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How would the proposed Humboldt offshore wind project affect whales and other marine mammals?

Although there is currently a lot of misinformation (1) circulating about the impacts of offshore wind to marine mammals, there has yet to be a documented case (2) of a marine mammal being harmed by activities associated with an offshore wind project in the United States. Early reports of potential fatalities from fixed-bottom offshore wind turbines on the East Coast were later determined to be primarily caused by ship strikes (3) associated with other existing ocean industries, and not caused by the wind industry (4).

Humpback whale (Megaptera novaeangliae) tail flip.

Humpback whale (Megaptera novaeangliae) tail flip.

Source: Jim Harper via Wikipedia (CC BY-SA 1.0) (x)

That being said, there are some potential impacts from offshore wind on marine mammals that need to be considered and addressed. These potential impacts are discussed below. It is important to note that many of the potential threats to whales associated with offshore wind turbines already exist to some degree due to current ocean activities; therefore, solutions need to be implemented for all industries. Despite these potential impacts, some whale scientists are cautiously optimistic (5) about offshore wind turbines as an effective form of renewable energy, as they see climate change as one of the greatest threats to whales. To take just one example, scientists believe that warming ocean temperatures could significantly reduce the amount of breeding habitat (6) available to humpback whales. To learn more about potential impacts to whales on the East Coast, where one offshore wind energy project has been operating (7) since 2016, visit this New York State Environmental Technical Working Group website (8).

Potential impacts of offshore wind energy development and operation on whales, seals, and other marine mammals include injury due to physical interactions with associated vessel traffic, entanglement, response to increased underwater noise, displacement from foraging or migratory habitat, and impacts associated with port development and expansion.  The potential impacts on different species will vary depending on the location and operation status of OSW development and operation components.  For example, offshore wind turbine site development, operation, and maintenance activities will potentially affect different marine mammals, including large migrating whales.  The development and construction of OSW infrastructure in nearshore and bay environments (9) may affect locally resident nearshore species like harbor seals, harbor porpoises, and seasonally abundant marine mammals like sea lions and migrating gray whales. Considering the site-specific potential impacts is particularly important in Humboldt Bay where significant port development is proposed (9).  The following is a discussion of some potential impacts from OSW development.

Vessel Strikes

Potential vessel strikes (10) associated with increased vessel traffic in support of turbine construction and maintenance are likely one of the largest threats to whales and other marine mammals from Humboldt’s proposed offshore wind project. Anytime vessels are moving through the ocean, there is a risk of potential collisions with marine mammals. To mitigate these risks, we must know more about the distribution and abundance of marine mammals using the areas targeted for offshore wind development. This is a critical step to mitigating potential harm.  In addition, the California Coastal Commission has set a 10-knot speed limit (11) for all ships associated with offshore wind, and is requiring all vessels to have trained “protected species observers” to monitor for whales and other at-risk species. These precautions are more stringent than those placed on fishing and shipping vessels currently operating off the coast of Humboldt. Listen to this informative report on the “Complicated Truths About Offshore Wind and Right Whales” (5) by the Science Friday team.

Entanglement

Entanglement (12) occurs when a marine mammal gets wrapped up or trapped in some kind of manufactured object and is either injured, cannot swim normally because movement is restricted, or becomes malnourished as a result. This is often the result of entanglement in fishing gear (13) and is one of the leading causes of whale deaths off the California coast. The risk of direct entanglement (14) in offshore wind tethering and transmission cables is considered low because the cables are approximately 8 to 11 inches in diameter (15) (about the size of a dinner plate) and are large and obvious enough for whales and other marine mammals to avoid. The tethering cables will also be

A humpback whale entangled in fishing gear.

A humpback whale entangled in fishing gear.

Source: E. Lyman / HWS and NOAA (x)

taut or semi-taut to keep the floating wind turbines from moving around too much, which further reduces the risk of direct entanglement. If the export transmission cables are buried, most marine mammals are unlikely to come into contact with them on the seafloor. One exception might be gray whales, which feed on invertebrates living in mud in shallower waters (up to 50 meters deep).

However, there is a risk of secondary entanglement (16), in which whales and other marine mammals could become entangled in fishing gear or trash that gets caught on offshore wind mooring cables. Solutions to this problem include requiring offshore wind operators to use sensors (17) to monitor for marine debris near wind turbines and cables (and removing it when possible), alternative fishing gear (18) that is safer for marine mammals, and other technology that is in development.

Noise

Noise (19) produced by human activity in the ocean can make it difficult for marine mammals to detect important sounds like calls from other whales (masking), can cause marine mammals to avoid noisy areas which could reduce their foraging success or, in rare cases, may cause physical harm (20).  The world's oceans are getting noisier every day (21) with increased sounds created by ships, seismic surveys, echolocators, and offshore gas and exploration. Increased sound production associated with offshore wind energy activities during exploration, infrastructure construction, operation, and maintenance of offshore wind farms may impact marine mammals.  The federal government has developed strict rules (19) surrounding surveying techniques used in the exploration and monitoring phases of OWE operations to protect marine mammals.

PSB_Soundscape_Infographic_03312021.jpg

The marine soundscape.

Source: NOAA Fisheries (x)

 Off Humboldt Bay, RWE (20) conducted the first site assessment surveys (21) in the summer 2024, using very low intensity survey equipment — below what federal government thresholds.  Protected species observers were on board to monitor marine mammal response to activities.

Electromagnetic Fields

Another potential impact to marine mammals come from electromagnetic fields (EMFs) (22) that are produced by all cables and wires carrying electric current. Cables associated with transmitting energy from the turbines to shore will emit EMFs, but it is thought that the impact will be minimal. Common household appliances, including TVs, hair dryers, and electric drills, can emit EMFs similar to or higher in intensity (23) than those emitted by offshore wind cables. EMF emissions are reduced in some offshore wind energy operations  by burying them under the seafloor thereby decreasing the intensity of the EMFs. Research is ongoing into the effects of EMFs on marine mammals and other wildlife, but early indications (24) are that the impact may be negligible.​

Species of Local Interest & Concern

Much of the concern surrounding the potential impacts of offshore wind energy on marine mammals has been focused on whales in the offshore waters where turbines will operate. However, whales, seals, and sea lions depend on near and inshore waters to migrate, forage, rest, and breed. For example, in the Humboldt Bay area, gray whales depend on these waters to both migrate and summer, while harbor porpoises and harbor seals are year-round residents that depend on the near and inshore waters. We’ll identify a few species of local interest and concern.

Marine mammals in and around the nearshore waters of Humboldt Bay will likely be

exposed to disturbance from increased vessel traffic.  The increased potential of vessel

collision and increased sound production may impact the movement and habitat use of

gray whales. Twenty thousand Eastern North Pacific gray whales migrate along the

coastline from breeding grounds in Baja to summer feeding grounds in Alaska.

Approximately 200-300 whales, however,  forage between Northern California and

British Columbia from the beginning of June to the end of November. These Pacific

Coast Feeding Group (PCFG) whales use baleen to filter both sediment from the seafloor

and seawater to gather a variety of benthic, epibenthic, and pelagic invertebrates such

as crab and shrimp larvae, olive snails, and marine worms. They are mostly found in

nearshore waters up to 50 meters in depth and have even been seen foraging in

Humboldt Bay. Surveys and construction along the cable routes in State waters could

impact these whales, along with increased vessel traffic during surveys, construction, and maintenance of the wind turbines and inshore infrastructure construction.  An understanding of baseline abundance and habitat use of gray whales will assist in informing management decisions to mitigate potential harm to these whales.

noaa_close_up_rs6337_gray_whale_breaching.jpg

Gray whale (Eschrichtius robustus). 

Source: Washington Department of Fish & Wildlife (x)

Harbor porpoises (25) are locally resident small marine mammals that reside in nearshore waters.  These animals are cryptic and travel in small quiet schools in and around Humboldt Bay. They are vulnerable to entanglements and extremely sensitive to human disturbance - particularly to underwater noise. Little is known about the behavior and ecology of the local population of harbor porpoises. Early identification of critical habitat and behavior is essential to mitigate potential impacts (26) on this population.

fced115bf7e846c28b4568cb3256e453.webp

Pacific harbor porpoise (Phocoena phocoena vomerina). 

Source: madfox [CC BY-NC 4.0] (x)

Harbor seals (27) are the most abundant marine mammal in Humboldt Bay, where they

are year-round residents. Harbor seals use Humboldt Bay mudflats to rest and raise their

pups, and they depend on the Bay and nearshore waters for breeding and foraging.

Harbor seals are particularly sensitive to disturbance when hauled-out (on land) and to

underwater noise.    Potential impacts of offshore wind activities include potential direct

impacts of vessel strikes and entanglement, and indirect impacts associated with

construction of the Heavy Lift Terminal being proposed on the Samoa Peninsula. Noise

from pile-driving during construction of the new terminal, along with increased noise and

vessel traffic in the bay would likely be disruptive to harbor seals, potentially altering

their behavior, foraging, and reproductive ability. Additionally, dredging new areas of the bay could mobilize legacy contaminants, increase turbidity and erosion, and remove mudflats, all of which could negatively impact the health of harbor seals and their prey. Baseline studies of harbor seal  abundance, distribution, habitat use and health are important to determine before offshore wind energy infrastructure construction begins in Humboldt Bay.

White_harbor_seal_on_moss_by_Dave_Withrow,_NOAA.png

Harbor seal (Phoca vitulina). 

Source: Dave Withrow/NOAA (x)

More research is needed to understand the full implications of offshore wind energy development, whether negative or positive. Methods of assessing risks to marine mammals are still being developed (28). Watch this California Coastal Commission presentation discussing potential impacts from floating offshore wind infrastructure on marine mammals and sea turtles (29). Careful monitoring will be critical, and even more important will be the response to that monitoring (known as adaptive management). Fortunately, experts on the East Coast have been working on these issues, and have developed a plan for coordinating the scientific research (30) necessary for adaptive management to be effective.  There are early efforts (31) on the West Coast to coordinate scientific expertise and coordinate research.

On the West Coast, we have the opportunity to establish a baseline understanding of what is “normal” for marine mammal species before offshore wind development and operation, but that window is closing.  While careful monitoring is important, without a baseline, it will be difficult to identify potential impacts on local populations.  Now is the “before” on the west coast of the US. 

References

  1. Marvell, P. (2023, September 19). Wind opponents spread myth about dead whales. Yale Climate Connections. https://yaleclimateconnections.org/2023/09/wind-opponents-spread-myth-about-dead-whales/ 

  2. Larson, C., McDermott, J., Whittle, P., Perry, W. (2023, December 23). Contrary to politicians’ claims, offshore wind farms don’t kill whales. Here’s what to know. AP News. https://apnews.com/article/offshore-wind-whales-deaths-trump-5158af7f5bf0f5ef9e1530564ff791a9

  3. Lewis, A.S. (2023, March 8). The East Coast Whale Die-Offs: Unraveling the Causes. Yale Environment 360. https://e360.yale.edu/features/humpback-whale-strandings-u.s.-east-coast

  4. Axelrod, J. (2024, June 26). The Science is Clear: Offshore Wind Isn't What's Killing Whales. Scientific American. https://www.scientificamerican.com/article/whales-are-dying-but-not-from-offshore-wind/

  5. Science Friday. (2024, March 29). The Complicated Truths About Offshore Wind And Right Whales. www.sciencefriday.com/segments/offshore-wind-misinformation-right-whale-deaths/

  6. Kieran Mulvaney. (2022, June 8). Humpback whales face a major setback from climate change. National Geographic. https://www.nationalgeographic.com/environment/article/humpback-whales-face-a-major-setback-from-climate-change

  7. Clean Energy States Alliance. (2024). Offshore Wind Power Hub Interactive Map. https://offshorewindpowerhub.org/power-hub

  8. New York State Environmental Technical Working Group. (n.d.). Wildlife and Offshore Wind Resources. www.nyetwg.com/wildlife-and-offshore-wind-info

  9. Ocean Science Trust. (2024). Impacts to Whales and Other Marine Mammals. https://www.oceansciencetrust.org/wp-content/uploads/2024/07/OST-Science-Factsheet-4-Whales-Final.pdf

  10. NOAA Fisheries. (n.d.). Understanding Vessel Strikes. www.fisheries.noaa.gov/insight/understanding-vessel-strikes 

  11. Kalt, J. (2022, May 31). Coastal Commission Approves Offshore Wind Exploration Plan—with Conditions. Humboldt Waterkeeper. https://humboldtwaterkeeper.org/offshore-wind-energy/1572-coastal-commission-approves-offshore-wind-exploration-plan-with-conditions 

  12. NOAA Fisheries. (n.d.). Entanglement of Marine Life: Risks and Response. www.fisheries.noaa.gov/insight/entanglement-marine-life-risks-and-response 

  13. NOAA Fisheries. (2024, January 22). NOAA Announces Confirmed Large Whale Entanglement Numbers in 2022. www.fisheries.noaa.gov/feature-story/noaa-announces-confirmed-large-whale-entanglement-numbers-2022 

  14. Jaramillo, C. (2023, March 31). No Evidence Offshore Wind Development Killing Whales. FactCheck.org. www.factcheck.org/2023/03/no-evidence-offshore-wind-development-killing-whales/

  15. Offshore Wind Scotland. (n.d.). Fact Sheet 4: Cables & Accessories. https://www.offshorewindscotland.org.uk/media/ns2flsmx/04-cables-accessories.pdf

  16. Natural Resources Defense Council et al. (2022). Recommendations to Reduce the Potential Risk of Entanglement of Marine Life During Floating Offshore Wind Energy Development. https://www.nrdc.org/sites/default/files/floating-offshore-wind-entanglement-risk-20220929.pdf

  17. Seabird Scientific. (2016). Guide to Inductive Moorings. https://www.seabird.com/eBooks/IM-Explained-Sea-Bird-Scientific-2019

  18. Sommer, L. (2023, June 25). This fishing gear can help save whales. What will it take for fishermen to use it? National Public Radio. www.npr.org/2023/06/25/1183727733/this-fishing-gear-can-help-save-whales-what-will-it-take-for-fishermen-to-use-it 

  19. Ocean Science Trust. (2024). Impacts from Noise. https://www.oceansciencetrust.org/wp-content/uploads/2024/07/OST-Science-Factsheet-6-Noise-Final.pdf

  20. Nabe‐Nielsen, Jacob, et al. Predicting the impacts of anthropogenic disturbances on marine populations. Conservation Letters 11.5 (2018): e12563. https://conbio.onlinelibrary.wiley.com/doi/10.1111/conl.12563

  21. NOAA Fisheries. (2022, Feb 18). A Whale's World of Sound. https://www.fisheries.noaa.gov/feature-story/whales-world-sound

  22. Ocean Science Trust (2024). Impacts from Electromagnetic Fields. https://www.oceansciencetrust.org/wp-content/uploads/2024/07/OST-Science-Factsheet-7-EMFs-Final.pdf

  23. U.S. Bureau of Ocean Energy Management. (2023). Electromagnetic Fields from Offshore Wind Facilities. https://www.boem.gov/sites/default/files/documents/renewable-energy/state-activities/BOEM-Electromagnetic-Fields-Offshore-Wind-Facilities_1.pdf

  24. Tethys Engineering. (2022). Electromagnetic Field Effects on Marine Life. U.S. Offshore Wind Synthesis of Environmental Effects Research. https://tethys.pnnl.gov/sites/default/files/summaries/SEER-Educational-Research-Brief-Electromagnetic-Field-Effects-on-Marine-Life.pdf

  25. NOAA, Species Directory, Harbor Porpoise. https://www.fisheries.noaa.gov/species/harbor-porpoise

  26. A K Holdman, N Tregenza, S M Van Parijs, A I DeAngelis. Acoustic ecology of harbour porpoise (Phocoena phocoena) between two U.S. offshore wind energy areas. ICES Journal of Marine Science, 2023. https://doi.org/10.1093/icesjms/fsad150

  27. NOAA Fisheries. (n.d.). Harbor Seal. https://www.fisheries.noaa.gov/species/harbor-seal 

  28. Brandon L. Southall. (2023). New risk assessment methods to understandvulnerability of marine mammals and sea turtles to offshore sustainable energy development. Southall Environmental Associates. https://documents.coastal.ca.gov/assets/upcoming-projects/offshore-wind/Th4/Th4-Southall.pdf

  29. California Coastal Commission (2023, May 11). Informational Briefing on Offshore Wind [Video]. https://drive.google.com/file/d/18DmNJakFcDvb5CuVjGZdFF1y7f3lTg1d/view 

  30. Regional Wildlife Science Collaborative for Offshore Wind. (2024). Landmark Research Plan Established for Offshore Wind and Wildlife. https://rwsc.org/landmark-research-plan-established-for-offshore-wind-and-wildlife/

  31. California Marine Sanctuary Foundation. (n.d.). Offshore Wind Environmental Monitoring Guidance. https://www.google.com/url?q=https://www.californiamsf.org/offshorewind&sa=D&source=docs&ust=1733179067647755&usg=AOvVaw0GmE4DdU9FjWLtnCPehBU5

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