Fisheries Areas Network

Good Practice Project

Better salinity and temperature data to improve flat oyster spat collection

The oyster farmers of south Brittany installed a high-frequency multi-sensing buoy to support the understanding of spat settlement of the flat oyster, a key resource in the area.


Oysters breed by releasing their eggs and sperm into the water, where fertilisation takes place. This creates tiny larvae, which after 2-3 weeks grow legs and ‘settle’ by attaching themselves to a solid surface, where they are known as ‘spat’. The oysters then stay put as they grow. In France, the two main flat oyster collection areas are Brest Bay and Quiberon Bay, both in Brittany. The wild oyster stocks, the main source of spat for breeding this species in captivity, are increasingly threatened by climate change and human action, which worsen water quality and give rise to large temperature fluctuations. Oyster spawning is becoming less predictable, which is making it harder to collect spat for cultivation.

Studies carried out locally by the national marine research institute Ifremer linked environmental conditions, such as temperature and salinity, to oyster spawning, which directly impacts spat settlement quality and quantity. Hence, the Regional Shellfish Farming Committee of South Brittany submitted a project proposal to install a high-frequency multi-sensing buoy to gather data on these parameters. This would allow them to analyse the changes in the oyster’s natural environment and work out the best time to collect the spat. This would in turn lead to more efficient spat collection and increased oyster production.

The Auray-Vannes FLAG played a key role by supporting the application for CLLD funding and coordinating the project partners. The buoy is one of the first devices of its type in France, but after its first contact with this new technology, the shellfish farming sector is already thinking of measuring additional parameters, such as chlorophyll and pollutants.


The buoy was installed in September 2018 in an oyster farm in Quiberon Bay. It has almost no environmental impact, as it floats above a seafloor already used for shellfish farming. The sensor measures the temperature and salinity of water every 20 minutes, and sends the data to an online platform twice a day. These data can be used by the whole shellfish farming community as well as the research institutes taking part in the project. They can be converted into graphics, which oyster farmers and researchers can use to develop models and improve their understanding of the environment.

Thirty months of data collection showed that the salinity of the sea falls after rain, when river flow increases. This information is being used by regional projects, such as FOREVER (Flat Oyster Recruitment and Growth), a three-year project funded under EMFF Aquaculture Innovation call to re-establish flat oyster stocks in Brittany.


To replicate this type of project, a good relationship between fish and shellfish farmers and researchers is needed. The data need to be useful for every partner involved in the project, as they will be in charge of maintaining the devices and analysing the data. The information collected can be used both to protect the environment and to improve the efficiency of production.

Lessons & contribution to CLLD objectives: 

Lessons: If the project is to have a real impact on the local community, long-term maintenance and data monitoring must be kept in mind. All stakeholders involved (shellfish farmers, scientific organisations and laboratories) need to agree on the procedure and on what data are to be collected. The location of the measurement devices is particularly important, to ensure the correct collection of relevant data, while minimising the impact on the environment.

Contribution to CLLD objective: (c) enhancing and capitalising on the environmental assets of the fisheries and aquaculture areas, including operations to mitigate climate change;


Total project cost €17 554
FLAG grant €17 554
  • EU contribution (EMFF): €8 777
  • Public contribution (national): €8 777
Beneficiary contribution €4 388

Project information

Timeframe of implementation From Mar 2018 to Dec 2021
Sea Basins
Type of area


Comité Régional Conchylicole de Bretagne Sud

Contact details

FLAG Contacts

Ms. Marion Mazodier
+33 2 22 76 03 59
Publication date: 
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