Reduction measures

The wind farm off the coast of Saint-Brieuc Bay, supported by Ailes Marines , obtained on April 18, 2017, from the Prefecture of Côtes-d'Armor, the administrative authorization known as "Single IOTA Authorization" under the provisions of the articles L.214-1 et seq. of the Environmental Code.

This authorization prescribes several environmental monitoring, reduction, compensation or support measures. The aim of the reduction measures is to limit the negative impacts of the project on the environment. They may attempt to reduce its duration, extent or intensity.

Reduction measures in favor of marine mammals during the construction phase

During construction:

Actual habitat loss due to avoidance
Disturbance from boat noise
Masking of communications due to noise
Risk of mortality/injury from noise

In order to respond to AU IOTA reduction measures 1 and 2, a Marine Mammal Mitigation Plan (MMMP) has been prepared by Ailes Marines . This plan will be deployed during the construction phase during piling operations and includes:

  • Visual detection by on-board observers (MMOs);
  • Acoustic detection by passive acoustic monitoring (PAM) operators;
  • Installation of acoustic deterrent devices to keep marine mammals (pingers) away;
  • Progressive start of threshing activities (soft-start).

The primary objective of the MMMP is to prevent hearing injuries to marine mammals near piling activities. This plan was included in the wind turbine installation contract and will be followed by the contractor during piling operations.

Procedure details:

Schedule and Status

Measure under development

Between 2021 and 2022, and only during piling activities during the construction phase.

Reduction in the disturbance of the Balearic shearwater during periods of internuptial presence

During construction:

Habitat loss/modification
Disturbance from ships
Risk of collision with ships

During operation:

Risk of collision
Loss / Modification of habitat

The objective of the measure is to inform site personnel to enable the avoidance of shearwater rafts by personnel transfer vessels (CTV) during work at sea and to raise public awareness.

This measure targeted departures from Saint-Quay-Portrieux (initial port of the construction phase), because the impact study had highlighted that rafts of shearwaters were present between this port and the construction area at sea. However, the location of the port has evolved and it will be located in Lézardrieux. Rafts of shearwaters are no longer found on shipping routes and the risk of encountering them is now negligible, thereby reducing the incidence identified in the impact study. The measure was therefore adapted to meet new needs.

The measure has a double scope:

Awareness-raising operations will be organized in two coastal communities to the east and west of the bay of Saint-Brieuc.

Schedule and Status

Measure under development


  • Awareness program for the construction phase 1% 1%


  • Raising awareness among the public and sea users 1% 1%

Reduction of photoattraction under construction

The impact study highlighted that certain species of birds in flight were more sensitive to light than others. In the absence of mitigation measures, the potential effects of light attraction were rated as medium for petrels and shearwaters and weak to negligible for other bird species. Although limited information is available regarding their (migratory) behavior.

This measure aims to reduce the impact of lights on ships during the work phase.

In accordance with the conditions attached to the IOTA AU, the effects of light attraction can and must be mitigated:

These requirements have been transcribed into the specifications of the works companies which will have to follow these obligations.

The first feedback from construction companies during the analysis of the offers shows that generally speaking, each vessel participating in the project will be equipped with all the external lights necessary to carry out its night operations, namely:

Navigation lights, in compliance with international regulations, classification and flag administration rules (either oriented horizontally (parallel to sea level), with prescribed angular sectors);

Signaling lights intended to warn aircraft and helicopters landing, in accordance with international aviation rules and regulations (pointed towards the sky, but only used when necessary);

Searchlights for search and rescue operations and passage through canals (the orientation is variable but these are only used in emergencies);


Floodlights for launching rescue equipment and boarding, in the event of emergency abandonment of the vessel, always oriented downwards and towards the boat systems, as well as the sea which directly surrounds it. here, in case of need;

Common deck lights to enable personnel to move around safely (pointing downward);

Floodlights to illuminate the work area, ensuring the operational safety of the project.

These first returns demonstrate that most lighting, unless prescribed by regulations or specific needs (in particular to ensure the safety of flight and working personnel) will be oriented downwards.

On construction ships.

Schedule and Status

Measure under development

This measure is planned for the entire duration of the construction phase.