In 1982, a dwarf minke whale was discovered swimming in a small ocean lagoon on Hook Reef in the Whitsundays.
At the time, the story of the whale made headlines and recently as Collections Manager at Museum of Tropical Queensland, I provided a recount of the whale’s story. If you missed The Saga of the Minke Whale on Hook Reef you can watch it on our YouTube channel here.
The story of the whale resonated with many people, generating more questions about minke whales, scientific procedures such as necropsies, the importance of the specimen and finally its significance to the Queensland Museum biodiversity collection.
WARNING: The following post contains scientific images that may be disturbing to some readers.
What is a minke whale?
Minke whales are the second smallest species of the baleen or “toothless” whales. They feed on small fish and tiny plankton by gulping large mouthfuls of seawater as they swim along.
The baleen is made of keratin and acts like a filter to trap the plankton. The whale takes a mouthful of water, then pushes the water back out through the baleen that hangs from the upper jaw, and the plankton (ie. krill and other small marine animals) remains in the mouth.
The dwarf minke whale occurs only in the Southern Hemisphere. They grow to 7-8 metres long and weigh 5-6 tonnes.
The annual migration
In the summer (December – March), dwarf minkes reside close to the South Pole (i.e. sub-Antarctic) and in the winter they make an annual migration north to warmer waters. They are frequently sighted around Australia, Africa and South America.
Annual migrations to the northern Great Barrier Reef are so regular that scientists and tourism agencies can predict the movements of dwarf minkes off the east coast of Australia. This is the only known predictable aggregation of dwarf minkes in the world, and it creates excellent research and whale watching opportunities.
The James Cook University Minke Whale Project (http://minkewhaleproject.org/) conducts long-term studies on minke whale populations, biology and behaviour, social and economic values of minke whales, and sustainable management of the associated swim-with-whales tourism industry.
The whales typically do not feed on the northward journey, and they give birth to calves along the way. The calves are about two metres long and weigh 300 kg at birth.
After 3 months swimming around the small lagoon on Hook Reef, the whale died of natural causes and the body was taken by researchers to the nearby Butterfly Bay on Hook Island in the Whitsundays. Here scientists from Museum of Tropical Queensland and James Cook University promptly performed a necropsy.
A necropsy is another term for autopsy and is an examination of an animal’s body to establish how it died. No definite cause of death was ever determined for the whale. There were signs of starvation, which was not surprising after months of minimal feeding. To this day, why she chose to stay in the small lagoon with minimal food, has never been understood.
The scientists collected a full set of measurements, which were later published in several research journals. You can review these results here.
Also collected for scientific study were the gut contents, for research on diet and feeding behaviour, parasites, and the entire skeleton of more than 100 individual bones.
The skeleton was cleared of flesh as much as possible then transported to James Cook University in Townsville where they began the long, labour-intensive process to fully clean the bleeding bones. This included soaking them in a large swimming pool, hand scrubbing and bleaching them.
The unique specimen
This minke whale skeleton is the largest specimen in the marine biodiversity collection at Museum of Tropical Queensland.
There are three types of minke whales – northern (or common) minke, Antarctic minke and dwarf minke.
The dwarf minke is thought to be most closely related to the northern minke (Balaenoptera acutorostrata), though it is smaller and has distinctly different colouration with white flippers and shoulders.
The dwarf minke whale is yet to be formally described by the scientific community. If we describe the species based on this specimen, it will then become known worldwide as the ‘holotype’ – the single specimen upon which the concept and description of the species is based.
Images 1-6: Copyright: Commonwealth of Australia (GBRMPA), Photographer: Len Zell