Feeding junior without the female eating herself is hard to comprehend. The mother is capable of producing up to 600 litres (or three 44 gallon drums) a day and the calf's daily growth-rate is between 45 and 60 kg!
The milk is squirted directly into the calf's mouth and often whale watchers can see from the calf's behaviour pattern, that it is being fed. Mum and calf will dive down and whilst the female stays there for half an hour, junior returns to the surface after 4 to 5 minutes (feeding) for a breath of air (maybe a burp), swim in a kind of a circle for 2 to 3 minutes and dive again for another feed.
Another interesting method of feeding has occasionally been observed by lucky whale watchers, where mum will position herself vertically, with her tail out of the water, for as long as twenty minutes to feed her calf. Just like a beacon. Is this to warn vessels of her presence and ongoing activity? For whale watch vessels it is important to keep their distance, when feeding takes place, but to wait generally proves very worthwhile. When mother returns to the surface and both start swimming away, often the calf will become playful and start breaching. As the whale watch operators get more familiar with the behaviour patterns of mother and calf pods, they will also become more accurate in their predictions of what may happen next.
Often one vessel will advise another vessel, as it approaches a pod: stay with them, they will be "good value".
The female continues to feed the calf for up to twelve months. This is roughly the time, that they return to the warmer waters, the following year. It is believed that Humpback whales can reach an age of fifty years, perhaps even more, but this of course was seldom reached during the years of commercial whaling.