These birds have a, shall I say, colorful history in Finland, and are undoubtedly the most controversial topic when it comes to birds here. They went basically extinct from the Baltic Sea and were recently reintroduced. As such they became a protected species, until it was discovered that they weren't the same species as the "original". Fishermen fear competition and islanders only see the destruction and smell they cause wherever they nest.
I see these birds a lot while sailing, but I have a different view on them. Yes, I'm familiar with the smell, and it's not pleasant. I've also seen the bare islands where all the vegetation has been destroyed. Do I hate them? Absolutely not! I've also seen how the flock moves to another island after "destroying" one, and how the vegetation grows back in just a few years - usually stronger than it was because of the fertilization. The harm people see them cause is temporary at worst, and they haven't caused significant damage to fish populations either - especially for the ones the fishermen are after. And there is something else they've greatly benefitted - the eagles. It wasn't that long ago when the eagle population was on the brink of extinction in Finland. I remember people talking of a population of maybe 30 birds - that didn't nest frequently and usually failed even when they tried. But after the cormorant population was reintroduced and it grew in size, the eagles learned their young were easy prey and the eagle population skyrocketed. Now there are thousands of eagles and I see them pretty much every time I'm at the sea! It's fantastic! What I see isn't a problem, it's the environment regaining balance.
As for them being an "invasive species", as far as I know, both species have inhabited this territory so that claim isn't exactly true either. However, the truth is that the environment has changed so much that the "original" species no longer finds it suitable, but these birds clearly do. Both the climate and the sea itself have changed too much for the same species to thrive here as hundreds of years ago.
Either way, I admire the beauty of these birds and see them as an important part of the ecosystem that now exists here. Their abilities in catching fish are impressive as well (you should watch some videos of Chinese fishermen using them for fishing, that's quite fascinating as well!).
That's enough bird-talk for the day, but my longing for the sea made me draw this gorgeous creature tonight. I really miss sailing the sea and seeing all these animals.