PROVINCETOWN, MA – Beneath the rolling Atlantic, a silent crisis brews as the hammering sounds of offshore wind farm construction clash with the delicate acoustic world of the North Atlantic right whale.
A study entitled “Impacts of Noise from Wind Farm Construction and Installation on Large Whales A Brief Summary” by Karen Stamieszkin of the Provincetown Center for Coastal Studies shows how offshore wind surveying, construction, and operations negatively impacts marine mammals.
These rare whales, along with humpbacks, fins, and minkes, rely on low-frequency calls to navigate, forage, and communicate across vast stretches of ocean.
But the pounding of steel monopiles into the seafloor—sometimes reaching sound levels above 200 decibels—may drown out or even damage the hearing of these marine giants.
Key Points
- Offshore wind turbine construction can generate underwater noise above 200 decibels, within the right whale’s vocal range.
- Sound exposure from pile-driving may trigger behavioral changes up to 20 km away and cause injury at close range.
- Operational turbines emit lower, continuous vibrations that may disrupt whale communication but are less likely to cause harm.
Four zones of impact define whale risk
Researchers classify noise exposure into four distinct “zones”: audibility, responsiveness, masking, and injury. While the first marks the faintest detectable sound, the latter three can trigger behavioral disruption or physical harm—legally defined as “harassment” under federal protection laws. Injury thresholds for cetaceans begin around 180 decibels, but studies suggest even lower levels may cause temporary hearing loss.
Ambient ocean noise already fluctuates naturally due to wind, waves, and distant shipping traffic. When human activity—such as pile-driving or dredging—is added, total background sound can rise significantly, particularly in the 100 to 1000 Hz range that overlaps with right whale calls.
Construction creates the loudest threats
The greatest danger occurs during the installation of turbine bases. Pile-driving a single steel monopile can last several hours, with impacts occurring once per second. Recordings show source levels over 200 decibels at one meter, concentrated at frequencies between 100 and 1000 Hz—directly within right whale communication bandwidth.
Studies of related species, such as bowhead whales, reveal avoidance behavior beginning at roughly 120 decibels, extending 20 kilometers from noise sources. That distance suggests a wide acoustic disturbance zone for wind farm construction sites.
Operational noise raises long-term concerns
Once turbines are operational, sound levels drop considerably but remain persistent. Vibrations from rotating blades and internal machinery travel through air, steel, and seafloor sediments into the water. These noises, often between 16 and 400 Hz, may alter whale behavior over several kilometers, particularly in quiet coastal zones.
Although no studies have directly linked operational turbine sound to injury, the overlap between these frequencies and whale vocalizations raises concern over long-term masking effects that could impede communication or mating calls.
Calls for stricter timing and monitoring
Marine scientists recommend strict seasonal restrictions on turbine construction and decommissioning, limiting noise exposure during migration or calving periods. While operational noise remains less intense, cumulative impacts over time remain uncertain—especially as offshore wind development expands along the U.S. East Coast.
Regulators face the complex challenge of balancing renewable energy goals with the survival of a critically endangered species whose population numbers fewer than 400. For the North Atlantic right whale, every decibel may count.
Under former President, Joe Bidem, the NOAAA downplayed the impact offshore wind has on whales, first denying that any of the recent whale strandings and deaths were the result of the industry, but saying that offshore wind developers are permitted to harass marine mammals to a certain degree.
“At this point, there is no scientific evidence that noise resulting from offshore wind site characterization surveys could potentially cause whale deaths. There are no known links between large whale deaths and ongoing offshore wind activities,” NOAA said. “Offshore wind developers conduct high resolution geophysical surveys to image the ocean bottom. The noises these surveys produce may disturb marine mammals. This is why offshore wind operators have requested Incidental Harassment Authorizations to allow for Level B harassment. This includes actions that could disturb, but not injure or kill, a marine mammal by disrupting behavioral patterns, including migration, breathing, nursing, breeding, feeding, or sheltering.”
The NOAA also downplayed the impact on seismic surveys on the marine mammal population.
“The sound from these high resolution geophysical surveys are very different from seismic airguns used in oil and gas surveys or tactical military sonar. They produce much smaller impact zones because, in general, they have lower noise, higher frequency, and narrower beam-width,” NOAA said. “The area within which these sounds might disturb a marine mammal’s behavior is orders of magnitude smaller than the impact areas for seismic airguns or military sonar. Any marine mammal exposure to sound from these surveys would be at significantly lower levels and shorter duration, which is associated with less severe impacts to marine mammals.”