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A large whelk present in France
It's a large gastropod, reaching 18/20 cm and weighing almost 1 kg. It belongs to the murex family. One of its most striking features is the pronounced orange color of the shell's interior. Its outer opening is fitted with small, elongated teeth.
Originating in the Indo-Pacific (China Sea, Sea of Japan), it has appeared almost everywhere over the last twenty years. It is now present in the Black Sea, Adriatic Sea, Marmara Sea and Aegean Sea. It can also be found in Chesapeake Bay, Uruguay, Argentina, the Netherlands and Brazil. In France, it is reported in southern Brittany, Charente-Maritime and the Etang de Berre.
It likes soft bottoms and spends most of its time buried in the substrate, leaving only its siphon to breathe. It is resistant to wide fluctuations in temperature, salinity, pollution and low oxygen levels.
A predator, it preys on mussels, oysters, clams, cockles, scallops and scallops. It also preys on carrion that may be at the bottom of the water. Its lifespan is estimated at between 10 and 20 years.
A threat?
It is considered a real threat in the Arcachon basin, a shellfish-producing area.
In the Etang de Berre, its presence has been revealed since 2015, and clutches of eggs have been photographed in 2020, 2021, 2022 and 2023, clearly demonstrating its presence on this site.
An important note: this shellfish is edible, it's a large whelk. A little anecdote from a specialist who keeps a close eye on this species: when this gastropod invaded the Black Sea, restaurant owners spread the rumor that it was an aphrodisiac. The invasion of this shellfish didn't last long, so this may be an avenue to follow to eradicate it...
Measuring the scope of your installation
Ifremer is carrying out sampling campaigns to measure the extent of the installation and the possible risks to the shellfish resources exploited.
Ifremer is keeping a close eye on this issue, and as part of its observation missions, the institute is helping to assess the presence of this mollusc in the Charentais Pertuis. An observation form can even be filled in.
This species has invasive/invasive status and is classified as :
- Black list of invasive species in the Mediterranean (IUCN)
- List of non-native species to be monitored in Occitania (Réseau Alien Occitanie)
- List of non-native species to be monitored in PACA (Réseau Alien PACA)
- List of non-native species to watch in Normandy (Réseau Alien Mer Normandie)
- List of non-native species to watch in the Bay of Biscay (Réseau Alien Golfe de Gascogne).
