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Replacement of Cockle Creek bridge

09/07/2014

Visitors to Cockle Creek in Tasmania's Far South are advised that the Cockle Creek bridge will be closed from approximately 14 July to the end of August 2014, while the old bridge is removed and a replacement bridge is constructed.More

Firewood theft can be costly

08/07/2014

The Parks and Wildlife Service (PWS) is warning that unlawfully cutting trees for firewood on reserved land can be a costly exercise and that remote cameras are being used to catch offenders.More

Caretakers wanted for island's historic site

08/07/2014

Fancy spending a few weeks at the fascinating Quarantine Station on Bruny Island? The Parks and Wildlife Service (PWS) and Wildcare Inc Friends of Bruny Island Quarantine Station are seeking volunteer caretakers for the station for the 2014/15 summer.More

Whales


Seen a whale?  Call the Whale Hotline

  • 0427 – WHALES
  • (0427 942 537)

Call this number to report: whale sightings in Tasmanian waters, whale or dolphin strandings, injured whales, dolphins or seals, strange or unusual marine mammals and turtles.

Humpback whale

Our attitudes towards whales have undergone a massive change in the past few decades. Growing worldwide concern for these gentle marine creatures has fuelled the transition from a commercial exploitation that severely depleted the global population of large whales to an almost universal ban on whaling. Today, a rapidly growing tourist industry provides people with the opportunity to see these remarkable animals in their own environment, while instances of mass strandings bring great public support in efforts to return the animals to the sea. (See our page on whale strandings - how you can help)

Biology

Whales, of course, are mammals. Like their land-based relatives, whales are warm-blooded, breathe air and suckle their young on milk. Some species possess hair, particularly around the mouth, but in most species hair has been lost to minimise drag. Whales and dolphins belong to a group of mammals collectively known as cetaceans and are believed to share a common ancestry with the ungulates, a diverse group of hoofed mammals that includes modern-day horses, pigs, sheep, deer, antelopes and camels. Their land-based ancestors adopted a marine existence over 50 million years ago.

Cetaceans are divided into two groups -- the baleen whales and the toothed whales. The toothed whales, as their name suggests, use teeth for feeding, possess only one blowhole opening and have asymmetrical skulls. Baleen whales use baleen (a rigid, keratin-like material similar to our fingernails) which hangs in vertical strips from the upper jaw. Baleen acts like sieves to filter out the tiny crustaceans (krill) on which they feed. Large whales, such as the humpback, can consume over two tonnes of krill each day.

A number of feeding strategies are used to maximise the intake of krill. A remarkable example is the 'bubble-netting' behaviour of the humpback whale, in which the animal expels a stream of bubbles from the blowhole while slowly ascending in a spiral to the surface. The bubbles form a cylindrical wall which surrounds the krill and traps them. The whale then swims upwards through the cylinder with its mouth open, consuming the concentration of krill.

Adaptations to the marine environment

Many aspects of cetacean biology reflect their adaptation to the marine environment. Increased size and the development of a thick, insulating layer of fat, or blubber, allows whales to maintain a constant body temperature despite the cold environment in which they often live. The buoyancy provided by water has led to decreases in bone density and a reduction of supportive tissues for internal organs. Because of this, large, stranded whales are in a perilous situation. Their bones can break easily and damage can occur to internal organs due to increased pressure. Whales must come to the surface to breath, although species such as the sperm whale have been known to remain submerged for over 1 1/2 hours and dive to depths in excess of two kilometres. The blow of a whale is the result of expired air (not water) and an oily residue secreted from the lining of the windpipe being forced out through the blowhole. The particular size and shape of the blow can be used as an aid to identification of the species.

Most species of toothed whale are able to use echolocation to form what is effectively a mental picture of their surroundings. These whales produce pulses of very high frequency sound which strike objects and return as echoes. From these echoes, the animal is able to gain detailed information on the size, shape, distance, and even texture of the objects around them. It is believed that the spectacular behaviour known as breaching also serves as a means of communication. Whales such as the humpback often smack the surface of the water with their tail to warn of danger.

Whale Song

The vocalisations made by some species of whales, notably the humpback whale, are often referred to as whale song. Among humpback whales, only the male sings, and only on calving grounds and only in the mating period. The song is similar within single populations, but varies between populations. Although we have no clear understanding of the purpose of whale song, it is likely a part of sexual behaviour.

  Listen to a small portion of the song of a humpback whale (Recording courtesy of Cath Samson).

Cetaceans in Tasmanian waters

The most frequently seen cetaceans are the common and bottle-nosed dolphins. Among the larger species of baleen whale, southern right whales and humpback whales can be seen at east coast vantage points such as Frederick Henry Bay and Great Oyster Bay. While most species migrate some distance off the continental shelf, the humpback and southern right whale come sufficiently close to the coast to allow regular sightings from land. Humpbacks travel northward to breeding areas off the coast of Queensland and Western Australia between May and July and return southward to their sub-antarctic feeding grounds between September and November.

Southern right whales travel north from June to September to the waters of southern mainland Australia and return southward between September and late October. A proportion of the population gives birth in Tasmanian waters. Most sightings occur on the east coast. Although this may be simply a consequence of the higher population of human observers in the east, it is likely that the humpback and southern right whales prefer the calmer waters of the east coast.

Whale watching is one of Tasmania’s most popular tourist activities, and many companies offer chartered trips that provide intimate encounters with these animals. However, although whales may commonly appear placid at sea, and dolphins often initiate contact with humans directly, it is important not to disturb cetaceans by approaching closely. Whales and dolphins are particularly vulnerable to damage from hull and propeller strikes on motorised vessels, and due to their size, accidental contact with human powered craft such as sea-kayaks, or with swimmers could potentially result in serious outcomes. In addition to the obvious collision risk the acoustic disturbance from engines, hull noises and disturbance of the water close by may alarm and disorientate animals, particularly if juveniles are present. This is especially important for southern right whales, as they have only recently begun breeding again in Tasmanian waters following their near extinction from whaling activities.

A minimum approach distance of 100m when encountering any cetacean species is recommended.

Research

The Biodiversity Conservation Branch of DPIPWE is currently assisting in research into the recovery of the southern right whale. Along with many other species, the southern right whale suffered massive population declines during the years that commercial whaling ventures operated in Australia, with an estimated 26 000 individuals taken from southern waters of Australia and New Zealand. Today, only some 2, 400 southern right whales migrate to the southern waters of Australia, but numbers are increasing.

The stranding record provides an indication of the species that occur in Tasmanian waters. Some species have been recorded only once and have never actually been observed alive in Tasmanian waters.

Further information on why whales strand, and what you can do to help, can be found here. The following table presents the Tasmanian stranding record to the end of 2010.

Tasmanian stranding record up to the end of 2010



Toothed Whales

Number of Stranding Events

Number of Stranded Individuals

Long-finned pilot whale

81

3441

Common dolphin

169

550

False killer whale

21

538

Sperm whale

87

533

Bottlenose dolphin

103

249

Strap-toothed beaked whale

31

35

Cuvier's beaked whale

22

23

Gray's beaked whale

22

22

Killer whale

10

18

Hector's beaked whale

6

8

Dusky dolphin

5

7

Pygmy sperm whale

6

7

Striped dolphin

2

7

Southern right whale dolphin

5

5

Andrew's beaked whale

4

4

Southern bottlenose whale

3

3

Arnoux's beaked whale

2

2

Blainville's beaked whale

2

2

Short-finned pilot whale

2

2

Spectacled porpoise

2

2

Pygmy killer whale

1

1

Risso's dolphin

1

1

Shepherd's beaked whale

1

1

True's beaked whale

1

1

Baleen Whales

Number of Stranding Events

Number of Stranded Individuals

Pygmy right whale

82

85

Minke whale

20

20

Humpback whale

14

14

Southern right whale

5

5

Blue whale

3

3

Fin whale

3

3

Sei whale

2

2

Bryde's whale

1

1

Further Information

There are numerous web sites with further information on whales. These include:

Other publications include:

Dalton, T. and Isaacs, R. (1992). The Australian Guide to Whale Watching. Weldon Publishing, Sydney.

Evans, P. G. H. (1987). The Natural History of Whales and Dolphins. Facts on File Publications, New York.

Tucker, M. (1989). Whales and Whale Watching in Australia. Australian National Parks and Wildlife Service.