Nicoletta Biassoni has written:

'Preliminary results of the effects of SURTASS-LFA sonar on singing humpback whales' -- subject(s): Humpback whale, Whale sounds, Monitoring, Effect of sound on, Vocalization, Environmental effects, Measurement, Sonar

vocalization

by vocalization and scent marking.

Whale sounds or whale vocalization consists of what are called "songs" -- strings of vocal sounds of varying frequency and length. These are not an actual phonetic language but are sounds associated with a concept, feeling, or intention. They are very similar to human vocal music, or singing.

(see the related link for more information)

Yes ... a secondary function.