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Restoring oyster populations in Southern Brittany is about more than aquaculture. It is central to maintaining water quality, biodiversity, and long-term coastal resilience. Flat oysters, once abundant across the region, have nearly disappeared due to overfishing, disease, and changing environmental conditions. Their recovery depends on precise monitoring and informed management decisions.
REPARE Project Overview
Location: Morbihan region, South Brittany, France (Baie de Quiberon, rivers near La Trinité-sur-Mer)
Objective: Restoration of native flat oyster reefs and monitoring of table oysters.
Advances in subsea robotics and aerial imaging are now making this work more practical and effective. Remotely operated vehicles (ROVs) provide stable, diver-quality visuals in strong currents and turbid water, enabling teams to assess oyster health, track larval settlement, and detect predators without the risks of constant diver deployment. Combined with drone-based photogrammetry, these tools reduce labor, increase survey repeatability, and open new opportunities for data-driven restoration planning.
“Being able to carry out underwater inspections easily and at low cost, while still obtaining high-quality data,” was a central challenge in executing the project, which led to the use of robotics.
This project highlights how modern inspection technology not only simplifies demanding underwater work but also creates pathways for broader environmental monitoring, habitat protection, and sustainable aquaculture practices in marine ecosystems.
What is the Goal of Oyster Restoration in France?
The restoration project, REPARE, in southern Brittany focuses on reintroducing flat oysters (Ostrea edulis), a native species that nearly disappeared by the 1970s. This initiative is supported and funded by the Agence de l'eau and the Fond vert, and guided by historical research, including a 1906 habitat chart identifying former oyster beds - especially flat oysters beds in the Belon and Aven rivers. Conservation teams compare current seabed conditions with these historical records to select restoration sites. Some areas remain remarkably unchanged since the early 20th century, continuing to support natural fishing activity.
Background
- Flat oysters were nearly extinct by the 1970s. Current projects aim to restore natural reefs and track growth over a 10-year period.
- Two types of oysters are present:
- Table oysters: Raised above seabed, inspected primarily with aerial drones.
- Flat oysters: Native, seabed-dwelling, requiring in-water observation for restoration tracking.
Who Is Involved In The Oyster Restoration Project?
The project is led by the CRC Bretagne Sud, and Gilles Raibaut, a sworn officer with the Comité Régional de la Conchyliculture de Bretagne Sud (Regional Shellfish Farming Committee of Southern Brittany). The committee represents the interests of shellfish farmers across the region, covering oysters, clams, cockles, and mussels. Their responsibilities extend to resource management and environmental protection.
As Gilles explained, “I am a sworn officer, mainly responsible for monitoring farms and natural beds, conducting field inspections: water quality sampling, monitoring predation, monitoring oyster reproduction, assessing farm conditions, and carrying out inspections after accidental or weather-related damage (storms), etc. To perform my tasks, I use a boat, a paddle board, aerial drones (for aerial views + photogrammetry), and more recently, a Deep Trekker PHOTON ROV.”
His background as a police diver gives him a strong appreciation for the ROV’s stability and camera control, which are vital for precise assessments in restoration areas.
“As a former police diver, I can say piloting the ROV feels close to real diving. With the PHOTON ROV, I’ve found again some of the same sensations and reflexes I had as a diver (camera orientation during descent, depth stabilization, heading control) - the screen output is very similar to what a diver actually sees.”
Giuseppe Grassano, Sales & Marketing Director from Escadrone, supported the equipment sale and integration, ensuring the tools matched operational requirements. The project also benefits from knowledge-sharing across borders, including partnerships with restoration teams in Scotland, where whiskey distillers fund similar oyster recovery initiatives.
How is Technology Used to Monitor Oyster Farms?
Daily inspections are carried out using both ROVs and aerial drones:
- Flat oysters are monitored with ROVs for conservation tracking, predator detection, and habitat assessment.
- Table oysters are inspected using aerial drones and photogrammetry at low tide to map bed layouts and assess density.
The combination of boat-deployed ROVs and paddleboard-launched drones allows access to diverse environments while reducing diver risk.
Gilles emphasized the PHOTON ROV’s practical advantages, noting its “small size, quick and easy deployment, excellent video quality, and ability to take samples with the grabber.”
“Heading hold and depth stability are also impressive,” he added. “In one project, we placed rebar tables in the sea for oyster larvae to attach to. The ROV lets us check the baby oysters growing on the metal, circling around the tables and filming. It’s very stable.”
ROV Deployment for Oyster Farm Monitoring
As explained by Gilles, “The ROV was funded as part of a project to restore the European flat oyster, native to the Brittany coastline. It is used for underwater inspections, particularly in Quiberon Bay: the flat oyster still reproduces there naturally, and the area is one of the largest in Europe for deep-water oyster farming (flat and cupped oysters seeded on the seabed, then dredged).”
Capabilities Highlighted:
- Detailed observation of small reefs and camouflaged oysters.
- Captures still images and video for post-survey analysis at the office.
- Grabber claw allows for collection of oysters and starfish.
Gilles also noted, “Since I work alone on a small boat and sometimes on a paddle board, the compact size of the ROV is a major advantage for deployment. Farm depths range from 3 to about 15 meters.”
Workflow
- Historical charts used to locate natural oyster beds.
- GPS coordinates collected for survey points.
- Video and imagery captured at each point.
- Data shared with state agencies for long-term monitoring.
Gilles provided an example of a recent project:
“In Ria of Etel River, there was a project to reintroduce flat oysters in a channel. The state required us to establish a baseline before reintroducing oysters. So, in that part of the river, I recorded 4 GPS points spaced about 500 meters apart, and I filmed about 20 minutes of video around each point. I provided the videos on a shared drive to the state services. They asked us to repeat this over a 10-year period with regular checks. That’s why the ROV is useful - especially the video quality, which is impressive. The auto white balance colour correction is excellent, and the turbidity filter has been useful in winter when the water is not as clear.”
Gilles also highlighted an unexpected advantage, stating “The speed and ease of processing photos and videos is a huge benefit, making it possible to integrate them into inspection reports (environmental studies) and share them with government authorities easily.”
Can ROVs Detect Structural Damage Such As Net Holes Or Mooring Issues?
ROVs are used to assess the integrity of farm equipment by navigating along nets and moorings, capturing high-resolution video to identify tears, broken lines, or misalignments. The footage provides a permanent record for maintenance planning and trend analysis, reducing the need for divers in hazardous conditions while integrating smoothly with broader reef monitoring and photogrammetry surveys.
Capabilities:
- Ultra high-resolution video allows detection of small net tears, broken lines, and mooring misalignments.
- Video documentation supports maintenance planning and long-term monitoring records.
The ROV follows along net perimeters and mooring lines, capturing high-resolution video and stills at areas of concern. This approach reduces the need for divers in potentially hazardous conditions, provides a permanent record for trend analysis, and integrates seamlessly with other survey activities such as reef monitoring and photogrammetry.
Discover how Natural England uses ROVs to improve marine habitat monitoring, reduce costs, and improve marine protected area surveys across the UK coastline.
What Methods Are Used To Restore Flat Oyster Populations?
Restoration efforts follow a multi-step approach:
- Historical mapping - Using Joubin's 1906 map to pinpoint former oyster grounds.
- Seabed surveys - ROV inspections identify suitable habitat and confirm absence of eelgrass, which would indicate competitive ecological priorities.
- Larval monitoring - Water samples are collected starting in May with a pump to detect oyster larvae during spawning season.
- Habitat structures - Oyster growth structures are built from rebar and biodegradable materials to encourage settlement.
Photogrammetry and Bathymetry
Photogrammetry and bathymetry are used to map oyster reefs and seabed topography. High-quality ROV imagery supports measurements of reef growth and larval settlement, while bathymetric data helps assess substrate suitability and restoration success. This approach provides a stable, diver-like perspective for documentation and verifies growth on artificial substrates for reseeding efforts.
Conservation and Restoration Work
Conservation and restoration efforts focus on monitoring oyster spawning cycles and supporting larval settlement through careful sampling and reseeding practices.
“Flat oysters spawn larvae at the end of June to early July. I take regular water samples, filter them, and with a biologist from the research firm COCHET ENVIRONMENT, check under the microscope to see oyster larvae and assess the maturation of broodstock. Professionals then use collectors - plastic plates coated with lime - that larvae attach to. These are left in the water about 8 months before being harvested and reseeded. This requires regular monitoring. From May onwards, we pump water and check under the microscope for larvae. The pump filters about 2 cubic meters of water through a very fine mesh to collect only the larvae. The larvae need about 10 days to mature in the water. At first, they are not mobile, but after 8 days they can swim and attach themselves to rocks, metal, or the collectors placed in the water.”
What Impact Could Oyster Restoration Have On Local Ecosystems?
Reintroducing flat oysters can improve water filtration, enhance biodiversity, and stabilize seabed habitats. Over time, restored oyster beds may support commercial fishing, ecotourism, and improved coastal resilience against erosion. The integration of modern technology into these efforts increases efficiency, reduces diver exposure, and provides verifiable scientific data for long-term monitoring.
What Environmental Risks Are Associated With Oyster Aquaculture?
ROVs provide critical insights into risks such as predation, disease, and water quality fluctuations. Clear video allows operators to identify predators like starfish and oyster drills, as well as evaluate structural issues with nets and moorings. Combining drone and ROV observations accelerates detection and mitigation.
Gilles expanded further, explaining, “For the canal inspection project, the state also asked us to confirm that there was no seagrass (Zostera). With the video we could show there wasn’t any, which allowed reintroduction of flat oysters. There’s no direct link between oysters and seagrass, but seagrass is protected, so it was important to check.”
How Are Predators Like Starfish And Oyster Drills Controlled?
Predatory species, including seabream, starfish, and oyster drills, are a significant threat to both flat and table oyster stocks. The ROV’s high-quality camera, automatic white balance, and turbidity filter enable clear identification of these predators, even in murky summer waters. Samples of starfish are retrieved with the ROV’s grabber for further study.
How ROV Technology Is Helping Solve Real-World Underwater Inspection Challenges
The Southern Brittany oyster restoration project, REPARE, demonstrates how ROV technology is transforming marine habitat monitoring and coastal conservation. Using the Deep Trekker PHOTON ROV, restoration teams gain reliable underwater inspections to track oyster reproduction, assess larval settlement, monitor predators, and evaluate the impact of storms on farm infrastructure. This capability provides consistent, verifiable data for long-term restoration efforts while reducing diver risk and survey costs.
“I recommend this brand. It’s easy to use and durable, unlike cheaper, more fragile models with smartphone controllers and all-plastic construction,” Gilles emphasized.
By combining advanced subsea robotics with traditional aquaculture practices, the project sets a model for sustainable oyster farming, improved water quality, and stronger coastal ecosystems.
When you're ready to secure your very own Deep Trekker vehicle, contact us and we'll be happy to provide you with a customized quote tailored precisely to your requirements.
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