Landowners can be punished for allowing invasive species to spread

People have a legal duty to prevent invasive species from spreading from their property into the wild, and inaction can also lead to penalties, Merike Linnamägi, an adviser at the Climate Ministry’s biodiversity protection department, told ERR’s Vikerraadio programme Ökoskoop.

“Being a landowner is nice, but it also comes with responsibility,” Linnamägi said.

Estonia currently has 1,014 invasive species on its list, she said. These are species that have reached the wild through human activity, including gardens and pets. About 1 percent are considered highly invasive.

The most problematic species include hogweed, balsam, lupine, Canadian goldenrod, raccoon dogs, mink and various invasive crayfish, which authorities are trying to control.

The ecological impact of Spanish slugs is not yet fully known. They clearly eat plants in the wild and have been found to attempt to eat chicks in bird nests, Linnamägi said. Their main damage, however, is in people’s private gardens.

Because Spanish slugs live in private gardens and are active at night, nationwide control is difficult. The main method is collecting them at dusk or in darkness. Local governments can organise communal control efforts, but regional initiatives are more likely to work, Linnamägi said.

Authorities are seeking to eradicate hogweed completely. All known colonies are being controlled, and newly discovered colonies are treated immediately. Invasive crayfish are also being controlled through trapping.

Recent amendments clarified that the law covers not only deliberately promoting the spread of an invasive species, but also allowing it to spread through inaction. The changes followed disputes in which landowners said they had not planted a species and that it had spread on its own.

Linnamägi said the amendment did not mean that every garden in Estonia would be inspected. Authorities have enforcement measures available, but fines would not be the first response.