How fish-friendly is a ‘fish-friendly’ pump, really?
It is difficult to imagine our Flemish waterways without pumping installations. Higher precipitation peaks, rising sea levels and increasing periods of drought due to climate change are placing even greater demands on water management.
Axial flow pumps are the most commonly used pumps in Flanders to move water to higher ground. However, these are also the most harmful pumps for fish when they move between different habitats. Fish must be able to move unhindered between different parts of waterways where they can feed, hide or reproduce. That is why ‘fish-friendly’ pump alternatives are being developed.
In our study, commissioned by the Flemish Environment Agency (VMM), we compared the impact of a new ‘fish-friendly’ axial pump with that of an older, conventional axial pump. With a survival rate of 100%, the fish-friendly pump could be considered safe for eel. In this study, no eel was pumped through the conventional axial pump, but previous studies show a survival rate of only 3% for comparable pumps. For roach and bream, the survival rate was 70% and 24%, respectively, for the fish-friendly pump. Larger fish that passed through the fish-friendly pump at the highest speed had the lowest survival rate; we looked at this up to 24 hours after they passed through the pump. The conventional axial pump appeared to be more than five times more harmful to roach than the ‘fish-friendly’ variant.
The ‘fish-friendly’ variant clearly scores better, but is not yet safe for all fish species studied.
Stijn Bruneel, Ine S. Pauwels, Sarah Broos, Lore Vandamme, Jeroen Van Wichelen, Johan Coeck, Gert Toming, Jeffrey A. Tuhtan & David Buysse
Read more: A fish-friendly axial flow pump turns out to be eel safe, roachunfriendly and bream unsafe
