Hydro energy or gigantic fishes?

I was walking up the stairs in a kindergarten, watching a new collection of historic photos hanging on the wall, when this one nailed my stare. Beluga or great sturgeon, 1930s. Staggering is the fact that it was taken not somewhere in the Amazon River or other exotic places but in the middle of Europe, near the place on the link below, somewhen in 1920s or 1930s. This photo is a reminder that hydroelectricity may not be as sustainable as it's touted. "Migrating fish was suddenly meeting a concrete wall on its way and, gathering in this bag, was swarming on water surface," citing memoirs of Pavel Malenyov, a journalist and political activist, who was a teenager living in that region through the 1940s and 1950s and witnessed construction of the Gorky hydroelectric power station. According to Malenyov, three years after the dam was built, fish migration exhausted. Great sturgeons are critically endangered now and you definitely can't see them in Volga anymore. Convention...