For centuries, the North Sea has hosted trade, fishing, and migration routes. Now, it’s becoming home to another force of movement: offshore wind. But beneath the surface, another set of migratory patterns is at play — and they’re just beginning to be understood.
A new study from Wageningen University offers rare insight into how sharks and rays (collectively known in science as elasmobranchs) interact with the network of offshore wind farms expanding across European waters. These elusive, often threatened species, are now caught in a fascinating tension between conservation and clean energy development.
Their presence in wind farms isn’t just an academic curiosity. It’s shaping how we understand the future of marine biodiversity — and how to build the next generation of renewable energy with nature in mind.
What Are Elasmobranchs?
Though the term sounds obscure, elasmobranchs are simply a group of cartilaginous fish — including sharks, skates, and rays — characterised by their flexible skeletons and exceptional sensory abilities.
These are not the fearsome predators of myth. In the North Sea, species such as the thornback ray, starry smooth-hound shark, and basking shark play crucial ecological roles. They regulate fish populations, act as prey for larger species, and support overall ocean health.
Yet they’re also under threat — not least from overfishing, habitat loss, and climate change.
The Wind Farm Conundrum
Offshore wind farms (OWFs) are being rapidly deployed to meet Europe’s clean energy goals. That’s good news for decarbonisation, but it raises questions about how this new underwater infrastructure affects marine life.
The study focused on four wind farms off the Dutch coast — Borssele, Gemini, Luchterduinen, and Hollandse Kust Zuid — and used environmental DNA (eDNA) to track elasmobranchs without disturbing them. This method detects tiny genetic traces shed by organisms into the water, offering a non-invasive way to monitor biodiversity.
Over two years and 436 water samples later, the results were both reassuring and eye-opening.
Findings: Presence and Patterns
The study confirmed the presence of five elasmobranch species in wind farms — two sharks and three skates. Though detection rates were low (an average of 8.5%), the diversity was significant. One species in particular, the starry smooth-hound shark (Mustelus asterias), showed a clear seasonal presence, especially along subsea power cables.
This suggests that these sharks may be using wind farm corridors as migratory routes — and that the farms are not blocking or deterring their movement. Similarly, the thornback ray (Raja clavata) appeared in multiple sites and seasons, consistent with population recovery trends.
Of special note was the winter detection of DNA from the basking shark (Cetorhinus maximus), a rare filter-feeder typically found in warmer waters. Its appearance may reflect subtle changes in migratory behaviour — or even hint at broader climate-driven shifts in habitat use.
Electric Fields and Safe Havens
Subsea cables used to transmit electricity from wind farms produce electromagnetic fields (EMF), which some scientists feared might confuse or repel marine species. Elasmobranchs are particularly sensitive to electric signals — they use them to hunt and navigate.
But this study found no clear evidence of harm or deterrence. In fact, some species were more frequently detected near these cables than elsewhere. This raises intriguing possibilities: are sharks and rays attracted to these areas? Are wind farms, often closed to bottom-trawling fisheries, acting as accidental refuges?
Early signs suggest they might be. Hard seabed structures around turbines could act as artificial reefs. The exclusion of trawling reduces seabed disturbance and by-catch risk. Together, these factors might provide a more stable and safer environment for marine life.
Designing for Coexistence
The implications are far-reaching. With European targets aiming for 300 GW of offshore wind capacity by 2050, much of the seabed will soon be shaped by human infrastructure. If wind farms can double as biodiversity havens, they could help restore populations of sensitive species.
But there’s a catch. Calls to open wind farm areas to commercial fishing — including bottom trawling — would undo many of these ecological gains. This research offers a timely reminder that multi-use strategies must be carefully considered, balancing energy, food, and nature.
From Monitoring to Stewardship
The researchers urge more studies, combining DNA monitoring, acoustic tagging, and visual surveys to understand how these species really use wind farms — whether for feeding, breeding, or migration. They also point to tools like the EU’s Nature Restoration Law and Biodiversity Strategy 2030 as frameworks where such insights can shape real policy.
For countries like Norway, Sweden, and Canada — each with vast marine territories and fast-expanding renewable sectors — this study provides a model for integrating wildlife protection into energy transition planning.
A New Kind of Marine Map
We often think of wind farms as industrial zones. But if we choose wisely, they could become something more: stepping stones in a wider marine network, where wildlife and renewable energy can not only coexist but strengthen one another.
For the first time, we’re starting to chart where rays and sharks swim — not just for science, but for sustainable living.
Source
Elasmobranchs in offshore wind farms, Ocean and Coastal Management, 2025-04-09
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