Ecologist André Breukelaar is in a jubilation. “It’s very special,” he says of the catch. The shad has long since disappeared from the Netherlands and does not spawn here, but in Germany. Since the beginning of this century a lot of effort has been made to get the shad back. Nice that we can now see that that has an effect. “
The shad is a herring-like migratory fish, which was common in the Rhine, Maas and IJssel in the nineteenth century. Overfishing and poor water quality caused the shad to become practically extinct in the Netherlands, Germany and Belgium between 1930 and 1940.
“Since 2004, German researchers have taken young elves and elves’ eggs from Bordeaux and released them in Germany. Now we are finally seeing adult animals for the first time.”
Herring gates ajar
The researchers caught two elves in so-called salmon stings. “We are running an experiment to see how salmon and sea trout pass through the Haringvlietdam,” explains Breukelaar. The Haringvliet locks have been ajar since the beginning of last year, allowing such fish to pass through the locks to spawn in areas upstream.
“We can’t put the whole lock ajar all at once, we do that very carefully.” This mixes fresh water from the rivers with salt water from the sea. “The fresh water may become a little salty, but not too much. Because we also need that fresh water for agriculture, as drinking water and for other facilities.”
Thus, by chance, live elfs were discovered during that investigation. It is difficult to say what that means for the stock of the shad. “In any case, we cannot fish so efficiently that we have fished them all out, so there are probably more.”
Research on fish stocks
The research at the Haringvliet is being carried out by Rijkswaterstaat, but at the same time the Hollandse Delta Water Board is also investigating the fish stocks in 43 waterways in South Holland. That is done every six years.
“How much fish is in it, what species and what length says something about the quality of the water,” says Thomas de Bekker of the water board. Researchers have been working on this since the beginning of May to mid-October.
“Healthy water is important for everyone. We can draw conclusions from the reports and take action if necessary.” Those research results are expected at the end of this year.
The reporters traveled through the region for six weeks during the Summer Tour, Destination Rijnmond. This week, Goeree-Overflakkee will be featured on TV, radio, the website and social media. The stories and reports are here to find back.