The first findings of the Chinese sleeper (Perccottus glenii), an invasive alien species, have been made in Finland. The Chinese sleeper was discovered at the end of summer in a pond in Southwest Finland, where it has been released by people. The Chinese sleeper is not hazardous to people, but it threatens our native aquatic species. It is defined as an invasive alien species throughout the EU, and its spread must be prevented.
The Chinese sleeper originates from northeast China, the northern parts of the Korean Peninsula, and the Russian Far East. It thrives in small waterbodies, such as ponds and lakes. People have brought it to new regions in Russia and all the way to Central Europe. As a result, the species has spread rapidly in Europe. Previous findings of the Chinese sleeper close to Finland were made in Estonia and in the eastern parts of the Gulf of Finland in Russia.
“The first finding of the Chinese sleeper in Finland was made as an observation by a citizen. Citizen science plays an important role in controlling invasive alien species. Any observations should be reported on the vieraslajit.fi website, with a photo of the species attached,” says Sanna Kuningas, senior scientist at the Natural Resources Institute Finland (Luke).
The Chinese sleeper withstands difficult living conditions (e.g. eutrophic and low-oxygen waterbodies), and it has a high reproductive potential. It is an effective predator which can be particularly harmful for amphibians living in the same waterbodies. The Chinese sleeper competes over living space and food with other fish species.
“We are currently investigating the further measures we need to take as a result of this finding,” says Juhani Salmi, fisheries biologist at the Centre for Economic Development, Transport and the Environment (ELY Centre) for Southwest Finland.
Because the Chinese sleeper found its way to the pond as a result of human activities, the exact location of the pond will not be mentioned due to the risk of spreading. The Chinese sleeper is defined as an invasive alien species throughout the EU. It is illegal to import the Chinese sleeper to Finland, have it in possession, and release it into the environment (act on invasive alien species 1709/2015, Criminal Code of Finland 1889/39).
“Alien species” means a plant, an animal or other organic species, whose spread outside their natural habitat human activities have helped intentionally or unintentionally. Certain alien species spread to new regions are invasive. Invasive alien species threaten biodiversity or related ecosystem services.
