Sperm whales may take as much pleasure in singing well-timed duets as humans do. New underwater recordings have shown that the whales carefully coordinate their song to match the calls of their singing partner.Report here. Duets here and here.
On threats to cetaceans in general, Nicolas Entrup wrote back in August that:
We need a classification system and political action that is based on respect towards individual animals and focuses on the protection of marine mammals within their social units and their habitats.[Further reading includes ten books on whales recommended by Philip Hoare.]