Noise pollution is increasingly disrupting whale migration

A new study by the University of Melbourne and Politecnico di Torino reveals the damaging impact of noise pollution on whale migration.

The research shows that noise pollution created by shipping, sonar, seismic exploration (used for resource extraction), and offshore construction are disrupting and confusing whales. This causes significant delays in their migrations and can even lead them off course.

Communication in whales

Whales communicate using a fascinating array of sounds, including moans, clicks, and songs. These sounds vary widely among different species and can serve many purposes, such as navigating through dark or murky waters, finding food, attracting mates, and maintaining social connections within their pods.

Songs and calls

Some whale species, like the humpback whale, are known for their complex songs, which can last for hours and are believed to play a role in mating rituals and asserting dominance. Each song consists of sequences of moans, howls, cries, and other vocalizations, which can travel vast distances underwater.

Echolocation

Toothed whales, including dolphins and sperm whales, use echolocation to navigate and hunt for food. They emit a series of high-frequency clicks that bounce off objects and return as echoes, allowing the whale to determine the location, size, and even the internal structure of objects.

Social sounds

Whales also make a variety of other sounds to communicate with each other, such as grunts, barks, and groans. These sounds are essential for maintaining social bonds, coordinating activities among group members, and conveying information about their environment or emotional state.

The ability to produce and perceive these sounds is crucial for whales’ survival, making them highly sensitive to noise pollution in the oceans, which can interfere with their communication.

Noise pollution near whales

“[The] simulation study suggests that the current soundscape for whales – compared to pre-industrial conditions – might be causing a three-to-four-day delay in migration arrivals, representing an extra 20 percent in travel time,” said study co-author Dr. Stuart Johnston.

Even more concerning, the simulation revealed that if noise levels continue to rise, some whales may never even reach their destinations.

How noise pollution impacts whales

Noise pollution is impacting whale migration in the following ways:

Decreased communication range

Whales sing and call to each other over vast distances. Noise pollution reduces this range, making it harder for them to find partners, stay together in groups, and avoid dangers.

Finding Partners

Whales rely on their complex songs and calls to attract mates over long distances. Noise pollution shrinks the area where those songs can be heard, making it harder for potential partners to connect. This can limit breeding opportunities and reduce the genetic diversity of future generations.

Staying together

Pods, or social groups of whales, use sound to stay coordinated and organized. Noise interference limits their ability to communicate effectively for hunting, navigation, and protection from predators.

Avoiding dangers

From loud ships to other threats, whales communicate warnings and alerts. Reduced communication range means they may not hear critical alarm calls in time, leading to collisions, pod separation, or stranding.

Stress response

Loud, persistent noise causes whales stress. Chronic stress can affect their health and make them more susceptible to beaching or stranding.

Physiological impact

When exposed to loud or chronic noise, whales experience a stress response that releases stress hormones. Over time, this constant stress can weaken their immune systems, impact their ability to reproduce, and put them at higher risk for disease.

Behavioral changes 

Stress from noise can make it difficult for whales to rest, find food, and perform vital behaviors. This disruption can lead to altered migration patterns or even force them to abandon important habitats.

Beaching and stranding

While the direct link between noise and strandings is complex, chronic stress and disorientation caused by noise pollution are considered contributing factors that can put whales at an increased risk of becoming beached or stranded.

Noise pollution masks whales natural cues

Many whales use sounds from their environment to understand their surroundings and navigate. Noise makes these signals harder to hear – affecting their ability to chart their migration routes.

Ocean landmarks

Natural sounds like crashing waves, distant storms, and the breaking of icebergs help whales create a mental map of the ocean. Noise pollution masks these vital acoustic cues, making it far more difficult for them to determine their location and direction.

Finding food sources

Some whales rely on echolocation to hunt or detect schools of fish. Noise pollution can disrupt this intricate process, limiting their ability to secure enough food to survive, particularly for long migrations where they need to build energy stores.

Veering off course

What does it actually mean for whales when their environment is too noisy? “Whales will avoid uncomfortable environments when there is significant noise, and this could lead to increased journey time or even failure to arrive,” explained Dr. Johnston.

Whales migrate vast distances between feeding grounds and warm waters where they have their calves. They’re on a tight schedule. Increased journey time means less time to reproduce, feed, and nurture young – putting their populations in danger.

For many whale species, reproduction is tied to specific locations and times of year. Delayed migration caused by noise pollution can lead them to arrive at breeding grounds outside the optimal window. This reduces their chances of encountering potential mates and successfully reproducing.

Migration demands a lot of energy

Furthermore, whale migrations are incredibly demanding, requiring whales to build up significant energy reserves beforehand. Extra travel time due to noise disrupts this crucial preparation phase. Whales may arrive at feeding grounds weakened and struggle to find enough food to replenish their energy stores or nourish their young.

The warm waters reached at the end of migrations provide a safe haven for whales to give birth and raise their calves. Delayed arrival due to noise pollution shortens the amount of time available for these critical activities. This can impact the health and survival of newborn calves, jeopardizing future generations.

Successful reproduction and healthy calf survival are essential for whale populations to thrive. Delays and disruptions caused by noise pollution can lead to population decline over time.

Urgent need for change

“These incredible animals journey up to 10,000km each year during migration – it’s a huge investment of time and energy. We must find a solution within the shipping and construction industries that don’t come at the cost of whale activity and breeding,” said Dr. Johnston.

As human activity in the oceans continues to rise, science-based decisions are critical to protect whales and the fragile balance of marine ecosystems.

Pressing pause on noise pollution

Ocean noise pollution is a problem we can solve. Now that we understand the negative impacts, we can work towards quieter ships, better construction methods, and more careful exploration techniques to preserve the whales’ acoustic environment. They rely on a quiet ocean to thrive, and ensuring that is a responsibility we share.

• Quieter ships: Designing ships with modified propellers, improved hull insulation, and other advancements can significantly reduce the amount of noise they produce. Additionally, simple actions like lowering vessel speeds in known whale habitats can make an immediate difference in reducing noise levels.
• Improved construction methods: Offshore construction for wind farms, resource extraction, and other purposes often involves noisy activities like pile driving. Exploring alternatives like vibratory pile driving (which is quieter), or scheduling such activities outside of crucial whale migration periods, can greatly lessen the impact.
• Responsible exploration techniques: Seismic surveys for mapping the seafloor or searching for resources frequently utilize loud air guns. Researchers are exploring marine vibrators, which create a less disruptive type of sound wave. Being mindful of the timing and location of these surveys is crucial to minimizing harm to whales.
• Collective responsibility: Addressing ocean noise pollution requires collaboration among governments, industries, and researchers. Implementing regulations, investing in quieter technologies, and making conscientious choices about ocean development are vital steps towards protecting the delicate acoustic environment of marine life.

The study is published in the journal Movement Ecology.

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