Dwarf Minke Whale Biology

LIFE HISTORY

Dwarf minke whales mature at a smaller size than Antarctic minke whales. Females as small as 6.4m long may be sexually mature (whereas female Antarctic minkes are not mature until about 8m in length).

We don't know where dwarf minke whales mate. If its timing is the same as that of the Antarctic minke whale, the breeding season of the dwarf minke whale probably peaks in August-September. There are fewer sightings of dwarf minke whales on the northern Great Barrier Reef at this time but we do not know whether this is because most whales have left the area or whether they just approach vessels and swimmers less frequently.

We have no information for dwarf minke whales, but in other minke whales births are thought to occur about 10 months after conception.

Calves of dwarf minke whales are about 2m long at birth, distinctly smaller than in the other forms of minke whales. There does not appear to be a distinct calving area. Strandings of newborn or very young animals have been recorded from near Melbourne, Victoria to Fraser Island, in southern Queensland on the east coast, and around Perth on the west coast of Australia. However, we have seen very young dwarf minke whales at reefs north of Port Douglas so the calving area may be extensive.

In other minke whales, the calves suckle for only a short time, with weaning at about 4-6 months.

The breeding cycle of other minke whales is just over a year, which is more rapid than the larger baleen whales (e.g. humpback and right whales which may have 3-4 year breeding cycles).

POPULATION SIZE

This is unknown for any population of dwarf minke whales. The Action Plan for Australian Cetaceans considers it insufficiently known to assess its conservation status. The International Whaling Commission estimates the population of Antarctic minke whales as 761,000 (510,000 to 1,140,000) based on surveys during the 1980s. It is presently reviewing results of more recent surveys to provide an updated population estimate.

HUNTING

The dwarf minke whale was originally described by Dr. Peter Best in 1985, mainly based on animals examined at the shore whaling station in Durban, South Africa. However the number of dwarf minke whales taken was small and they were probably generally ignored by whalers because of their small size. There were no confirmed records of dwarf minke whales from Japanese and Russian commercial whaling in the Antarctic, although a few records (referring to whales with a white flipper band) might have been dwarf minke whales. In 1989 and the early 1990's, a small number of dwarf minke whales were harpooned at about 55-62°S, as part of the Japanese scientific whaling program. This is further north than the main commercial whaling grounds which may, with the small size of dwarf minkes, explain why they apparently escaped the attention of commercial whalers. At present, there appears to be no commercial whaling for dwarf minke whales and they have not been taken as part of the Japanese scientific whaling program since 1993. Other forms of minke whales continue to be hunted, either through scientific whaling programs (in the Antarctic and northwest Pacific around Japan) or as commercial and/or and indigenous hunts (off Norway and Greenland).