Higher river discharge helps young salmon
Low river discharge reduces the likelihood of young Atlantic salmon reaching the North Sea. Fewer salmon reach the Haringvliet sluices, and their passage takes longer, making them more likely to fall prey to predators. Using so-called predation tags, researchers were able to demonstrate for the first time that this predation occurs largely before the Haringvliet sluices and is probably mainly…
River discharge significantly impacts the survival rate of young Atlantic salmon as they migrate from the Haringvliet to the North Sea. Lower river discharge increases the likelihood of predation and slows their passage through the Haringvliet sluices, while higher discharge improves their chances of reaching the North Sea. Researchers utilized predation tags and acoustic telemetry to study the migration patterns of 74 young salmon in 2024 and 2025.
In low discharge years, only 6% of the fish reached the North Sea compared to nearly 50% during high discharge years. Predation primarily occurred upstream of the sluices, mainly by predatory fish such as pike and pike-perch. Opening more sluices during the peak salmon migration could enhance survival rates, potentially aiding the recovery of Atlantic salmon populations.
However, climate change might exacerbate challenges for young salmon as low discharge periods become more frequent. Further research is needed to determine the effects of various sluice management strategies and to better understand bird predation on young salmon.
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