Marine Invasive Non-Native Species

Status of marine non-natives: Stable with some concerns

(Baxter et al, 2011)

Status of marine non-natives: Stable situation since 2012

(United Kingdom Marine Monitoring & Assessment Strategy, n.d)

Non-native species (NNS) refers to species which are found beyond their native range. This can happen in terrestrial and marine environments. NNS are introduced to new areas through unintentional means, for example accidental or careless human behaviour, or intentionally, normally to seek economic gain from the species. NNS can cause damage to the native species, biodiversity, social, and economic aspects of an area once they become established. Once the NNS are aggressively thriving, to the detriment of native species, biodiversity or activities they are considered ‘invasive’ NNS (INNS). Classifying a species as NNS or INNS is specific to the site and species.

According to AquaNIS there are 147 species accounts of non-indigenous and cryptogenic marine species across Britain, including microbiota such as bacteria etc, as of January 2020. This is a high estimate as it includes microbiota. Alternatively, in 2015 the Scottish Environmental Protection Agency (SEPA) reported that at least 30 non-native plant and animal species have been found within inland and marine waters around the UK (Scottish Environment Protection Agency, 2015).

Although the exact number of NNS we have in the UK cannot be conclusively known, one thing is certain, the number of NNS is increasing. In the marine environment reasons for this increase include;

  • lack of awareness of NNS and therefore spreading NNS unintentionally or giving the NNS species time to become established without control measures,
  • the rising intensity of ocean use and travel,
  • rising sea temperatures, providing a more hospitable environment for some NNS while also lowering the resilience of native species (see Climate Change – Impacts on Marine Life and Processes)
  • careless or reckless behaviour.

Biosecurity measures are actions through which people can limit the risk of spreading NNS through good practice and preemptive measures.

As this review covers the Solway Firth coastal and marine area, freshwater species and associated plans do not fall within the scope of this section. However, it is worth noting that there are several biosecurity plans covering rivers entering the Solway. These include; Cumbria Freshwater Biosecurity Plan (2011 – 2015) which covers both fresh water and brackish water species, the River Nith Catchment biosecurity plan (2011-2016), River Annan Trust biosecurity plan (2010-2016).

The two biosecurity plans which cover the Solway are; North Western Inshore Fisheries and Conservation Authority (NWIFCA) Biosecurity plan 2014-2019 (although this plan covers the entire NWIFCA area), and Solway Firth Partnership Biosecurity Plan 2018-2021.

Although there are two biosecurity plans for the Solway Firth, INNS are discussed in several other plans which cover parts of the Firth. For example, the Solway Tweed River Basin Management Plan (2015 Update) and Managing Invasive Non-Native Species in Scotland’s Water environment: A Supplementary Plan to the River Basin Management PlansSite Improvement Plan for the Solway Firth SAC and Upper Solway Flats & Marshes SPA, and NSA Management Strategies for Nith Estuary, Fleet Valley and East Stewartry Coast, to name a few.


Image; Japanese wireweed. © Solway Firth Partnership

Marine Invasive Non-Native Species

How do marine INNS arrive?

Pathways and vectors are the routes through which marine INNS spread. Species not native to the UK are transported into UK waters, and similarly our native species can be exported elsewhere around the globe. The most common way that INNS arrive is through hitchhiking in their larval or planktonic stages on marine vessels or equipment. 

The main pathways INNS are transported through are;

  • Commercial fishing vessels introducing marine INNS or disease from other areas
  • Escapes of plants and animals from fish farms, ponds and gardens
  • Fish and shellfish from the aquaculture industry acting as disease vectors
  • Fishing gear (including aquaculture cages, dredges, clothing and boots) introducing marine INNS or disease from other areas
  • Fouling of hulls and ballast water (discussed in more detail below) of marine commercial and private vessels (including construction vessels)
  • Fouling of recreational water-sports equipment and vessels
  • Importation or movement of new species, shellfish or stock for aquaculture
  • Improper control and disposal measures
  • Intentional introduction or release
  • Mussel and cockle bags used for transportation may be exchanged between vessels both in the Solway area and around other fisheries and shellfish processing plants in the UK
  • Natural occurrences e.g. storm events, sediment transport
  • Organisms attached to structures and equipment subsequently relocated e.g. pontoons acting as ‘stepping stones’
  • Relaying of infected seed mussel harvested from outside the district and potential for disease transfer to nearby naturally occurring beds
  • Vehicles used to launch boats or quads introducing marine INNS or disease from other areas
  • Marine Litter can travel over long distances and can carry marine INNS with them. Marine INNS which travel with marine litter may have been able to adapt during their journey due to the slow movement of litter in the marine environment providing time to adapt too changes such as temperature. For more information on marine litter see the section of the Solway Review discussing Marine Litter.

Solway specific pathways and actions to reduce the risk of spreading INNS for each pathway are discussed below in the ‘prevent the spread’ section. Certain areas of the Solway will be at higher risk of INNS due to their traffic and activities, such as ports on either side of the Solway.


Ballast water;

Ballast water is one of the most widely recognised methods of INNS transportation. Vessels take on sea water in the port where they are removing cargo in order to replace the removed weight. Ballast water, held in ballast tanks, can contain thousands of marine microbes, plants and animals from the location where the water was taken onto the vessel. This water can then be transported around the world on the vessels onward or return journey before being released. Untreated ballast water released at the ship’s destination could potentially introduce a new INNS.

The Ballast Water Management Convention came into force in September 2017.

The Ballast Water Management Convention provides requirements for ships which travel internationally to reduce the risk of introducing INNS into coastal waters.
For more information on the Ballast Water Management Convention see the video opposite.


Video; © International Maritime Organisation 2017. Publicly available via YouTube

Marine Invasive Non-Native Species

INNS Impacts

The damaging effects of INNS can be vast and varied depending on the species, location, and services the ecosystem provides (the potential ‘high, medium, or low’ level of impacts from each INNS currently present in the Solway are listed on the next page alongside the species). The effects of INNS can span economic, environmental and social costsMachinery or underwater structures may be smothered, clogged, or damaged due to INNS. Within the Solway this effect could harm the fishing industry, shipping, and aquaculture. The effects of INNS become more severe, advanced and detrimental as the population grows and, potentially, spreads further. Furthermore, there is the potential for extensive damage to the biodiversity of the marine area, and even de-designation of protected areas where INNS become established. Social costs are extremely difficult to quantify and therefore are not discussed here. There is the potential for changes in cultural use of areas, or the character of areas, and local recreational enjoyment. Carpet Sea Squirt, for example, can completely cover structures and equipment in marinas and so could interfere with recreational use of the coast and marine area.


Economic Costs

In 2010, CABI released a paper entitled The Economic Cost of Invasive Non-native Species to the British Economy, which estimates that INNS (including terrestrial INNS) cost Great Britain in the region of £1.7bn per year. This is now likely to be significantly more considering 10-12 new NNS become established each year (Department for Environment, Food, and Rural Affairs, 2015). Of this £1.7bn, £244,736,000 was spent in Scotland and £1,291,461,000 in England (Williams et al, 2010). Furthermore, it was estimated in this 2010 paper that costs to the aquaculture industry alone from INNS was £722,000 in Scotland, and £4,370,000 in England, with Great Britain’s aquaculture sector as a whole spending £7,145,000 on INNS (Williams et al, 2010). Although, it must be noted that there is little distinction made between native and non-native species during pest control operations.

The GB Non-Native Species Secretariat (GBNNSS) is responsible for coordinating the approach to tackling NNS in Great Britain (Scotland, England, and Wales). As such the GBNNSS has created an INNS Strategy. This strategy was originally published in 2008, reviewed in 2013, and was replaced by a new strategy in 2015. According to this strategy between 10 and 15% of NNS which are introduced (terrestrial and marine NNS) become invasive, although marine NNS are more likely to become INNS. Difficulties arise in terms of the cost of eradicating NNS and also becoming aware of the introduction of a NNS. This is why the GBNNSS approach to INNS focus’ on preventing introduction. Once INNS are introduced it is difficult to eradicate them, as doing so is technically complex in the marine environment.


Environmental Costs

INNS can become nuisances or out-compete native species, overwhelming them, consuming them or destroying them. Some INNS are known to create monocultures, such as the invasive bryozoan Schizoporella Japonica, which has been observed on the west coast of Scotland colonising artificial structures (MacLeod et al, 2016). The biodiversity of the Solway is invaluable. The effects of INNS could damage the designated areas or associated features in the Solway and risk de-designation.

The Marine Strategy Framework Directive (MSFD) aims for the EU marine waters to achieve Good Environmental Status (GEnvS) by 2020. The Water Framework Directive (WFD) seeks for all waters, including marine waters out to 1 nautical mile to achieve Good Ecological Status (GEcS) and good chemical status by 2027 at the latest. The presence of INNS can interfere with these aims as they can cause failure to achieve GEnvS (Descriptor 2) and contribute towards failure to achieve GEcS, although INNS presence alone cannot prevent the achievement of GEcS.

In SEPA’s 2015 cross border Update to the Solway Tweed River Basin Management Plan (covers coastal waters out to 3nm), 9 water bodies (7 Rivers and 2 Lakes) were failing to achieve ‘Good’ status because of INNS. There is a map provided in ‘figure 24’ of the Update to the River Basin Management Plan showing the Solway Tweed water bodies at worse than good status or at risk of deterioration as a result of invasive non-native species. All of the water bodies failing to achieve ‘Good’ status were in the Scottish part of the river basin but none of these failings were in the Solway and were the result of the freshwater species North American signal crayfish (Pacifastacus leniusculus). The treat of this freshwater species to the Solway itself is limited but it may impact rivers flowing into the Solway. This information illustrates the potential threat which INNS pose to environmental quality. This document also identifies Leathery sea squirt (Styela clava) as an immediate threat to the quality of water body within the Solway Tweed District. The species is known to be present in the Solway Firth and may impact the quality of the water in the future. As can be seen in the map in the Update to the River Basin Management Plan (available here), areas of the Solway are at risk of deterioration due to INNS. For more information on the WFD classifications for any waterbody in the Scottish Solway you can explore the National Marine Plan Interactive data layer; Water Framework Directive Waterbody Classification 2007-2017 (SEPA). The data is from 2007 up to and including 2016 and covers the class, confidence level, and category, in addition to other data. Information can also be found in SEPA’s Water Environment Hub.

The Environment Agency manages the North West River Basin District and has a River Basin Management Plan most recently updated in 2015. Part of the plan includes the Cumbrian Solway from Dubmill Point down to St Bees Head. In discussing pressures preventing waters from reaching ‘Good’ status, this document identifies two instances where INNS was a pressure stopping a waterbody from achieving ‘Good’ status. Although the most recent data on the Environment Agency’s website shows that the waterbody of the South Outer Solway did not fail to achieve ‘good’ status due to INNS, according to Environment Agency Data Explorer.

For more information and data updates on water body status in terms of the WFD, please visit the SEPA water classification hub, or Environment Agency’s Catchment Data Explorer.


Video; The video opposite is a short clip taken of an INNS monitoring panel removed from Stranraer Harbour in 2019. On the panel you can see a variety of native species which grew, but also a large number of the INNS Japanese Skeleton Shrimp (Caprella mutica). This INNS are easy to spot once they are removed from the water. The small stick-like shapes which are waving in the video are Japanese Skeleton Shrimp. © Solway Firth Partnership. 

Marine Invasive Non-Native Species

NNS Present or Threats to the Solway

Records of INNS;

Data from all over the UK and from many different sources is aggregated by the National Biodiversity Network Atlas. The network can show records of species around the UK including INNS, but it is worth noting that INNS are often more difficult to record than traditional terrestrial species due to, for example, limited awareness or species confusion. There may also be knowledge of the presence of INNS which has gone unrecorded.

Non-native species records can be submitted directly to iRecord or through local schemes and societies.

SFP provides species and locational information on INNS in the Solway. The most recent revised version of the Biosecurity Plan for the Solway from SFP was prepared in 2017, and covers 2018-2021 (the 2021-2024 update will be available in April 2021). As well as providing an action plan for INNS, this document lists marine INNS currently present across the entire Solway and their potential environmental and socio-economic impact level;

Known location Potential Environmental Impact Potential Socio-economic Impact
Loch Ryan, points along North Solway Medium Low
North Solway – various points Medium Low

North Inner Solway and South Inner Solway – various points Medium Low
North Solway including Loch Ryan Low Medium

North Inner Solway and South Inner Solway – various points Low Low

Loch Ryan Low Medium

Loch Ryan, North Solway Low Low

 Loch Ryan, marina High Medium
Solway, landed at Workington High Medium
(Ficopomatus enigmaticus)
Whitehaven Marina Low Medium

Table Source; Solway Firth Partnership (2018) Please see Solway Firth Partnership’s Biosecurity Plan for the Solway Firth for a detailed description of each of the INNS listed above.

The NWIFCA Biosecurity plan 2014-2019 outlined that, in 2014, eleven NNS had been reported within NWIFCA waters. It is worth noting that NWIFCA waters cover the inshore waters (out to 6 nautical miles) on the west coast of England from the Scottish Border to the Welsh border and therefore also cover a large area of coastline outside of the Solway, and encompass the large port at Liverpool. Therefore some of these species may be present elsewhere in the NWIFCA area, but not in the Solway. The INNS listed as present within NWIFCA waters were; 

  • Acorn/ Darwin barnacle (Elminius modestus)
  • Chinese mitten crab (Eriocheir sinensis)
  • Common cord grass (Spartina anglica)
  • Green sea fingers (Codium fragile)
  • Japanese skeleton shrimp (Caprella mutica)
  • Leathery sea squirt (Styela clava)
  • Orange tipped sea-squirt (Corella eumyota)
  • Pacific oyster (Crassostrea gigas)
  • Tube worm (Ficopomatus enigmaticus)
  • Wakame (Undaria pinnatifida)
  • Wireweed (Sargassum muticum)
    (North Western Inshore Fisheries and Conservation Authority, 2014)

A 2016 a report studied two sites on the English side of the Solway at Whitehaven and Maryport for INNS. Settlement panels were placed in each location, however none of the Maryport panels were recoverable. The Whitehaven panels showed presence of NNS. Across the five panels there was an average coverage of;

  • Tubeworm, Ficopotamus enigmaticus – 16.6%
  • Darwin/ Acorn Barnacle, Austrominius modestus – 0.2%
    (Hurst, 2016)

Threats to the Solway;

SFP has identified 5 species which are not currently present in the Solway but are potential threats;

Common Name, Latin name Risk of Introduction Impact Locally
Chinese mitten crab (Eriocheir sinensis) High Risk High
Carpet sea squirt (Didemnum vexillum) High Risk High
Killer shrimp (Dikerogammarus villosus) High Risk High
Zebra mussel (Dreissena polymorpha) Medium Risk High
Slipper limpet (Crepidula fornicate) Low Risk Medium

Table Source; Solway Firth Partnership (2018) Please see Solway Firth Partnership’s Biosecurity Plan for the Solway Firth for a detailed description of each of the INNS listed.

The Asian Shore Crab (Hemigrapsus sanguineusalso poses a threat to the waters of North West of England according to the NWIFCA Biosecurity Plan 2014-2019. The threats listed in the table above as potential threats to the Solway are also listed within this NWIFCA plan (2014), with the exception of the Chinese Mitten Crab. This is because the NWIFCA plan reports that this INNS is already present within the district. This record is outside the Solway, and therefore poses a potential threat.


Image; Pacific oyster. © N. Coombey/ Solway Firth Partnership.

Marine Invasive Non-Native Species

Prevent the spread

Regulated and Unregulated Activities;

Marine plans can have an effect on the management of INNS through authorisation decisions or public authority functions provided by the Marine and Coastal Access Act 2009 and Marine (Scotland) Act 2010. For unregulated activities (such as recreational sports) authorities work closely with external organisations. One Example is the Royal Yachting Association‘s Biosecurity Guidance for Ribs, Sports boats, and outboard Engines, which promotes good practice to minimise the spread of INNS.

A matrix tool can be used for prioritising areas for detailed assessment. Natural England also suggests risk assessments should be based on the likelihood of entry, establishment, spread and potential level of impact.


Guidance, Actions, and Awareness Campaigns;

The GB NNSS has published an Event Biosecurity Support Pack, including a cleaning station checklist and associated risk assessment sheet and information on the Check, Clean, Dry Campaign.

Marine Scotland are supportive of the biosecurity planning approach to risk management in the marine environment with regard to NNS and have also produced a Code of Practice in 2012 to accompany the revision of the Wildlife and Natural Environment (Scotland) Act 2011 (WANE(S) Act). Marine Scotland leads on the enforcement of the WANE(S) Act, and as part of this work convenes the marine NNS working group which coordinates activity and shares information across relevant departments, organisations and agencies.

NatureScot (NS) published guidance on how to construct a marine biosecurity plan for a site or operation based on the Code of Practice.

The Environment Agency and Natural England currently use existing legislative powers, such as the Keeping and Introduction of Fish Regulations 2015 and Wildlife and Countryside Act 1981, to control movements of INNS. A recent change in legislation, implemented in April 2014, introduced a ban on selling five high risk plant species including water primrose and floating pennywort. The Species Control Provisions: Code of Practice for England sets out how provisions from the Act should be implemented by the authorities. The Marine Management Organisation (MMO) uses policies within emerging marine plans and marine policy statements to support controlling and mitigation against INNS. The Draft North West Marine Plan includes 2 policies on marine INNS.

Natural England manages INNS at selected protected sites as appropriate.


Preventative Actions to stop the spread of INNS in the Solway;

Pathway Preventative Action Stakeholder
Ballast Water Follow Ballast Water Convention and do not pump non-treated water out in harbours or into the Solway Firth Port Authorities, Harbour Masters, vessel operators and owners
Hull Fouling Annual haul-out of vessel and treatment with antifouling.
Hull design to prevent fouling and encourage easy cleaning
All vessel manufacturers, operators and owners
Port Infrastructure as a Receptor Good housekeeping.
Design to discourage fouling.
Port Authorities, Local Authorities
Fouling of recreational Equipment ‘Check, Clean, Dry’ all marine equipmentand clothing between use and before moving from one water body to another All marine groups, associations and users using water-based equipment
Relocation of structures and equipment ‘Check, Clean, Dry’ all structures and equipment before moving from one water body to another Port Authorities, marinas, fisheries, offshore industries
Attached to marine debris/litter Minimise marine litter / debris National Marine Litter Strategy, Fishing for Litter campaign, beach cleaning activities Local Authorities, Fisheries, SFP, NTS, Solway Coast AONB, MCS, general public
Escape or release of animals/plants from aquaria Do not release animals and plants from aquaria.
Use native species whenever possible
Stockists, general public
Natural Dispersal Understand tidal currents and spread risk for each invasive species. NS, GB NNSS, SEPA, Environment Agency

Table Source; Solway Firth Partnership (2018)


Video; The video opposite is a video about how and why Solway Firth Partnership monitor for marine INNS around the Solway Firth. © Solway Firth Partnership. 

Marine Invasive Non-Native Species

Rapid Response

If you find a non-native species please email with the following information (if possible):

  1. What species you saw. Please be as specific as you can to help us confirm it is a non-native. If you can also include the number, was it alive, sex, was it an adult or juvenile (if possible)
  2. Where you saw it. Please be as precise as possible, an OS grid reference or GPS coordinates
  3. When you saw it. Records from the past are fine but please be as specific as possible.
  4. Your name, along with the name of the person who ID’d the species, if it wasn’t you

We will only pass on the information provided to the appropriate organisations that monitor the spread of non-natives (by emailing this information we assume your permission to share this information with the appropriate organisations).

In the Solway, at present, species that would require a GB or Scottish high priority response are:

  • Chinese Mitten Crab
  • Carpet Sea Squirt (You can also report a sighting directly to the Biological Records Centre)
  • Slipper limpet
  • Killer shrimp
  • Zebra mussel

The response to reports of these species would be to follow the procedure:

  1. Report to SFP who will pass the information onto GBNNSS, NatureScot, South West Scotland Environmental Information Centre or another agency/group if necessary)
  2. Determine the extent of infestation
  3. Isolate area where practicable
  4. Follow relevant Codes of Practice to prevent further spread

Species requiring a local priority response at present are:

  • Common cord grass
  • Pacific oyster
  • Japanese wireweed (You can also report a sighting of wireweed directly by emailing
  • Orange tipped sea squirt
  • Green sea fingers
  • Acorn/Darwin barnacle
  • American lobster
  • Tube Worm
  • Japanese skeleton shrimp

The response to reports of these species in new locations would follow the procedure:

  1. Report to SFP who will send onto appropriate local record centre
  2. Determine the extent of the infestation
  3. Surveys in course of normal work to establish and map distribution
  4. Identify source and close pathways if possible
  5. Include new areas in eradication / control programmes
  6. Monitor the invaded area
  7. Follow relevant Codes of Practice to prevent further spread

SFP has also produced an ID guide for INNS, which helps boost public awareness of INNS around the Solway. Increased awareness hopefully leads to increased identification and reporting. This ID Guide has assisted in the positive identification of Japanese Skeleton Shrimp in Stranraer. Early reporting of NNS supports early actions towards eradication before the Non-Native Species become Invasive Non-Native Species.


For any records in Dumfries and Galloway contact South West Scotland Environmental Information Centre or call 01387 760274. 

For any records in Cumbria contact Cumbria Biodiversity Data Centre or call 01288 618732 618770. 


Image; Green sea fingers. © Solway Firth Partnership.

Marine Invasive Non-Native Species

Policy and legislation

The UK has international obligations to address INNS issues as well as a need for national work to combat INNS. It may appear that there is a vast array of obligations, advice, and documents on marine INNS. There is, but there are good reasons for this. As marine INNS are difficult to monitor, track, and eradicate, especially while maintaining the existing native species and biodiversity, effort is heavily placed on trying to spread awareness, preparedness, and preventative targets. This is why the overarching approach to handling INNS is to 1) Prevent their introduction 2) Rapid Response to new invasions, and 3) Control and contain those which have already invaded. Not all legislation relating to INNS is listed below as it spans a wide variety of sectors and issues, such as transport, conservation, biosecurity, water quality, and others. Given the potentially vast affects of INNS and the fact that their introduction is possible through a cross-border, international, transit they are often discussed in high level international and EU legislation.



The Convention of Biological Diversity (CBD) is a framework directive, and is the only legally binding international instrument across all groups and vectors. It seeks three broad aims; conservation, sustainability, and benefit sharing of biodiversity, and also obliges nations to carry out national biodiversity planning under the overarching framework of Strategic Plan for Biodiversity 2011-2020 (in the UK this is through UK Biodiversity Action Plan). It is widely considered that INNS are one of the biggest threats to biodiversity, and therefore the CBD states under Article 8(h) that each Contracting Party shall “prevent the introduction of, control or eradicate those non-native species which threaten ecosystems, habitats or species.”

CBD Strategic Plan 2011-2020, includes the Aichi Biodiversity Targets which are a 10 year framework as well as specific targets sought. Target 9 is within Strategic Goal B, of the Aichi Targets and states; “By 2020, invasive alien species and pathways are identified and prioritised, priority species are controlled or eradicated, and measures are in place to manage pathways to prevent their introduction and establishment.”
The UK has UK Biodiversity Indicators to measure progress towards the Aichi Targets, most recently published in 2019. Indicator B6 is a pressure indicator focussed on ‘Pressure from Invasive Species’. Scotland and England have biodiversity strategies to implement the strategic plan on an England/Scotland specific level along with the EU Biodiversity Strategy (Discussed below) Biodiversity 2020: A strategy for England’s wildlife and ecosystem services & 2020 Challenge for Scotland’s Biodiversity.



Member States work towards ‘Good Environmental Status’ (GEnvS) of their marine waters by 2020. There are 11 high level descriptors of GEnvS provided in Annex I including. Descriptor 2 (D2) is specifically in regards to INNS or, as they are referred to in the Directive, ‘non-indigenous’ species (NIS). The progress towards GEnvS is assessed with the indicator of newly recorded INNS, seeking the high level objective that; “The rate of introduction of NIS, spread and impact of invasive NIS caused by human activities is not adversely altering ecosystems” (Department for Environment, Food, and Rural Affairs, 2019).

The UK has an updated 2019 Marine Strategy assessment of GEnvS, including D2. According to this 2019 update, GEnvS was not achieved in terms of INNS in the UK, with (low confidence) data indicating that there was no ‘significant’ reduction in the risk of INNS in the Celtic Seas when comparing 2003-2008 data to 2009-2014 data. 

The Water Framework Directive (WFD) includes all water bodies within Member States, and includes marine waters out to 1 nautical mile (1nm) within its remit (3nm in Scotland and for chemical status 12nm). This Directive overall aims for Member States to achieve ‘Good Ecological Status’ (GEcS) by 2015 for all surface water, this deadline can be extended to 2027 at the latest. Marine INNS are included within the remit of the WFD as their presence could negatively impact the ecological status of water bodies, damaging the ecological status of the area, while the WFD does not permit ecological deterioration. As long as INNS have not damaged native plants and animals then ‘Good’ status can still be achieved, but ‘high’ ecological status cannot, and the water body is at risk of a failing to achieve ‘good’ ecological status at all. The presence of INNS in the Solway Firth puts the firth at risk from deteriorating water quality.

This regulation details the INNS of concern to the EU, and the measures or restrictions placed on those species, for example restricting keeping them as pets, being intentionally brought into the EU, or being permitted to reproduce. Further requirements are placed on Member States, requiring them to take action to limit accidental introduction, manage and eradicate currently present INNS, and also rapid response to detection of new NNS.

In attempting to implement INNS regulation the European Commission are supported by; The Committee on Invasive Alien Species (IAS), Scientific Forum on IAS, Working Group for IAS, and the Invasive Alien Species Expert Group.

The list of EU invasive species of concern has been updated twice since the original list was compiled in 2016, once in 2017 and then again in 2019, to remain relevant to current threats. Member States or the European Commission can propose new species for the list, and the most recent opportunity to submit risk assessments for inclusion was Feb 2020.
Species of interest to the Solway on this list are; Chinese mitten crab a high risk threat to the Solway, and the American signal crayfish a freshwater species noted inland from the Solway.


National Legislation;

England and Wales legislation – is comprehensive and sectoral, in response to particular problems. The legislation with the greatest bearing upon INNS is The Wildlife and Countryside Act 1981 which significantly controls the release of new species. A detailed outline of all legislation and regulations can be accessed via the GBNNSS. When new invasions occur, rapid response is led by the Great Britain Programme Board (made up of senior representatives from across Britain’s administrations) who work with partners to eradicate species, where practicable.

Makes it illegal to allow any animal which is not ordinarily resident in Great Britain to escape into the wild, or to release it into the wild. It is worth noting that Scotland and England have separate versions of s.14;

s.14(1) Scotland s.14(1) England
Subject to the provisions of this Part, any person who—

(a) releases, or allows to escape from captivity, any animal—

  • (i) to a place outwith its native range; or
  • (ii) of a type the Scottish Ministers, by order, specify; or

(b) otherwise causes any animal outwith the control of any person to be at a place outwith its native range,

is guilty of an offence.”

“Subject to the provisions of this Part, if any person releases or allows to escape into the wild any animal which—

  • (a) is of a kind which is not ordinarily resident in and is not a regular visitor to Great Britain in a wild state; or 
  • (b) is included in Part I […IA or IB] of Schedule 9,

he shall be guilty of an offence.”

Under s.14 of this Act the Scottish Ministers created the Code of Practice on Non-Native Species

The 2011 Act amends the 1981 Act (above) and forms a three tiered approach to INNS– Prevent, Rapid Response, and Eradication. The Solway Firth Biosecurity plan summarises the regime the 2011 Act introduces Species Control Agreements and Species Control Orders. These will enable relevant bodies (Scottish Ministers, NS, Marine Scotland, SEPA and Scottish Forestry) to set out measures that must be taken to control or eradicate INNS – plant or animal – when control is considered to be both viable and of sufficient priority. The Scottish Government has published a Code of Practice to accompany the 2011 Act, which fits in under section 14c of the Wildlife and Countryside Act 1981 to help people understand their legal responsibilities with regard to non-native plants and animals. Further, this Act is a means to translate the Bern Convention into Scottish national law.


Policy Papers;

Good biosecurity is the most cost effective and practical way to reduce NNS introduction and slow the spread of those that are already present. Biosecurity are measures aimed at promoting good practices which reduce the potential to introduce or spread NNS. Efforts such as the ‘Check, Clean Dry’ and ‘Be Plantwise’ campaigns spread awareness of the issues NNS can cause, what to look out for and how to minimise the potential introduction and spread of NNS.

When new invasions occur, rapid response is led by the Great Britain Programme Board, which works with partners to eradicate species where practical, and has established priorities in the case of rapid response eradication. Although eradication is difficult it is not impossible.

Despite efforts, however, some species cannot be eradicated, and when this is the case containment of the species is aimed for. In order to be able to implement rapid response of eradication or containment, a national early warning system is maintained for priority species (‘Species Alert’). The GBNNSS issues species alerts with information posters and contact information to report sightings. Please see the species alerts here.

This plan looks to the future of the environment and broadly describes what environmental aims are being sought over the next 25 years. Some of this document is applicable to the whole UK, however those sections covering INNS are applicable only to England as matters relating to the environment are devolved. This government-led plan is a policy document which features non-natives, understanding the threat they pose to the health of native biodiversity. The plan seeks to take actions such as strengthening biosecurity, maintain alert systems for high risk species, reducing the risk from high risk pathways, and continuing a focus on pre-emptive action and effective intervention across England.


Image; Japanese Skeleton Shrimp. © Solway Firth Partnership.

Marine Invasive Non-Native Species


Convention on Biological Diversity (2010). What are Invasive Alien Species? Available here. (Accessed: 10.03.18)

Department for Environment, Food, and Rural Affairs (2019). UK Biodiversity Indicators. Available here. (Accessed: 28.01.20)

Department for Environment, Food, and Rural Affairs (2017). Species Control Provisions, Code of Practice for England. Available here. (Accessed: 11.06.20)

Department for Environment, Food and Rural Affairs (2011). Biodiversity 2020: A strategy for England’s wildlife and ecosystem services. Available here. (Accessed: 28.01.20)

Dumfries and Galloway Biodiversity Partnership (2009). Dumfries and Galloway Local Biodiversity Action Plan. Available here. (Accessed: 28.01.20)

Dumfries and Galloway Council (n.d.). National Scenic Area Management Strategies (Fleet Valley, East Stewartry Coast, Nith Estuary). Available here. (Accessed: 11.06.20)

English Nature (2006). Upper Solway Flats and Marshes Site of Special Scientific Interest / Wildlife and Countryside Act 1981 – Appeals under Section 28F(1) of Countryside and Rights of Way Act 2000. (Letter to Mr Scott, 27 Feb 2006)

Environment Agency (2019). Catchment data explorer. Available here. (Accessed: 29.01.20)

Environment Agency (2016). North West River Basin District, River Basin Management Plan. Available here. (Accessed: 29.01.20)

Environment Agency (2016). Part 2: River basin management planning overview and additional information. Available here. (Accessed: 29.01.20)

International Maritime Organisation (n.d.). Ballast water management – the control of harmful invasive species. Available here. (Accessed: 10.04.18)

ITV News (2012). Crayfish pose ‘serious threat’ to sea life in Solway. Available here. (Accessed: 29.01.20)

Marine Management Organisation. (n.d). Marine Planning Evidence Base. Available here. (Accessed: 14.05.18)

Marine Scotland (n.d.). Scotland’s National Marine Plan Interactive. Available here. (Accessed: 06.08.19)

Mills, F., Sheridan, S. and Brown S., (2017). Clyde Marine Region Assessment. Clyde Marine Planning Partnership. pp 231, Available here. (Accessed: 14.05.18)

Minchin, D., Cook, E.J. & Clark, P.F. (2013). Alien species in British brackish and marine waters. Aquatic Invasions, 8 (1): 3–19. Available here. (Accessed: 29.01.20)

Natural England (2014). Site Improvement Plan, Solway Firth (SIP220). Available here. (Accessed: 09.06.20)

Natural England & NatureScot (2010). Solway European Marine Site, Natural England’s and NatureScot advice for the Solway European marine site given in compliance with Regulation 33(2) and in support of the implementation of the Conservation (Natural Habitats &c.) Regulations 1994. Available here. (Accessed: 11.05.20)

National Biodiversity Network (n.d.). Species Records. Available here. (Accessed: 10.04.18)

Scottish Environmental Protection Agency (2013)Managing Invasive Non-Native Species in Scotland’s Water Environment: A supplementary plan for the river basin management plans. Available here. (Accessed: 10.04.18)

Scottish Environmental Protection Agency (2012). Water Bodies Data Sheets. Available here. (Accessed: 13.03.18)

Scottish Government (2013). 2020 Challenge for Scotland’s Biodiversity. Available here (Accessed: 28.01.20)

Scottish Government (2012). Non-Native Species; code of practice. Available here. (Accessed: 16.04.20)

Solway Firth Partnership (1996). The Solway Firth Review, Solway Firth Partnership, Dumfries. Available here. (Accessed: 23.07.19)

UK National Ecosystem Assessment (2011). The UK National Ecosystem Assessment Technical Report. UNEP-WCMC, Cambridge. Available here. (Accessed: 28.05.18)

United Nations (1992). Convention on Biological Diversity, Rio de Janeiro, Brazil. Available here (Accessed: 28.01.20)


In-Text References;

AquaNIS. (n.d.). Information system on aquatic non-indigenous and cryptogenic species. Available here. (Accessed: 23.01.20)

Baxter, J.M., Boyd, I.L., Cox, M., Donald, A.E., Malcolm, S.J., Miles, H., Miller, B., Moffat, C.F., (Editors), (2011). Scotland’s Marine Atlas: Information for the national marine plan. Marine Scotland, Edinburgh. pp 191. Available here. (Accessed: 22.07.19)

Department for Environment, Food, and Rural Affairs (2019). Marine Strategy Part One: UK updated assessment and Good Environmental Status. Available here. (Accessed: 11.05.20)

Department for Environment, Food, and Rural Affairs (2015). The Great Britain Invasive Non-Native Species Strategy. Available here. (Accessed: 04.02.20)

Hurst, H. (2016). Cumbria Wildlife Trust, Monitoring invasive non-native species in marinas of North West England, Report to Natural England. Available here. (Accessed: 23.01.20)

Macleod, A., Cook, E.J., Hughes, D. and Allen, C. (2016). Investigating the Impacts of Marine Invasive Non-Native Species. A report by Scottish Association for Marine Science Research Services Ltd for Natural England & Natural Resources Wales, pp. 59. Natural England Commissioned Reports, Number 223. Available here. (Accessed: 18.06.20)

North Western Inshore Fisheries Conservation Authority (2014). Biosecurity Plan 2014-2019. Incorporating marine invasive non-native species and shellfish disease. Available here. (Accessed: 29.01.20)

Scottish Environmental Protection Agency (2015). The river basin management plan for the Solway Tweed river basin district: 2015 update. Available here. (Accessed: 13.04.20)

Solway Firth Partnership (2018). Marine Invasive Non- Native Species in the Solway 2018 – 2021. Available here. (Accessed: 04.05.20)

United Kingdom Marine Monitoring & Assessment Strategy (n.d.a). Summary of Progress towards Good Environmental Status. Available here. (Accessed: 15.12.20)

World Maritime News. (2017). Ballast Water Management Convention Enters into Force. Available here. (Accessed: 11.02.20)

Williams, F.E., Eschen, R., Harris, A., Djeddour, D.H., Pratt, C.F., Shaw, R.S., Varia, S., Lamontagne-Godwin, J.D., Thomas, S.E. & Murphy, S.T. (2010). The economic cost of Invasive Non-Native Species on Great Britain. pp. 198. CAB/001/09. Available here. (Accessed: 11.05.20)

Image; Cord grass. © N. Coombey/ Solway Firth Partnership.