Whale Songs Soar As Ocean Food Sources Flourish

Quick Smiles:

• Whale songs have nearly doubled as food sources have become more plentiful.
• Researchers use underwater microphones to track the songs of baleen whales.
• Humpback whales show adaptability by switching between different prey.

Eavesdropping on the melodic tunes of whales over the past six years has unveiled intriguing insights into these magnificent ocean dwellers.

Scientists in California have discovered that the frequency of whale songs is linked to the availability of their food sources, with the days humpbacks are heard singing nearly doubling.

Dr. John Ryan, a biological oceanographer, explains that monitoring these large marine animals in the vast oceans poses a “major challenge” for ecologists.

To tackle this, the team deployed underwater microphones, known as hydrophones, to study and track baleen whales, which communicate over long distances through sound.

“Surprisingly, the acoustic behavior of baleen whales provides insights about which species can better adapt to changing ocean conditions,” said Dr. Ryan, who led the study.

The researchers monitored the songs of blue, fin, and humpback whales off the U.S. West Coast to assess what these vocalizations could reveal about the ecosystem’s health.

Published in the journal PLOS One, the findings showed “large” year-to-year variations in whale song detection.

“The amount of humpback whale song continually increased, with their songs being detected on 34% of days at the beginning of the study and rising to 76% of days after six years,” said Dr. Ryan.

These increases were in sync with improved foraging conditions for humpback whales, marked by “large increases in krill abundance, followed by large increases in anchovy abundance.”

In contrast, blue and fin whale songs surged primarily during years when krill numbers rose.

“This distinction of humpback whales is consistent with their ability to switch between dominant prey,” Dr. Ryan noted.

An analysis of skin biopsy samples confirmed dietary changes in the whales.

He further explained that while other factors, such as local whale abundance, may have influenced song detection patterns, changes in foraging conditions were the most consistent factor.

“Overall, the study indicates that seasonal and annual changes in the amount of baleen whale song detected may mirror shifts in the local food web.”

The results suggest that understanding the link between whale song detection and food availability might help researchers interpret future hydrophone data, aiding both scientific research and whale management efforts to protect endangered species.

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