Salmon largely disappeared from the Netherlands due to the construction of water mills,ecologists from Radboud University conclude (Scientific Reports, 20 July). The construction of water mills caused the destruction of the gravel beds in streams, or making them unsuitable for salmon to spawn. Whereas it was previously thought that water contamination was the most likely explanation,archival research demonstrates that salmon stocks had already dwindled prior to the invention of the steam engine.
Source: phys.org