Have OSW sonar surveys caused many whales to die and wash up on Atlantic beaches?
At a Glance:
You may have heard that offshore wind sonar surveys may be a cause of increased occurrence of whale deaths. NOAA has declared the increases in deaths of humpback, minke, and North Atlantic right whales beginning around 2016–2017 as Unusual Mortality Events (UMEs) starting in 2016 and they continue. OSW opponents are focusing on the humpback UME given their high charisma factor and the fact that many of the strandings have occurred in the mid-Atlantic, especially New York and New Jersey. There is absolutely no scientific evidence for any link between the humpback UME and the wind farm surveys. The actual cause of the humpback UME is a combination of factors causing more whales to get hit by ships or drown in fishing gear (the same causes that killed whales before the UME began)—an increase in shipping traffic, more whales present in the mid-Atlantic, increases in the stocks of fish that the whales feed on, and broad ecosystem changes due to warmer oceans.
It should be noted that the offshore wind survey equipment is much less powerful than what the oil industry uses.
A Deeper Dive:
This NPR podcast is an interview with Professor Andy Read, the director of Duke University’s Marine Lab. Professor Read states, “There is no evidence linking offshore wind development to the deaths of any whales along the east coast.”
https://thepublicsradio.org/episode/theres-no-evidence-offshore-wind-kills-whales
The UME deaths have been primarily humpback whales which have a global population of about 140,000 and are not considered as threatened. That global population recovered from as few as 5000 in 1960. The humpback whale UME which has been much in the recent news began in 2016. BOEM authorized Orsted to begin survey work on Ocean Wind off the New Jersey Coast in May 2018 and authorized US Wind to begin survey work in March 2018, two years after the Unusual Mortality Event commenced. Atlantic Shores was authorized to begin surveys after April 2021.
OSW surveys are correctly described as “sonar surveys” which are high resolution geophysical (HRG) surveys that produce sounds to obtain images of the seafloor and shallow geophysical features. You may have seen them mislabeled in the news and on social media as “seismic surveys”, which are very much louder sound sources used for oil and gas exploration to locate fuels that lie deep down in the layers of bedrock. The sound sources used in the HRG surveys can cause behavioral disturbance, or possibly minor injury if a whale was really close (sometimes less than its own body length), but never serious injury or death. In fact, the sounds produced by a large ship passing by or even a singing blue whale are louder than some HRG sources and are commonly encountered by whales.
There are many anti-offshore wind groups in every state from Maine southward along the coast. Many were created in the last year and routinely suggest that for every whale death, it is probably offshore wind activities that caused the death and cast doubt on NOAA reports. These suggestions of offshore wind causing whale mortalities are neither factually accurate nor evidence based. There are corporate and political groups that are opposed to renewable energy supporting anti offshore wind as documented in other sections of this website.
Understanding Complexities:
These are some excellent sources for further reading on this topic:
Figure 1. Comparing the hearing capabilities of marine animals to underwater sounds created by humans: The top panel shows the hearing ranges of seven different classes of marine animals from low infrasonic (1 Hertz) to high ultrasonic (1 megaHertz) on a logarithmic scale (where each number on the scale is 10 times higher than the one before). For comparison, the hearing range of humans is about 20 Hz (0.02 kHz) to 20 kHz. The bottom panel shows the ranges for sixteen sources of anthropogenic noise, arranged from quietest at the bottom (an operating wind turbine) to loudest at the top. Each bar shows the range of frequencies produced by that source. The four noise sources in the purple boxes are those used in high-resolution geophysical surveys to study potential offshore wind sites. The two off to the right are above the upper end of the hearing range (and far above the most sensitive range) of low-frequency cetaceans. All the baleen whales, like humpback, right, fin, and minke whales, cannot hear them at all. The two sources in the yellow boxes are the much louder sources that offshore wind opponents are trying to mislead you into thinking are being used. “Air guns” are used in the “seismic” surveys by fossil fuel companies in searching for oil and gas reserves buried deep in the bedrock. (Source: Bureau of Ocean Energy Management, Center for Marine Acoustics).