A simple management tool for planning the restoration of river longitudinal connectivity at watershed level: priority indices for fish passes

Abstract

Summary The present study aimed at defining and testing a simple and widely applicable management tool, based on already available or easily collectable data, which could allow Watershed Authorities to prioritize the interventions for river longitudinal connectivity restoration, reopening fish migration routes. The proposed priority indices for fish passes are based on obstacle characteristics, length of the potential reopened reach and fish species distribution and migratory behaviour. The indices were applied to two Italian watersheds (Arno and Magra Rivers) covering a total river length of more than 400 km. The priority lists produced by the application can function as a first step in defining a watershed restoration plan and could help the Watershed Authorities to address the available resources towards more detailed studies to be carried out at sites classified with the higher priority levels. This is the case of the Regional Natural Park Monte Marcello-Magra, where, within a recently funded LIFE+ project (P.A.R.C. –‘Petromyzon And River Continuity’), the first results of the priority indices application will be analyzed in greater detail and will consequently lead to the design and construction of fish passes to restore fish migration routes with a particular focus on sea lamprey (Petromyzon marinus).