Humpback Surprise

[This was written by Fran Siebrits and published online by Wild Magazine http://www.wildcard.co.za/, 2010]


Seeing as it is peak whale season, what better way to kick-off than with a new development on the research front of those gloriously magnificent mammals that roam the oceans!


As we all know, humpback whales (Megaptera novaeangliae) are seen around the South African coast when they are en route to feed in the polar waters or when they come to breed in the protected sub-tropical water. The cycle of these patterns has been known for years. Or so we thought …

The movement of past humpback migrations along our coastline has been comfortably predictable. They move between the warm waters of Mozambique and Angola to breed and calve as well as heading to the colder Antarctic waters to feed. This all takes place in May to November, peaking in spring (September/October) or what we call whale season. The rest of the time they live off their fat reserves.

Recent data from a study published earlier this year has thickened the plot quite a bit, though: whales no longer stick to the seasonality and behaviour previously expected during this time. Humpbacks have now started feeding in South African waters. This occurs from October to March, much later than the peak time of their southern migration.

Scientific research along the West Coast explains that this change may involve the humpbacks’ prey. It is suggested that the whales have a more flexible eating pattern than experts thought they formerly did.

Apparently, these whales have found something equally as tasty to snack on here that they don't have in the polar waters. The research shows that it's specifically the females that are driving this initiative for new treats. They have a greater need to feed at the first available opportunity if they are pregnant or nursing.

There is now research which shows that humpback whales no longer feed solely in polar waters in summer. They now snack off the South African coast while either moving between warmer waters to breed or as a stop-over on their way to the pole.

Mother Nature’s dominance over human intelligence is once again proved by this example. However, this doesn’t detract from the wonder which gathers crowds along the shoreline to get a glimpse of a fin, a tail or hopefully a full-on breech!

So, before the excitement is over, make your way to the coast for a humpback surprise.

Humpback Facts

• They are the most diverse of the baleen feeders. Their diet consists mainly of krill and small fish such as herring, pollock, haddock, salmon, sand lance, capelin and mackerel either They actively hunt by either attacking their prey or by stunning them when they hit their pectoral fins on the water. They mainly feed in summer, living off fat reserves in winter.
• They range in length from 12-16 metres.
•  The males have a complex whale song which can last up to 20 minutes and is often repeated for hours on end.
• They migrate anything up to 25 000 kilometres a year.
•  Recreational activities include breeching.
Creative capturers: they swim in a circle below their prey, say a school of small fish, blowing bubbles which rise up in a 'net' effect around the school. Once the school is contained, they swim up with mouths agape to capture their 'herded' prey. This technique is known as bubble net feeding.

Migration redefined? Seasonality, movements and group composition of humpback whales Megaptera novaeangliae off the west coast of South Africa
Authors: J. Barendse; P. B. Best; M. Thornton; C. Pomilla; I. Carvalho; H. C. Rosenbaum
Published in: African Journal of Marine Science, Volume 32, Issue 1, June 2010, pages 1 - 22