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Management Measures for the Conservation of Freshwater Pearl Mussel (Margaritifera margaritifera) and Brown Trout (Salmo trutta) in Portugal †

CIMO-Centro de Investigação de Montanha, 5300-253 Bragança, Portugal
cE3c-Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal
CIBIO/InBIO-Centro de Inv. Biodiversidade e Recursos Genéticos, Universidade do Porto, 4485-661 Vairão, Portugal
Freshwater, Sociedade Unipessoal Lda, Estrada do Cando 42, 5400-010 Chaves, Portugal
BIOTA Lda-Estudos e Divulgação em Ambiente, Lda., 2510-718 Gaeiras, Portugal
CESAM-Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, 3810-193 Aveiro, Portugal
ICNF-Instituto de Conservação da Natureza e das Florestas, 5000-567 Vila-Real, Portugal
CBMA-Centro de Biologia Molecular e Ambiental, Universidade do Minho, 4710-057 Braga, Portugal
Author to whom correspondence should be addressed.
Presented at the IX Iberian Congress of Ichthyology, Porto, Portugal, 20–23 June 2022.
Presenting author (poster presentation).
Biol. Life Sci. Forum 2022, 13(1), 134;
Published: 20 June 2022
(This article belongs to the Proceedings of The IX Iberian Congress of Ichthyology)


The project “Recovery and Protection of Margaritifera margaritifera” (POSEUR-03-2215-FC-000096) was developed to protect and restore freshwater pearl mussel M. margaritifera and brown trout S. trutta populations in Portugal. To conduct this, in the last 3 years, several in situ and ex situ conservation measures were applied, and several tasks were defined, namely the following: (1) assessment of the spatial distribution and conservation status of the target species; (2) evaluation of the biological and ecological quality of salmonid rivers; (3) analysis of vulnerability to human disturbances; (4) an increase in habitat suitability; (5) definition of management plans for salmonid watercourses; 6) captive reproduction of M. margaritifera and S. trutta; (7) monitoring of M. margaritifera and S. trutta stocking programs; (8) genetic characterization of wild populations of S. trutta. Results showed that M. margaritifera is currently distributed in seven rivers (mainly in Rabaçal and Tuela rivers, and residually in Mente, Paiva, Neiva, Tâmega and Beça rivers). In Portugal, only S. trutta functions as a suitable host for M. margaritifera. Both species are highly vulnerable to human disturbances and the main threats include habitat fragmentation and degradation (e.g., dams and alder tree disease), invasive alien species (e.g., American crayfishes, Pacifastacus leniusculus and Procambarus clarkii) and climate change (e.g., droughts and heatwaves). A riparian area of 2.91 ha was restored, and several management plans were specifically developed in different rivers to contribute to the recovery of both native populations. Moreover, the ex situ reproduction of M. margaritifera produced more than 100,000 juveniles, allowing the implementation of reintroduction actions. Complementarily, eight wild brown trout stocks were selected, based on the genetic diversity, and acclimated to captivity in ICNF fishfarms (Castrelos, Bragança and Torno, Amarante) for future stocking programs according to national legislation. Overall, this project is a first step to improve the conservation status of pearl mussel M. margaritifera and its fish host, brown trout S. trutta.

Author Contributions

The authors contributed in equal parts for the several components of the manuscript; All authors have read and agreed to the published version of the manuscript.


This research was funded by POSEUR (03-2215-FC-000096) and Portuguese Environmental Fund.

Institutional Review Board Statement

The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by Instituto de Conservação da Natureza e das Florestas (Licença 172/2022/CAPT; Credencial Pesca nº 35/2022).

Informed Consent Statement

Not applicable.

Data Availability Statement

Data availability can be found in project website (accessed on 9 April 2022).

Conflicts of Interest

The authors declare no conflict of interest.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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MDPI and ACS Style

Teixeira, A.; Oliveira, J.M.; Lopes-Lima, M.; Jesus, J.; Reis, J.; Barros, T.; Martinho, A.; Sousa, R. Management Measures for the Conservation of Freshwater Pearl Mussel (Margaritifera margaritifera) and Brown Trout (Salmo trutta) in Portugal. Biol. Life Sci. Forum 2022, 13, 134.

AMA Style

Teixeira A, Oliveira JM, Lopes-Lima M, Jesus J, Reis J, Barros T, Martinho A, Sousa R. Management Measures for the Conservation of Freshwater Pearl Mussel (Margaritifera margaritifera) and Brown Trout (Salmo trutta) in Portugal. Biology and Life Sciences Forum. 2022; 13(1):134.

Chicago/Turabian Style

Teixeira, Amílcar, João M. Oliveira, Manuel Lopes-Lima, Joaquim Jesus, Joaquim Reis, Tânia Barros, António Martinho, and Ronaldo Sousa. 2022. "Management Measures for the Conservation of Freshwater Pearl Mussel (Margaritifera margaritifera) and Brown Trout (Salmo trutta) in Portugal" Biology and Life Sciences Forum 13, no. 1: 134.

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