Shetland’s Marine Non-native Species

Can you help spot marine non-native species on your local beaches?

For a few years, the NAFC Marine Centre UHI has been keeping check of the number of marine non-native species arriving in Shetland. Non-native species are those which come from elsewhere in the world and have become established here, usually transported on hulls of boats or ballast water. In the past, species were also transported with shellfish aquaculture when novel species were brought into and trialled across Europe (back in the 1960-1980s). The NAFC has been monitoring ports and marinas, as this is usually where species enter first.

Download our NNS ID Guide here…

The NAFC has found that compared to elsewhere in the UK, Shetland has relatively few non-native species, perhaps reflecting Shetland’s cooler waters, making it harder for some species to colonise. However, non-native species can compete with native wildlife and smother aquaculture structures which have caused economic impacts elsewhere in the UK.

Very few non-native species make it into the ‘wild’ (beyond man made structures such as pontoons), but there are some exceptions that establish there first. That is why we need your help, we are keen to hear from anybody who spots anything odd. The NAFC has produced a leaflet to help you to spot non-native species but the two we’d really like people to watch out for are the Orange-tipped Sea Squirt (Corella eumyota) and Wireweed (Sargassum muticum), both originally from Japan.


Copyright Lisa Humphray

Lisa Humphray recently spotted an Orange-Tipped Sea Squirt in Scalloway harbour, while turning over rocks on the beach. This is only the second time it has been found in the wild in Shetland and indicates it is spreading beyond marinas and harbours. We’d be really interested to hear if anybody else finds it, as it would help us to understand how fast it is spreading around Shetland. It loves living right at the bottom of the shore and under rocks. At marinas it’s found under floats and buoys.

JDD Bishop (c) JDD Bishop

The second species we’d like you to look out for is Wireweed. It has been spotted twice in Orkney but hasn’t yet managed to become established. It can drift long distances in the current, so could easily make it to Shetland too. In Orkney it was found in the ‘wild’ rather than at a marina. Once established it can grow rapidly, clogging boat propellers and smothering our native animals.

GBNNSS © Crown Copyright 2009
Paul Brazier (CCW) © Crown Copyright 2009

We also don’t know if either the Orange-tipped Sea Squirt or Wireweed can survive Shetland’s wet ,windy and cold winters, so year round and year-to-year data is really important to understand how a species is establishing and spreading, particularly as the climate changes.  

For more information have a look on the NAFC Marine Centre’s webpage on non-native species here.