How do offshore wind turbines affect whales and fishing?

The offshore wind industry is growing rapidly, making it increasingly important to understand the potential effects of ocean-based wind turbines on the marine environment. Norway’s Institute of Marine Research (IMR) is actively researching these issues, providing guidance to the Norwegian government and the industry at large to mitigate any unintended consequences of offshore wind farms.

Both the US and Europe are encountering challenges in developing offshore wind energy with regard to protecting marine life and the marine environment. However, these markets are very different. 

Europe benefits from stronger political backing, cohesive policy frameworks and favourable public opinion. Conversely, the US grapples with greater political division, a more influential fossil fuel lobby and local opposition, all of which can hinder the advancement of offshore wind projects. In the case of whales, there has been much more opposition to offshore wind projects in the US because many people believe that offshore farms contribute to the whale deaths occurring along the coastline.

In the US, the National Oceanic and Atmospheric Administration (NOAA) is responsible for a number of regulatory processes under the Marine Mammal Protection Act and the Endangered Species Act and for ensuring that energy projects comply with this legislation. Research conducted by NOAA has concluded there is no scientific evidence suggesting that noise from offshore wind sites causes whale deaths. Nor are there any known links between whale deaths and ongoing offshore wind activities.

Although no whale deaths have been linked to offshore wind turbines, there are disturbances caused by construction, operation and dismantling. In the US, offshore wind operators have requested Incidental Harassment Authorisations to allow for Level B harassment, which include actions that could disturb, but will not injure or kill, a marine mammal. These disturbances could potentially disrupt behavioural patterns such as migration, breathing, nursing, breeding, feeding or sheltering. A primary concern is that the increased ship traffic associated with wind farm construction and maintenance will increase the risk of ship strikes on whales.

Whales are known to have sophisticated navigation and echolocation abilities that help them to detect and avoid large objects like wind turbines, but an offshore wind farm can force the whales to change their route and habitat.

According to the IMR, electromagnetic signals from the cables transmitting electricity from wind turbines to the mainland generate electromagnetic fields on the seabed that could disturb marine organisms. Research thus far has shown minimal effects, but more research is needed.

Wind turbines and mooring equipment create barriers in the ocean but can also serve as artificial reefs. These structures provide surfaces on which algae and shellfish can grow, attracting fish and other marine life seeking food and shelter. In the open ocean, where the sea floor is sandy, these artificial reefs could boost biodiversity. However, they could also act as pathways for invasive species, aiding their spread to new areas.

Recent research indicates that fish populations are higher within the area of a wind farm compared with the surrounding sea. It is unclear whether this is due to an actual increase in fish numbers, to lower fishing pressure, or to a redistribution of fish around the turbines.

On the downside, noise, light and electromagnetic fields from the turbines may decrease productivity and increase mortality rates among fish. Here too further research is needed to determine the effects on fish.

Offshore wind turbines have primarily been installed on fixed foundations in shallow waters. However, floating turbines, which are placed further offshore, are becoming more common. Both types of foundations can have a negative impact on local flora and fauna, including seabed-spawning fish. The IMR advises against developing offshore wind farms in vital habitats for species such as capelin and sand eel that lay their eggs in sandy bottoms.

The commitment to ongoing research underscores the importance of safeguarding marine life amid growing offshore wind activity. Continued research and monitoring are essential to striking a balance between industry growth of and the protection of marine ecosystems.