Pygmy blue whalethe (Balaenoptera musculus ssp. brevicauda) Audio recordings collected over a decade and a half were analyzed by an Australian research group from the University of New South Wales, and the Frontiers in Marine Sciences His results were recently published in a journal.
The pygmy blue whale is a subspecies of blue whale that, instead of having a body length of 32 metres, grows “only” to 25 metres. This subspecies is native near Australia and travels seasonally in the eastern Indian Ocean. For 16 years, underwater microphones have continuously recorded whale songs that indicate their presence, so the data has been available long enough to find identifiable behavioral trends through analysis of the songs. The researchers were confident that changes in the environment would be reflected in the associations found.
It turns out that the amount of singing that is heard varies from year to year, and that whales sang more during La Niña years, indicating that climate greatly influences the migration of blue minke whales.
La Niña is a state of climate oscillation in the Pacific Ocean, when the sea surface is cooler, and this affects sea behavior and global weather. The area has recently recovered from a La Niña period of about 3 years.
“We found that the number of songs detected depends on when La Niña occurred and how severe it was, suggesting that it may be an important factor in whale migration,” said study leader Gary Truong. “We came to the conclusion that the number of songs detected in La Niña years can be up to ten times the number of songs in El Niño or neutral years. This indicates that whales respond to climate cycles.”
The whale song was recorded by an underwater microphone system whose primary mission is to monitor the non-nuclear nuclear treaty, courtesy of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). The voice of a pygmy blue whale has a frequency of less than 100 Hz, which is not audible to the human ear, but these microphones detect it well. If more whale sounds are recorded, this indicates that more animals are migrating and therefore their reproduction may be more successful. Although the species has come back from the brink of extinction due to whaling, its numbers are increasing very slowly.
Climate change affects the amount and type of food available to whales, so observing their migration, even with the help of their songs, provides data on this. the past The researchers will analyze the data from the La Niña years again, in greater detail, in the hope that they can learn more information about the relationship between dwarf blue whale behavior and climate.
