Researchers have recorded, reportedly for the first time from the waters off Kerala, the song of blue whales.
The recording was more or less serendipitous. A hydrophone deployed off Vizhinjam to capture the sounds of migrating humpback whales had instead recorded the call of the endangered blue whale.
The research team consisted of Dipani Sutaria, a marine mammal expert and member, IUCN Cetacean Specialist Group, and A. Biju Kumar, head, Department of Aquatic Biology and Fisheries, University of Kerala. Deployed with the help of deep-dive experts, the hydrophone had been retrieved in June this year. The study was locally supported by Kumar Sahayaraju, a marine biologist and resident of coastal Thiruvananthapuram.
Low-frequency moans
While humpbacks are known for their high-frequency vocalisations, blue whale songs are a series of short, low-frequency moans. Whale sounds (moans, cries, chirps and cries) are essentially communication tools, for activities such as socialising and mating. Call patterns can vary from population to population, Dr. Biju Kumar said.
So far, the presence of blue whales in the waters off Kerala have been reported through a few carcasses that beached. But the recording of their calls confirms their presence along this stretch of the western coast, he said.
Pygmy blue whales
Though the larger blue whale populations are found around Antarctica where krill, their favourite food, is available, the occurrence of pygmy blue whales is reported in the Indian Ocean.
“Research teams from the University of Kerala have identified several whales that beached on the Kerala coast earlier, including Bryde’s whale. A whale stranded at Valiaveli in 2019 was identified as a blue whale through DNA barcoding,” Dr. Biju Kumar said.
Divya Panicker, a doctoral student in oceanography, had recorded the blue whale song from the Lakshadweep waters.
