Portugal’s WindFloat Atlantic became a no-fishing refuge where octopus and fish stayed more abundant after eight years
Three semi-submerged turbines sit out at sea off the coast of Northern Portugal in the Atlantic Ocean. WindFloat Atlantic was designed to harness the power of the wind to generate green energy. However, for eight years now, there has been something else going on below the surface, which scientists have finally been able to quantify.
A wind farm built for power — and claimed by the sea
WindFloat Atlantic is not your regular offshore wind farm. It is operated by Ocean Winds, which is a joint venture company owned 50/50 by EDP Renewables and ENGIE. WindFloat Atlantic is the world’s first floating offshore wind farm using semi-submersible technology. The wind farm uses three turbines that produce 25 MW from deep waters of the Atlantic Ocean.
All offshore wind farms are associated with a navigation exclusion zone where commercial fishing boats are not allowed to operate within the perimeter of the turbines. This rule exists for the sake of navigational safety, rather than the biological safety of fish in the area.
But what is left for us to wonder about now is whether future projects will be designed in a way that this effect could become their intentional outcome.
But here is an interesting thing that happened behind the scenes. Over eight years, Ocean Winds employed independent consultancy Blue Grid (along with MARE-ULisboa and MARE-IPLeiria) to analyze what was really going on in the off-limits zone.
Eight years underwater: What the data actually showed
And the key conclusion is obvious: octopuses and fish, mainly elasmobranchs, appeared to be more plentiful within the exclusion zone compared to control sites outside of it. More than 270 species were observed in the WindFloat Atlantic area during the whole study period.
Of course, there were not only positive results. However, the balance was maintained. The impact of the wind farm did not have any negative effects on the lower trophic levels. Phytoplankton and zooplankton communities stayed intact, while positive effects appeared at higher trophic levels: invertebrates and fish. The wind farm did not disrupt the ecosystem, but rather improved some parts of it.
Natural seasonal and interannual variability continues to shape the larger-scale marine community structure. However, the wind farm did not replace these processes, but rather supplemented them.
The reef effect: Why turbine foundations attract life
What lies beneath is quite simple in terms of physics. Steel structures underwater — such as mooring lines, anchors, semi-submersible hulls — give rise to substrates where none existed before on the sand floors of the Atlantic. Organisms attach themselves to these substrates, fish come to feed on them, and their predators follow.
The exclusion zone takes this process to the next level. Eliminate fishing and provide new habitat at the same time, and you have what scientists call a double barrier.
The ecological cascade extends upward. Richer habitat at the base draws octopus and elasmobranchs. Dolphins and porpoises were observed more frequently during the operational phase. Teresa Simas, Blue Grid’s CEO, put it plainly: “The project generates measurable ecosystem service outcomes — including enhanced fish and invertebrate abundance through reef and refuge effects — and highlights the importance of sustained environmental monitoring to inform the responsible scaling of floating wind technology.”
Beyond the turbines: Mammals, birds, and a migration corridor
A very broad range was covered by the monitoring programme. Five species of marine mammals, 33 species of birds, three species of bats, and 52 species of fish were documented in the OceanWind’s WindFloat Atlantic region. The site serves mainly as a migratory path for most of these species.
No bird collisions were detected, and no bat roosting incidents were recorded. Some vulnerable and critically endangered species appeared in the data, underscoring both the ecological sensitivity of the area and what the refuge effect may be protecting.
Lino Costa and Bernardo Quintella of MARE-ULisboa reflected on the broader value: “The monitoring of WindFloat Atlantic has been an excellent opportunity to increase the knowledge about the marine ecosystem of northern Portugal and to better understand how to reconcile the development of floating wind farms with biodiversity conservation and fisheries.”
What this means as floating wind scales up globally
WindFloat Atlantic is a 25 MW pilot. The next generation of floating wind farms will be orders of magnitude larger — more submerged infrastructure, wider exclusion zones, far greater potential for incidental refuge creation. The implications compound quickly.
Scientific studies have shown that offshore wind farms may contribute to the development of commercial fishing in the vicinity due to being source populations that diffuse into nearby areas, a service provided far outside the boundaries of the exclusion zone. As Catarina Rei, Director of Permitting and Environment at OceanWind, pointed out, “The findings from WindFloat Atlantic provide robust, data-driven evidence that floating offshore wind can coexist with biodiversity, and even create positive local ecological effects.”
Eight years of data make it difficult not to take the refuge effect into account. But what is left for us to wonder about now is whether future projects will be designed in a way that this effect could become their intentional outcome.
Kelly is an experienced writer with 15 years of experience exploring the big stories that shape our world, from tech breakthroughs and space exploration to climate, energy, and the fascinating quirks of science. She has a talent for turning complex ideas into sharp, memorable insights that stay with readers long after they’ve finished reading.
