Two blue whales (Balaenoptera musculus), the largest mammals on Earth, were recently spotted off the Mangalore coast during a marine survey carried out by the Central Marine Fisheries Research Institute (CMFRI), Kochi.
They were sighted — a rare instance, say researchers — from the ocean research vessel Sagar Sampada, at a depth of 100 metres, from a distance of more than 130 metres said Anoop Balan, photographer and researcher associated with studying marine mammals in the Exclusive Economic Zone and contiguous seas.
Blue whales are not commonly sighted in the Arabian Sea. There have been no records of their presence there since 2003. They are mostly found in the deep waters off Sri Lanka, Dr. Balan said.
Live recording of blue whales are rare and the institute plans to step up observation following the spotting, said E. Vivekanandan, Principal Scientist of the Demersal Fisheries Division of the CMFRI in Chennai.
Quoting a report, Dr. Vivekanandan said a blue whale was killed in a suspected propeller hit recently.
Blue whales are long-distance migrants known to undertake long journeys in search of food and mating grounds. Recently, upwelling (an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water) was reported in the Malabar coast extending from Kozhikode to Mangalore, making the stretch abundant in fish and prawn varieties. The whales could have come in search of food. A few dolphins were also spotted during the period, Dr. Anoop said.
Dr. Vivekanandan said there was a possibility that blue whales were already present in the Arabian Sea. With new sightings, research activities in this direction needed to be strengthened.
The blue whales belong to the Rorquals family, which includes the humpback, fin and minke whales. Their skin is greyish blue with light grey mottling on the back. They can grow up to 33 metres in length and weigh up to 200 tonnes.
