Freshwater pearl mussel
Structure & Staff
Collaboration Raise of NGOs and Population
Baltic Aquatic Warbler
Waste Paper
Site Management Plans
Implementation of Mire Habitat Management Plan
Restoration of Floodplains
Northern Gauja Valley
Lake Engure
Other projects
Literature & Publications


liela izmēra apavi

Project Title

Freshwater pearl mussel

Project Duration



Latvian Fund for Nature,


Latvian Environmental Protection Fund

Project Area



Mudīte Rudzīte








Rīga, Kronvalda Bulvāris 4

LV-1010, Latvija

Summary of year 2004

The fresh water pearl mussel is an endangared species not only in Latvia, but also in the main part of the distribution area of this species globally. Therefore the aim of the project was to perform bailout measures to give the fresh water pearl mussel extra possibilities to survive.

The conditions currently are inappropriate for the young mussels to survive in any of the Latvian Pearl rivers. In 2000 the Gauja national park supported the project “Ziemeļu upespērlenes pavairošanas programma Gaujas nacionālajā parkā” – “ Breeding the Freshwater pearl mussel in Gauja national park”. During this project the best places to obtain the new generation of mussels were found out by Valmiera Regional Environment Department and the Hidrobiological laboratory of the Biological Institute at the Latvian University. 2571 mussels were displaced from unfavourable and beaver-destroyed places in river Rauza basin to the Gauja national park during 2004. These mussels were measured and marked with numbers; the place of release was fixed on the GPS. In the same places 4000 small trouts were released, for realisation of the pearl mussel life cycle. Trouts are bred in “Foreļu audzēšanas un pārstrādes sabiedrība” Ltd.

The merging of Amata river pearl mussel population and mussel displacing to the Gauja national park is completed too.

Summary of year 2003

The freshwater pearl mussel Margaritifera margaritifera L. is included in the Bern Convention (Appendix III) the EU directive 92/43/EEC (II and V Appendices), since 1985, listed as a Category I species in the Latvian Red Data Book and included in the State list of protected animals since 1957.

In the 1999 the Danish Environmental Protection Agency finansed a project “Inventory of species and biotopes, preparation of conservation plans and development of nature conservation structures in Latvia in connection with transposition of the EU Birds and Habitats Directives”. In the course of the project, Action plan for the freshwater pearl mussel was also prepared.

The freshwater pearl mussel Margaritifera margaritifera L. protection program was established at the Latvian Fund for Nature. This program includes some already completed projects:

The breeding of freshwater pearl mussel in the Gauja National Park (2000), Specially Protected Nature areas in the localities of freshwater pearl mussel (2001), Investigations on rivers in the North-Vidzeme Biosphaere Reserve (2002), The Compensation for revocation of a fish pound-building project on the Rauza river (Valmiera Regional dept., 2000), Hydrological, hydrochemical und hydrobiological investigations on localities of freshwater pearl mussel ( LU Institute of Biology, 2002).

In 2003 “The update of “Action plan for Margaritifera margaritifera” was completed. The plan, initially made in 1999, was reviewed and updated. The new plan is prepared for submission to the Nature protection administration, responsible for verification and further submission of the plan to the Nature Protection Board.

A booklet “Surviving of the River mussels” is published (1000 ex.).

The goal of the project 2003 was to investigate, concretize and estimate eventual freshwater pearlmussel Margaritifera margaritifera localities in the basins of rivers Liela Jugla, Maza Jugla, Ogre and Veseta. There are 28 rivers, 92.6 km investigated. Live pearl mussels were found in one river, empty shells – in two rivers. Valuable information was obtained about localities from where pearl mussels have disappeared, as well as about distribution and condition of Unio crassus populations.

There are 106 forms filled about the investigated rivers, originals are in the Zoological Museum of the Latvian University. This information is available for all specialists for scientific purposes. For mass media this information is available through the organizations mentioned above.

The cooperation partner of the project was the State Stock Company “Latvia’s State Forests”.

 Summary of year 2002

The main goal of the project was to investigate and estimate eventual Freshwater Pearlmussel Margaritifera margaritifera rivers in the North Vidzeme Biosphere reserve. There are 59 rivers, 147,3 km investigated. Pearlmussels were not found, but valuable information about localities where pearlmussels have disappeared and about Unio crassus was obtained.

There are 128 forms filled about the investigated rivers, originals are in the Latvian Fund for Nature, one copy in the Zoological Museum of Latvian University, second copy in the North Vidzeme Biosphere reserve, in Salacgriva. This information is available for all specialists for scientific studies. For mass media this information is available through the organizations mentioned above.

The malacologist Dr.I.Valovirta and 3 professional scuba divers Panu Oulasvirta, Vili Englund, Pekka Tuulenvire from Finland took part in field works. Diving was used in Salaca, Svētupe, Vitrupe and Korģe and allowed to obtain information about mussels in deepest stretches of these rivers. It was a useful experience and helped to approbate the use of divers in Latvian rivers.

Biotopes suitable for Pearlmussels were found in 25 rivers. For survival of Pearlmussels very important is quality of water during a long period of time. The ecosystems of all North Vidzeme Biosphere reserve rivers are influenced by eutrophication. The causes for extinction of Pearlmussels in rivers of the reserve are: 1) wide agricultural lands in basins of all mentioned rivers, 2) waste waters from towns, 3) dams and pounds on rivers, 4) melioration and regulation of rivers.


Summary of year 2001

Short information about the actualities and priorities in the freshwater pearl mussel Margaritifera margaritifera protection plan is summarized in this project.

Since 1999, when protection plan was prepared, some of actions have been completed, some will be carried out in the near future. Therefore it would be advisable to run through this plan next year. The aim of protection: to stop the perishing of species and to restore normal reproduction and development – is still actual. The species is endangered to extinct in Latvia during the next 30 years, only some specimens would survive some ten years after. There is a larval stadium of mussels found – glochidia. So, mussels are able to reproduce, and the main factor for population obsolescence is mortality of youngsters due to unsuitable living conditions.

Map drafts and recommendations for individual management in 3 new Nature parks in the basins of rivers Pērļupe, Rauza and Tumšupe are prepared. For definitive territory plans and preparation of protection regime in shelter belts  consultations with the Hydrobiological laboratory of Institute of Biology are necessary, since this institution carries out a research in the above mentioned territories. Consultations with forestry and agriculture specialists about the permitted and forbidden actions in these territories are necessary as well.




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