Published Friday, 14 September 2012
The sea squirt pictured at Strangford Lough. (© PA)
Samples from a recent survey of marinas have caused such concern among marine experts in Northern Ireland that a senior scientist from Wales has been called in to investigate.
The expert from the Countryside Council for Wales has been asked to undertake dives and advise on how to manage the threat from the foreign organism.
Its identity is still being confirmed but it could threaten native marine habitats and species while interfering with fishing because of its suffocating nature.
And if investigations prove positive, this would be the first record of Didemnum vexillum for Northern Ireland, having previously been recorded in the Republic of Ireland, the south coast of England, Wales and Scotland.
Environment Minister Alex Attwood said: "I am concerned about this. It is particularly hard to prevent invasive species spreading in the marine environment and even more difficult to control them once they are there.
"The possible presence of Didemnum vexillum (carpet sea squirt) adds a new challenge to managing Strangford Lough which is so important for its marine life."
The invasive squirt is believed to be native to Japan, where waters are similarly temperate.
It can attach itself to any hard surface like docks, lines and ship hulls or form mats on seabeds.
The organism can spread through larvae or fragmentation but is mainly transported over longer distances on boat hulls, fishing equipment and nets.
It is an offence to release the squirt into the wild or cause its further spread.
The Northern Ireland Environment Agency has invited Dr Rohan Holt, a senior Welsh scientist and expert on the survey and eradication of Didemnum vexillum, to dive suspected locations in Strangford Lough.
He will also advise the Agency on possible management measures.
It is hoped these dives will take place next week.
Island-studded Strangford Lough is the largest sea inlet in the British Isles, covering 150 square kilometres. It is a popular tourist attraction noted for its fishing. It is a conservation area and its wildlife is recognised internationally for its importance.
The Agency is encouraging all coastal water users, especially in Strangford Lough, to report possible sightings with photos through the "alien watch" facility of the Invasive Species Ireland website.
Members of the public are urged not to remove them from vessels and structures in the sea as fragments can survive and be carried to colonise other locations.
Mr Attwood said he was establishing a working group to agree on appropriate actions in response to this potential threat.
"I will be ensuring that those actions take place as a matter of urgency and I will be keeping a very close eye on this," he said.
An all-Ireland workshop on invasive species is to be planned in the near future.