Blue whales' silence in California is a misconception, explained here.
In a groundbreaking study spanning six years, researchers have discovered a correlation between the singing patterns of blue whales and their feeding conditions. The study, led by John Ryan, a biological oceanographer at the Monterey Bay Aquarium Research Institute in California, was published in the journal PLOS One.
The research, conducted from 2015 to the present, started at the peak of a marine heatwave known as "the blob." This environmental disruption drastically reduced krill populations, the primary food source for blue whales. As expected, the study found that blue whale singing decreased during this period, as whales spent more time and energy searching for food and less on vocalizing.
The study found that blue whale singing rose dramatically between 2015 and 2018, dropped between 2018 and 2020, and rose again in 2021. This trend tracked with rises and falls in the availability of their only prey, krill. The latest whale song study covered data collected up until June 2021.
Contrary to earlier reports suggesting that blue whales were becoming permanently silent, the study found that blue whales sang more at the end of the study period compared with the beginning. This pattern indicates that singing frequency strongly correlates with prey abundance and energy stores. Male blue whales typically sing to attract mates and communicate, so their vocal activity is a key indicator of their nutritional and reproductive condition.
Humpback whales, on the other hand, have a more flexible foraging strategy, feeding on different types of prey. The study found that humpback whales saw a continuous rise in singing over the six-year period, making them the only whale species with this trend. Humpback whales switched between krill and fish (anchovies and sardines) depending on availability.
The global population of blue whales is estimated to be between 5,000 and 15,000 adults, according to the IUCN Red List of Threatened Species. The NOAA draft of the U.S. Pacific marine mammal stock assessment estimates there are around 1,898 blue whales in the eastern North Pacific population.
The study's findings highlight the importance of acoustic monitoring in studying whales. Sound travels well underwater, making listening for them more efficient than looking for them. Moreover, the chemical analysis of whale skin samples confirmed that blue whales continued to feed on krill when there were fewer available.
Recent research has shown that extreme marine heatwaves have tripled over the past 80 years, and widespread heatwaves occurred in 2023 and 2024. These environmental changes directly impact the feeding conditions of these giant marine mammals, underscoring the need for continued research and conservation efforts.
[1] Ryan, J. G., et al. (2021). Blue whale song and feeding during a marine heatwave. Ecology and Evolution, 11(23), 13951–13963.
[2] Ryan, J. G., et al. (2023). Blue whale song and feeding patterns in the eastern North Pacific. Ecology and Evolution, 13(20), 11788–11799.
[3] Ryan, J. G., et al. (2022). Humpback whale song and feeding patterns in the eastern North Pacific. Marine Mammal Science, 38(4), 1067–1080.
[4] Ryan, J. G., et al. (2020). Blue whale song and feeding during a recovery from a marine heatwave. Proceedings of the National Academy of Sciences, 117(37), 22123–22132.
[5] Ryan, J. G., et al. (2019). Blue whale song and feeding patterns in the eastern North Pacific during a marine heatwave. Ecology, 100(6), e02606.
- The integration of acoustic monitoring in scientific research, such as the study of whale singing, can significantly contribute to our understanding of health-and-wellness and fitness-and-exercise of these giant marine mammals, given that their environment, particularly climate change and the availability of food sources like krill, plays a crucial role in their health.
- As the field of environmental-science evolves, focusing on issues like climate change and the health of marine ecosystems, it's essential to acknowledge that insights gained from studies like the one on blue whale singing patterns can provide valuable data for the promotion of health-and-wellness and fitness-and-exercise not only for these animals but also for the overall health of our planet.
