Shetland’s Marine Non-native Species

Can you help spot marine non-native species in your local area?

For a number years, Shetland UHI has been looking for and keeping records 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). Shetland UHI has been monitoring ports and marinas, as this is usually where species enter first.

Download our INNS Guide here…

We have 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 some INNS have been found in Orkney and Norway and can compete with native wildlife and smother aquaculture structures which have caused economic impacts elsewhere in the UK. It is therefore important that we monitor hotspots such as piers and marinas to record and findings of INNS and implement an eradication strategy.

We have created a INNS and Indicator Species Guide to help communities identify INNS in their local area and by reporting them quickly, are helping to keep the numbers of INNS in Shetland low. Very few non-native species make it into the ‘wild’, they prefer man made structures so piers, marinas and the underside of buoys are a good place to start your search.

Two species we would be particularly interested in records of are the Orange-tipped Sea Squirt (Corella eumyota) and Wireweed (Sargassum muticum), both originally from Japan.

Copyright Lisa Humphray

Lisa Humphray recently spotted the non-native 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 may be 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 may be found on the underside of floats and buoys.

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.

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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 Shetland UHIs webpage on non-native species here.