In 1972, only three species of fish could be found living in Paris' Seine River, a clear condemnation of the quality of the water, polluted by industrial toxins and agricultural waste. But this month, researchers announced the surprising results of a census of the river's fish populations carried out via video camera - 32 species were found making their way through Paris.
Thanks to nearly 20 years of rigorous water quality controls, including pollution regulations and efforts to remove plastic detritus from the water, salmon were rediscovered in the Seine in 2009. Because the species is especially sensitive to water pollution, it is seen as a "bio-indicator," and its presence is particularly encouraging.
The French National Institute for Agricultural Research (INRA) noted that all the salmon found were wild - no farm-reared salmon have bee introduced into the river since the 19th century. They concluded that restoring the environment is preferable to interfering with fish populations.
Indeed, so many fish have moved back to the Seine that Parisian fishermen are once again having success - even one who insists on using Gruyere cheese as bait.
But the more relevant and inspiring message to be taken from this story, is that once polluted environments and their inhabitants can bounce back, if we are willing to clean up our acts.