Invasion of alien species of crayfishes and other animals

As the result of massive die-out of native crayfishes due to crayfish plague, there was an idea to substitute the native species with the North American ones that are resistant to the disease. This is how the spiny-cheek crayfish, the noble crayfish worst challenger, came to Poland. Max von dem Borne, a German grower, imported this species from Pennsylvania to his ponds in Barnówek (West Pomerania province) in 1890. About 100 of the spiny-cheek crayfishes were released to about 1000 m2 pond, situated next to the Myśla river, and this led to its spreading across Poland and Europe.
The spiny-cheek crayfish increases its distribution range by about 20 kilometres per year, mainly due to dynamic territorial expansion, which is typical for this species. At present this species is common in Europe. It was recognised as the invasive species. It poses a large threat to native species, because it is potential vector of crayfish plague, and is capable of displacing native crayfish species (faster growing, larger fecundity and higher adaptation to unfavourable habitat changes).
Besides that, other American species of crayfishes: the signal crayfish (which was observed in other Polish waters – Wieprza, Drawa and Słupia basin) and crayfishes imported to the aquaria in zoological shops (the red swamp crayfish, Florida crayfish, deceitful crayfish and others) are next potential invaders. 
Besides non-indigenous crayfish species, the noble crayfish is also threatened by another invasive species, particularly by the American mink.