It still doesn’t make sense to ban a fish in areas where it can’t survive. It’s just laziness on big brothers part. It’s like in school when the teacher punished the whole class because of a few.
One would think so, but as the famous saying goes, "...nature will find a way".
Even in the coldest places, there are small areas where unexpected colonization events can take place.. And these are not that infrequent or unusual. Happens all the time. The warm affluent outside a wastewater facility or cooling plant for an energy supply setup. The confluence of two streams where conditions are not the same as on either stream (upstream), and potentially downstream, depending on the sizes of the individual flows. And then, some species are so incredibly adaptable that they can withstand quite a range of conditions, at least seasonally. And let's not forget climate is changing such that the 'temperate zone' is growing north at a fast speed, and the 'tropical/subtropical' growing north and south into the temperate'.
That is why the laws are in place (or should be), even if it appears a certain species may not be likely to establish itself.
