06 June 2023
An invasive sea-squirt, which originates from Japan but has spread to other parts of the world
in recent decades, has been discovered at Jersey’s Elizabeth Marina.
The Carpet Sea-Squirt (Didemnum vexillum), sometimes known as Sea-Vomit, was found
initially in four small colonies on the underside of several pontoons last month. It has since
also now been spotted attached to boats in the marina.
Routine monitoring using an underwater camera showed up the potential presence of the
organism in Jersey’s waters. Photographs were then sent to experts at Marine Scotland. As
visual identification of Carpet Sea-Squirt can be difficult, samples were also taken for DNA
analysis, which confirmed its presence. States of Guernsey colleagues also assisted to confirm
Alastair Christie, Senior Scientific Officer for Invasive Species in Jersey, said: “Carpet Sea-Squirt
originates from Japan but we’ve seen it spread to the British Isles over the past few decades,
arriving in Ireland and north Wales in 2008. More recently it has had a presence in southern
UK ports, so it was likely to be just a matter of time before it arrived here in Jersey.
“It’s a concern as it may have some impacts on aquaculture businesses in damaging stocks,
marine leisure in increasing the fouling of boat hulls, and also upon our native marine ecology
as a competitor with our existing marine species.
“Unfortunately, with many marine invasive species, there is often little that can be done once
they are well established. The hope is that this current incursion is minimal and that swift
removal, followed by continued monitoring, will avoid a significant infestation and the impacts
will be low.”
Further surveying of Elizabeth Marina, other harbours and other parts of the coast is underway
to assess the extent of the infestation. This work is being carried out with the help of Ports of