Sharks and rays found using offshore wind farms as habitat

Elasmobranchs confirmed through eDNA sampling

For the first time, scientists from Wageningen University & Research have been able to confirm the active presence of elasmobranchs within Dutch wind farms through eDNA traces in seawater. The study combined new fieldwork with data from The Rich North Sea Programme. In total, 436 seawater samples were collected, enabling researchers to detect species that had passed through an area without the need for physical capture.

“We’re trying to understand whether these animals are actually using the wind farms as habitat, or whether they’re being displaced by them,” says Annemiek Hermans, PhD candidate at Wageningen University & Research.

Five elasmobranch species identified across four wind farms

Five different shark and ray species were detected in four offshore wind farms: Borssele, Hollandse Kust Zuid, Luchterduinen, and Gemini. The thornback ray (Raja clavata) was the most frequently observed species, occurring year-round in three of the sites. Remarkably, basking sharks (Cetorhinus maximus) — a large, migratory species — were detected during winter in Hollandse Kust Zuid, providing insight into their seasonal movements.

Other species identified include the starry smooth-hound (Mustelus asterias) and the blonde ray (Raja brachyura), both found across multiple seasons and sites.

Offshore wind farms as potential safe havens

Trawling and other forms of seabed-disturbing fishing are prohibited within offshore wind farms, allowing benthic ecosystems to recover. Researchers believe that these more stable habitats could benefit vulnerable species such as elasmobranchs. “We must tread carefully,” Hermans cautions. “If we start allowing bottom trawling in these areas, we risk losing the very protection these zones may offer.”

Non-invasive techniques aiding marine study

The use of eDNA is a promising, non-invasive tool for marine ecology. “It’s like finding a fingerprint in the water,” Hermans explains. “Even if you don’t see the shark, the DNA tells you it’s been there.” The method is fast, cost-effective, and animal-friendly, opening up new possibilities for biodiversity monitoring in challenging marine environments.

Findings support marine policy and conservation

The findings provide valuable insights for marine spatial planning and policy, particularly as the EU pushes forward with initiatives such as the Habitats Directive and the new Nature Restoration Law. The study explores how offshore energy infrastructure might be integrated with marine conservation strategies, offering potential win-wins for biodiversity and renewable energy.

Part of the ElasmoPower project

Annemiek Hermans is conducting this study as part of the six-year ElasmoPower project, led by Wageningen University & Research. The project investigates whether electromagnetic fields from subsea power cables in offshore wind farms affect elasmobranch behaviour, as these species rely on electrosensory perception for hunting and navigation. The work combines lab experiments with field studies using underwater cameras, sensors, and molecular techniques. Partners include TenneT, WOZEP (part of Directorate General for Public Works and Water Managemen), Naturalis Biodiversity Centre, The North Sea Foundation and consultancy Witteveen+Bos, where Annemiek Hermans also works part-time.

More Information

• The findings have been published in the scientific journal Ocean and Coastal Management. Read the article: Elasmobranchs in Offshore Wind Farms - ScienceDirect

Text: Cecile Leuverink, Wageningen University & Research
Images: Wageningen University & Research (lead photo: gathering eDNA in wind farms)