Tidal turbines’s dark side no one talks about — Fish have started creating “superhighways” and where they go worries experts

Most likely, when you hear the term “renewable energy,” you’d picture solar energy or wind power installations rather than enormous underwater turbines.

However, engineers are tying these machines to the ocean floor along some North American and U.S. coastlines in order to harness renewable tidal power.

It seems like an almost imperceptible, dependable, and clean system. However, scientists are observing something concerning in their impact on underwater ecosystems.

When someone thinks about putting a wind turbine underwater

You would not be wrong if you pictured big devices under the sea when someone said “tidal turbines.”

A more recent innovation in clean energy, tidal turbines have been in the works for decades as engineers have sought to capitalize on the ocean s natural movements.

Like underwater windmills, they generate electricity from turning blades that are driven by the sea’s current.

But don’t feel like you’ll be making use of some ancient tech; tidal turbines have yet to realize their potential as a source of renewable power.

They don’t just produce energy. They can modify their environment

Offshore wind farms have been linked to altered migration routes and increased mortality in bird life.

Underwater tidal turbines bring a similar twist to the marine world. These machines don’t just produce energy — they change how the ocean environment behaves.

Because tidal turbines sit smack in the middle of currents and migration routes, they can cause changes in water flow and acoustics, and influence behavior patterns that fish have used for millennia.

That’s why people refer to the routes fish form as “superhighways” — continuous pathways they start using around and through the turbine installations instead of their traditional corridors.

But here’s the worrying part: scientists still don’t fully understand where those fish are going along these new routes, or how these behavioral shifts could ripple across entire ecosystems. That uncertainty is exactly what has experts raising red flags about the use of underwater turbines, and it’s important to understand how much damage is being done.

Fish have started building “super highways”. Now we know where they lead to

This is where the tidal energy story gets unexpectedly biological.

Ocean currents and tidal flows don’t just push water. They shape where fish go. Around powerful tidal sites like Canada’s Bay of Fundy, researchers have observed patterns in fish movement that almost resemble highways — consistent routes that fish follow as they migrate along the currents.

Studies in the Bay of Fundy, especially around areas where tidal turbines are being tested, have shown that big migratory species — including shad, salmon, herring, and striped bass — travel long distances through the macrotidal channels year after year. This is one of the conclusions from Natural Resources Canada, a government’s agency.

Scientists use tagging and tracking to map these movements and are starting to treat them like migratory superhighways through the tidal system.

What’s fascinating — and concerning — is that these routes intersect with where tidal energy devices are being deployed.

From Canada to New Zealand: But it’s not the same highway

Half a world away in New Zealand’s Cook Strait, another tidal hotspot, scientists are also mapping how strong, complex tidal flows influence marine life patterns.

Although specific “superhighways” haven’t been formally labeled yet, Cook Strait’s powerful bi-directional tidal currents drive migration and movement for a wide range of marine species, from schooling fish to cetaceans, underscoring how currents alone can shape travel routes through what looks like open ocean.

So now it’s not just turbines and energy potential we need to think about.

We’re tracking the effects of renewable power installations and trying to figure out what happens when human infrastructure interacts with a natural ecosystem.