Minke Whales

Antarctic Minke Whale, Balaenoptera bonaerensis and Dwarf Minke Whale, Balaenoptera acutorostrata subs x

Antarctic Minke Whale, Balaenoptera bonaerensis

This whale differs from the Dwarf in the following ways;

It is around two metres longer. It has a light grey flank patch which extends up the back to just in front of the dorsal fin. Although it can have two tone flippers it does not have the noticeably white flipper and shoulder patch of the dwarf. It has a visible blow unlike the dwarf’s fainter and sometimes invisible one. The dorsal fin it set further back and relatively shorted due to body size.

These whales are also very difficult to tell apart from Bryde’s whales in Algoa Bay especially at distance. This is further confounded by the sea conditions, which although maybe good for whale watching are not always good for identification purposes. They are four metres shorter than the Bryde’s whales and only have a single longitudinal ridge and pointed rostrum whereas the Bryde’s has three ridges.

The adults average nine metres although the largest recorded was 10, 7 metres. The can weigh up to nine tons and live for forty years. Peak calving is in July and August after a gestation of ten months. There breeding areas do not seem that well defined and are more spread out than for other baleen whales. Average length at birth is 2, 8 metres and they are suckled for six months. The four metre specimen we found in the harbour must have been a young calf that did not make the migration back south.

They are found in our waters during winter when they come to calf in the more temperate waters. The Durban whaler usually caught them further than 60km from shore. In summer they head south to the Antarctic where they can be seen in feeding aggregations of many hundreds. Unlike their dwarf cousins they have no substantial fish component in their diet, although their presence in Algoa Bay must surely indicate that fish is also part of the menu? In Antarctica there diet is 100% krill while off Durban it also contains other euphausiids.

Once the large whale populations became depleted the whalers turned their attention to these smaller guys. Although around 100 000 of them perished on the end of whaler’s harpoons there is still some debate about the population size. Average estimate for the Southern Hemisphere stocks are around 600 000 while for the north 180 000.  The Norwegians and Icelanders are still hunting them. During 2018 I assisted pressure groups in Iceland trying to put a stop to this. It is a very complicated issue and will still take a while to resolve. The Japanese have been hunting them in the Antarctic under the International Convention for the Regulation of Whaling Permit. It states that any contracting government may “grant any of its nationals a special permit authorizing that national to kill, take and treat whales for purposes of scientific research”. Although the Japanese have stopped hunting them in the Antarctic as of last year, they are in seas closer to home.

Dwarf Minke Whale, Balaenoptera acutorostrata subs x

Once these whales get assigned to a species they will become the smallest rorqual and second smallest baleen whale after the Pygmy right whale. The largest measured was 7, 8 metres although the average is around five metres. They can live for fifty years. We do get Pygmies here in Algoa Bay as known from