Scientists tagged 33 lobsters at turbine bases nine miles off the Welsh coast, and over half were still inside the boulder piles four months later

The boulder pile looked like nothing special from the surface.

A ring of rough rock dumped around a turbine leg to stop the seabed from washing away beneath it.

But under less than a hundred feet of grey water, European lobsters had found something in that rubble that the design never set out to provide.

They had found home.

The question is what it is about a pile of engineering rock that makes a lobster refuse to leave.

What a lobster needs that open sandy seabed cannot give

A lobster does not roam open ground. It finds a crack, backs into it, and defends it, returning to the same crevice after every feeding trip. That instinct works beautifully on rocky reefs, but the sand and gravel floor of Liverpool Bay offers very little of that shelter.

Scour protection changes the arithmetic entirely. When engineers drive a steel monopile into soft sediment, currents begin carving the seabed away from the base, so builders pile boulders around it to hold the ground in place. Those boulders are sized for engineering loads, not for biology, and no one designed them with shellfish in mind.

Stacked loosely on the seafloor, though, they create exactly the kind of dark, rocky gap a lobster spends its life looking for. The sand gives nothing. The rock gives crevices, shadow and hard surfaces to grip.

The animals treated engineering rubble like a reef

Tracked inside a wind farm roughly nine miles off the north Wales coast, the lobsters behaved much as the species does on natural rock. They clustered around the scour protection, made short trips out across the surrounding sediment, then returned to the same boulder ring rather than wandering on.

Site fidelity is normal for this animal where hard ground exists. What the tracking showed is that a ring of imported boulders is apparently enough to trigger it in a place built entirely of soft sediment. Individuals repeatedly used the same patches of scour as their base, visit after visit.

That is a striking result from a seabed that, beyond the boulder rings, is flat featureless sand.

What the tracking and the logbooks showed

Biologists glued acoustic transmitters to the carapaces of 33 lobsters at three turbine locations in the Irish Sea, then listened for them on receivers moored at each site. More than half of all detections were recorded within 115 feet of the scour protection, and over half the tagged animals were present at their tagging sites for 70 percent of the study period.

Four months on, most lobsters were still in the same areas of scour where they had first been detected. Very few detections came from more than about 300 feet beyond the edge of the rock, which is a remarkably tight home range for an animal capable of much longer movements.

A second study by the same group used a commercial fishing logbook kept by one fisher who potted lobsters at individual turbines between 2015 and 2022. Modeling of those records predicted landings nearly 1.5 times greater at turbines with scour protection than at turbines without it, alongside strong month to month and year to year variation in catches.

Where the effect gets complicated

The researchers frame this as the artificial reef effect: adding hard substrate to a soft sediment seabed changes which species can live there. They are explicit that the work is early, and that the most suitable boulder size for creating lobster sized crevices still has to be identified before anyone designs scour with shellfish in mind.

There is also the question of access. Restrictions on fishing inside operating wind farms complicate the idea of a fishery benefiting from lobsters living around the foundations, and the team has said it is working with the north Wales fishing community on the practicalities. Other foundation types raise separate questions, including Scottish jacket foundations installed without rock protection at their bases.

The deeper uncertainty is whether structures like these make new animals or merely gather existing ones. Work on Jonah crab tissue chemistry off Rhode Island targets that same attraction versus production question, which remains genuinely open rather than settled.

What stays open and what the lobsters already decided

Several things the tracking cannot yet answer. Whether lobsters breed and molt successfully around the boulders, rather than simply sheltering there, is not established. Nor is it known whether the food available within a short excursion of each rock ring can support a population over the long term.

Even so, the measured part is concrete: tagged animals held tight to the scour, most detections fell within about a hundred feet of it, and more than half the lobsters were still present four months later. The landings modeling pointed the same direction.

The authors put their own conclusion plainly: “Our new study shows the European lobster is making use of the scour protection as shelter.” The seabed around each turbine is still mostly flat sediment. But in the boulder rings, something has moved in and is not leaving.