Boat Owners Warned about Invasive Species Threat


    Carpet Sea Squirt 

A Marina in Wales has been found to be hosting a potentially highly damaging species of Sea Squirt. Didemnum Vexillum, known as the Carpet Sea Squirt, was found earlier this year by a research student investigating non-native species in North Wales. Didemnum Vexillum is potentially deadly to aquatic life as it smothers marine habitats in thick sheet-like growths. Colonies can be found on wood and metal pilings, moorings, ropes, chain, rocky outcrops, gravel sea beds and boat hulls. The animal can suffocate organisms such as other sea squirts, sponges, seaweeds, scallops, mussels and oysters, and where these colonies occur on the sea bed, can act as a barrier between fish and their food.

A task force of experts was brought in to deal with the problem, with the first action being to remove the fouling from the boats that had the sea squirt on them, thus ensuring that they would not transport the organism to other areas. The fouling was then disposed of on land. Particularly badly affected were two boats that had not had hull cleaning carried out for at least two years.  The marina took a proactive approach with all of its berth holders and neighbours. Berth holders were written to with details of how to spot and deal with the possibility of having Didemnum Vexillum living on their boat hulls. And posters were distributed to neighbouring boat clubs and other marinas showing what the organism looked like.

As it is extremely difficult to identify non-native species, the best course of action for boat owners is to ensure that their hulls are properly scrubbed and antifouled regularly.

See The Green Blue website for more information on non native species, and guidance on antifoul.

Please note that a poster has been put up on the Carrick Castle Notice Board about this.