Bare sandy seafloor around 69 turbines in Taiwan’s commercial fishing grounds transformed into reef within eight years, and 86 fish species now crowd the steel foundations that fishermen once feared
Off the western coast of Taiwan, fishing boats have worked the same sandy shallows for generations.
The bottom here was always bare.
Flat, shifting sand, no reef anywhere, no hard surface for barnacles or sponges to grip.
The boats that once resented the turbines now find the densest catch concentration within a few hundred feet of the very structures they originally feared.
Then came the steel piles, and eight years later a scientific survey counted what had gathered around them.
The number was 86 species. What made the steel do that?
What the steel pile does to a sandy seabed
Sandy seafloor is essentially a desert for reef life. It moves with the current, offers no grip, and smothers any organism that tries to settle. The moment a rigid surface arrives in the water column, everything changes.
Mussels, barnacles, sponges, and anemones need a stable foundation to anchor their larvae, and a steel monopile sunk into the seabed delivers exactly that from the waterline down to the scour protection, the ring of boulders and rock bags layered around the base to stop sediment from eroding. At the Formosa site that scour protection extends roughly 65 feet around each foundation, with rock density decreasing toward the outer boundary. Beyond that zone the seabed transitions back to featureless sand flat.
Once the first organisms settle on the steel, they form a living skin that traps sediment, creates crevices, and draws in predators. Each layer recruits the next. That is why eight years proved enough to produce a community that normally takes decades to assemble on a natural reef.
The farm and the fishing ground it landed on
The Formosa Wind Farm sits in the Taiwan Strait, a body of water known for strong, consistent winds and for equally consistent fishing pressure. The project comprises 69 turbines spanning roughly 35 square miles, and because the site overlaps with historically productive fishing grounds, concerns arose from the start about whether the installation might harm the original demersal fishery.
Those concerns were legitimate. The area is accessible from two harbors, one roughly six miles to the east and another about four miles to the south. Fishing crews who had worked these waters for years suddenly found 69 steel towers standing in their grounds, each rising from a foundation encircled by boulders that could snag a trawl net.
What nobody predicted was the direction the change would run. Instead of driving fish away, the steel pulled new species in from distant reef habitats. The boats that once resented the turbines now find the densest catch concentration within a few hundred feet of the very structures they originally feared.
What the survey recorded
A study published in Frontiers in Marine Science documented 86 reef associated fish species clustered within about 165 feet of the turbine foundations eight years after commissioning. The surrounding flat sandy areas had none. The contrast is almost total.
The steel monopiles, plus the rock armor layered around their bases, together function as an artificial reef system that project planners never designed and environmental assessments never fully anticipated. Fish assemblages near the turbines show similar diversity and trophic structure to those found at long established artificial reefs.
A decade of standing in a fishing ground can make a wind turbine foundation ecologically equivalent to a reef built deliberately over a much longer span. That is a significant finding, and offshore wind foundations deliver it on a profile shifting sand never can.
The catch that comes with the catch
The transformation creates genuine operational complications. A service vessel approaching a turbine for routine inspection now navigates through water that is actively being fished, and maneuvering a crew transfer vessel in those conditions demands maritime coordination nobody wrote into the original maintenance plan.
The scour protection that anchors the reef community also complicates underwater access. A diver or remotely operated vehicle sent to inspect a monopile base works through a dense biological layer, encrustation thick enough in some cases to obscure weld seams and corrosion points engineers need to see. That is a maintenance window problem the industry is only beginning to price.
A parallel is already visible in the United States. A Rhode Island wind farm had dense blue mussel aggregations around its foundations within four years of construction, and acoustic surveys found high fish density within roughly 400 to 500 feet of the structures. If Formosa’s timeline holds, every steel pile driven into a sandy sea bottom carries a reef community as part of its long term cost of ownership.
What comes next, and what stays open
The Formosa findings arrive as offshore wind expands fast into waters with the same sandy profile. Much of the seafloor planned for development along the US East Coast, the southern North Sea, and parts of Australia is flat, sandy, and historically productive for bottom fishing. Every project dropped into that environment is now, in effect, a slow motion reef experiment.
A North Sea project that installed half its machines over summer faces its own installation window pressures, but its sandy seabed will begin the same ecological transformation the moment steel touches bottom. Some operators have begun incorporating reef monitoring into operations and maintenance contracts, treating the biological layer as an asset to document rather than an obstacle to clear.
Next generation turbines with far larger foundations will put proportionally more hard surface on the seabed, amplifying both the ecological effect and the maintenance challenge. Whether 86 species clustering around 69 piles represents a genuine net gain for the regional fish population or simply a concentration effect that masks a wider decline will take another decade of sampling to resolve. Meanwhile the turbines keep standing, the reef keeps building, and the science catches up.
Hugo is an engineer with strong technical expertise. Multilingual from an early age, his writing combines technical clarity with a strong interest in science and energy.
