Open season has been declared on a range of animals and plants found on an EU list of alien species.

Member states are now required to wipe them out or at least try to keep them contained.

Among them are animals such as the raccoon, the grey squirrel and North American bullfrog.

Plants found on the most wanted list include curly waterweed, Persian hogweed and American skunk cabbage.

The 23 animals and 14 plants on the initial list were selected because of their potential to do harm to local biodiversity or to cause significant economic impact, explained Ciarán O’Keeffe, a principal officer at the Department of Arts, Heritage, Rural and Regional and Gaeltacht Affairs.

The EU regulations aimed at stopping the spread of “invasive alien species” come into effect on Wednesday, he said.

“It is an alien species if it is transported into a new area, becomes invasive and thrives at the expense of things already there,” Mr O’Keeffe said.

12,000 invasive species

EU countries have to contend with 12,000 invasive species which cost about €12 billion a year, including controlling them and coping with damage they cause.

The regulations take into account that some species are embedded and would be very difficult to clear out.

The curly leaved waterweed is an example, he said. This plant has taken over Lough Corrib and has been distributed to ponds.

Another is the grey squirrel, which has invaded most counties west of the Shannon.

“If the species is new, we will try to eradicate it. If it is there then we will put a management plan in place,” Mr O’Keeffe said.

The regulations are meant to halt the spread of these species more than eradicate them.

Spreading diseases

Raccoons, for instance, have moved into locations in Germany and are spreading diseases among other species, but are unlikely to reach Ireland.

Germany, however, will be expected to contain or exterminate the animal.

“Some commonplace species now were formerly invasive,” Mr O’Keeffe said.

These include plants such as fuchsia and montbretia and the Little Egret, which began breeding here in 1997.

“We have to allow for things arriving naturally,” Mr O’Keeffe added. There may also be new arrivals due to climate change.

The department is planning to set up a surveillance system so invaders can be found and assessed.

It also works with Customs and Excise and the Department of Agriculture to help catch alien species either accidentally or intentionally brought into the country.