The population of European mink, one of the seven species that were declared in 2018 in Spain as “in critical situation”, is estimated at 142 specimens throughout the country, with a range of between 130-157 individuals. This is the result of a national survey coordinated by the Ministry for the Ecological Transition and Demographic Challenge (Miteco) and which has had the participation of all administrations with the presence of this species and the collaboration of expert researchers from Cibio – Portugal and the IREC-CSIC.
To carry out the estimation, non-invasive genetic methods (based on collecting samples in more than 4,000 hair traps throughout the distribution area) and spatially explicit capture-recapture models have been used.
The European mink (Mustela lutreola) is one of the species included in the Spanish Catalog of Threatened Species with the category “in danger of extinction” and its low population and decline justified its situation being considered critical.
Spain has a great responsibility in the conservation of this species at a global level, since only three subpopulations survive in the world. Specifically, in northwest Europe (Russia, in very limited areas and a reintroduced population on the island of Hiiuma, in Estonia); in the southeast of the European continent (Danube and Dniester deltas, in Romania and Ukraine); and in Western Europe (northern Spain and southwestern France). For all of them, a reduction in the distribution area of ??more than 95% has been estimated since the mid-19th century.
In Spain, the European mink has had a National Conservation Strategy since 2005 and, given the delicate nature of its situation, an ex situ conservation program was approved in 2008. Currently, this program is providing about 20-30 offspring annually that are released into the environment to reinforce the existing populations, distributed mainly in the upper part of the Ebro river basin. This includes territories of Álava, Guipúzcoa, Vizcaya, Navarra , La Rioja, northern Castilla y León (provinces of Burgos and Soria) and, in Aragón, small towns in the northwestern sector of the province of Zaragoza.
There is a Working Group for this species made up of MITECO and the autonomous communities where the European mink is present, and which has the advice of the main experts in the field. One of the priorities detected by this working group was the need to know the distribution and population of the European mink, for which non-invasive sampling was planned during 2022.
This sampling was carried out during the fall of 2022 using hair traps. These are PVC tubes with adhesive strips inside and a bait. The mink, attracted by the bait, penetrates the tube, leaving a few hairs attached to the adhesive strips. The hairs are collected and used for the individual identification of the animals to which the samples correspond. In this way, almost 4,000 hair traps were placed throughout the species’ distribution area, which made it possible to collect about 700 hair samples from Rioja, Álava, Aragón, Navarra, Burgos and Soria.
Next, the collaborating laboratory extracted the DNA from the hairs and proceeded to genetically identify the species to which they belong and to identify them individually to find out how many different specimens they come from. The results showed that approximately half of the hair samples corresponded to European mink, coming from tubes installed in Álava, Aragón, Burgos, La Rioja and Navarra.
The rest of the samples corresponded to different mustelids (marten, marten, weasel, polecat, American mink) and other carnivores (cats, genet, fox and, in one case, raccoon), as well as several species of rodents.
The genetic analysis of individual identification allowed us to recognize the existence of a minimum of 87 European mink specimens in the samples (50 females and 37 males). From this information, and using spatially explicit occupancy and capture-recapture models, a cartography of mink occupancy and an estimate of its total population have been obtained, which is estimated at 142 with a confidence interval of 130-157. individuals.
This represents an important call to attention about the need to intensify ongoing actions to reverse the regressive trend of this mammal and achieve an improvement in its conservation status.
After the declaration of the European mink “in critical situation” in 2018, in addition to the need to have national esteem, the importance of promoting captive breeding and intensifying the fight against the American mink, a species included in the Spanish Catalog, was identified. of Invasive Exotic Species and one of the main threats to the European mink.
Miteco and the autonomous communities have been investing significant resources for years in selective trapping of American mink, much more intensely in the area of ??contact between the distribution of both mink. The objective should be to maintain the control that is already exercised, and to intensify it wherever possible.
Regarding captive breeding, different centers collaborate with Miteco and the autonomous communities in this matter (such as FIEB in Toledo, Sacha in Álava, Pont de Suert in Lérida) and, after identifying the need to have a public Center for reference with high capacity, its construction is underway at the Ribavellosa Estate, located in the municipality of Almarza de Cameros (La Rioja) and managed by the Autonomous Organization for National Parks (OAPN) of MITECO. It is expected that its completion and commissioning will also provide a new and important boost to this aspect of the conservation of the species.
