Invasive Alien Species in Switzerland. Factsheets
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> Environmental studies > Organisms > Invasive alien species in Switzerland Factsheets > Fact sheets 3 > 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 An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006 4 Fact sheets Vertebrates > Fact sheets 5 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. An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006 6 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. > Fact sheets 7 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. An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006 8 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 > Fact sheets 9 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)