Researchers repeated a 21-day sea bass trial beside France’s FLOATGEN turbine, finding similar biological trends before acoustic analysis
What happens to fish when a floating wind turbine becomes a part of their underwater environment? That’s the question scientists in France are investigating as part of the ECHO project, which studies the sound environment of floating offshore wind turbines and its potential impact on marine life. After a first 52-day experiment, the team went to sea in May 2026 for a second test with the FLOATGEN turbine, this time with juvenile sea bass kept in experimental cages for 21 days.
The experiment starts below the surface
ECHO is part of a larger French initiative to study the interaction of offshore wind development with marine environments. The National Offshore Wind Energy Observatory has launched research programs to improve knowledge of the marine environment and the interactions between offshore wind farms and biodiversity.
Researchers used the SEM-REV offshore test site to study it, where the FLOATGEN floating wind turbine offered a real-world environment for the study and is supported by Fondation OPEN-C, which is involved in offshore renewable-energy research. In the first campaign, about one hundred juvenile common sea bass were placed in cages at two sites.
That’s the most interesting part of the experiment: the answer to how floating wind turbines impact marine life may not even be visible from above the water at all.
Some were close to the floating turbine, and others were at a control site away from it for 52 days.
A second similar experiment was conducted with a shorter exposure time of 21 days in cages deployed in May 2026. This time, the researchers were looking for something very specific: Would the biological patterns observed in the first campaign be repeated?
A similar trend emerged in the second trial
From a scientific perspective, the preliminary results of the second campaign appear to be encouraging, as they show trends similar to those observed previously. That doesn’t mean the researchers have demonstrated the turbine is ineffective. Instead, the repeated observations seem to validate the experimental protocol, providing the team with a different set of biological information to compare with the first campaign.
The first 52-day experiment had already produced an interesting result. Survival rates were similar between fish exposed near the turbine and at the control location and were high (80%–100%). The fish did lose some weight and had lower energy reserves than fish raised in the lab. However, their nutritional condition was generally similar to that reported for wild sea bass in other studies.
Since no difference was found between the two sites, the researchers proposed that the body condition changes could be linked to confinement rather than the presence of the wind turbine. Biology alone cannot answer the central question.
The missing piece is underwater sound
The next part of the investigation involves acoustic data. Researchers are analyzing biological responses alongside measurements of the underwater sound environment at the experimental and control sites. Additional analyses also examined cortisol, a hormone associated with stress, as well as cellular stress markers.
And that is where the ECHO project becomes very interesting. The research is looking for more subtle biological responses that might come from exposure to the sound environment of the turbine, which might not be evident from survival or body condition alone.
The broader program also includes research on cetaceans, benthic species, pelagic ecosystems, and other interactions between marine biodiversity and offshore wind development. The next clues for ECHO will come from integrating the state of the fish, their physiological responses, and the acoustic environment around them.
Now, we have a second 21-day trial that has another layer of evidence. The biological trends look familiar, but the sound data may provide some insight into what is going on beneath the surface that the fish are quietly recording. That’s the most interesting part of the experiment: the answer to how floating wind turbines impact marine life may not even be visible from above the water at all.
