The minnow and the northern pike are examples of native species that are being spread deliberately or accidentally and that have caused significant changes to the original life in lakes and rivers. Some of the introduced species are pathogenic organisms that cause great harm. They include the fungal parasite Aphanomyces astaci, which causes a lethal disease in crayfish, and the salmon parasite Gyrodactylus salaris, which has wiped out the salmon population in a number of rivers.
Alien freshwater species that have become established in Norway
English name |
Scientific name |
Origin |
Arrived year/period |
|
Fam. Cyprinidae |
|
|
| Carp |
Cyprinus carpio |
Asia |
|
| Goldfish |
Carassius auratus |
Europe and Asia |
|
| Tench |
Tinca tinca |
Europe and Asia |
|
| Sunbleak |
Leucaspius delineatus |
Europe and Asia |
|
| Gudgeon |
Gobio gobio |
Europe |
1980s |
|
Fam. Ictaluridae |
|
|
| Catfish (Dwarf bullhead) |
Ictalurus nebulosus |
North America |
1890 |
|
Fam. Salmonidae |
|
|
| Rainbow trout |
Oncorhynchus mykiss |
North America |
|
| Canadian char |
Salvelinus namaycush |
North America |
|
| Brook char |
Salvelinus fontinalis |
North America |
|
|
Fam. Centrarcidae |
|
|
| Pumpkinseed |
Centrarchidae |
North America |
1990s |
| Signal crayfish |
Pasifastacus leniusculus |
North America |
Approximately 1980 |
Examples of alien, pathogenic organisms that have become established in freshwater
Source: Norwegian Institute for Nature Resarch (NINA) and Directorate for Nature Management