Invasive alien species in Switzerland - Schweizer ...

2 > Vertebrates – Vertebrata 55
there is an increasing number of records from Germany. The introduced species in
Switzerland, the marsh frog, is native in Austria and Germany.
Species of edible frogs may be illegally released as a food resource and game animal.
In certain areas, notably western Switzerland, R. ridibunda is still imported in large
numbers for human consumption and it is likely that some escape. This has been
particularly true in the past with less rigid control of transport and containment. Thus,
the current populations have most probably developed from these escapees. It seems
likely also that some amphibians are released or escape from captivity as pets. Thus the
pet trade should have a responsibility to educate the public about the potential threat of
alien species to native biodiversity. Trade in certain species, such as the American
bullfrog, should be prohibited.
All three species discussed here are known to cause severe damage to native amphibians
by preying on the smaller species, through competition as tadpoles, as vector of
diseases, or through hybridization. No negative economic impact has been reported.
The major recommendations to reduce the risks caused by alien amphibian species are:
> A stricter regulation of the (pet) trade and implementation of laws and conventions.
> Besides the legislative options, the public needs to be made aware of the potential
threats to native biodiversity. Some of them might voluntarily act in a more responsible
way.
> Any established populations of American bullfrogs should be eradicated.
Tab. 2.5 > Established alien amphibians in Switzerland.
Scientific name Family Origin Year Pathway Impact Note
Rana ridibunda Ranidae East Europe, 1920s? Released (as food resource?) Competition with native amphibians Spreading
Pallas probably Hungary Escaped from imports for Genetic changes in native green frog
human consumption complex
Triturus carnifex Salaman- South Europe, Few Released or escaped from Replaced the great crested newt Native to Switzerland
(Laurenti) dridae including the Ticino decades containment for scientific
ago studies
Rana catesbeiana Ranidae Central and eastern Recent Released or escaped Feeding on native amphibians and Probably no breeding
Shaw North America reptiles population in CH, as
Competition with native amphibians
Disease vector
yet
2.5 Fish – Pisces
The situation with regard to introduced fish species in Switzerland is interesting because,
with the exception of asp (Aspius aspius (L.)), all other species are individually
mentioned in Appendixes 2 or 3 of the Fisheries Act of 1993 (Ordinance relevant to the
federal fisheries law). In this Act, Appendix 2 describes situations (garden ponds,