A bottlenose dolphin jumps in a vessel’s wake off the coast of Miami, Florida. Credit: Claudia Campi, Shark Research and Conservation Program, University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science.
Vessel traffic can influence marine megafauna behaviour, communication, stress physiology, and even long-term population trends.
A new study provides a comprehensive global synthesis of how vessel traffic affects large marine wildlife, including whales, dolphins, seals, manatees, sea turtles, sharks and rays.
Drawing on over four decades of published scientific research, the meta-analysis combined findings from more than 200 peer-reviewed studies conducted around the world.
In total, nearly 1,900 comparisons were compiled between scenarios with and without vessel presence, allowing for a robust assessment of how vessels impact marine wildlife.
The analysis examined documented responses to vessel activity across various megafauna species, geographic regions, and types of behavioural and physiological reactions.
The results indicate that vessel traffic can alter animal behaviour, disrupt communication, and affect stress physiology.
Additionally, these disturbances may influence long-term population trends in marine megafauna.
Vulnerable
Many species are especially vulnerable to vessel disturbance because they are long-lived, reproduce slowly and rely on coastal and surface waters where boat traffic is concentrated.
By identifying consistent patterns across decades of research, the findings offer insights to inform conservation policy and marine management.
The researchers found that exposure to boats consistently alters how large marine animals behave and function.
Lead author Julia Saltzman, who is a doctoral student in the Shark Research and Conservation Program at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science and the Department of Biology at the College of Arts and Sciences, said: “Even when vessels do not directly strike animals, their presence alone can disrupt feeding, movement, communication, and stress levels.
“These small, repeated disturbances can add up over time and affect populations.”
They also identified uneven research coverage among species groups.
Co-author Emily Yeager, who is a doctoral candidate in the Department of Environmental Science and Policy at the Rosenstiel School and the Abess Center for Ecosystem Science and Policy, added: “Some groups, particularly sea turtles, show stronger responses to vessel disturbance, while others, including large fishes, sharks and rays, remain relatively understudied despite frequent spatial overlap with vessel activity.”
Consequential behaviour
The analysis found that species already listed as threatened or endangered may be more strongly affected by vessel disturbance.
Animals at higher risk of extinction often exhibited larger or more consequential behavioural or biological responses, suggesting that vessel activity can intensify existing conservation threats.
Catherine Macdonald, an associate professor in the Department of Environmental Science and Policy and director of the Shark Research and Conservation Program at the Rosenstiel School said: “Because vessel activity and wildlife distributions shift across space and time, static management approaches are not always sufficient to protect species from disturbance.
“Dynamic management strategies, including seasonal speed restrictions, adaptive buffer distances and targeted closures of key habitats, can provide flexible, evidence-based tools to reduce vessel impacts while allowing continued human use of the ocean.”
The study is published in Ocean Sustainability.
