Individual differences in inhibitory control may influence how endangered eels deal with river barriers during migration

The European eel is currently facing a critical risk of extinction. One of the contributing factors is that its catadromous migration is often obstructed by artificial barriers such as dams. Migrating juvenile eels display a strong rheotactic behaviour. Therefore, we hypothesized that inhibitory control, the ability to suppress motivated behaviour, in this case rheotaxis, could facilitate the search for alternative routes when encountering a barrier. Using a detour test and a test in which a shelter was blocked by a transparent barrier, we demonstrated that migrating eels exhibit some degree of inhibitory control, with evidence of individual differences in performance. Crucially, individual differences in these inhibitory control tests significantly predicted how eels behaved in a simulated river system with barriers. Individual eels may adopt distinct strategies to overcome migration barriers and these differences might be partly driven by variations in inhibitory control.