Wild American mink (Neovison vison) may pose a COVID‐19 threat

Over the past year, farmed American mink (Neovison vison) have gained notoriety due to their unfortunate susceptibility to the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), the virus that causes COVID‐19 in humans. SARS‐CoV‐2‐infected mink have been reported on fur farms across Europe and North America (OIE 2021), and whole‐genome sequencing of the virus isolated from mink on farms in the Netherlands has provided evidence of both human‐to‐mink and mink‐to‐human transmission of the virus (Munnink et al. 2021). Further sequencing of samples from humans infected with mink‐related SARS‐CoV‐2 in Denmark has revealed that the virus had accumulated mutations with potentially adverse consequences for human health (Larsen et al. 2021). In response, animal welfare organizations and others have called for the closure of mink farms on public‐health grounds in Europe (FOUR PAWS in Europe 2020) and elsewhere (Xia et al. 2020).

But it’s not just on farms that American mink pose a potential disease threat. Mink farms are porous, and feral populations exist in almost all countries where mink are currently farmed or have previously been farmed (Bouros et al. 2016). American mink are native to North America but now occur in the wild across most of Europe and Russia, and as far afield as Argentina (Figure 1).

Figure 1.

Global distribution of wild American mink (Neovison vison), showing their native North American range and their introduced range, where they are considered an invasive species, in Eurasia and southern South America. Note that although American mink were eradicated from the Estonian island of Hiiumaa, they are present on the mainland; for further country‐specific details, see CABI (2019). Image credits: CABI 2019 (map); © A Harrington (photo).

Outside their natural range, American mink are invasive, and often have negative impacts on native taxa (eg Macdonald and Harrington 2003), including prey species and other predators that they outcompete and sometimes kill (eg the critically endangered European mink [Mustela lutreola]; Maran et al. 2016). Under the current global COVID‐19 pandemic, the susceptibility of American mink to the virus (Molenaar et al. 2020; Oreshkova et al. 2020; Sharun et al. 2021), their widespread presence in semi‐aquatic habitats (Macdonald and Harrington 2003), and siting of fur farms in rural locations (Bouros et al. 2016) suggest that American mink may now pose a new threat to both humans and native wildlife. Although mink are a solitary species, which might minimize virus transmission and persistence (Delahay et al. 2021), the home ranges of individuals overlap (Macdonald et al. 2015) and like other mustelids they deposit feces at prominent marking spots that are investigated by neighbors (Hutchings and White 2000); such behaviors could facilitate viral transmission. In addition, during the mating season males will visit multiple females (Macdonald et al. 2015), and there is widespread and sometimes extensive movement of both males and females during the autumn when the young‐of‐the‐year disperse from their natal territory (eg Oliver et al. 2016); both of these behaviors would also potentially facilitate viral spread if movements involve infected individuals. In Canada, there is evidence that the Aleutian Mink Disease virus – a parvovirus that causes spontaneous abortions in and mortality of mink and other mustelids – may be transmitted from farmed to feral mink (Nituch et al. 2011). Although human‐to‐human transmission of SARS‐CoV‐2 is currently the dominant mechanism for the spread of COVID‐19, the establishment of a wildlife reservoir could undermine efforts to combat the virus, by providing a source for re‐emergence at any time and promoting conditions for the emergence and potential spread of new variants (Delahay et al. 2021; Sharun et al. 2021). Amongst wildlife, a disease outbreak could be devastating for the last remaining European mink populations.

Reports of escaped SARS‐CoV‐2‐infected mink in Oregon (ODA 2020) and an apparently wild mink in Utah that may or may not have been a fur farm escapee (OIE 2021) have already made the news. To date, known escapees have apparently been recaptured but there is no guarantee that future escapees will not evade capture, if they have not already. Countries without mink farms (eg the UK) are not without risk either, given that feral mink could potentially be exposed to SARS‐CoV‐2 through sewage released into rivers (Franklin and Bevins 2020) intentionally or unintentionally (eg during flooding). Banning mink farming provides only a partial solution: it does not remove the risk of the establishment of a viral reservoir in wildlife.

In Europe, there are policies in place for the management of invasive species; for instance, under EU Regulation (1143/2014) on Invasive Alien Species (IAS), member states are obliged to implement “effective management measures” for species included on a list of Union Concern. In March 2018, a risk assessment proposing the addition of American mink to this list (Bouros et al. 2016) was submitted to the European Commission (EC). However, despite approval by the EC’s Scientific Forum on IAS, mink were excluded from the EC’s proposed list and from discussion in the voting process. Denmark led the opposition to the listing of mink in order to protect its fur farming industry, which, ironically, the pandemic has now destroyed (at least temporarily), as Danish fur farmers were compelled to slaughter millions of farmed mink in an attempt to contain the disease following reports of SARS‐CoV‐2‐infected mink at more than 200 farms worldwide (WHO 2020). Mink farming has now been banned in Denmark until 2022.

Formal listing of American mink as a species of Union Concern would probably not have affected the fate of the Danish farmers or their mink in the current global pandemic; nevertheless, beyond the captive farmed environment, we argue that it is time to reconsider the place of invasive mink in the countryside. We urge vigilance and action in all European countries, and elsewhere, around mink farms. Testing for exposure to SARS‐CoV‐2 in wild American mink is required, which would, in countries where they have been introduced, be most efficiently achieved in combination with removal trapping. This approach would have considerable additional biodiversity benefits but only if carried out at a large scale, with coordinated action among neighboring countries. Europe has recorded some of the highest COVID‐19‐associated human mortality rates in the world; it would be a great pity if the EU failed to take the actions necessary to substantially reduce the risk of a virus reservoir becoming established in feral mink. For the benefit of conservation and human health, we believe that the landscape‐scale management of invasive mink that many scientists have long advocated is warranted.

Front Ecol Environ. 2021; 19(5): 266–267, doi: 10.1002/fee.2344