Protecting Our Marine Wildlife During Offshore Wind Surveys

We need offshore wind, and we need to do it right. Offshore wind will help eliminate dangerous greenhouse gas emissions, promising healthier air as well as thousands of well-paying clean energy jobs. But as we fight climate change, we can and must avoid, minimize, and mitigate threats that offshore wind development also poses to vulnerable ocean life.

Protections for our valuable marine wildlife are important at every stage of offshore wind development—from site assessment and characterization through construction and operations to decommissioning. 

A lot of attention is given to offshore wind construction, but site assessment and characterization activities can have serious impacts as well. Before offshore wind turbines can move forward, developers need to map the seabed using a “geophysical survey.” Geophysical surveys involve the collection of data using soundwaves (sonar) to create a map of the seafloor and geological layers beneath. Surveys help determine the characteristics of a specific area, such as water depth, sediment types, presence of archaeological sites, and potential hazards such as shipwrecks or other obtrusions. The resulting maps help offshore wind developers determine available options for cable routes, pile driving locations, mooring conditions, foundation type, and turbine layout.

Some of the soundwaves used in geophysical surveys overlap with frequencies for marine mammal hearing, meaning they can be detected by these animals. Noise exposure from geophysical surveys has the potential to damage the hearing and sensory abilities of some species if they are close to the source of the sound when it occurs. Disturbance from noise can also cause stress and negative health effects, and drive animals from preferred feeding and breeding areas or known migratory paths. Survey vessels traveling at fast speeds also pose a lethal risk of collision, particularly for large whales. Vessel collisions are one of the primary factors driving the North Atlantic right whale to extinction.

While individual geophysical surveys occur in relatively small areas, there are many of these surveys taking place—and the cumulative effects of these multiple surveys quickly adds up. As of December 2021, NOAA Fisheries had issued nearly 30 permits for offshore wind geophysical surveys off the East Coast, allowing 6,300 total survey-days of geophysical activity. NOAA Fisheries anticipates more than 109,000 singular events of harassment for marine mammals during these surveys. Of these events, NOAA Fisheries authorized the critically endangered North Atlantic right whale to be harassed 243 times, and harbor porpoises—a species particularly susceptible to hearing damage from geophysical surveys—nearly 8,500 times. Each new offshore wind project that advances brings the potential for additional harassment activities.

NOAA Fisheries and the Bureau of Ocean Energy Management (BOEM) are required by law to protect marine mammals from any adverse impacts posed by the surveys to the full extent practicable. To do this, the agencies should follow the principles of the mitigation hierarchy and avoid, minimize, and mitigate impacts. Proven mitigation measures must be used to reduce impacts, including restricting vessel speeds to 10 knots or less to reduce the likelihood of vessel collisions, and new technologies to detect marine mammals and reduce noise emitted by the survey equipment should be used as they become available. The permitting process should be adaptable to reduce risks that may be identified in the future as more information on species and offshore wind development is available.

To advise NOAA Fisheries and BOEM on the necessary protections for marine mammals, a number of environmental organizations including NRDC developed a set of mitigation measures based on best available scientific information that are needed to ensure offshore wind advances responsibly. Given the precarious status of the North Atlantic right whale, these measures are tailored to ensure responsible offshore wind development brings the protections necessary to allow these whales to feed and migrate undisturbed.

We recommend the following types of measures:

• Seasonal and temporal restrictions: surveys are to be avoided in essential habitat areas year-round or, for migratory species, during months of high use. Surveys must only start up during times of good visibility (e.g., daylight, clear weather conditions) when marine mammal presence can be sufficiently monitored.
• Observation and detection: before and during noise-producing activities, visual observers and passive acoustic monitors should both be used to look and listen for marine mammals and activate a shutdown of activities if a marine mammal is detected within a predetermined exclusion zone. Thermal detection cameras should also be used for activities extending into darkness or low-light periods.
• Vessel speed limits: vessels must maintain speeds of 10 knots or less at all times to reduce the risk and severity of collision during surveys or transiting to and from survey areas.

These fundamental requirements are necessary to protect the critically endangered North Atlantic right whale from potential impacts posed by offshore wind energy site assessment and characterization work. Many of these measures offer important benefits to other marine mammal species and sea turtles.

For offshore wind to succeed over the long term, it must be paired with smart protections for the ocean life we rely on. These recommendations help us secure the clean energy we need, while safeguarding the ocean wildlife we love. We urge NOAA Fisheries and BOEM to require these mitigation measures as the standard for offshore wind geophysical surveys off the East Coast and to develop similar measures for offshore wind development in the Gulf of Mexico and off the West Coast.