According to the Countryside Council for Wales, the carpet sea squirt (Didemnum vexillum) threatens to “spread rapidly, colonising natural habitats and devaluing the mussel lays in the Menai Strait”.
The carpet sea squirt originates from Japan, says the CCW, and was most probably introduced to Holyhead via leisure boat hulls. It is already established on Ireland’s east coast.
The aim now is to control the growth before it can spread more rapidly come spring and summer next year.
Through the winter, CCW marine staff are to fix large bags around the submerged structures of Holyhead’s marina, where the species is particularly prevalent.
The idea is that, by stopping or severely slowing the flow of water, the sea squirts will suffocate and die.
Boat owners will be asked to ensure that their vessels are dried out and scrubbed clean before venturing forth for the 2010 boating season, in order to prevent transfer of the sea squirts to new locations.
Other marinas and popular mooring areas in Wales will be monitored.
Didemnum vexillum is a spongy-textured sea squirt, of a mustardy beige colour and with leaf-like surface veins carrying tiny pores.
It often appears as flat patches or like a wax dripping, attached just below the surface to structures such as pontoon piles.
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