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Accompanying measures

The wind farm off the Bay of Saint-Brieuc, carried by Ailes Marines, obtained on 18 April 2017, from the Prefecture of Côtes-d'Armor, the administrative authorisation known as "Autorisation Unique IOTA" under the provisions of Articles L.214-1 et seq. of the Environment Code.

This authorisation prescribes several measures for monitoring, reducing, compensating or accompanying the environment. The accompanying measures are part of a more global strategy and aim to improve the efficiency of the compensatory measures.

Monitoring of marine mammals by photo-identification

During construction:

Habitat loss/change
Risk of mortality/injury due to noise (threshing)
Disturbance due to vessels and noise
Risk of collision with vessels

During operation:

Negligible impacts

The objective is to contribute to the knowledge of marine mammals in GNB by contributing to the catalogue currently being compiled by the GECC. This measure therefore includes outings financed by Ailes Marines.
Two species are targeted by this measure: the bottlenose dolphin and the Risso's dolphin.

The bottlenose dolphin

Risso's dolphin

The objective is therefore to participate in the enrichment of the photo identification catalogue of bottlenose dolphin individuals present in the GNB, and to participate in the creation of this catalogue for Risso's dolphins. This method thus allows the acquisition of precious information relative to the fidelity to a site, the areas of movement and living space, the periods of frequentation, the individual relationships, the life cycle and the ecology of the species in the broad sense.

A letter of intent from the GECC has been issued for the implementation of this measure. Discussions will be held with this organization in 2022 to prepare for the implementation of this measure.


Location of the GECC's area of action

Planning and Status

Measure under development

Three follow-up sessions will be organized:

  • 2023-2024 2% 2%
  • 2027-2028 0% 0%
  • 2032-2033 0% 0%

Study of the impact of noise on the fisheries resource

During construction:

Crushing (presence of piles and protections, anchoring of ships and the laying and protection of cables)
Resuspension of sedimentary particles and their deposition
Noise and vibration nuisance

During operation:

Habitat modification
Reef effect

This accompanying measure focuses on assessing the impact of noise on various species emblematic of the fishery resource of interest in Baie de Saint-Brieuc: scallop, prairie, lobster and cuttlefish. Knowledge of the impact of sound on invertebrates and crustaceans at different stages of their development is still very incomplete.

This study in a controlled environment (laboratory) but also natural for the case of the scallop, aims to better understand the effects of noise on these organisms (such as lobster) and to subject certain species to pile driving and drilling sounds of various intensities (to simulate a gradient in distance between the individual and the noise source). This pioneering study brought together a college of international scientists at the forefront of underwater bioacoustics research (CNRS, LEMAR, MNHN, BeBEST and the Polytechnic University of Catalonia) and the contribution of CDPMEM 22.

This study is divided into two subparts, one dealing with cuttlefish (SONSETC project led by Michel André) and the second with the other species studied (IMPAIC project led by Laurent Chauvaud).

These two studies will be the subject of several scientific publications in international journals. All the results will be presented publicly once the scientific articles have been submitted. All the preliminary results have been presented to the fisheries committees as well as to the State services.

the scallop


the prairie



Illustration of an experimental device allowing the exposure of individuals to a known sound environment.

Planning and Status


Measure put in place

  • IMPAIC study 85% 85%

The IMPAIC study started in December 2018 and will be completed by the end of 2020. Three preliminary oral restitutions have been organised, in the presence of the State Services and representatives of the professional fishing industry, between 2019 and 2020.

  • SONSETC study 100% 100%

The SONSETC study began in March 2019 and was completed in February 2020. An oral presentation was held in May 2020 before the State Services and representatives of the professional fishing industry.

Participation in the management of marine protected areas

Measure MS22 is presented in the IOTA authorisation in Article 24. It is stipulated:
"Independently of the financing of the ERCA regulatory measures listed in articles 21 to 23 of this decree, and in order to compensate for the loss of bird and marine mammal habitats, the project owner contributes financially to the management of existing or future protected areas, whether or not contiguous to the zone, but close and functional for the species in question.
The amount of this contribution represents the financing of a full-time position of project manager at least at technician level, over a period of 40 years. This point will be the subject of subsequent agreements between the project owner and the actors concerned (State, public institutions, local authorities, etc.), in association with the management and monitoring committee. »

The aim will be to target actions for the protection of the bird and marine mammal species concerned by the request for derogation protected species.

The modalities of implementation of this measure are currently being discussed between Ailes Marines, DDTM 22 and the OFB. The aim is to reach an agreement before the end of the year.

The following points in particular were discussed:

  • Lead agency for the measure
  • Calls for projects for 3-5 years, with specifications and selection committee
  • Type of projects that could be funded : The area(s) chosen or the project(s) selected must be the result of collective decisions, involving the State services and Ailes Marines. No single MPA should be selected for the entire duration of the measure.
  • The actions may focus on mapping, site restoration, or studies on marine mammals or birds, with a view to improving knowledge. They may also involve the financing of a post of project manager or the purchase of equipment to carry out studies.
protection-watersheds map

Several areas are currently under consideration, including the Natura 2000 areas shown in the figure above.

Planning and Status

Measure under development

The measure is intended to be implemented over the entire operating life of the wind farm off the Bay of Saint-Brieuc.

Turbidity modeling in the work phase

During construction:

Modification of water quality
Disturbance of halieutic and benthic species
Disruption of uses
Modification of water column transparency

The AU-IOTA prescribes that prior to the start of work on the foundations, the project owner must model the dispersion of suspended matter and assess their impact on the fish resource.
The project owner submits a report to the management and monitoring committee for its opinion:


Modelling results and impacts on the fisheries resource

The conditions and procedures for carrying out the work

The conditions for carrying out follow-up and monitoring measures

The alert and critical thresholds for carrying out the work

In order to assess the influence of drilling work for a tailings discharge close to the bottom or surface, a three-dimensional hydrodynamic and sediment modeling system was set up, calibrated and validated by comparison with the measurements acquired by Ailes Marines in the siting area (Actimar, 2019). It can then be used to represent the variation of the various parameters (current, turbidity, deposition) over the entire water column and to estimate the influence of the vertical position of the discharge on the dispersion of sediments at sea, which is necessary to identify the conditions of least impact with regard to environmental preservation.

In line with previous studies carried out by Actimar on the same subject, the assumptions on drilling scenarios have been considerably refined for greater realism. In particular, as the work technique depends on the vertical structure of the nature of the seabed, this has been taken into account based on coring and granulometric analyses in order to reproduce, as realistically as possible, the volumes of material discharged at sea and the phasing of operations within the modelling system.

The study led by Actimar also focused on assessing the natural variability of in situ turbidity and the impact of the work on the local fisheries resource. In fine, these studies led to the proposal of thresholds and a turbidity monitoring programme during the work phase. The thresholds and the monitoring methodology were the subject of a prefectoral decree.


Planning and Status

Finalized measure

The modeling was carried out and presented to the Management and Monitoring Committee.

Noise reduction during the construction phase

The construction phase will induce a significant noise level due to the pile driving of 34 foundations. Today, systems to reduce the propagation of underwater acoustic waves are implemented when site conditions allow (bubble curtains for example, Hydro Sound Damper, cofferdam...).

Ailes Marines will follow the requirements for testing a noise reduction system during pile-driving operations on 2 foundations.

Special site conditions require the development of a specific system. The implementation of the system will be carried out on two rammed foundations. Several hydrophones will be installed at different distances to evaluate the effectiveness of the system in the specific oceanographic conditions of the Bay of Saint-Brieuc.

In accordance with the AU-IOTA, the measures will be tested and validated within 2 years from the start of the installation work.

bubble curtain

Photo trianel-borkum

bubble curtain diagram

Windfarmbase diagram

At the same time, and in the logic of reducing the impact linked to pile-driving noise as presented in the AU-IOTA, Ailes Marines is working to reduce noise during the construction phase by reducing the number of piles driven in favour of drilling at a lower intensity.

The technical studies are in progress and Ailes Marines will present to the local authorities and the CGS the measures that may have been taken to reduce noise pollution and the impact of noise.

Experimenting with a collision avoidance system for birdlife

During operation:

Risk of Collision
Habitat Loss / Modification

This accompanying measure concerns the testing of a system to avoid bird collisions with the blades of operating wind turbines. The system consists of a network of cameras, which detect the trajectories of different categories of birds, connected to a sound scaring system, which is activated once a bird enters a risky perimeter around the turbine rotor. Various systems are available on the market and have been operational for a number of years on onshore wind farms. Marine-based versions adapted to offshore sea conditions are currently being developed, however they do not benefit from as much feedback as their onshore counterparts. For this reason, the choice of system has not been fixed in the prefectoral authorization decrees.

This measure aims to test an existing system, at a rate of 3 devices each attached to a wind turbine, distributed at the south and north ends as well as in the centre of the wind farm (see figure below).

Ailes Marines has approached potential suppliers and a call for tenders will be issued shortly.


wildlife escape map

The three devices will be distributed along a north/south axis. Wind turbines n°57, 31 and 3 are currently preferred, subject to technical validation.

Planning and Status

Measure under development

The follow-up will begin when the wind turbines are commissioned for a period of two years during the operating phase of the wind farm, i.e. in 2024 and 2025.

definition and implementation of a tourist offer in conjunction with the stakeholders in the area

During construction:

Gradual change in landscape perception
Opportunity to build a new tourism, based on the values of the territory and people

During operation:

New identity for the territory
Supporting tourism stakeholders in an "all-weather offer"
Participating in a better opening up of the hinterland and a networking of tourism service providers
Enriching the tourism offer, making it more dynamic and revealing it
Showcase for innovative territory

The measure concerns the commitments made by Ailes Marines in response to the French government's call for tenders No. 2011/S 126-208873 to develop a wind power project off the coast of Saint-Brieuc and the administrative authorisations for the offshore wind power project, obtained in December 2017.

Tourism being the second sector of economic activity in the Côtes-d'Armor department, the question of the insertion of the offshore wind farm in the department's tourist offer was raised. Ailes Marines is committed to promoting the attractiveness of the department and the integration of the wind farm project into the tourist offer of the territory.

Ailes Marines approached the Côtes-d'Armor Departmental Tourism Committee (now CAD) and signed a first agreement with the organisation on 01 October 2015, renewed by endorsements on 28 June 2017. A second agreement was signed on 18/07/2019 in order to continue the study aimed at integrating the offshore wind farm in the bay of Saint-Brieuc into the current tourist offer of the Côtes-d'Armor.

By highlighting the landscapes of the east and west coasts of the Bay of Saint-Brieuc, through the proposal of a high added value itinerary based on the GR 34 (Customs Trail), the tourism project aims at a global approach of the territory by facilitating the practice of itinerant stays (GR furniture, gourmet stops, unusual nights) and by creating new viewpoints over the bay (artistic belvederes), suggesting to visitors a new angle of view on the territory and integrating places of mediation related to the offshore wind farm (information panels).

The tourism project linked to the offshore wind project is based on the GR34 (sentier des Douaniers) which runs along the Bay of Saint-Brieuc on the east and west sides.

Planning and Status

Measure under development

The programme of the tourism project will be implemented from 2020 to 2024 after approval by all stakeholders.