Distribution Of Invasive Species

I recently read an article about an invasive species in Europe. It is a species of sleeper (Percottus glenii). The interesting thing is that they were NOT introduced through aquariums, by sport fishermen, or by aquaculturists. What scientists have found out is that for some reason, there was a change in migration matterns of aquatic birds. Like pike, these sleepers are very adaptive and their eggs can stick to the legs of wading birds and survive digestion. Thus, in only a few decades, this sleeper (known as the Rot-an) spread from it's native range (China, Korea, Eastern Siberia) into central russia, then Eastern Europe, and as far as France, all because of changed migration patterns of birds! True, humans did have a small role in releasing rot-an from aquariums, but for it to be so wide spread and to become so common there would need to be myriads of aquarumists who released a rot-an. In some areas, they have become dominant and cannibalistic (like some brown trout in the U.S.).

I don't know if this could happen here with something else as adaptive, but with global warming, birds could change migrating patterns and so on.

Sorry but I'm a strong skeptic of the 'bird transfer' theory in most any case..In most cases invasive and exotic introductions are anthropogenic and directly due to human involvement..I find this 'birds feet' idea of establishment to be a distraction from real problems and issues. There is no real good evidence of this being a real vector of fish distribution out side of established range.

there were populations of large mouth bass, sunfish on Petitboy Island off the cost of MS before hurricane Katrina. This island is underwater during most major hurricanes, (Camile 1969, Fredrick 1979, etc) I actually caught 2 large mouth off of a brackish lagoon on the north (sound) side of Petitboy between 1984 and 1992, i saw juvenile sunfish and what i think may have been top minnows (I was in high school at the time, my father and I regularly fished these islands, my father still does, for speckled trout) My father has a picture of a large mouth bass that he caught in the same place in the early 1960's.

after hurricane Fredrick in 1979, my father and myself caught many redfish in lake Shelby in Gulfshores, AL. We caught them for 3-4 years after the storm, i can vividly remember my father catching them while fishing for bass (or green trout as we like to call them, I was 5-6 at the time) The juvenile redfish or eggs must have been washed into the lake by the storm. either the largemouth and sunfish eggs were washed by storms to petitboy, or they were transported by birds. Humans could certainly have done it but i can not fathom why.

this sleeper probably was distributed through estuaries, but only by the time it got to the Baltic Sea (through ballast water) because the rot-an (Chinese sleeper) can tolerate Estuarine levels of salinity. The new regulations on ballast water did not come too soon, otherwise this sleeper would have done the same thing as the ruffe did. Chinese sleepers also don't get very big and they would have been just as useless and damaging to the Great Lakes as the ruffe.

So that would be how the Chinese sleeper got from Eastern to Western Europe. But what about from the Amur to the Baltic?

Long, Long, ago, from their point of origin, several European Cyprinids (bream, ide, rudd...) along with pike, burbot, and sticklebacks made their way from central europe and distributed themselves up to Kamchatka. Northen Pike, burbot, long-nosed sucker, and the three-spined stickle back also got to north america (all three tolerate salinity to some degree, while almost all cyprinids do not). I don't know how for sure how they got there but one possibility is by birds. If anyone else has any ideas, please post them here.

And our earth changes all the time through natural processes. Something may have triggered bird migrations.

Ok, hypothetically the bird hypothesis would work. So if we assume that the birds did change their migration pattern and that the fish got to weatern europe that way. The last piece of the puzzle is to look at the climate changes that affected the migration patterns and if the changes were caused by humans. If humans were not a fault, then the fish wouldn't be invasive per se as they got there naturally.

Sorry I'm late to the party, but I had to respond to that last post.

How an organism arrives in an ecosystem, whether through anthropogenic or non-anthropogenic ("natural") means, has nothing to do with whether or not the organism is invasive. It also has nothing to do with what our response should be: if a "naturally" spreading species is damaging our valuable ecosystems, we should try to limit its spread. The goal of conservation and management is not to maintain the Earth in the state it would be if humans weren't here; it's to maintain it in a state that is beneficial to humans. That has always been the case; it's just that in recent years we have realized the value to us of things like keeping intact communities, rather than just the directly valuable species, and of ecosystems formerly considered 'wasteland'. We are largely trying to maintain the status quo, because we have realized how much we do not know about ecosystems, what they do, and how they work.

How an organism arrives in an ecosystem, whether through anthropogenic or non-anthropogenic ("natural") means, has nothing to do with whether or not the organism is invasive. It also has nothing to do with what our response should be: if a "naturally" spreading species is damaging our valuable ecosystems, we should try to limit its spread. The goal of conservation and management is not to maintain the Earth in the state it would be if humans weren't here; it's to maintain it in a state that is beneficial to humans. That has always been the case; it's just that in recent years we have realized the value to us of things like keeping intact communities, rather than just the directly valuable species, and of ecosystems formerly considered 'wasteland'. We are largely trying to maintain the status quo, because we have realized how much we do not know about ecosystems, what they do, and how they work.

Impressively sensible!