Blue Whales Silent: Caused by Food Crisis and Noise Pollution?

Liputan6.com, Jakarta Blue whales, the largest mammals on Earth, are now facing a worrying phenomenon: they are vocalizing less than before, as reported by The Independent.

Scientists have highlighted a significant decline in the vocalizations of these giant marine animals, a behavioral change that indicates serious problems in their habitat.

According to research published in the journal PLOS One, the primary causes are a severe food crisis and increasing anthropogenic noise pollution in the oceans.

Six years of acoustic data collected from the seabed off the coast of California provide clear evidence of this drastic change.

This situation is a warning sign for the health of the marine ecosystem as a whole.

Biological oceanographers like John Ryan of the Monterey Bay Aquarium Research Institute explain that the whales have stopped singing because they are forced to expend all their energy searching for food.

“When you really break it down, it’s like trying to sing while you're starving,” John Ryan, a biological oceanographer at the Monterey Bay Aquarium Research Institute told National Geographic.

“They were spending all their time just trying to find food.”

One of the main triggers for the recent phenomenon is a scarcity of food source, according to the journal.

Blue whales rely heavily on krill and anchovies as their primary diet, but populations of these prey items have declined drastically.

Without an adequate supply of krill, blue whales struggle to obtain sufficient nutrition to survive and function normally.

This food shortage was exacerbated by an unprecedented marine heat wave known as "The Blob."

In some places the ocean temperatures were more than 4.5 Fahrenheit above average due to the heating.

The Blob grew and covered a 500 mile wide and 300 feet deep region in the Pacific Ocean.

By 2016, it covered approximately 2,000 miles of the Pacific Ocean.

Significant increases in seawater temperatures disrupted and even eliminated krill and anchovy habitats in some areas.

The marine heat wave not only reduced food availability but also triggered toxic algal blooms.

These algae poison the marine food chain, increasing stress on the ecosystem and indirectly affecting the health of blue whales.

As a result, blue whales must expend more energy foraging, reducing the time and energy available for vocalization.

John Ryan, a biological oceanographer, suggests that starving blue whales will shift their focus.

They would "expend all their energy searching" for food, reducing previously important vocal activity.

This explains why blue whale vocalizations declined by nearly 40 percent following the collapse of krill and anchovy populations.

In addition to the food crisis, anthropogenic noise pollution also plays a significant role in the phenomenon.

Human-made ocean noise, such as from shipping activities, sonar use, and oil drilling, has increased dramatically in recent decades.

These sounds create a noisy and disruptive acoustic environment for marine life.

Blue whales are known to be highly sensitive to noise in their environment.

Unlike some other species that may increase the volume of their calls, blue whales tend to become silent.

They reduce their calls or even change their migration routes when ambient noise overwhelms their sonic environment, indicating a significant stress response.

This disruption in communication has serious consequences, especially during the mating season.

Vocalization is crucial for males to attract females and ensure reproductive success.

Reduced vocal activity can lead to less successful matings and, ultimately, a decline in the growth of already threatened blue whale populations.

Studies show that blue whales do not increase the volume of their calls in response to ship noise, making them highly vulnerable to disturbance.

This silence is not a choice, but rather an adaptive response to an environment that no longer supports their natural communication.

The phenomenon of "blue whales going silent" is more than just a single species issue; it signals an urgent danger to the health of the entire marine ecosystem.

Blue whales serve as ecosystem sentinels, and their calls are important indicators of food availability, stress levels, and habitat disturbance in the ocean.

Tracking their vocal behavior provides real-time insights into ocean conditions.

The silence of blue whales indicates that the entire marine system is under extreme stress.

There are ecosystem-wide consequences from marine heatwaves and increasing noise pollution.

This could signal a decline in biodiversity and deeper environmental damage, potentially irreversible if not addressed urgently.

Broader impacts include potential disruptions to the carbon cycle and complex marine food web.

The duration of marine heatwaves has tripled since the 1940s, demonstrating a worrying trend.

The silence of blue whales may be one of the clearest indicators that our oceans are reaching a tipping point due to climate change.