Sweden- Restoration of the Freshwater Pearl Mussel and its habitats (LIFE04/NAT/SE/000231)

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Sweden- Restoration of the Freshwater Pearl Mussel and its habitats (LIFE04/NAT/SE/000231)

Factsheet: Sweden- Restoration of the Freshwater Pearl Mussel and its habitats (LIFE04/NAT/SE/000231)

Country SE
River Name 21 different water courses
Site Name Sweden- Restoration of the Freshwater Pearl Mussel and its habitats (LIFE04/NAT/SE/000231)
River Characterisation
    River typology
    Location (Lat Lon) 59.1421349497426, 12.1728515625
    Altitude lowland: < 200 m
    Catchment area small: 10 - 100 km2
    National code/
    River type name
    Hydromorphological quality elements

    Biological quality elements
    Ecosystem Services
    EU Directives
    Project size -1
    Approximate costs > 1 000 000 Euros
    Status Realised
    Period of realization 2004-2009
    Evaluation Hydromorphological and ecological changes
    Implemented by WWF Sweden

    This webpage is currently under construction. Comments with regards to the contents or possible lack would be gratefully appreciated.

    Key features of the case study

    In the following section, background and motives of the restoration project which led to the initiation of the project are introduced

    Drivers and pressures

    The freshwater pearl mussel (Margaritifera margaritifera) population has disappeared from several streams all over Europe. 95 % of the Fresh Pearl water mussel population in Central Europe has actually fallen during the last century. The specie is then classified by IUCN as endangered and is also included in the EU habitat directive (NATURA 2000). The decline is mainly due to water quality changes, inadequate regulation of water-flow, and habitat degradation which either affect the mussels directly, or its hosts, brown trout and salmon carrying the mussel larvae. Forestry and agriculture have a responsibility in those changes; improper forestry and agriculture practices led to large inputs of sludge and nutrient leaching in the streams. The dramatic fall in the freshwater pearl mussel population drove WWF Sweden to initiate the project in the autumn of 2004 which is part of a broader approach at the national scale (national action plan for Margaritifera margaritifera

    Global objectives

    Species enhancement and habitats improvement were the main objectives of the project which aimed to develop and test methods to achieve a favorable conservation status for the freshwater pearl mussel (Margaritifera margaritifera) in Sweden (at 21 different sites). However, freshwater mussel was not the only target specie of the project. A freshwater mussel population decrease is a warning sign of the deterioration of the environment, the improvement of freshwater mussels habitats will thus benefit to other aquatic species such as host fish.

    21 location sites of the LIFE Project

    Specific goals

    In order to achieve the conservation of Margaritifera margaritifera, the project aimed to improve the longitudinal connectivity by eliminate the migration obstacles to host fish along ten watercourses, improve the river bed in eight watercourses, to manage the banks along two small rivers and to enhance the Margaritifera margaritifera population by re-introducing young mussels (test in one stream).

    Site description

    Measures selection

    The following section introduces which measures were prepared, implemented and whether they were successful in reaching their related goals

    Diverse measures were implemented in the frame of the LIFE project aiming to restore the Margaritifera margaritifera population. First of all, 1 000 mussels collected from a nearby watercourse in the same basin were re-introduced in one stream. Then, a dam that regulates the water flow into the stream Lillsjöbäcken was repaired to avoid water shortage in summer. The blocking of 17 ditches with wood and ground materials was undertaken to reduce negative impact from siltation. Moreover, obstacles were removed, culverts incorrectly placed were fixed, and bypasses around migration obstacles were built in order to improve the longitudinal connectivity of the streams. Substrate was also improved by deposition of gravel and small stones in fast-flowing river sections (restoration of around 1300 m2 of stream grounds across eight sites). Finally, the removal of spruce and other vegetation which impact on streams were undertaken, in favor of deciduous trees along two shoreline sites (a total of 4.5 hectares buffer zone were thinned and cleared along the streams Sollumsån and Bratteforsån)

    Every measure was not implemented as foreseen due to different constraints. Some actions were actually compromised due to historic cultural values, and one action was postponed due to disagreement with landowner. Furthermore, the planned deposit of gravel was less than anticipated due to research which revealed lower need.

    Success criteria

    The mussel recruitment is expected within the coming 10–20 years. None measurable criteria were actually set in the frame of the LIFE project due its too short time frame. However, measurable criteria with regards to the Margaritifera margaritifera recruitment have been set in the frame of the Swedish national action plan for Margaritifera margaritifera [1] which has a longer tem approach.

    Ecological response

    Due to the complex life cycle of the freshwater mussel, it will take 5-10 years (at least) before it is possible to assess the real conservation impact of the implemented actions. However, the first monitoring has showed some encouraging signs such as an increase of freshwater pearl mussel larvae on the fish gills.

    Hydromorphological response

    Monitoring before and after implementation of the project

    All the components of the ecosystem (biotic, chemistry and hydromorphologic) were assessed both before and after restoration. The purpose of the pre-assessment was mainly to select suitable sites by evaluating the viability and the size of the population. The main features of the monitoring are given below:

    • The biotic component was assessed by monitoring freshwater pearl mussel and host fish. Electric fishing were carried to evaluate the host fish population (and to assess mussel larvae parasites on fish gills) and mussels inventories were done by using an Aquascope or peep box (monitoring according to the standard method recommended by the Swedish Environmental Protection Agency)
    • Riverbed substrates were also monitored by documenting the rate of sedimentation of riverbeds, the distribution of substrate size from silt to boulder, the turbidity of the water and the level of sedimentation (June-September).

    Sedimentation samples were taken before and after the restoration to see whether the siltation/sedimentation has decreased. This monitoring aimed to evaluate the success and efficiency of the restoration and of land use change (bad forestry management is a common source to sedimentation)

    • Finally, water was sampled to evaluate the changes in pH and the nutrients contents.

    The post-monitoring, carried on by the County Administrative Board, is actually still running for the Margaritifera margaritifera population and also electric fishing. Besides, the University of Karlstad is currently monitoring the sedimentation of the river beds.

    Socio-economic aspects

    In the following section, ways of cooperation, interaction and information with partners, stakeholders and wider audience of the project are introduced as well as their related success in reaching their participation objectives.


    The project involved the following partners: County Administrative Boards in the counties of Kalmar, Västmanland, Örebro and Västra Götaland, the Swedish Forest Agency, the Karlstad University and the City of Göteborg. All partners were great actors and carried out most of the fieldwork. The Forest Agency was a great resource of carrying out the knowledge improvement and information to landowners. Furthermore, the project has increased the cooperation between authorities and other actors such as NGOs and has contributed to the national action plan for Margaritifera margaritifera. All those factors are important for a long nature conservation perspective.


    The fresh pearl mussel status is actually largely dependent on external factors related to land use outside and upstream of the mussel sites. Therefore, the project managers wished to actively involve stakeholders (mainly forestry owners and other landowners) aiming to increase their awareness which could lead to a change of practices.

    Those changes and their related effects cannot be evaluated so far because they must be assessed in a long term perspective. An increase of knowledge about aquatic conservation will obviously lead to a better conservation of forest streams. Nevertheless, some local changes have already been noticed such as wider buffer zone along the water, use of temporary bridges when driving the machines etc. Project managers still persuade forest owners to integrate water resources management in the forest planning in order to protect sensitive areas and valuable habitats.


    Information and education focused on several audiences such as public, restoration practitioners, forestry owners and others landowners. The objectives were mainly to increase the knowledge and consideration of the aquatic conservation within the forest sector and to collect all the experiences and knowledge in a manual. Efforts were thus devoted to education by the following means:

    • Seminars and conferences such as the Aquatic Conservation with Focus on the freshwater pearl mussel Margaritifera margaritifera held on August 12–14, 2009
    • Several information materials such as brochures, field signs, home page, poster and a film
    • A manual that summarizes the project practical experiences in order to share and increase restoration knowledge “Restoration of freshwater pearl mussel Streams” [2]

    The project has improved the knowledge and understanding for aquatic conservation. The conference allowed a great knowledge exchange between several experts and succeed by building a national and international network around aquatic conservation (especially for Margaritifera margaritifera) The Swedish experiences and knowledge, summarized in the manual, is now shared and used in several countries. It has successfully been communicated and is currently used both as a practical tool for planning restoration work and also as an inspiration for aquatic conservation. Nevertheless, project managers must be aware that communication and information is a constantly ongoing action.


    The following section gives an overview of cost and funding of the project

    Cost: 1 006 983 Euros
    European Union: 50%
    State (Swedish Environmental Protection Agency): 16%
    Others partners: 28%
    Self financing (WWF): 6%

    Contact person within the organization

    WWF Sweden
    Sofi Alexanderson, project manager/coordinator
    Telephone: 0046 8 624 74 00
    E-mail: sofi.alexanderson@wwf.se

    Extra background information

    The Margaritifera margaritifera conservation continues through the national Swedish conservation plan (especially the monitoring part). The LIFE project was actually the starting point of this national plan and therefore added lots of technical and scientific inputs in this broader management plan.

    While carrying the project, managers were faced to some constraints which prevented to carry out all the work as planned. Most of the lessons learnt are summarized in the manual “Restoration of freshwater pearl mussel Streams” [3] However, some extra information is given below. First of all, LIFE Nature Fund is a great opportunity for river restoration practitioners. It helps them to implement a broad range of measures by making a large amount of money quickly available but also by giving access to a large network (contacts with other LIFE Nature projects). On the other hand, project managers must be aware that the LIFE bureaucracy has a heavy administrative part. Besides, the 5 years time frame is way too short to evaluate specie enhancement measures. In the “Margaritifera margaritifera” case, it will take at least 10 years before knowing whether the restoration was a success or a failure. Others lessons are listed below:

    • The importance of gathering all the actors/stakeholders of the catchment area and create an interaction with them. (Agreement and dialog with the landowners for example)
    • The importance of information and education of actors within land use (mainly forestry)
    • Remember to document and save all photos and monitoring information
    • The importance of develop a detailed action plan


    Related Measures

    Related Pressures