Marine scientists have uncovered yet another way human activity interferes with the lives of migrating humpback whales. In a recent study by Dr Riona McNamara and Dr Rebecca A. Dunlop, published in 2025, the researchers found that whales — while migrating — alter their social calls when exposed to the booming sounds of offshore oil-and-gas exploration.
The study focused on whales equipped with acoustic tags. Some groups (12 in total) were deliberately exposed to seismic “air-gun” blasts – massive underwater sound pulses used in commercial surveys. Others (21 groups) were used as controls. The result: whales exposed to the air-gun noise generally increased both how often they called and how loudly they called, compared to their behaviour before exposure and to unexposed whales.
This behaviour likely reflects what scientists call the “Lombard effect” – when an animal (or person) speaks louder in a noisy environment so its message still gets through. But that’s not the full story. Some whale groups did not raise their calls, and some even reduced them. Even more puzzling: the increase wasn’t neatly tied to how loud the noise was or how close the whales were to the source. In other words, being closer or hearing more noise didn’t always mean a stronger reaction.
Why This Matters
Humpback whales rely heavily on sound. These giant mammals use calls for social interaction, mother-calf communication, group coordination, and navigating on their long migrations. When humans invade their acoustic world with powerful pulses of sound, the whales may have to compensate, change behaviour, or flee. This research shows one of those disruptions in action.
Importantly, even when whales increase calling rate or volume, that is not necessarily a sign that “everything is okay”. In fact, it may be a sign of stress, energy expenditure, or communication interference. The whales might be working harder just to maintain “normal” social contact. Over time, that extra work could reduce feeding efficiency, slow down migration, interfere with mating or calf rearing — in short: it could affect survival and reproduction.
Because the whales’ responses were inconsistent, the study points to complexity: group composition (mother + calf, or mother + calf + escort), behavioural context (migrating vs feeding vs breeding), and perhaps other unknown factors all play a role in determining how a whale reacts to human-generated noise.
The Human Footprint Beneath the Waves
The study is part of a larger story of how humans shape the ocean’s soundscape – not just through shipping, sonar, and exploration, but via everyday noise that travels underwater. Seismic air-guns, for example, generate percussive pulses that can travel many kilometres and overlap with the frequency bands whales use for communication. Discovery of Sound in the Sea -+1
As one marine-mammal review puts it: even relatively low-level seismic noise can interfere with whale calls and responses. Convention on Biological Diversity+1
When whales cannot hear or be heard, when they have to shout louder or call more often, when they alter group behaviour or avoid areas altogether – the consequences may ripple through their life-history. For a migrating humpback, the stakes include reaching feeding grounds in good condition, keeping the calf safe and in contact, and proceeding to the next stage of the life-cycle.
What Can Be Done? A Few Practical Steps
How can we reduce these impacts and give humpback whales and other marine mammals a quieter, safer acoustic environment? Here are several practical ideas, widely discussed among scientists and conservationists:
- Timing and routing of seismic surveys
Avoid conducting loud surveys during peak migration, breeding or calving seasons for whales. Spatially route survey vessels away from known whale corridors and staging areas. - Use quieter technologies and ramp-up procedures
Developing and adopting less noisy exploration technologies helps. Gradually ramping up sound output (“soft start”) gives whales time to react or move away. - Establish ‘quiet zones’ or buffer zones
Marine protected areas, acoustic quiet zones, or minimum-distance buffers around sensitive habitats (e.g., calf-rearing zones) can reduce exposure of whales to high-level noise. - Monitoring and adaptive management
Use acoustic monitoring (hydrophones) to track whale presence and noise levels in real-time, and adjust operations if whales are detected close by. - Regulation, planning and cross-industry collaboration
Governments, industry and conservation groups can work together to set limits on underwater noise, enforce mitigation measures, and share best practices globally.
A Final Word
The recent study by McNamara & Dunlop adds a clear and troubling piece of the puzzle: migrating humpback whales are responding to human-generated noise, one way or another. Whether by turning up the volume or possibly falling silent, these changes are a red flag. We cannot assume that because whales still call, everything is fine. Communication is being disrupted. Behaviour is being forced. The long-term implications remain to be fully understood.
But we do know this much: the ocean is getting noisier. The whales cannot turn off the sounds. We can — or at least we can change how we operate. By rethinking seismic exploration, shifting schedules, developing quieter technologies, setting up acoustic safe zones — we can give humpback whales and their calves a fighting chance to carry on as nature intended.
Leave a Reply