You can miss it and the smell doesn’t start to bother you: thousands of dead fish on the canal. The fish in the ponds of the Bemptpark and the Josaphatpark are also dying. Brussels Environment talks about an oxygen shortage due to the hot, dry days. But the sewage system also plays a role.
They have been floating en masse since Friday: the dead fish in the canal, near Sainctelette, up to the locks of Anderlecht. “It already stinks pretty hard,” reports one reader. Brussels Environment first spoke of a hundred, but already thousands of dead fish. They are mainly bass and cyprinid fish such as bream. A pleasure fisherman also reports a dead water turtle and ducks to our editors. Final death figures are still pending. “The analyzes are still ongoing,” the administration said.
It is not the first time that the canal resembles an animal graveyard. Last year the same in similar weather conditions. Warm days with little rain, followed by heavy thunderstorms: this is the recipe for little oxygen in the canal, especially in smaller strips and where the stone quays retain the heat longer.
“When it is warm, the amount of oxygen in the water. If it doesn’t rain for a long time, the water also changes more slowly,” says Sylvain Godefroid of the Port of Brussels. And if it then starts to thunder again, such as last Thursday, excess sewage can end up in the canal through overflow. “The sewage water produces organic waste. And breaking down such waste requires even more oxygen,” says biologist and water expert Renaud Bocquet of Brussels Environment.
The high fish mortality comes not long after criticism from Brussels environmental organizations. At the beginning of March, 23 organisations, including the non-profit organization Canal It Up, demanded a ban on sewage discharges into the canal. They asked for more and better storm basins to absorb heavy rain. Last week, Environment Minister Alain Maron (E) had to file in the parliamentary file that the 37 existing storm basins in the region should be used. For example, 10 million cubic meters of sewage water still ends up in Brussels waterways every year. Water company Vivaqua that its storm basins worked well last week.
Nevertheless, Brussels Environment speaks in this case about a real interplay of heat and drought, and only additionally of the sewage discharge. A Mechelen pleasure fisherman actually announced to our editors two weeks ago, before the fierce thunderstorm, a lot of dead fish. Walleye make their nests near Sainctelette, but I haven’t seen any mating places this year, says the fisherman.
Also, the fish mortality is not limited to the canal. Several ponds in Brussels, such as the Bemptpark in Forest, the Maloupark in Woluwe-Saint-Lambert and the Josaphatpark in Schaerbeek, also have dead fish. “We are now measuring oxygen there too,” says biologist Renaud Bocquet. In the canal it turned out that the oxygen level had dropped to unlivable values. “Not a good time, now that the fish are mating,” says Bocquet.
In the meantime, the fish are still floating – and smelling – on the canal. The Port of Brussels has already cleared four cubic meters of fish since Friday. “But as long as we are still alive with fish, it is difficult to triage. We first have to swim further to water with more oxygen before we clean up,” says Godefroid. Brussels Environment is that all dead fish will be gone by Tuesday.
The question remains how Brussels intends to affect this in the future. Summer brings even more hot and dry days, and global warming is amplifying that. “There’s not much we can do at a time of crisis like this,” Bocquet says. The canal is 14 kilometers long, which makes quick solutions difficult. “We could add with small mills, but they only work very locally. To move the fish, you should already be fishing the entire length. And changing water is also difficult during a major drought.”
Bocquet thinks more about prevention. “We have to keep the canal as good as possible: don’t feed ducks with bread, don’t throw packs of chips into the water. Because everything that is organic has to be digested,” says the biologist. New, green island rafts in the canal offer the fish shelter and the water cool. Brussels environment minister Maron included the fish mortality “not exclusively Brussels,” but says the phenomenon is planned “the need to continue a resilient urban policy, taking into account heavy rain”.