River herring once swam up Connecticut’s streams to reproduce by the billion, and then reverse their journey back to sea. In recent years, though, their migration has become increasingly perilous, and their numbers have plummeted. Obstructions like dams have been added to many of the streams and rivers and the population has been drastically overfished.
Click here for original story, The travails of an alewife: Dams, drought, and climate change
Source: Phys.org