I visited Chernobyl a couple of years ago and was stunned by the amount of large fish in the waterways (a canal now cut off from the Dnieper river, IIRC). It seemed you could almost walk from bank to bank on the swarming fish.<p>It made me wonder if this is what European waterways were generally like before us humans fished and fished and fished and polluted the Rhine, Danube, Volga, Dnieper, and other major European rivers.