Today, in western Lake Constance are found: the North American spinycheek crayfish ("Orconectes limosus"), which was introduced into European waters in the mid-19th century to increase the yield, occasionally the Chinese mitten crab ("Eriocheir sinensis"), and in the lake's tributaries, the signal crayfish ("Pacifastacus leniusulus"). As these species of large crayfish are immune to crayfish plague, but spread the pathogen, they are a great danger to native species such as noble crayfish, white-clawed crayfish or stone crayfish. The animals are often undemanding, multiply rapidly and lead predatory lives, thus also posing a threat to various small species of fish. The ISF has been systematically researching the subject since 2003.