basically, when the whales numbers were low back in the 60s, whales had to switch to a higher frequency in order to attract mates…but now that the numbers are rebounding and there are more blue whales, they have switched back to a lower frequency
Blue Whales Croon A New Tune
In other words, the guys had to shout to be heard. But now that blue whales are more numerous, Hildebrand thinks the males have gone back to singing bass because it makes them sound bigger and more attractive to females. He says males of many species use lower tones to attract mates.
