Some experts are concerned about the threat tidal turbines – which generate renewable energy through the ebb and flow of the tides – pose to marine wildlife. To find out more, scientists in Washington State in the US conducted an experiment to determine the risk of collisions.
They put a camera underwater for 141 days to film marine life interactions with a tidal turbine and captured footage on 109 of those days.
After combing through 1,044 instances where fishes, birds or seals came close to the turbine, they observed just four collisions, according to a new paper published in PLOS One.
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“Four fish were observed colliding with the moving turbine and in all but one case the animals swam away following the collision,” says the paper. “No instances of collision with seabirds or marine mammals were observed.”
The researchers note that the sampling was limited at nighttime, adding “many animal interactions with the moving turbine at night were likely not recorded.”
The findings suggest that there is a low risk of seabirds crashing into the turbine as they were never observed while the blades were in motion. Although seals were spotted near the rotating turbine, the researchers concluded that they were at low risk of swimming into it.
“When we observed seal encounters with the turbine while it was rotating, their behaviour indicated that they were capable of evasion, even when pursuing prey,” says the study. To minimise the chance of a seal getting hurt when a stationary turbine started moving, they suggested “devices could be programmed with a “soft start” wherein the turbine ramps up to its operating state slowly, giving any animals present the time to move away from the device.”
Top image: Seal swims past tidal turbine. Credit: Cotter et al., CC-BY 4.0
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