A study evaluating taxonomic units within Eurasian vipers confirmed the species status of Vipera seoanei, considering the high genetic divergence and geographic isolation from its sister species V. berus (Freitas et al. 2020).

Two subspecies have traditionally been recognised, but this is not supported by an mtDNA study which recovered only a single lineage (Martínez-Freiría et al. 2015).

Vipera seoanei is listed as Near Threatened (NT) on the basis of the projected impacts of climate change, which may lead to a decline in the extent of suitable habitat of more than 70% over the next 27 years (fewer than six generations assuming a generation length of five years, the minimum age at reproduction; the true generation length is unclear but likely longer). This may correspond to a decline greater than 35% over the next three generations, however, as habitat suitability models cannot be taken as a direct surrogate for either habitat loss or population decline it is unclear whether the population is likely to decline to this extent over this period. As such the species is likely to be close to, but does not quite, qualify as Vulnerable applying criterion A3c.

This species is considered nearly endemic to the Iberian Peninsula. It is distributed across northwest Portugal and northern Spain, with some subpopulations penetrating a few kilometres into southwest France (Martínez-Freiría and Brito 2014, Brito 2021). Three isolated subpopulations are present in Portugal, centred on Paredes de Coura, Castro Laboreiro/Soajo and Tourém/Montalegre/Larouco (Brito 2008, Martínez-Freiría and Brito 2014). In Spain, the species is present in almost all of Galicia (except in the areas with a Mediterranean climate such as the lower Minho, Sil, Limia and Támega Valleys), Asturias and Cantabria, and in the provinces of Bizkaia and Gipuzkoa, in the Basque Country. It can also be found in the Atlantic climate areas of North León, Palencia, Burgos, Araba and Navarre, and in the highest ranges of Sanabria, in the western part of the province of Zamora (Braña 2002, Martínez-Freiría and Brito 2014). In France, it is known to be present only in four localities within a narrow area of 10–60 km in the Western Pyrenees, within the department of Pyrénées-Atlantiques, including the Atlantic coast of Saint-Jean-de-Luz, the Sare forest (Eastern Rhune), the high valley of Aldudes, and the Irati and Artixilondo massifs (Martínez-Freiría and Brito 2014, SHF 2019). It occurs from sea level up to 1,900 m asl (the latter in the Cantabrian Mountains in northern Spain), but generally up to around 800 m (Geniez 2018).

This species can occur in apparently very high densities in Spain (Braña 2002, Speybroeck et al. 2016). It is among the most abundant snakes in the Cantabrian Mountains, localised but moderately abundant in Portugal (Brito 2021). It is relatively rare at the periphery of its range, for instance in Galicia and southern Portugal (Asensi 2011, Martínez-Freiría 2014). This information is however derived from opportunistic observations, as there is no quantified data on trends anywhere in this snake's range (F. Martínez-Freiría pers. comm. 2022). Based on a study modelling population trends based on citizen science data collected between 1980 and 2017 in Spain (at the scale of 10 x 10 km grid cells), the population was stable over this period, with a minor decline of 8.0% over a three generation length period (Santos et al. 2022).

By 2050 (six generations assuming a minimum generation length of five years) a projected decline in the area of suitable habitat exceeds 70-77% (Martínez-Freiría et al. 2015), i.e. a decline in habitat suitability of at least 35% in three generations. It is however unclear whether this is likely to correspond to a comparable rate of population decline, or whether this rate of decline will be constant over this period.

This species is typically associated with areas with an Atlantic climate, characterised by mild winters and short, rainy summers. It occupies open wet oak forests (Quercus robur and Quercus pyrenaica), ecotones between meadows and forests and areas with abundant understorey or shrubby vegetation (including blackberry-bordered pastures and drystone walls, as well as heathland with bracken and broom, well-vegetated rocky scrubland, abandoned gardens and hedgerows - Martínez-Freiría and Brito 2014, Speybroeck et al. 2016, Geniez 2018, Brito 2021). This characteristic habitat is quite homogeneous across the species’ whole distributional range. The activity period extends from March to October and is continuous between April and September. Winter activity is rare. Mating takes place in spring, from the end of March until the beginning of May (Saint Girons and Duguy 1976, Martínez-Freiría and Brito 2014, Brito 2021). Sexual activity and mating have been observed also in autumn (Pillet and Bonnet 2018, Vázquez and Martínez-Freiría 2021). Females have a biennial reproductive cycle and give birth to 3-10 live young (Braña 1978). Animals reach sexual maturity between four and five years of age, and a maximum longevity of 13 years has been recorded (Braña 1978).

In Portugal the species' subpopulations are isolated and vulnerable to habitat loss (Brito 2008), which is also the case for the marginal subpopulation in France and for some Spanish subpopulations (Martínez-Freiría 2015, Brito 2021); extinction for some French isolates was predicted by Saint-Girons (1989). The main driver of habitat loss is agricultural intensification and mechanisation which removes hedgerows and stone walls, the development of pine and eucalypt plantations and associated wildfire (e.g. in Galicia and northern Portugal), and the deliberate burning of scrub (summarised by Brito 2021), and in some areas (e.g. Navarra) infrastructure development (Braña 2002).

Southern Europe is predicted to experience particularly extreme climate warming (up to 10 °C in some areas) by 2100 and increasing aridity (IPCC 2013). Martínez-Freiría et al. (2015) conducted climate modelling (IPCC scenarios a1b, a2 and b1, ranging from 'business as usual' to optimistic projections - Carter 2007) using niche-based models at the scale of 1 x 1 km. His results suggest that, while stable refugia will persist in most of the northwest Iberian Peninsula, these will increasingly be confined to high-elevation mountains and the species' distribution is likely to decline drastically by 2050 and especially by 2080, becoming highly fragmented by the latter time point (Martínez-Freiría 2015). The area of suitable habitat within the species' range is predicted to fall by 73.51–77.24 by 2050, and by approximately 93–95 compared with a 2015 baseline (Martínez-Freiría et al. 2015). There is a high probability that this will increase the isolation at the species' southwest margin (where genetic diversity is greatest) and will likely result in local extinctions, increasing population isolation and likely promoting inbreeding (F. Martínez-Freiría pers. comm. 2023). Martínez-Freiría et al. (2015) cautions that data on dispersal were unavailable to incorporate into the model, but this and related species are believed to have low vagility. Despite the caveats associated with applying ecological niche models to climate modelling (discussed by Martínez-Freiría et al. 2015), this author notes that the results are consistent with expectations for a temperate snake associated with humid microhabitats, as its favoured conditions presently occur over a relatively narrow range in the northern Iberian Peninsula and are expected to become rarer.

The species is subject to direct mortality primarily from persecution, but secondarily (and potentially significantly at local levels - Brito and Álvares 2004, Martínez-Freiría and Brito 2012) from roadkill (Martínez-Freiría and Brito 2014, Brito 2021).

There may be no significant use of or trade in this species. Trade in small vipers as pets is common in Europe, but there is little information on whether this species is included in this trade.

This species is listed on Annex III of the Bern Convention and it occurs in several protected areas. The species is considered Near Threatened in both Portugal and Spain, and as Vulnerable in France. Ongoing habitat degradation and predicted long-term effects of climate change suggest that peripheral populations (i.e. from Portugal and France, and southern Galicia and northern Navarra, in Spain) could decline in the medium term, and habitat protection is recommended. Local monitoring programs are needed to evaluate population trends in these regions and define appropriate conservation strategies. Research is needed to clarify the degree to which this species can adapt to climate change is urgently required (Martínez-Freiría et al. 2015). There is an important need for formal education, awareness and communications regarding this and other snake species to emphasise their ecological role, and to reduce human persecution.