Global and European regional assessment: Endangered (EN)
EU 27 regional assessment: Endangered (EN)

This species is assessed as Endangered (EN) under criteria A2ace+4ace both globally and for the EU27 Member States. Occupancy declines have been documented in Spain, France, Andorra and Portugal, and an overall population decline of 50% over the last ten years is plausible. Major threats relate to a reduction in quality of the water networks used by this species, as well as an increase in populations of a non-native predator. These threats have not ceased, and it is realistic to expect a further decline over the next ten years.

The Iberian Desman (Galemys pyrenaicus) is endemic to the Iberian Peninsula, where it is restricted to Andorra, France, northern and central Spain, and northern Portugal. In Spain, the species has undergone a marked decline of 68% between 1990-2010, with such trends observed in the Central System, Iberian System, Pyrenees, Vasque area and northwestern region (Gisbert and García-Perea 2010a, 2014). The most severely affected populations have been those found in the Spanish Central System: by 2010, no desmans were detected in the eastern region, and surveys have identified only three relict populations in the western area of the Central System. These populations are fragmented and isolated (Gisbert and García-Perea 2014; Fernández-González et al. 2015, 2016, 2017b, 2019a).

Range contractions have been observed along the western, southern, and eastern edges of its distribution in Portugal (Quaresma 2001, Cabral et al. 2005), and, recently, a decline of more than 50% in occupancy in the last two decades has been documented in northeast Portugal (Quaglietta et al. 2018). In the French Pyrenees, range contractions of up to 60% have been observed along the river network between 1985-1992 and 2012-2013 (Charbonnel et al. 2016). Additionally, in Andorra, a 70% range contraction has been documented (Aymerich and Gosàlbez 2018).

Population density values obtained from different geographic areas, and over different time periods, are varied: Pyrenees, 0.67 to 6 individuals/km (Stone and Gorman 1985, Nores et al. 1998, Lim et al. 2021a); northwestern Spain, 0.32 to 8.8 individuals/km (Nores et al. 1998; Quaresma et al. 1998; Chora 2001; Fernández-González et al. 2015, 2016, 2017b, 2022a); Central System, 2.22 to 5.5 individuals/km (Gisbert and García-Perea 2004, Fernández-González et al. 2019b); Iberian System, 4 individuals/km (González-Esteban et al. 2011). However, when analysed chronologically, a decrease in population density is observed. Values from the 1990-2004 period vary between 2.6 and 8.4 individuals/km, in the 2005-2015 period vary between 2 and 6 individuals/km, and in the 2016-2022 period they vary between 0.32 and 2.67 individuals/km, indicating a decline in abundance.

In Spain, it was estimated in 2018 that the extent of occurrence of the Iberian Desman had declined by 87% over the previous 30 years (Gisbert and Garcia-Perea 2019). Similarly, surveys in Andorra indicate a 70% reduction in rivers inhabited by Iberian desmans since 2000-2003 (Aymerich and Gosàlbez 2018). Range contractions have been also observed along the western, southern, and eastern edges of its range in Portugal (Quaresma 2001, Cabral et al. 2005), where it is speculated that there are fewer than 10,000 mature individuals divided into small and isolated subpopulations due to the existence of physical (e.g. dams) and ecological barriers (Cabral et al. 2005). Finally, recent range declines of approximately 60% during the last two decades have been documented in Northeast Portugal (Quaglietta et al. 2018) and in the French Pyrenees (Charbonnel et al. 2016).

This species is perfectly adapted to a semiaquatic lifestyle (Quaglietta 2018) with its preferred habitats being fast-flowing mountain streams, though it is occasionally found in slow-moving water bodies such as canals and lakes (Peyre 1956, Richard and Valette Viallard 1969, Quaresma 1995, Nores and García-Alvarez 1995, Aymerich and Gosàlbez 2018, Charbonnel et al. 2015, Biffi et al. 2016). It favours watercourses where the margins offer some shelter, and it requires clean and well-oxygenated water, mostly due to the requirements of its main prey, aquatic macroinvertebrates (Biffi et al. 2017, López-de Sancha et al. 2022).

Its diet is mainly made up of three groups of invertebrates linked to the aquatic environment: Ephemeroptera, Plecoptera and Trichoptera, which constitute approximately 75% of its total prey, although desmans will also predate other invertebrates such as Diptera, Coleoptera and Odonata species (Bertrand 1992, Santamarina 1993, Castién and Gosàlbez 1995, Fernández-Salvador et al. 1998, Biffi et al. 2017, López-de Sancha et al. 2022). This species is considered a generalist that will consume the most abundant prey, but does select those that are primarily aquatic, with soft bodies, slow moving, and with higher energetic value (Biffi et al. 2017, López-de Sancha et al. 2022). It has also been observed feeding on vertebrates when captured by surveyors, though this has not been documented under completely natural conditions (Quaglietta and Beja 2019).

The Iberian Desman is restricted to fluvial environments, so it is very vulnerable to human activities. Its historical decline has been linked to a combination of factors: widespread use of DDT-based insecticides in agriculture deposited as runoff into streams and rivers; discharge of wastewater from village sewage systems, without purification, into rivers causing an increase in organic and chemical pollution; construction of water reservoirs for human consumption which create physical barriers for dispersal of desmans; construction of weirs, channels and mini hydroelectric power plants creating impassable obstacles for desmans; abandonment of the maintenance of irrigation ditches and channels leading to a reduction of the local water networks and of the dispersal routes of the species; and escape from fur farms and range expansion of the American Mink in the Iberian Peninsula (Queiroz et al. 1996, 1998; Nores 1999, 2007; Cabral et al. 2005; Gisbert and García-Perea 2010b, 2014; Romero 2010, 2015; Fernández-González et al. 2012, 2014b; García-Díaz et al. 2013; Pedroso and Chora 2014; Cosentino et al. 2020). In some local areas, such as certain river sections of Galicia (northwestern Spain), up to 27% of American Mink scats have been found to contain desman remains (Romero 2015). The threat posed by American Mink is likely increasing in many areas of the Iberian Desman's range: in Spain, between 1985-2012, its distribution increased by 17 times and, by 2012, it occupied 25.6% of mainland Spain (as assessed on a 10 x 10 km grid scale; Põdra and Gómez 2018). The distribution of American Mink has also increased in northern Portugal, where one study found that its range had rapidly expanded southwards from Cávado River to Sousa River by approximately 45 km in only two years (Rodrigues et al. 2015). Indeed, by 2020, it was estimated that one quarter of the Iberian Desman's range area overlapped with that of the American Mink (Cosentino et al. 2020).

The resulting fragmentation and isolation of desman populations has been linked to low genetic diversity and high levels of inbreeding (Igea et al. 2013; Escoda et al. 2017, 2022; Gillet et al. 2017). In addition, the species faces several newer threats, such as river fragmentation and impoundment by damns, the overexploitation of water resources for agriculture and livestock, the replacement of riparian forests with species of timber interest, and recreational activities in riverbeds (e.g. canyoning). Climate change causing, e.g. severe droughts and altered rainfall patterns, will probably be a key threat to this species in the future, especially in Mediterranean environments (Nores 2007; Gisbert and García-Perea 2005, 2010b; Némoz et al. 2011; Fernández-González et al. 2014b, 2019b; Biffi et al. 2016; Aymerich and Gosàlbez 2018; Quaglietta et al. 2018; Braz et al. 2023). Similarly, forest fires pose significant risk to this species as they draw large amounts of ash and other plant debris into rivers, rapidly degrading the invertebrate community (Fernández-González 2021, 2022a). Other threats include public works on river banks, river bed sealing by alluvial deposits due to ground disturbance by anthropic activities, and the use of poison, nets and explosives as fishing methods (Cabral et al. 2005, Pedroso and Chora 2014). The potential negative impact of other invasive species, such as the Red Crayfish and the Signal Crayfish needs to be investigated (Quaglietta et al. 2018).

Anecdotes exist about the fur of the species being used in the past (40 years ago) in the northeast of Portugal and west of Spain to protect clothes in storage, as the fur was thought to repel moths (Gisbert and García-Perea 2014, L. Quaglietta pers. comm. 2023). Such use is not known to occur currently.

It is strictly protected under the Bern Convention (Appendix II) and the EU Habitats and Species Directive (Annexes II and IV), and there are state-level laws protecting the Iberian Desman in the four countries where it occurs. Furthermore, in Spain and France, the species is considered Vulnerable, except populations within the Spanish Central System, which are considered Endangered. In Portugal, the species has been recently considered as Endangered (Braz et al. 2023). In Andorra, its status has also recently been re-evaluated and the species has been assigned to the Critically Endangered category.

Parts of its range fall within protected areas. In Portugal, it has been found in “Parque Nacional da Peneda-Gerês”, “Parque Natural de Montesinho”, “Parque Natural da Serra da Estrela” and possibly the “Parque Nacional de Aiguestortes y Lago de San Mauricio”. In France, it has been recorded at least in the “Parc National des Pyrénées”, “Parc Naturel Régional des Pyrénées Ariégeoises”, and in the “Parc Naturel Régional des Pyrénées Catalanes”. In Spain, it occurs in the “Parque Nacional de Picos de Europa”, in the “Parque Nacional de Aigüestortes i Estany de San Maurici” and it occurred in the past in the “Parque Nacional de Ordesa y Monte Perdido” and in the “Parque Nacional de la Sierra de Guadarrama”. It also occurs in the following natural parks in Spain: “O Invernadeiro”, “Baixa Limia – Serra do Xurés”, “Fragas do Eume”, “Somiedo”, “Redes”, “Fuentes del Narcea”, “Ponga”, “Las Ubiñas – La Mesa”, “Saja – Besaya”, “Collados del Ansón”, “Aiako Arria”, “Urbasa – Andía”, “Señorío de Bértiz”, “Roncesvalles – Selva Irati”, “Posets – Maladeta”, “Valles Occidentales”, “Alt Pirineu”, “Sierra de Gredos”, “Lago de Sanabria”, “Fuentes Carrionas y Fuente Cobre”, and “Garganta de los Infiernos”.

A number of conservation initiatives have been carried out. In France, two “French Conservation Action Plans for the Pyrenean Desman” have been developed (Némoz et al. 2011, Lim et al. 2021b). The first was implemented between 2009 and 2014, and the second is planned for the period 2021-2030. A LIFE project was also undertaken in France between 2014 and 2020. Spain has had a statewide Strategy for the Conservation of the Iberian Desman since 2013 (Gómez-Calmaestra et al. 2013), and two autonomous regions have specific conservation plans. Four LIFE projects have been carried out between 2010 and 2020 in Spain. In Andorra, a Recovery Plan has recently been prepared (Fernández-González et al. 2022b). Finally, in Portugal, a LIFE project was developed in 1994-1997 (Queiroz et al. 1998), and a network of "Important Sites for Conservation of Iberian Desman" (SIC Galemys) was planned (Pedroso and Chora 2014).

Actions proposed by the various species action plans include appropriate management of water courses, habitat restoration, improvement of knowledge of threatened populations, and use of the Iberian Desman as a flagship species to promote river conservation. Further research is necessary to ensure the efficacy of hydroelectric and hydraulic project mitigation measures, as well as to estimate minimum viable population size, and assess the genetic variability between populations and the impact of the American Mink and invasive crayfishes (Pedroso and Chora 2014, Quaglietta et al. 2018).