World record largest oyster found at Belgian coast | Flanders Marine Institute

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World record largest oyster found at Belgian coast

Oostduinkerke, Belgium (2015.08.28) - Earlier this week, on the beach near the nature reserve Zwin, tourists found the shell of what seems to be the largest oyster ever encountered at the Belgian coast. It is an Japanese oyster, 38 cm long and possibly 25 years old. This individual seems to be 2,5 cm bigger than the current world record. In expectation of an official confirmation by the Guinness World Records book, the specimen will be on display in the National Fisheries Museum NAVIGO in Oostduinkerke. From the 1st of September onwards the shell will be part of the temporary exposition "Oyster passion". 

Press release by: National Fisheries Museum (NAVIGO) and Flanders Marine Institute (VLIZ)

The observation took place on 26th of August at the beach of Knokke-Heist, near the nature reserve Zwin. Alice and Clémentine, daughters of Marc & Susan Lechat - Luxemburg tourists - found the empty oyster shell of 38 cm long. They realised this was an exceptional discovery and got in contact with the nature centre of the Zwin and the Flanders Marine Institute (VLIZ). The latter could confirm their conjucture: a pecularly large specimen of a Japanese oyster (with the appropriate scientific name Crassostrea gigas). 

In the 60s the Japanese oyster was imported in Zeeland, The Netherlands from the far East. The cultivation of the autochtonous European oyster (Ostrea edulis) got in trouble after the cold winter of 1963 and infections with the Bonamia parasite. To meet the high demand of the market for oysters, aquaculture farms started to experiment with several exotic species, of which the Japanese oyster was the most successful. Nowadays the Japanse oyster - also named ‘creuse’ - dominates the market (95%). However, the species escaped from the culture beds into the wild. Gradually the species could be found along the North Sea coasts; from the early 1990s also at the Belgian coast. "The specimen found is much larger than the largest individuals generally found on our coast. It can, counting the annual rings, be estimated as 25 years old. This dates back to about the year when the species was settled on our coast. We can speak of a "grandma-oyster" , says Jan Seys, marine biologist and spokesman of VLIZ. Generally, the Japanse oysters do not grow much bigger than 8-15 cm in our regions.

Most likely this specimen is the largest oyster shell ever recorded. In March 2014 the Dutch nature center Ecomare announced on its website a discovery of a 35.5 cm sized Japanese oyster by marine biologist Christine Dittlefsen in the Danish Wadden Sea, that has been taken up in the Guinness Book of Records. The animal was still alive and could be kept in the aqiuarium of the Danish Wadden visiting center Vadehavscentret, where it died last winter. 

In the mean time the Japanese oyster is a general species along our coast, growing on hard substrates in harbours, groyns, sluices, buoys, natural banks of molluscs ...) up to a depth of 15-40 meter. As a young oyster the animal attaches with its lower shell to a substrate to become up to 30 years old. Oysters can form large reefs, made up by oyster growing in between and on top of each other. They filter the water for food (microscopic plankton and other organic particles) at a high rate. One square meter of oysters can filter almost 700 liter of sea water an hour. The species needs a relatively mild climate to be able to reproduce: a minimum temperature of 18°C for at least 4 to weeks is necessary. Japanese oysters are transgenders: they start their life as a male, but become a female under certain temperature and food conditions. One female oyster can produces up to a 100 million eggs. These are disposed in the water to be fertilised.The mini larvae drift with the currents for 2-4 week. When they start to develop a little shell, they become too heavy and settle onto a hard substrate where they remain the rest of their lives.

Record oyster on display at the National Fisheries Museaum NAVIGO

The record holder can be seen from the 1st of September onwards till the 22th of November 2015 at the exposition “Oyster passion” in the NAVIGO museum in Oostduinkerke, Belgium.  

Press contacts

Contact discoverer: Marc Lechat (+35-269-19 29 999 -

Contact & info: Jadrana Demoen - Communication and education Musea Koksijde (+32-491-35 62 82 - )

Press relations B.AD: Koen Duyck (+32-51-79 00 43 - )


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