Kemp’s ridley sea turtles rank among the most endangered sea turtle species on the planet. They live along the East Coast and Gulf Coast of North America, sharing these waters with some of the busiest shipping routes in the world. Scientists already know that fishing gear, pollution, and ship strikes threaten their survival. What remains less certain is how much human-made noise affects these turtles as they move through such crowded environments.
In JASA, published on behalf of the Acoustical Society of America by AIP Publishing, a research team from Duke University Marine Laboratory, the National Oceanic and Atmospheric Administration, and North Carolina State University set out to examine how Kemp’s ridley turtles hear. Their goal was to better understand whether the turtles are especially vulnerable to noise created by human activity.
“They face a variety of threats, including accidental capture in fishing gear, vessel strikes, ingestion of plastic debris, and degradation of nesting beaches and coastal habitat,” said author Charles Muirhead. “Because they occupy nearshore and shelf waters of the Gulf Coast and western North Atlantic — areas with intense human activity — they are frequently exposed to overlapping stressors throughout much of their life cycle.”
Why Ocean Noise Matters
Like many marine animals, Kemp’s ridley sea turtles depend on sound to interact with their surroundings. Underwater sound can travel far, particularly at low frequencies. These low frequency sounds are commonly produced by ships and industrial equipment, and they can overlap with the natural sounds turtles may use to orient themselves and navigate through the ocean.
Measuring the Turtles’ Hearing Range
To test how well the turtles hear, researchers attached noninvasive sensors to the turtles’ heads and recorded the electrical activity traveling along their auditory nerves. The team exposed the turtles to sounds ranging from 50 hertz, which is near the lower limit of human hearing, up to 1,600 hertz. The results showed that the turtles were most sensitive to sounds around 300 hertz, with hearing ability decreasing at higher frequencies.
“Our findings indicate that the turtles are most sensitive in the same low-frequency band where much industrial and vessel noise occurs,” said Muirhead. “This does not automatically mean that harmful effects are occurring, but it highlights where further monitoring and targeted impact studies should be focused.”
What Comes Next for Sea Turtle Research
The researchers now plan to observe how sea turtles respond to sound in real-world ocean conditions. They also want to better connect the sound signals measured in the lab with the physical effects that noise may have on turtles in their natural habitat.
“These efforts will help refine our understanding of how human-caused noise interacts with sea turtle sensory systems. They will also support evidence-based management approaches aimed at minimizing unintended impacts while balancing human activities in coastal and offshore waters,” said Muirhead.
