Creation of man-made snowdrifts to improve the breeding success of the Saimaa ringed seal, Finland

Climate change poses a long-term threat to the Saimaa seal population, because the successful breeding of the species depends on ice and snow cover. Seals give birth typically to a single pup in a subnivean lair that is situated in snowdrifts formed on the shoreline of the lake. The mother-pup pair uses the lair over the nursing period. It provides shelter against predators and harsh climate.

In winters with good snow conditions, about 8% of the pups are found dead in lair sites. However, a mild winter and a lack of snow can cause higher perinatal mortality (as in 2006 and 2007, ca. 30%). The snow cover of Lake Saimaa has been insufficient during some of the recent years. For example, the winter of 2020 was exceptionally mild, causing a total lack of snowdrifts needed for the seal lairs. This situation is further exacerbated by global warming-related changes in climatic conditions. Model-based analyses of ice and snow conditions in Lake Saimaa under climate change scenarios show a clear long-term decline in breeding habitat quality. For example, the mean depth of shoreline snowdrifts is projected to decrease by approximately 50% from the reference period 1981–2010 to 2070–2099. The duration of ice cover is expected to shorten by about 1.5 months, with ice melting already before the end of the pupping season during the mildest winters (Jakkila et al., 2024). Moreover, due to the land-locked lake habitat, the Saimaa seals are not able to move to more favourable areas in response to climate change.

The Saimaa ringed seal has an IUCN status of endangered sub-species. In the Habitat Directive, this status implies that such a species needs strict protection (Council Directive 92/43/EEC, Annex IV). According to this latter, the deterioration and destruction of a habitat, breeding site, and resting place important for the survival of a species (or sub-species) under strict protection is prohibited. Therefore, the EU funded LIFE project has obtained the permits from for the local Centre for Economic Development, Transport and the Environment for piling up the man-made snowdrifts at the seal’s lair sites.

In addition, the following legal elements are relevant for the Saimaa seal conservation project.

Conservation policy

The Saimaa ringed seal was protected in 1955 by a statutory decree based on the Finnish Hunting Act. In 1993, legal protection was transferred to the Nature Conservation Act. The responsibility for management was given to the Ministry of Environment and in practice to the Parks & Wildlife Finland. It is a public agency that forms part of the state-run enterprise Metsähallitus. A conservation strategy and action plan for the Saimaa ringed seal was adopted in 2011 and updated in 2017 and 2022 (Saimaannorpan suojelun strategia ja toimenpidesuunnitelma 2022).

Conservation areas and programmes

In Lake Saimaa district, the establishment of the Linnansaari National Park in 1956 represented a significant basis for the protection of Saimaa seal (9,600 hectares, winter stock of 65-86 seals). Kolovesi National Park was established in 1990 and the protection of the Saimaa ringed seal was the main contributing reason for conservation of the area (2,300 ha, winter stock app. 9-12 seals). There are also some privately owned conservation areas established for the protection of Saimaa seal.

The Finnish National Shoreline Conservation Program, adopted in 1990, gives the means to protect the breeding habitats of the Saimaa ringed seal. In the lake Saimaa, the conservation programme covers 92,000 ha (mostly water areas). Most of the distribution area of the seal is also included in the Natura 2000 Network. The Natura 2000 areas cover a total of 157,426 ha (33,022 ha land, 124,404 ha water). Respectively, the Shoreline Conservation Programme and the Natura 2000 network, partially overlapping in the geographic coverage, protect approximately 70% and 95% of the shorelines where the seals’ lair sites are located. To implement the conservation programme and conservation goals of Natura 2000 network, nature conservation areas were established and areas acquired by the state for conservational purposes. The Natura 2000 network is implemented also by means of land use plans in line with the Land Use and Building Act, fishing restrictions according to the Finnish Fishing Act and establishment of restriction areas under the legislation regulating motor vehicle use in terrain.

Fishing restrictions

At Lake Saimaa, fishing has been restricted since the 1980s to protect the Saimaa ringed seal. Fishing closures and restrictions are the main conservation measures for the ringed seal population. The restriction areas have increased from 1.5% to ca. 7% of the lake’s surface area. At present, the fishing restriction decree (357/2026) established one spatial (covering ca. 70% of the lake), and two temporal (spring-time and year round) fishing restrictions. During spring (from 15 April to 30 June), the most critical period for pup survival, the use of gill nets is banned. In addition, the use of most lethal fishing gear types for seals are banned year-round (e.g. fish traps with an opening wider than 15 cm, strong-mesh gill nets, hooks baited with fish and multifilament nets). Despite the spatial enlargements, the areal coverage of the decree is still smaller than the distribution area of the Saimaa ringed seal, especially in the northern and southern parts of the lake. In addition to the decree, voluntary fishing restriction agreements are concluded both within the area covered by the decree and in adjacent water areas. Financial compensation is paid to water area owners (holders of fishing rights) who enter into these agreements. These agreements also enable the expansion of the area regulated by the decree during the decree validity period. This for example applies when new pups are observed in areas at the edge of or outside the current decree area.

The EU LIFE Saimaa seal project and the Our Saimaa Seal LIFE follow up project aimed to reduce the main threats to the Saimaa ringed seal, which were identified in the Saimaa seal conservation strategy and action plan. In particular, the projects sought to reduce risks related to climate change, fishing, and human induced disturbance. The results of the projects were used in the conservation strategy and related regulations’ updating.

One of the main goals of the projects was to facilitate adaptation to climate change by piling up man-made snow drifts and build artificial nests to improve the Saimaa seal´s breeding success during mild winters. Other goals include reducing by-catch mortality. This was achieved through developing seal-friendly fishing methods, reducing human-induced disturbances, involving various (local) stakeholders in conservation actions and awareness raising initiatives. The projects also aimed at updating knowledge as the basis for effective monitoring and conservation, such as essential functioning of ecological interrelations and potential threats to the seals.

The man-made snowdrift method was developed at the University of Eastern Finland. It was implemented as a new conservation method on full scale to improve the seal’s pup survival in mild winters when the snow cover is not sufficient for lairs. It was implemented during the EU LIFE Saimaa Seal project and continued in the Our Saimaa seal project.

During the winters with poor snow conditions, man-made snowdrifts were piled up at the breeding habitat of the seal. The drifts were piled annually in January and early February. The shape and size of the man-made drifts mimic the natural wind drifted snow mounds. Saimaa ringed seal lairs are located on ice in snowdrifts on shoreline. Man-made snowdrifts were piled using natural snow collected nearby the drift site using snow shovels and pushers. The drifts were located in the vicinity of the potential lair sites. Minimum snow cover on ice for making a snowdrift is around 5 centimetres. The exact dimensions of the snowdrift depend on the location and amount of snow available. However, snowdrifts should be large enough for large birth lairs, i.e., approximately 1 m high, 3-6 m wide and 8-15 m long.

Each year, more than 300 volunteers participated in lair censuses and/or the construction of man-made snowdrifts. Based on findings from lair census, conducted annually, creating human-made snowdrifts resulted an effective conservation method. During the project ‘Our Saimaa seal LIFE’, 1,130 snowdrifts were built, largely made by volunteers. Around half of these snowdrifts were used as a resting or birth lair and 171 pups were born in them. Due to this conservation action, the perinatal mortality remained significantly lower compared to earlier winters with poor snow conditions. When the snow conditions made it impossible to create man-made snowdrifts, artificial floating nest structures were built and placed. The artificial nests are floating structures that can be installed either in open water or on ice. Throughout the project, 120 of these artificial nests were deployed and half of these were used by the seals.

The projects also implemented other measures that do not address the effects of climate change but reduce seals’ mortality, and therefore also increase their resilience to climate change. Seal-safe fyke nets (a type of fish trap used by professional fishermen, for perch and pike-perch) were developed in collaboration with local professional fishers. In the first Saimaa Seal project, nearly 300 gill nets owned by recreational fishermen were replaced by seal-safe fish traps (a different fishing gear type, smaller than the fyke net mostly used by professional fishermen). Moreover, nearly 1,500 “stoppers” were distributed to fishermen. Stoppers make the traditional fish traps ‘seal-safe’: they prevent the maximum opening width exceeding 15 cm and thus blocking the seals way into the trap. During the course of ‘Our Saimaa seals LIFE’ project, one additional thousand seal safe fish traps have been built by over 1700 participants in 135 workshops. Those actions enabled to replace approximately 150 gill nets with 600 seal safe fish traps. At fishing events during the two Life projects, about 1100 individual recreational fishers signed the agreement to refrain from gill net fishing in the breeding area, in exchange for the seal-safe fish traps. Moreover, Our Saimaa Seal LIFE Project reached over 23.000 people through environmental education.

Furthermore, ensuring genetic diversity within the ring seal population is considered fundamental for coping with changing environmental conditions posed by climate change. To address this issue, three seals within the Saimaa Lake were successfully translocated and monitored during the project. Future research may help to verify whether this has helped to increase genetic diversity.

Management plans for Natura 2000 areas vital for the Saimaa ringed seal were prepared during the LIFE Saimaa Seal project from 2013-2018. 34 ha land (islands) and 670 ha of water were acquired for nature conservation. Finally, initiatives for awareness raising and educational purposes were also undertaken.

In the following years (2020-2025), additional protection and conservation measures were implemented for the two most important habitats of the Baltic ringed seal, located in the Archipelago Sea and Åland. Within the ‘Our Saimaa seals LIFE’, three new protected areas were established in the Åland archipelago. Additionally, the protection of the Baltic ringed seal was added as a mandatory criterion for six existing protected areas (Our Saimaa Seal LIFE report 2025).

Monitoring results indicate that man-made snowdrifts resulted in a reduction of the perinatal ringed seal mortality. During the winters of 2014-2016, when man-made snowdrifts were piled, the perinatal mortality fluctuated from 8% to 16%. Conversely, before the method was implemented, the mortality was near 30% (e.g. 2006 and 2007). During the last five years (2020-2025), the seals have accepted around 50% of man-made snowdrifts as a lair site and 171 pups have been born in them. In the same period, due to the conservation measures implemented, the Saimaa ringed seal population increased from 425 to 530 individuals. These results come from the lair census which begins every year in spring when the roofs of snow lair collapse and become detectable. This census extends over about 70% of Lake Saimaa’s shorelines (about 11500 km).

Metsähallitus, Parks & Wildlife Finland is responsible for most of the conservation and monitoring measures of the Saimaa seal. The University of Eastern Finland played a crucial role not only in developing the man-made snowdrift method and participating in annual lair censuses. More broadly, it also advanced Saimaa ringed seal conservation by providing new monitoring and conservation methods, as well as scientific knowledge to support decision-making.

The role of the volunteers is also extremely important both for making the snowdrifts and for monitoring and evaluating the population dynamics. During the years, experienced local volunteers participated in the annual lair censuses of the Saimaa ringed seal. These volunteers know the demanding field work conditions on the ice and the location of the traditional breeding sites of the ringed seals. This network of volunteers grew significantly during Our Saimaa Seal LIFE project from 2020-2025. Based on this initial group of key volunteers, the project started building a larger scale network of volunteers to cover the whole distribution area of the seal to be prepared for the possible challenges of warming winter climate. In addition to the conservationists, the volunteers included recreational fishermen, politicians (local and national), policymakers, local inhabitants, summer residents and NGO members. It is a good example of how a concrete conservation action can induce openness and involvement of locals to conservation and bring people together.

In the period 2020-2025, more than 300 volunteers were active annually in making snowdrifts and or lair censuses. Their efforts accounted for a total of almost 3500 workdays. Considering the entire period of the two EU LIFE projects (2013-2018 and 2020-2025), the effort of volunteers accounted for 5770 workdays. In addition to volunteers and Metsähallitus, also other cooperation partners, like University of Eastern Finland, WWF Finland and local Centres for Economic Development, Transport and the Environment, participated to realise the human-made snowdrifts in a notable effort.

135 workshops were organised to inform and educate stakeholders. During these events, seal-safe fish traps were built with the help of fishers, school children, and water area managers.

Success factors

A crucial element of success for this adaptation option is the generally positive local and national attitude towards the Saimaa Seal (IUCN SSC, 2025). In this regard, volunteers were fundamental for the success of the project and for monitoring sail population dynamics. The man-made snowdrifts have shown to be an effective method to decrease the pup mortality in winters with poor snow conditions. A key success factor is that due to their steadfastness, seals return to the same location every year to build their lair. This helps to facilitate the successful placement of human-made snowdrifts (IUCN SSC, 2025).

The success demonstrated with the first project (LIFE Saimaa seal project) prompted its follow-up through the Our Saimaa Seal LIFE project. This project has received the Biodiversity Award 2013-2014 awarded by the National Committee of Finland for the International Union for Conservation of Nature (IUCN). Due to publications in international journals and media dissemination, the results also raised interest outside Finland.  It was promoted as a new, simple and innovative solution to mitigate the adverse effects of climate change on a highly endangered population that was successfully tested under real conditions.

Limiting factors

However, the man-made snowdrift method is effective only as long as there is some snow available and the lake has contiguous ice cover. Since the first LIFE project, in some areas the amount of snow and/or ice has been a limiting factor for creating man-made snowdrifts. Therefore, the development and testing of long lasting artificial lair structures, started in the first LIFE project, continued in the second project and were considered particularly relevant.

Costs

The total LIFE Saimaa Seal project budget was EUR 5,261,612. A share of 75% of the total budget was funded by European Union’s LIFE+ (Nature and Biodiversity Programme). The action “Improving breeding conditions of the Saimaa ringed seal with man-made snowdrifts” is one of the 63 actions in the project. The costs for this specific action is about 4% of the total project budget. The total project budget of ‘Our Saimaa Seal LIFE’ was EUR 7.1 million, of which the EU contributed EUR 5.3 million.

Benefits

Around 50% of the pups were born in lairs created in man-made snowdrifts. The perinatal mortality was significantly lower compared to earlier winters with poor snow conditions when the method was not in use. This highlights the usefulness and success of the technique (for further details refer to the “Solutions” section).

Beyond the direct conservation outcomes, the involvement of hundreds of local volunteers has had important social benefits. Participation in conservation work improved public attitudes towards the Saimaa ringed seal and its protection. It also strengthened trust between local communities and conservation authorities. Fishers, students and lake visitors were educated in seal conservation efforts. More aware behaviour and respectful fishing practices are therefore expected to enhance the results of the adaptation measures implemented during the two EU LIFE projects. Seal-friendly tourism was also developed. Participants in seal excursions received information about the Saimaa ringed seals and the conservation measures implemented to safeguard this species.

The LIFE Saimaa Seal project, ran from 2013 to 2018. It was followed by the Our Saimaa Seal LIFE which ran from 2020 to 2025. Man-made snowdrifts continue to be built annually. Their implementation takes a short period (a couple of weeks per winter and before the reproductive season).

Man-made snowdrifts only last one breeding season and thus need to be rebuilt every year. The man-made snowdrift method was included in the pool of established conservation practices of the Saimaa ringed seal.

Metsähallitus Parks & Wildlife Finland
E-mail: saimaannorppa@metsa.fi

Iucn-ssc-conservation-success-stories-2021-2025

Kunnasranta, M., Niemi, M., Auttila, M., Valtonen, M., Kammonen, J., & Nyman, T. (2021). Sealed in a lake—biology and conservation of the endangered Saimaa ringed seal: a review. Biological Conservation, 253, 108908.

Modelling climate change impacts on lake ice and snow demonstrates breeding habitat decline of the endangered Saimaa ringed seal | Climatic Change | Springer Nature Link

Kunnasranta, M., Niemi, M. & Auttila, M. (2022). Developing artificial nest boxes for a large aquatic mammal. Aquatic Conservation: Marine and Freshwater Ecosystems, 32(8), 1365–1371. https://doi.org/10.1002/aqc.3851

Our Saimaa Seal LIFE Layman report 2025