Challenges for Diadromous Fishes in a Dynamic Global Environment

Identification of Diadromous Fish Species on Which to Focus River Restoration: An Example Using an Eco-Anthropological Approach (The Seine Basin, France)

Eric Rochard, Patricia Pellegrini, Julie Marchal, Mélanie Béguer, Dominique Ombredane, Géraldine Lasalle, Erwan Menvielle, and Jean-Luc Bagliniere


Abstract.—The Seine River, like other large and developed European river basins, has lost most of its native diadromous fish populations since the Industrial Revolution. A restoration program has been planned to recover water quality and fish biodiversity in the Seine basin. In this prospective study, we used a dual approach (ecological and anthropological) to prioritize the 11 historic diadromous fish species for restoration. Using generalized additive models and geographic information systems, we assessed which species would have the highest probability of recovery and drew maps of their potential favorable habitats. Three fish appear to be good candidates as flagship species for a recovery plan: smelt Osmerus eperlanus, which has came back into the lower part of the basin; Allis shad Alosa alosa, a few individuals of which have recently been observed upstream from Paris, France; and brown trout Salmo trutta, which is limited to estuarine tributaries. Our anthropological survey revealed that for most citizens polled, these species have no particular significance. These citizens are not in favor of these fish species’ recovery because it would lead to changes (e.g., to restore the upstream–downstream connectivity) and new constraints (e.g., rules of management). To address this potential conflict, we studied a conciliation process with the human inhabitants from one subbasin.