Invasive alien species in Switzerland. Factsheets

204 Pages·2006·1.56 MB·English

> Environmental studies > Organisms
> Invasive alien species
in Switzerland
Factsheets

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> Fact sheets

> Index
Fact sheets Vertebrates 4

Fact sheets Crustaceae 44

Fact sheets Insects 57

Fact sheets Spiders and Allies 91

Fact sheets Molluscs 98

Fact sheets Other selected invertebrates groups 106

Fact sheets Fungi and a selected bacterium 111

Fact sheets Plants 124
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An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006

Fact sheets

Vertebrates
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> Fact sheets

Aix galericulata
Taxonomic status
Scientific name Aix galericulata (L.)
Family Anatidae
Taxonomic group Anseriformes
English name Mandarin duck
German name Mandarinente
French name Canard mandarin
Italian name Anatra mandarina
Description and identification
Description The male is unmistakable with its striking colours – ornamental orange ‘sail’ feathers and broad white
tapering supercilium. Females with their grey head and white eye-ring are easy to recognize, but
another alien duck, which sometimes escapes, the North American wood duck (Aix sponsa (L.) is very
similar. They can be differentiatedt by the white pattern in the face.
Similar species No similar native species, but see above for the wood duck.
Biology and ecology
Behaviour The Mandarin duck breeds mainly in tree holes. The European population is resident, although it is
migratory in its native range.
Food Feeds on water plants and seeds.
Habitat Forested margins of lakes and rivers. It prefers dense cover.
Origin East Siberia, north China and Japan.
Introduction and dispersal
History of introduction The striking birds are a favourite species for waterfowl exhibitions and were/are kept in parks, from
where they escaped during the 20th century. They built up an extensive population of about 7,000
individuals in the UK. Large populations are also found in the Netherlands and Germany. The Swiss
first brood was found in 1958 near Basel.
Pathways of introduction The species escaped from waterfowl collections and may also be illegally released in some places.
Dispersal Birds spread locally when the population is growing, but they are capable of long-distance travel.
Current status
Actual and potential distribution in There are about 15 breeding pairs in Switzerland throughout the Mittelland between Genève and
CH Basel. In that area there is more, as yet unused, suitable habitat, which could be colonized, so a
population increase is likely.
Introduced distribution The largest introduced populations are found in England, the Netherlands, and Germany. There are
also escapees in other countries.
Impacts
Environmental impact There is a possibility of competition with the native goldeneye (Bucephala clangula (L.)) (and other
cavity-nesting bird species) for tree holes.
Economic impact Probably no economic impact.
Management options While the current small population could still be eradicated, the necessity for this is questionable. The
main point to take into consideration is the small populations in its native range.
Information gaps Range of potential distribution in Europe. Impacts.
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An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006

References
Literature Burkhardt, M. and H. Schmid (2001) Vögel in der Schweiz. Schweizerische Vogelwarte, Sempach,
276 pp.
Davies, A. (1988) The distribution and status of the Mandarin duck Aix galericulata in Britain. Bird
Study 35, 203-208.
Kestenholz, M. and L. Heer (2001) Absichtlich und unabsichtlich ausgesetzte Vogelarten in der
Schweiz: Situationsanalyse und Massnahmenplan. Schweizerische Vogelwarte Sempach und
Schweizer Vogelschutz SVS – BirdLife Schweiz, Sempach und Zürich, 44 pp.
Madge, S. and H. Burn (2002) Wassergeflügel. Marixverlag, 297 pp.
Rutschke, E. (1989) Die Wildenten Europas. Biologie, Ökologie, Verhalten. Aula Verlag, Wiebelsheim,
368 pp.
Schmid, H., Luder, R., Naef-Daenzer, B., Graf, R. and N. Zbinden (1998) Schweizer Brutvogelatlas.
Verbreitung der Brutvögel in der Schweiz und im Fürstentum Liechtenstein 1993-1996. Schweizeri-
sche Vogelwarte, Sempach.
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> Fact sheets

Ameiurus melas / nebulosus
Taxonomic status
Scientific name Ameiurus melas and A. nebulosus (Le Sueur)
Family Ictaluridae
Taxonomic group Osteichthyes
English name American catfish
German name Katzenwels
French name Poisson-chat
Italian name Pesce gatto
Description and identification
Description The two American catfish species are very similar in appearance and biology, thus are consid-
ered here together. The American catfish have a round body; more laterally depressed towards
the rear, with a prominent head. Eight barbels (2 pairs below mouth, 1 above, and 1 on head
near nostrils) and a pectoral spine are diagnostic. The body colour is dark.
A. melas: Barbs on trailing edge of pectoral spines weak or absent
A. nebulosus: Barbs on trailing edge of pectoral spines strong, even near tip.
Similar species Both species are much smaller than the native catfish (which are in a different family), and the
species can also be distinguished by their fins (see above).
Biology and ecology
Behaviour The American catfish are nocturnal. The species can hear very well and distinguish between
different noises. They are also able to sense electrical currents. Eggs are laid in shallow water
and are guarded by one (or two?) parent(s), whose movements also enhance the available
oxygen.
Food Mainly bottom feeders, eating all available organic matter, including dead insects, etc.
Habitat In shallow waters of lakes, rivers and ponds with a good cover of submerged vegetation on sandy
or muddy soil.
Origin Central and eastern North Americ
Introduction and dispersal
History of introduction The species were imported to Germany at the end of the 19th century for aquaculture, but they
soon lost value as food. However, the species dispersed widely throughout Europe and reached
Switzerland, too.
Pathways of introduction Aquaculture and aquarium releases probably founded the existing populations.
Dispersal Natural dispersal in river systems. They can survive periods of drought for several months by
submerging in the mud of the riverbed.
Current status
Actual and potential distribution in CH They are found in only a few, scattered sites. They are likely to colonize more of the lowland
parts of Switzerland (they need warm water for spawning).
Introduced distribution The two species are widely distributed in Europe today. However, due to difficulties in distin-
guishing them, the distributions of the individual species are not well known.
Impacts
Environmental impact They are unpopular, because they form dense stunted populations.
Their adaptability and ferocious feeding behaviour make them a grave threat to the native fish and
amphibian fauna. In places, they have built up huge populations and replaced native fish species,
probably through competition for food.
Economic impact They have little sporting or commercial value.
Management options There is no great conflict of interest, as there is with many other species that are important for
fishing, thus regulations are straightforward. The species are in Appendix 3 (see text for explana-
tion) and their introduction is therefore forbidden.
Information gaps Actual distributions of the two American catfish species in Europe. Impact on community and
habitat in Switzerland.
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An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006

References
Literature Arnold, A. (1990) Eingebürgerte Fischarten. Die Neue Brehm-Bücherei, A. Ziemsen Verlag,
Wittenberg Lutherstadt, 144 pp.
Geiter, O., Homma, S. and R. Kinzelbach (2002) Bestandsaufnahme und Bewertung von
Neozoen in Deutschland. Umweltbundesamt, 308 pp.
Ladiges, W. and D. Vogt (1979) Die Süsswasserfische Europas. Paul Parey, Hamburg und
Berlin, 299 pp.
Welcomme, R.L. (1988) International introductions of inland aquatic species. FAO Fisheries
Technical Paper 294, 318pp.
Zaugg, B., Stucki, P., Pedroli, J.-C. and A. Kirchhofer (2003) Pisces, Atlas. Fauna Helvetica 7,
Centre Suisse de Cartographie de la Faune, 233 pp.
Other source http://www.fishbase.org/search.cfm
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> Fact sheets

Aristichthys nobilis
Taxonomic status
Scientific name Aristichthys nobilis Richardson
Family Cyprinidae
Taxonomic group Osteichthyes
English name Bighead carp
German name Gefleckter Tolstolob
French name Carpe marbrée
Italian name -
Description and identification
Description A large (more than 1-m long) fish with a big head and oblique mouth. Small eyes are low on
the head. Brown markings on light body.
Similar species Distinguished from other species by the head; the mouth and eyes are quite distinctive.
Biology and ecology
Behaviour A bottom-dwelling fish which prefers warm temperatures. The water temperatures need to
exceed 22°C for egg laying. The larvae hatch just 1-2 days later.
Food Feeds mainly on zooplankton. In colder environments it shifts to a more predatory behaviour.
Habitat Occurs in rivers and lakes.
Origin China
Introduction and dispersal
History of introduction Widely introduced for aquaculture and fishing.
Pathways of introduction Frequent releases for commercial and recreational fishing.
Dispersal Normal dispersal.
Current status
Actual and potential distribution in CH Only rarely found in Switzerland.
Introduced distribution Introduced to water bodies on several continents.
Impacts
Environmental impact As a specialized zooplankton feeder it can alter the community and change the nutrient flow of
the habitat.
Economic impact Positive – commercial fish.
Management options An Appendix 3 species (see text for explanation) and its introduction is therefore prohibited.
Information gaps Impact on community and habitat. Monitoring of breeding in Europe.
References
Literature Terofal, F. (1984) Süsswasserfische in europäischen Gewässern. Mosaik Verlag GmbH,
München, 287 pp.
Welcomme, R.L. (1988) International introductions of inland aquatic species. FAO Fisheries
Technical Paper 294, 318pp.
Zaugg, B., Stucki, P., Pedroli, J.-C. and A. Kirchhofer (2003) Pisces, Atlas. Fauna Helvetica 7,
Centre Suisse de Cartographie de la Faune, 233 pp.
Other source http://www.fishbase.org/search.cfm
http://www.ku.lt/nemo/mainnemo.htm
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An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006

Ctenopharyngodon idella
Taxonomic status
Scientific name Ctenopharyngodon idella (Valenciennes)
Family Cyprinidae
Taxonomic group Osteichthyes
English name Grass carp
German name Graskarpfen
French name Amour blanc
Italian name -
Description and identification
Description The grass carp is a large species of slender appearance. It is greenish above and whitish below.
The large scales have a dark edge producing a neat pattern. It has no barbels and a very short
snout.
Similar species The set of characters given above allows the grass carp to be distinguished from other fish.
Biology and ecology
Behaviour The grass carp prefers warm waters. When the temperature and other factors are met, it spawns
over gravel in faster flowing parts of its habitat.
Food Mainly, as the name implies, higher water plants.
Habitat Standing water bodies, mainly fish ponds, where it is stocked. It prefers large, slow-flowing water
bodies.

Origin China
Introduction and dispersal
History of introduction One of the world’s most important aquaculture fish. It is also released to control water vegetation
in eutrophic water bodies.
Pathways of introduction Stocking of water bodies for weed control or as a food fish.
Dispersal Dispersal can be extensive during spawning migration.
Current status
Actual and potential distribution in CH The grass carp is found patchily in the Rhine watershed. The populations are based on stocking;
no natural reproduction was found in Switzerland.
Introduced distribution Introduced to water bodies on five continents.
Impacts
Environmental impact Grass carps can remove a large percentage of the aquatic vegetation, which causes impacts that
can ripple through the entire biological community, causing structural changes. It inhabits a fairly
new niche in most areas and can alter the ecosystem.
Economic impact Positive – important aquaculture fish and used for weed control.

Management options An Appendix 3 species (see text for explanation) and its introduction is therefore prohibited.

Information gaps Impact on community and habitat in Switzerland. Survey of breeding populations in Europe.