Blue whales are loud. According to the National Oceanic and Atmospheric Administration, they are some of the loudest animals on the entire planet.
However, something is changing.
A study from earlier this year found that endangered whales’ songs have been detected less often than usual in recent years. It was published this February in the PLOS journal and authored by researchers from the Monterey Bay Aquarium Research Institute (MBAR). According to NOAA, blue whale pulses, groans, and moans can be heard by other whales up to 1,000 miles away. Scientists believe whales may use these sounds to communicate.
“The team found that the lowest levels of both blue and humpback whale songs were detected during the 2015 climax of a major marine heat wave,” said a press release from the MBARI regarding the new research. “While song detection for both whale species increased similarly over the next few years, it diverged after the third year of the study – humpback whale song detection continued to rise while blue whale song detection fell for two consecutive years.”
Humpback whales and blue whales are both types of baleen whales, a type of whale known for “singing” that includes rhythmic, structured arrangements of sounds, said MBARI. Though they are loud, blue whales have a very low pitch and humans can only hear them with special devices. In 2022, researchers from MBARI found that blue whale sounds indicated that the whales respond to changes in the wind or “dance with the wind” to track plumes of krill.
For the new study of humpback and blue whale sounds, the MBARI researchers “looked at variations in the intensity and persistence of blue and humpback whale songs over six years.” During this study period, NOAA fisheries noted that abundance of food sources for the whales (krill and fish) varied dramatically. Blue whales rely only on krill, while humpback whales also eat fish.
“As the ocean changes, some species will be more affected than others,” said John Ryan, a biological oceanographer who leads MBARI’s Ocean Soundscape Team and was the lead author of this new study. “Compared to humpback whales, blue whales in the eastern North Pacific may be more vulnerable due to not only a smaller population size but also a less flexible foraging strategy. These findings can help scientists and resource managers predict how marine ecosystems and species will respond to climate change.”
Blue whales are found in all oceans except the arctic and they typically migrate in different seasons. They are seen off both coasts of the U.S. These whales can live for 80 to 90 years, but they are vulnerable to vessel attacks, hunting, climate change and more. Per the International Fund for Animal Welfare, blue whales are the largest animals on Earth and they are listed as endangered by the IUCN Red List, but numbers of them have been increasing.
Earlier this month, the Marine Mammal Stranding Center said in a press release that another type of baleen whale, a minke whale, was found at Double Creek Channel in Barnegat Bay off the New Jersey coast. A necropsy revealed that the whale was thin, with external cuts, bruising to its blubber and muscle and blood in its lungs. In June, NOAA fisheries also reported that gray whales – yet another type of baleen whale – have had a continued low calf count since an unusual mortality event in 2023.