Ten years of adapted tidal barrier management in the Leopold Canal benefits European eels
In spring, during the tidal rise, Vlaamse Waterweg nv sets the tidal doors ajar in the ports of Nieuwpoort, Ostend, and Zeebrugge.. It has been doing this for 10 years now. The aim is to improve glass eel passage through tidal gates. Glass eels are juvenile eels that migrate from the sea to the rivers to continue their growth. Every year, INBO counts eels throughout Flanders through capture-mark-recapture campaigns, and we are seeing a positive effect of the adjusted tidal barrier management on the eel population.
This is mainly reflected in higher numbers, a broader length class distribution and a rejuvenation of the population. Growth rates are in line with or higher than values from comparable European watercourses, and eel densities have been increasing further upstream since 2020. All this points to successful glass eel migration and favourable growing conditions.
The European eel has been declining sharply in numbers for decades and is currently listed as critically endangered on the IUCN Red List. A major cause of this is the obstruction of upstream glass eel migration. On the Belgian coast, tidal barriers in the ports often form insurmountable obstacles for glass eels that want to migrate to the Flemish inland areas.
Appropriate tidal barrier management remains an important measure to facilitate eel migration, an obligation arising from the European Eel Regulation.
Image above © Pepe Brix