall et al, 2011) overpredation, and overfishing (Briand et al, 2003;Garcia De Leaniz, 2008) of populations that often suffer intense exploitation (McDowall, 1999). In view of this, understanding diadromous fish migration is a critical issue for conservation (McDowall, 1999) and can inform biodiversity policy (Barton et al, 2015). This is especially true for catadromous European eels (Anguilla anguilla), which spawn in the Sargasso Sea (Schmidt, 1923;Tesch, 2003) and grow in European continental waters after a few years long larval drift (Bonhommeau et al, 2009).…”