Contrary to the report, they are actually not difficult to keep as pets - they are just highly sensitive to pollutants in the water.

The unfortunate case for the wild population, is that they naturally inhabit a location which today has one of the highest human population densities in the world, and hence massive pressure on water resources. We could probably quite easily re-establish a breeding population in remote areas in Europe but would constitute an invasive species and hence wouldn't happen.

As a species, they are not endangered due to their very large populations now in the pet trade (though these then get inbred, become domesticated etc).