IMIS

Hydraulic structures such as navigation locks, pumping stations and hydropower plants play an important role in navigation, water management and sustainable energy production. However, these structures may severely impact the aquatic ecosystem and freshwater fish in particular. In Belgium, the Albert Canal connecting the river Meuse to the river Scheldt, is an important migration route for European eel (Anguilla anguilla) and Atlantic salmon (Salmo salar). Both critically endangered species have a downstream migrating phase in their lifecycle (respectively silver eels and salmon smolts), during which they are hampered by hydraulic structures. In the coming years, Archimedes screws are to be installed at the navigation lock complexes present in the Flemish part of the canal, which can function both as pumping stations and hydropower generators. A first installation is already present at the navigation lock complex of Kwaadmechelen. Before fish mitigation measures can be implemented, it is important to gain understanding on how the downstream migrating fish are affected by hydrodynamics around the complex. In this VPS study the downstream migration of European silver eels and Salmon smolts is investigated. Specifically, the fish tracks collected by the VPS indicate what downstream routes the fish took, at what conditions and why and how they are being delayed. The different routes the fish can take to pass the ship lock complex are (A) passing the ship locks together with a ship through the open gates, (B) passing the ship locks through the inlets of the filling systems of the ship locks, (C) passing the ship lock complex by passing the hydropower plant in the by-pass channel. The results indicate how fish downstream migration at such large shipping lock complexes can be facilitated, and how fish can be prevented of passing through the hydropower plant.