Which animals in the arctic are invasive species?

Answer 1

That's a very difficult question to answer for a number of reasons. First off, we still known very little about what is out there so far as "animals" goes. Sure, we know about the big mammals and even most if not all of the small ones. But we know little about insects and very little about fish and other associated marine life (again, except for the large mammals). So because we aren't really sure what is there, and therefore, native to the Arctic, it's difficult to say what is an invasive species. The term invasive itself seems to imply that it is a species that enters the area and manages to take over or at least persist and live in that area. There are numerous species that enter the Arctic annually, but don't live there on a regular basis. Many bird species fall into this category. They may be blown off course or sail on favourable winds and appear for a year, but may not be seen for years again (if ever). I don't think anyone would call those invasive. To me, an invasive species has to show up from a different area and establish a viable, reproducing population. If that's what is really meant by invasive species, then I'd wager that we don't yet know of any animals that have managed to do that. There are many rare species which show up from time to time, probably many more that we don't even see, but I'd say we have yet to identify any truly invasive species, largely because we haven't done enough surveys or research to determine what was originally present.