A camera watched a Washington tidal turbine for 109 days, and two fish that struck its spinning blades had been chased straight toward them by hungry seals

Tidal turbines are being actively explored for offshore clean energy generation, but more insight into marine wildlife impacts is needed.

Globally, space for renewable energy infrastructure is running out on land, urging growth in ocean-based generation.

Tidal energy offers distinct benefits over conventional offshore power production.

Furthermore, the inclusion of artificial reef dynamics in site planning can help increase marine conservation while expanding clean energy.

To ensure the spinning blades do not cause harm, an underwater installation in Washington State was monitored.

Will the findings help determine how ocean wildlife navigates marine energy infrastructure?

How available deployment space is rapidly running out

Highly ambitious climate targets have led to a significant increase in global renewable energy installations.

The current installed green capacity worldwide has exceeded 5,149 gigawatts, driven by record wind and solar infrastructure.

Despite this historic growth, Earth’s temperature continues to increase to dangerous levels.

Furthermore, the world’s electricity consumption has surged to unprecedented highs.

To curb emissions while meeting power demand, total generation capacity must increase by almost 2.5 times over the next decade.

However, this transition has become more complex, as available space for onshore installation is highly limited.

Competition over land use has intensified, as urbanization, residential zoning, agriculture, and conservation all compete for space.

Strict environmental protection, in particular, has frequently disqualified large tracts of land as potential development sites.

Resistance from local communities and fragmented property ownership are other common obstacles.

These reasons are why more developers are turning to the open ocean for green energy deployment.

The rise in offshore renewable energy capacity

Offshore green capacity has experienced major expansion, with offshore wind power leading the way.

The shift toward the ocean has enabled the sector to break free from land-use conflicts.

Beyond overcoming these barriers, the ocean also offers stronger, more consistent natural forces.

But conventional offshore generation, such as foundation-based and floating wind turbines, has its own set of limitations.

Alternative marine technologies like tidal turbines overcome these issues, leading to their rapid rise in popularity.

Mapping 30 years of ocean currents has established that this source dwarfs some of the world’s best wind farms.

The power of tides lies within predictable celestial dynamics, and not unpredictable weather patterns.

While tidal turbines can generate highly reliable and consistent electricity, their environmental impacts remain primarily uncertain.

To better understand potential ecological consequences, researchers monitored an underwater tidal turbine in Sequim Bay, Washington.

The study and its findings were made available on Tethys.

The Sequim Bay tidal turbine versus local marine wildlife

The currents flowing near tidal turbines can be surprising, but not as surprising as the species navigating these turbines.

A compact tidal turbine was deployed in Sequim Bay for 141 days of monitoring.

The installation included a specialized underwater package consisting of optical and acoustic cameras, hydrophones, and current profilers.

The goal was to track marine life and their fine-scale interactions near the blades.

Encounters during operation were caught on camera

As the turbine spun, 299 fish interactions were captured.

The majority drifted past safely or showed avoidance behaviors.

The fish gathered due to the “artificial reef effect,” as the installation offered shelter and forage.

However, four direct collisions took place.

Two occurred due to hungry seals chasing the fish, driving them into the rotating blade’s path.

Zero collisions occurred with the 406 observed seabirds. Additionally, 92 seals were sighted, but they easily maneuvered around the installation without any collisions.

These findings demonstrate that small-scale tidal turbines can pose ecological risks, albeit minimal.

As long as proper wildlife monitoring is in place, long-standing regulatory fears over blade collisions can be relieved.

Future projects should include advanced machine learning technologies in installations for continuous animal behavior observation.

Furthermore, the inclusion of artificial reef dynamics in site planning can help increase marine conservation while expanding clean energy.

More information on this study is available on Cotter, E., Bassett, C., Murphy, P., Scott, M., Runyan, A., Almokharrak, J. M., … & McMillen, S. A. (2026). Observations of marine animal interactions with a small tidal turbine. PloS one, 21(1), e0338376.