Downstream fish migration along the low Meuse River

PROJECT DESCRIPTION

BACKGROUND

The project area, which falls within catchment area of the Meuse river, has been defined as a heavily modified water body. The ecological status of this water body was assessed as average in 2013 and the target was set to achieve good ecological potential by 2021. The Meuse is home to 10 diadromous (species that spend part of their lives in freshwater and part in saltwater) fish species (highly migratory) and around 30 non-diadromous species. However, dams that were built between 1925 and 1935 to facilitate navigation have led to the loss of most of the diadromous fish species, as they have hindered the movement of these species on both their outward and return migratory routes.

In the 1980s, efforts were made to protect and restore habitats and diadromous species. Concerns for the recovery of migratory fish habitats in the Meuse international hydrographic district led to the drafting of a Migratory Fish Master Plan for the Meuse in 2010. The study zone covers the Meuse between Namur and the Belgium-Dutch border, over a stretch of almost 100 km. The river is largely channelled over this section, and six major obstacles to migration were identified and calculated to be responsible for the mortality of 70% of the silver eel stocks and 10% of salmon smolts migrating downstream along this stretch.

OBJECTIVES

The project plans to characterise the populations and downstream migration routes along the Lower Meuse River. It will implement and monitor the impact of innovative ways of facilitating passage of fish through hydropower facilities, such as repelling barriers and fish passes, along with new hydropower control strategies.

Specifically, the project aims to:

Increase the survival rate of silver eels and salmon smolts to 80% and 90% in downstream migration;

Increase the operation management capabilities of hydropower plants integrating fish migration intensity forecasts;

Demonstrate the performance and transferability of solutions proposed;

Identify migratory periods, downstream migration routes and influential parameters;

Validate and demonstrate tools for monitoring downstream migration;

Establish and demonstrate the value of a River Meuse stakeholder committee; and

Establish a benchmark fostering large-scale replicability and transferability across the EU.

Furthermore, the project aims to establish maximum direct mortality rates measured at 10% and 20% respectively for Atlantic salmon smolts and silver eels for all six hydropower sites. This objective will be reached with the roll-out of a set of innovative solutions combining systems that repel and guide fish, creating outlets for downriver migration and a system for anticipating critical periods.

Expected results:

Integrated Lower Meuse River basin approach favouring eel and salmon conservation and protection;

Demonstration of a cumulated escapement rate exceeding 80% for eels and 90% for salmon;

A powerful migration modelling and monitoring tool;

An automated hydropower generation control and monitoring system;

Two effective behavioural barriers preventing fish passing through dangerous routes during migration;

A methodology taking into account local characteristics in operating hydropower plants;

The commitment of 31 stakeholders from the Meuse river basin; and

A transfer plan.