THIRUVANANTHAPURAM: It was a chance discovery. Marine biologists were on the trail of Luban, a humpback whale. But in the process, they discovered the chorus of blue whales in Kerala waters!
It all started in 2018 when A Biju Kumar, head of Department of Aquatic Biology and Fisheries, University of Kerala, received a call from marine mammal expert Dr Dipani Sutaria, alerting him about the journey of Luban, a female humpback whale, which was tagged by the research team. The whale had reached the Kerala coast.
The journey began, to track Luban, through the satellite information sent from Oman. But Luban was faster and then after spending several weeks between Trivandrum and Kanyakumari, the mammal returned to Oman. To learn more, hydrophones were set up under the waters. And that’s how the song of the blue whales got recorded accidentally.
The only presence of a blue whale that was ever recorded from the Kerala coast was when a blue whale got beached. That was in 2019.
“It was only through DNA analysis that we could identify it as a blue whale. The new discovery opens up a lot of questions. There is a 90 per cent chance of the blue whale arriving here as part of its migration. The probability of a resident population is also there,” says Biju Kumar.
With the sound of the blue whales being captured from the waters of Kerala, a first-ever discovery proving that the big mammals are frequenting the waters, a new chapter has been scripted in the field of marine explorations. Now, scientists are geared up to dwell more on and explore the reasons for the arrival of the mammal, the population it belongs to and so on.
The research team which made this breakthrough involves marine mammal researcher Dipani Sutaria, researcher and marine mammal expert, Ahmedabad, and member, IUCN Cetacean Specialist Group; marine mammal researcher Isha Bopardikar; and A Biju Kumar, head, Department of Aquatic Biology and Fisheries, University of Kerala. The researchers, with the help of deep dive experts, installed the hydrophone to record whale sounds in March and collected the instrument back in June 2021.
The assumption is that blue whales, whose sounds were recorded belong to the pigmy blue whale population, which is found in the Indian Ocean, according to A Biju Kumar. “We have been trying to record the sound of migrating humpback whales and identify their presence in the waters. The sightings of the humpback whales have been found between Thiruvananthapuram and Kanyakumari. So the hydrophones were placed in the waters between Vizhinjam and Poovar. The hydrophones were taken out after three months.
“And after analysing the sound in June, we could listen to the calls of only blue whales. The sounds of two blue whales were identified and it was a foraging call,” says Biju Kumar. The whales produce different sounds for different kinds of communication, including socialising, foraging and mating. “The particular sound captured was the one used while foraging,” said Biju Kumar. The healthy population of shrimp in the waters must have been their food source, he says.
While the humpback whales are known for their characteristic high-frequency vocalisations, the blue whale songs are a series of short moans of low frequency. Whale sounds (composition of moans, snores, chirps and cries) are for different kinds of communication, including socialising, foraging and mating. The pattern of sound or moans varies from population to population, said Biju Kumar. The data from three months was collected and it was while analysing this that the sound of a blue whale was identified.
“The discovery is significant in that they are the largest animal on earth. It is an endangered species and its presence here is of academic interest. The time they migrate through the Kerala coast, their migratory route, population size are all of importance, “ Biju Kumar opined.