Invasive Non-Native Species

Australian barnacleAustralian barnacle (Austrominius modestus) © Lara Howe

Help us learn more about marine invasive non-native species -- find out what to look for and how to report your sightings to us.

Invasive Non-Native Species (INNS) are any living organisms that have been transported outside of their natural range, by human activities or naturally.

The spread of INNS can outgrow, kill, or out-compete our local species which can impact food chains and biodiversity. They can damage our environment, the economy, our health and the way we live.

Why Monitor the Impacts of Invasive Non-Native Species?
INNS pose an increasing threat to the biological diversity (commonly known as biodiversity) of our seas.

Get involved - Report your Sighting to Us!

Having biological diversity is fundamental to the healthy functioning of an ecosystem. The various ecosystems around the Island provide various ‘ecosystem services’ which we humans depend on for our survival. Some examples of ecosystem services include:

• producing oxygen for us to breath,
• plants and animals as a food source,
• recreational activities, and
• education

How do they impact us?
The loss of overall biodiversity and the loss of certain species which our economy relies on can have a number of negative impacts both on the environment and on humans.

For example invasive non-native species may predate our native species or out complete native species for food and shelter; they may carry diseases; or they may modify the habitat (for example plant eating species may eat up all the vegetation).

All of these impacts could lead to the complete change of an ecosystem or the removal of some or all of native species. The result can be a loss of the biological diversity of a habitat which can have devastating impacts on the environment.

These devastating impacts on the environment ultimately have a negative impact on the economy.

The Great Britain Non-Native Species Secretariat (GB NNSS) estimates that the impacts of invasive non-native species cost £1.7 billion per year in Great Britain alone. These costs are estimated to be even larger when you include the indirect costs, such the loss of certain ecosystem services.

These effects are also likely to be more devastating to islands due to their vulnerability. These impacts are long lasting and compounding unless action is taken to eradicate and prevent the spread of invasive non-native species.

How do they find their way here?
In many instances the introduction of invasive non-native species has been accidental and unintentional.

One major pathway of introduction has been through ballast water, held in a ship's hull to keep it balanced on international journeys. When a ship isn't carrying any cargo, its tanks are filled with water from the local environment (Port A) then, before reaching its destination (Port B), the water - and potentially invasive non-native species in it - is released to increase buoyancy. 

Organisms can also be introduced when they attach themselves to the hull of commercial ships and recreational boats (also known as ‘hull fouling’); through the introduction of species and diseases through aquaculture (i.e. fish farms); introduction via live food; and also through anthropogenic or natural flotsam.

The Convention on Biological Diversity (CBD) proposes a three step method to prevent the harmful impacts of invasive non-native species. These steps include:

• Prevention
• Detection/surveillance and rapid response
• Control and eradication

Biosecurity in the Isle of Man
The Isle of Man Government is taking steps, through a marine biosecurity plan, to make sure that good practices are in place to reduce the risk of introduction and spread of invasive non-native species in Manx territorial waters, similar to the CBD approach.

What can be done about INNS?
Little is known about the impacts on our shores. This is why the Trust is keen to collect sighting information which will enable us, and the government, to better understand these species, where they can be found and what their possible impacts could be.

What can I do to help?
Get involved, learn what to look out for, and report all your sightings to us!

What am I looking for? How do I identify an INNS?
Manx Wildlife Trust has produced an identification guide describing (with photos) twenty invasive species, including shrimps, limpets, mussels, crabs, seaweeds, clams and barnacles. You can download the pdf at the bottom of this page.

What should I do if I find an INNS?
Please report sighting to the Trust via this link:

What information do I need to supply?
Please provide as much information as you can, by answering the questions provided on the above link.  Alternatively, complete this spreadsheet and email it to us at

Do I need to supply images?
If you have taken photos, then yes please. Attach images to the report (maximum size 5mb per report, please).  No photos? No problem, we'd still like to receive your sighting information!

What will happen to the information I supply?
The Trust will collate all the reports submitted and use them to help us better understand these species, where they can be found around the island and what their possible impacts could be. We will share the findings with the Isle of Man Government.

Where can I find out more about the INNS mentioned in the ID guide?
More detailed information is available here [pdf]

More information
Look out for news on Isle of Man Marine Biosecurity Plan on the Isle of Man Government’s website

Visit the website of the Great Britain non-native species secretariat

Images: From top: Australian barnacle; Oyster thief, Sargassum muticum


FilenameFile size
anglers-iom_leaflet.pdf3.59 MB
boats-iom_leaflet.pdf4.12 MB
Marine Invasive Species ID Guide 2.4 MB