Critics Feared Tidal Turbines Are “Underwater Blenders” But New Footage Proves Marine Life Knows How to Dodge Them

Seal swims past tidal turbine. Credit: Cotter et al., CC-BY 4.0 At the bottom of Sequim Bay’s tidal channel, four-bladed turbines churn through the water. Critics have feared devices like this act as “underwater blenders,” chopping up everything from seals to salmon. But an underwater camera system watching the site shows such concerns are unfounded: curious harbor seals, schools of Pacific herring, and diving cormorants generally steer clear. Marine life, it seems, is clever enough not to swim straight into a killing zone. After analyzing 1,044 unique interactions between marine life and the machine, researchers found a 98 percent safety rate for fish and zero collisions for seals or seabirds. These findings, released in a study by the Pacific Northwest National Laboratory, provide the first-of-its-kind data for North America. They could finally break the regulatory stalemate paralyzing an industry capable of powering millions of homes “The risk for collisions is low,” Christopher Bassett, a co-author and research scientist at the University of Washington, told Inside Climate News, noting that harbor seals were “clearly in control and avoided making impact with the turbine”. These findings could be the key to unlocking a renewable energy source that, unlike wind or solar, runs on a schedule as reliable as the moon. Watching in the Dark The study, published in PLOS One, was a feat of underwater surveillance. The team deployed a “Turbine Lander,” a platform equipped with an “Adaptable Monitoring Package” that included optical cameras, acoustic cameras, and hydrophones. Getting clear data in a churning tidal channel is incredibly difficult. The water is often murky, filled with drifting plant matter that looks suspiciously like small fish to a computer. To solve this, the team used strobe lights to illuminate the turbine and employed AI-driven software trained to detect the silhouettes of marine life. This tech allowed them to capture rare behaviors in total darkness. × Get smarter every day... Stay ahead with ZME Science and subscribe. Thank you! One more thing... Please check your inbox and confirm your subscription. Over a period spanning 109 days of operation, the cameras recorded a bustling aquatic highway. They saw schools of Pacific herring, curious harbor seals, and diving cormorants. They even spotted kelp crabs, jellyfish, and krill passing through the structure. The Seal That Dodged a Bullet A seal swims past the turbine while it is stationary. Credit: Cotter et al., CC-BY 4.0 One of the most encouraging discoveries concerns harbor seals. These intelligent mammals are common in Sequim Bay, and regulators have long worried they might be too curious for their own good. The cameras caught 92 interactions with seals, both day and night. The footage revealed that seals don’t stay passive to become victims. Instead, they skilfully perform evasive maneuvers to get out of harm’s way. “When we observed seal encounters with the turbine while it was rotating, their behavior indicated that they were capable of evasion, even when pursuing prey,” the study authors wrote. In one dramatic instance, a seal was chasing a...

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