Marine Alien Species Project

Most marine alien species do not cause problems, others thrive and can have serious consequences for native wildlife and the habitats in which they live. These are known as invasive non-native species.

It is thought that there are over 40 non-native species in Welsh waters, approximately 7 of these are thought to be invasive. For instance, several species of seaweeds have been found here in North Wales but only a few, wireweed for example, are fast growing and can outcompete local species. Although these are recent estimates this number is thought to be continually increasing.

Some species, such as the Pacific Oyster were introduced deliberately to be grown on farms, the escapees of which managed to establish populations elsewhere. Most however are introduced by accident and as shipping, recreational boating and aquaculture increases we’re seeing more and more settlers. Many - hundreds of species - are transported around the world in the ballast water of ships or as fouling on the hulls. Some are known to have arrived on flotsam and jetsam and as the plastic tsunami in our oceans continue to rise the transport of aliens in this manner is set to increase. 

Although the introduction of invasive non-native species is mainly out of our control, as people who love to be outdoors we can help prevent the spread within our patch. Once introduced to an area these species can quickly spread as eggs, larvae and viable plant fragments are carried around in our equipment or on clothing. To help prevent the spread Check, Clean, Dry your equipment and clothing and make sure that you never transfer water elsewhere. 

Here in North Wales Wildlife Trust we are asking you to keep an eye out for some of these species and let us know if you think you’ve seen them through the Marine Biological Association Sighting Scheme. If you have a camera on your phone you can also submit your photo!

We are looking for people within organisations, clubs and the community to become Marine Alien Champions and help us share information about marine aliens and the impact that they can have. Our Marine Alien Champions will help us by being our "eyes and ears" within their communities. Fancy it? Click here for more information.

Our Marine Aliens Project is part of the Marine Pathways Project, a multi-national project which aims to help prevent the introduction and spread of marine aliens by raising awareness of issues, preventing the spread and increasing the capacity to respond rapidly.