Our offshore wind project development activities are reviewed by multiple agencies and subject to protective conditions to ensure no adverse impacts to marine wildlife during the pre-construction, construction and operation of a wind farm, including:

• vessel speed restrictions
• time of year restrictions
• mandatory observers

Protecting marine life during offshore survey work

Just as you would survey the land and soil below before building a home, offshore wind developers survey the seafloor and geology below in lease areas and along proposed cable routes before building a wind farm. While conducting offshore survey operations, we take the following protective measures:

Vessel speeds

To reduce the risk of interaction with marine mammals and protected species, our survey vessels operate under a 10-knot speed restriction during transit and operations.

Observers on board

While conducting survey operations, all Ørsted-contracted survey vessels have trained observers onboard to watch for marine mammals and protected species 24 hours a day. Observers are equipped with visual technology, such as thermal imaging, that enhances detection ability, especially during periods of low visibility.

In compliance with regulations set by the National Marine Fisheries Service (NMFS), these observers actively look for whales, dolphins, other marine mammals, and protected species in the vicinity of the vessel and direct the vessel to conduct an array of mitigation measures, where appropriate, to prevent impacts. This can include a change of course or shutdown of the relevant sound sources.

All observations of marine mammals and protected species are tracked and recorded throughout our survey operations.

Types of offshore survey work

Prior to construction, offshore surveys using a variety of small nearshore and larger offshore vessels are conducted to acquire information for state and federal permits applications and shape project design. Benthic habitats important to marine life and archaeological resources important to indigenous people are mapped to minimize project impacts.

Two of the most common types of pre-construction survey activities are geophysical and geotechnical surveys. Both surveys require a permit and approval from federal and/or state agencies based on location.

Geophysical Surveys

High-Resolution Geophysical (HRG) surveys are conducted to map the seafloor, the geology beneath the seafloor, and to identify archaeological resources and debris left by other ocean users. Equipment used during these surveys includes both acoustic equipment using varying frequencies of sound and passive sensors that do not emit sound. The sensors are either hull-mounted or towed above the seafloor behind the vessel. During HRG survey operations, vessels typically move at a low speed, between 2-4 knots (3-5 mph) transiting along straight survey lines.

Only a few HRG sources used in offshore wind surveys operate at frequencies detectable to marine mammals. Federal agencies have determined that no injury to marine mammals or protected species is expected from these HRG sources as the sound has been shown to diminish rapidly with distance (BOEM 2018). The sources used in offshore wind that are detectable produce much lower energy and travel far shorter distances from the vessel than those used by oil & gas for exploration miles below the seafloor. The terms “seismic testing” and “seismic blasting” refer to powerful sound sources such as air guns used in oil & gas exploration and are not used in HRG offshore wind surveys.

Geotechnical Surveys

Geotechnical Site Investigations (GTSIs) collect data from the seafloor and up to 200 feet below to assess the mechanical behavior of soil and rock. Measurements of soil properties are taken, and physical soil and rock samples are collected for laboratory testing onshore. GTSIs do not produce any significant acoustic noise and therefore do not pose a risk to marine mammals (BOEM 2021). While undertaking GTSIs, the vessel remains stationary on-site.

Investing in partnerships and research to advance mitigation technologies

We’ve joined forces with environmental organizations and academia to advance noise reduction and habitat research. By investing in the use of marine mammal tracking software that calculates sightings in relation to our operations across multiple platforms and vessels, we’re helping to enhance situational awareness and aid observers in implementing mitigation measures. We’re also funding an innovative app called WhaleAlert that tracks rare whales and distributes information to mariners in real-time to help vessels avoid collisions.