2.3. Best Practice Approaches and Examples

  1. A global review of mink control strategies found 51 studies on mink control that have been carried out in 28 locations in Europe and South America since 1992 (López et al., 2023). Trapping experiments in Patagonia have been effective in removing at least 70% of the mink population in ideal circumstances and using the latest trapping techniques (Bonesi and Palazon, 2007). Despite the presence of invasive mink in 28 European countries, several local control projects appear to be effective in reducing invasive populations and protecting native biodiversity (Bonesi and Palazon, 2007).
  2. Control efforts in Scotland have been successful in substantially reducing mink populations through successive joint projects despite short-term funding (Lambin et al., 2019). Scottish mink control projects have included the Hebridean Mink Project which ran from 2001 until 2013, and the ‘Scottish Mink Initiative’ which focused on removing mink from north Scotland between 2011 and 2015 (MacLeod, 2023; McMullen, 2015). The current control mechanism for mink across a large scale in Scotland is the MCP.
  3. The Hebridean Mink Project was initiated in 2001 to address the threat posed by mink to native wildlife populations, particularly ground-nesting birds and migratory species found in SPAs, in the Outer Hebrides. The aim of the project was to completely eliminate mink from North Uist, Benbecula and South Uist, and to furthermore reduce mink density from neighbouring South Harris to prevent recolonisation of the Uists following mink eradication (NatureScot, 2024).
  4. The Hebridean Mink Project employed two primary methods to trap mink: operating coastal and riparian cage traps, and utilising trained dogs to trap mink at breeding dens. Trapped mink were then humanely destroyed. In the Uists, this effort involved 100,824 trap nights over four years between 2001 and 2005, along with 500 handler-days dedicated to den searches. A total of 228 mink were captured in the Uists, with the final capture occurring in 2005 (Roy et al., 2015). Following the Hebridean Mink Project, mink populations have declined across the Outer Hebrides, with only seven individuals captured in Lewis and Harris in 2016. Among these, one was a non-breeding female, and no juveniles have been captured since 2015. A surveillance network comprising kill traps has since been deployed across the Outer Hebrides to identify and eliminate the remaining few mink (NatureScot, 2024).
  5. The Hebridean Mink Project has resulted in widespread benefits for bird species across the Outer Hebrides, with the quantity and dispersion of seabird colonies throughout the project area consistently exceeding expectations. Anecdotal evidence suggests that other bird species, including divers, ducks and waders, has also increased in number throughout the project area (Scottish Natural Heritage, 2018).
  6. The Scottish Mink Initiative built on the success of the Hebridean Mink Project but with a focus on removing mink from north Scotland over an area of 20,000 km2 from northern Tayside across Aberdeenshire, Moray, and the Cairngorms National Park to the north and east Highlands. Due to its location, this project was less directly relevant to seabirds. However, the control of mink at river catchment level is vital in protecting important seabird breeding locations along the coasts of Scotland.
  7. The MCP, run by SISI, is currently the largest active project and continues to build on the successful work undertaken previously in Scotland. Between 2018 and 2021 the project caught 371 mink in 172 locations. The project found that just 78 trapping locations accounted for 75% of total captures (Invasive Species Scotland, 2024). SISI as an organisation is committed to managing and mitigating the impact of invasive species in Scotland, including both invasive habitat management and mink. The SISI team comprises eight staff members, including the Project Manager, who has been consulted by the Applicant with regard to the compensation. Their collective responsibility involves the planning, execution, and coordination of various programs aimed at controlling invasive plant species and the mink population across Scotland. The MCP operates approximately 650 mink trapping locations distributed throughout Scotland (Invasive Species Scotland, 2024). The trapping mechanism primarily involves the use of conventional live capture traps. These traps require daily checks to monitor and manage the captured mink.
  8. Further information on how the Applicant will deliver compensation in partnership with the MCP and SISI is presented with the Compensation Plan (appendix 2).
  9. Ireland also hosts a well-established mink population across both the mainland and islands where various seabird species are currently undergoing impacts associated with mink presence and predation. Roy et al. (2009) provides a review of mink control techniques and case studies (including reference to the various Scottish mink control programme mentioned above) with relevant lessons learned gleaned for future application across key Irish sites, with Irish SPAs suggested as a priority.
  10. The Collaboration on Offshore Wind Strategic Compensation (COWSC) is led by the Offshore Wind Industry Council (OWIC) and supported by key stakeholders including offshore wind developers, representatives from statutory nature conservation bodies, The Crown Estate, UK Government, Devolved Governments and environmental non-governmental organisations. COWSC aims to deliver a shared body of evidence on best-practice, research and practical pilot projects for offshore wind compensation in the UK spanning investment in four target measures with one being predator reduction to enhance seabird populations. While COWSC is yet to finalise and publish its proposed strategy, expert working groups as part of the process and chaired by seabird and eradication experts at the JNCC support the inclusion of mink control within the library of measures. This provides confidence that key stakeholders in the process of deciding on suitable compensation projects are supportive of mink control as a compensation measure to offset potential impacts associated with offshore wind farms.

2.3.1. Saint-Brieuc Offshore Wind Farm Compensation

  1. Saint-Brieuc offshore wind farm (located 16.3 km from the Breton coast, France) implemented a mink eradication project in 2017 as compensation for associated impacts from the offshore wind farm to various seabird species (Ailes Marines, 2024). The compensation is overseen by Ailes Marines, a subsidiary of Iberdrola—a prominent renewable energy developer. Ailes Marines also assumes responsibility for the development, construction, installation, and operation of the offshore wind farm in the Bay of Saint-Brieuc.
  2. This compensation measure aims to eradicate mink from Tomé Island (or île Tomé) (Brittany, France) as part of the multi-partnership programme (Trégor-Gestion-Vison) which was set up in 2014 following the first confirmed record of mink on île Tomé in 2012 (Lorvelec et al., 2024). This compensation is supported by the Conservatoire du Littoral, the Departmental Federation of Côtes d’Armor Hunters, the commune of Perros-Guirec, Lannion Trégor Community and Ailes Marines (Ailes Marines, 2024).
  3. The aim of Trégor-Gestion-Vison was to implement a campaign to eradicate and control mink on Tomé Island. The programme aimed to monitor mink on the Sept-Îles islands reserve, and to capture several individuals on the coast, between Perros-Guirec and Penvénan (Ouest-France, 2015).
  4. Since implementation, the compensation measure has involved a two-phased approach with the initial phase consisting of annual trapping and eradication efforts initiating in 2018 and spanning five years. Following this period, the second phase involves a three-year monitoring phase, which continues throughout the project's duration to ensure the eradication's effectiveness. The project identified multiple instances of recolonisation on the island, but this has now ceased thanks to an updated control plan and implementation of biosecurity measures.
  5. This recent case study provides a very relevant example of mink control being utilised as a compensation measure for an offshore wind farm, with the project’s involvement of the compensation measure being part of a wider scale, multi-organisational mink eradication project (Trégor-Gestion-Vison).
  6. The model of island eradication and subsequent biosecurity to prevent recolonisation is different from that of the MCP, which conducts mink control on mainland Scotland. The MCP is a long standing and highly successful control programme, which publishes annual documents and reviews of outcomes. This enables lessons learned to be incorporated into the planning of future work while also informing how to best manage current locations.

2.4. Summary

  1. There is strong evidence and support that mink reduction is an effective means of increasing the productivity of seabird species. This is particularly true for razorbill and kittiwake, species for which there exists compelling evidence of mink impacts from across their breeding range. The evidence above highlights benefits from previous reduction projects and indicates that maintaining mink control across the current areas within the MCP, as well as expanding control to areas where mink are present (both in partnership with SISI), can be an effective compensation measure.