Biodiversity Monitoring and Warning Network for the American Mink: We are promoting a project focused on the monitoring and conservation of river biodiversity and wetlands

An innovative citizen science project involving volunteers, fluvial custody entities, and managers of natural spaces.

With the support of the Tarragona Provincial Council, the Catalan Society of Sciences for the Conservation of Biodiversity (BioSciCat) has promoted the Biodiversity Monitoring and Warning Network for the American Mink. The Network aims to monitor the distribution of threatened native species and control the presence and expansion of the American mink in river habitats and wetlands.

This project is part of a citizen science initiative and it is carried out in collaboration with various entities involved in river conservation projects, natural space managers, and volunteers in the territory.

Background: aquatic ecosystems and invasive species

According to the Living Planet Index for Catalonia (LPI-Cat), in 2020 half of the habitats associated with inland waters and almost 80% of its species were in an unfavourable conservation status (DTES 2019). In the same year, invasive alien species were detected in 64% of river courses and 73% of wetlands in Catalonia, accelerating the degradation of these environments and exarcebating the loss of biodiversity (EXOCAT, 2020). In the period 2002-2023, the population trend for inland water environments was negative, with a decrease of 40% (Nature Observatory, 2025).

The main drivers of global biodiversity loss include habitat degradation and destruction, overexploitation of natural resources, and the spread of invasive alien species (LPI, 2024). These species, introduced outside their natural range, pose a serious threat to native biodiversity. In Catalonia, a notable example is the American mink (Neovison vison), a carnivorous mustelid native to North America. It is considered one of the most harmful invasive alien species in Europe and is listed in the Spanish Catalogue of Invasive Alien Species. Controlling and managing this invasive species is essential for conserving the biodiversity of the region's inland water ecosystems.

Introduction of the american mink in Catalonia

In Catalonia, the American mink was detected in the wild for the first time in 1982, when several individuals escaped from two fur farms located in Taradell and Viladrau. Since then, the species has colonized much of the Girona and Barcelona regions and, to a lesser extent, parts of Lleida and Tarragona.

In Tarragona, it was first detected in the Marmellà stream in 2005, and since then it has been recorded in the Gaià, Francolí and Siurana river basins. Its successful expansion is facilitated by the absence of predators and competitors, and especially by its high invasive potential.

Comparison of the distribution of the American mink in Catalonia between 1987 and the period 2015–2018.

Impacts of the american mink

Outside its native habitat, the American mink has a negative impact on the biodiversity of areas it colonizes. Ecologically, it competes intensely with certain native species for food resources and breeding areas, such as the European mink (Mustela lutreola), which is listed as critically endangered (CR) and is experiencing an alarming population decline.

The American mink also exerts predation pressure on several threatened and declining species. In fact, it is believed to be the directly responsible for the extinction of the southern water vole (Arvicola sapidus) across much of Catalonia. In the river systems of the Tarragona region, it's a threat not only to the water vole itself but also to the Iberian water shrew (Neomys anomalus), the white-throated dipper (Cinclus cinclus) and the white-clawed crayfish (Austropotamobius pallipes). Additionally, it represents a serious potential threat to many bird species that nest in the Ebro Delta.

Economically, the American mink can negatively affect the populations of hunting or fish fauna, as well as poultry and fish farms, by preying on these animals. From a health perspective, it also poses a risk as a carrier and transmitter of both the Aleutian disease virus and SARS-CoV-2.

American mink (Neovison vison).

 Creation of Biodiversity Monitoring and Warning Network for the American Mink.

In recent years, several entities have made efforts in Tarragona's river basins to control the American mink, halting the species' invasion and eliminating it from entire basins, aiming to develop effective results and techniques for the efficient implementation of the Strategy for the control and eradication of the species in Catalonia. Specifically, the species has been eradicated from the Siurana River basin since 2023. In that same year, the Montsant Natural Park implemented a monitoring and early detection system in order to capture any individuals entering the Montsant River.

Building on the success of the Montsant River system, and as an innovative step in the fight against the American mink, BioSciCat has promoted the creation of the Biodiversity Monitoring and Warning Network for the American Mink across all Tarragona regions. The Network is composed of control stations equipped with camera traps in various river courses and wetlands managed by different participants in the Network. This provides an up-to-date view of the distribution of several semi-aquatic species of conservation interest, such as Eurasian otter, water vole and the Iberian water shrew.

Eurasian otter (Lutra lutra). Credits: F. Aguilar

In the case of the American mink, the Network will enable the rapid detection of new colonizing individuals, allowing for proactive intervention before new populations become established and pose a threat to local biodiversity. In areas where they are detected, BioSciCat will respond immediately to capture the individuals using floating platforms equipped with trap cages - a selective and higlhy effective tecnhique for this species. For example, in regions such as the Outer Hebrides (Scotland) and East Anglia (England), monitoring and control programs have successfully led to a drastic reduction in American mink populations. Currently, only occasional sightings are reported, resulting in very positive outcomes for native fauna. (Bonesi L., Rushton, S.P. & Macdonald, D., 2006; Moore & Helyay, 2010;  Fraser et al., 2013; Martin A.R & Vince J, 2019)

Credits: Bioscicat

The Network was formally established on March 24 during a meeting with collaborators, in which it was agreed to keep the camera traps active for at least one month to detect species present in the rivers and wetlands where the traps are set. Initially, the Network will consist of 36 sampling stations, managed by eight entities (Conca de Barberà Natural History Centre, Freixe Nature Group, GEPEC-Edc, GEVEN, Graëllsia, Molí del Fort, Sínia and BioSciCat), along with several natural area managers and volunteers. BioSciCat coordinates the project by offering training, technical assistance, data processing and periodic reporting. The project remains open to new entities or individuals interested in participating, with the aim of expanding the Network to the other parts of the territory.

Location of the first 36 samplings stations of the Biodiversity Monitoring and American Mink Warning Network

The Network will promote the conservation of biodiversity in the Tarragona regions, focusing on fauna associated with river habitats and wetlands, which have suffered the greatest biodiversity loss in recent years. A specific database will also be created, and updated information will be contributed to projects such as the Mammal Atlas, and the Invasive Alien Species (IAS) Alert Network.

Funding and support

This project is carried out thanks to the support and funding of the Tarragona Provincial Council, within the framework of the subsidies for non-profit entities for the development of projects for the protection and improvement of the environment, with a subsidized amount of € 22000.