Source: IUCN Mediterranean


New mortality spots detected in Greece, Croatia, Turkey, Tunisia, France and Morocco. The parasite causing massive outbreak of Mediterranean penshell Pinna nobilis mortality continues to extend rapidly, revealing need for further and urgent action. IUCN-Med continues to work on an assessment to analyze the overall reach of this crisis while preparing the Red List Assessment for this species. In case you have information about non-affected areas please let us know.


Following a first outbreak in 2016, which caused the mortality of around 99% of the population in Spain, the spread of a disease caused by an haplosporidian parasite and perhaps other mycobacteria is seriously threatening the survival of the Mediterranean’s biggest bivalve mollusc. 

IUCN recommended actions to address the Pinna nobilis alarm

IUCN’s recommendations aim to achieve better understanding of the Pinna nobilis’ situation and to prepare an action programme in both affected and still unaffected areas, including:

  • Mapping the situation along all coasts, monitoring every 2-3 months to know the status of the populations and if any recruitment is happening even after the mortality event has occurred.
  • The populations in lagoons and enclosed bays have been less affected by these mortality events. These areas need to be closely monitored. It is important to develop actions to promote the survival of natural recruitment in these areas.  
  • Identifying high-density Pinna nobilis hotspots. Targeted removal of pen shells from highly dense grounds to analyze breeding or replacement in areas where pen shells can’t be found (particularly in inner bays or small lagoons) are also recommended. Caution should be taken to translocate pen shells from the sea to other areas with Pinna to avoid the transmission of the disease.
  • The eventual recovery of impacted populations will depend mainly on the existence of unimpacted populations, resistant individuals and recruitment. Therefore, it is extremely important to enhance larval recruitment and verify if larvae coming from unaffected sites or resistant individuals are reaching the impacted areas, thus potentially contributing to eventual recoveries. In this sense, IUCN has published specific guidelines to construct and install Pinna nobilis larval collectors:
  • Develop efforts in the aquariums with some pen shells to help close the species’ breeding cycle and understand the parasite/ mycobacterium that is affecting the specie. Disease outbreaks depend on increasing the knowledge of these interactions.

The Mediterranean noble pen shell is classified as a species of Community Interest in need of strict protection by the European Habitats Directive and as an Endangered Species by the Protocol Concerning Specially Protected Areas and Biological Diversity in the Mediterranean from the Barcelona Convention.

Acknowledgements for the information provided to all colleagues

  • Ministry of Environment, Oceanographic Institute, Instituto Oceoanográfico, Laboratorio de Investigaciones Marinas y Acuicultura, University of Valencia (Spain)
  • ISPRA and Italian Network (Italy
  • Institut Pascale, Institut océanographique Paul Ricard and French network collaborators (France)
  • University of Oran (Argelia)
  • Hellenic Centre of Marine Research (Greece)
  • Enalia (Cyprus)
  • Çanakkale Onsekiz Mar University, Turkish Marine Research Foundation, Institute of Marine Sciences METU and DEU-IMST(Turkey)
  • APAL, Tunisian researchers and partners: équipe MAIN/ASSEB, NGB/APPAL (Tunisia)
  • Fishermen association, PIM/APAL/ASKJ, University of Malta (Malta)
  • Agricultural University of Tirana (Albania)
  • Marine Explorers Society – 20000 Leagues (Croatia)
  • Network of Mediterranean divers, fishermen, researchers and swimmers

For further enquiries, please contact María del Mar Otero