Search for the Mediterranean noble pen shells

The noble pen shell (Pinna nobilis) is an endemic species of the Mediterranean and the second largest bivalve in the world.

Since 2016, a parasitic protozoan has appeared on the Spanish Mediterranean coasts and very quickly spread to the rest of the Mediterranean. This parasite alters the digestive gland of the animal, which prevents it from eating and inevitably leads to the death of the noble pen shell.

Thus, since 2016, it is estimated that between 90 and 99% of the Noble Pen Shell in the Mediterranean have disappeared. In Monaco there were more than 600 noble pen shell in the Larvotto MPA, today there are none left, the populations having been decimated during October 2018.

The Mediterranean noble pen shell (Pinna nobilis)

In order to see if the noble pen shell is making a comeback in the Larvotto MPA or if a few individuals have resisted infection by this parasite, each year the AMPN calls on volunteers, and in particular to divers of the Club d'exploration sous-marine de Monaco (CESMM), as part of citizen science operations to comb the MPA in search of noble pen shells, so far without success.

A recent hypothesis suggests that noble pen shells are gradually replaced by individuals of rough pen shell (Pinna rudis). The monitoring carried out, both in Monaco and throughout the Mediterranean basin, will lead to finding elements to validate or refute this hypothesis during the research campaigns.

The rough pen shell (Pinna rudis)