Dwarf Minke Whale Biology

• Summary
• Colour Patterns/Field Characters
• Anatomy
• Size
• Behaviour
  • Surfacing Behaviour
  • Underwater Behaviours
• Disturbance
• Feeding
• Diving
• Sounds
• Distribution
• Migration
• Life History
• Population Size
• Hunting
• Scientific Names
• Individual Recognition
• Classification
• List Of References
• Acknowledgements
• Whale sighting sheet (Word document)

Summary

Scientific name: Balaenoptera acutorostrata (an as yet un-named subspecies)

Described by: Dr Peter Best in 1985

Size: to about 8 metres long

Distinctive characters: Flippers white at the base with a dark tip; white shoulder patch where flipper joins the body; dark patches extending in front of flippers onto the throat.

Distribution: Known only from the southern hemisphere. Recorded from South Africa, Australia, New Zealand, New Caledonia and eastern coast of South America during the months March to December. Scattered records from the sub-Antarctic during December to March.

Distribution on Great Barrier Reef: Recorded from March to October, but in the Cairns section about 80% of sightings are in June and July.

Feeding: Food includes oceanic fishes and krill (shrimp-like animals which form enormous schools). Not known to feed in Great Barrier Reef waters.

Life history: Calves about 2m long at birth. No definite calving grounds known. Newly born animals have been seen, mostly in April to June, from Victoria to southern Queensland (near Fraser Island and Lady Elliot Island). Young calves have also been seen on the northern Great Barrier Reef, but there are still few confirmed records there. Calves are probably weaned by 6 months of age. Longevity is unknown but other forms of minke whales may live for 60 years.

Behaviour: Active, highly manoeuvrable whales which can swim at 12 knots for at least short bursts and may dive to at least 140 metres. Most sightings are of a single or pair of animals, but groups of up to 25 whales may occur around a boat during a single encounter. Regularly breach (jump from water) on northern Great Barrier Reef. Regularly approach anchored or drifting vessels and may remain with the vessel and swimmers for several hours. They usually surface once for a breath and dive for periods from half a minute to nearly twelve minutes.

Sounds: grunts, moans and belches which can be heard by snorkellers; also a distinctive sound with 3 short pulses followed by a slight upsweep. The low frequency sounds can travel great distances underwater and may allow scattered groups of whales to maintain contact over kilometres or tens of kilometres. Minke whales are not known to echolocate but their sounds could be used to detect large objects (e.g. reefs).

Population size: unknown

Hunting pressures: Because of its small size, the dwarf minke whale was rarely taken by commercial whalers. Japan wishes to resume hunting the larger Antarctic minke whale in the southern oceans. If such whaling were to resume it is possible that dwarf minke whales would also be taken.