Thirty-five species of seal inhabit the oceans of the world. They are found throughout the marine environment, from icy polar waters to the warm waters of the tropics. Much like whales and dolphins, seals are adapted to the marine environment with a streamlined body, limbs modified into flippers and a layer of blubber for insulation. They also have a specialised physiology system that allows them to sustain prolonged dives while feeding. However, unlike whales and dolphins, seals are not confined to the water but regularly come out of the water (haul-out) to rest, mate, moult and give birth.
See our pages on living with seals and seal viewing guidelines.
See also:
Management of Seals Onshore in Tasmania (421Kb)
A number of species occasionally visit our shores, however, only two species breed in Tasmanian waters.
The seals that breed in Tasmania are the:
Other seals that may be seen, or have been recorded, in Tasmania are:
Types of seals
Seals belong to the Order Pinnipedia. Pinnipeds are classified into three families:
- fur seals and sea lions (family Otariidae)
- the walrus (family Obdobenidae)
- 'true' seals (family Phocidae)
Otarid seals, also called 'eared' seals, include sea lions and fur seals. They have obvious external ears and large foreflippers, used for propulsion, which can be turned forward. They are able to bring their hindflippers underneath the body in order to walk or run, albeit somewhat awkwardly. Having flippers that bend forward also enables the otarid seal to "sit up" and lift its upper body from the ground and remain stable in this position. Fur seals have a well developed coat made up of long, coarse guard hairs overlying a thick, woolly underfur that traps a layer of air and insulates the animal. Sea lions have only one layer of fur.
Unlike Otarid seals, Phocid seals have no external ears or 'pinna'. Phocid seals are not as manoeuvrable. The hind flippers of the phocid seal extend behind the body and cannot be brought forward in order to walk. The hind flippers are used for propulsion. They raise themselves briefly from the ground but cannot maintain a sitting position like the Otarid seals. Instead, the Phocid seals are limited to movement when on land, crawling and wriggling, using their foreflippers for traction. The Phocid seal has a thinner coat, made of short, stiff guard hairs. In the absence of a thick coat, the Phocids have a thick blubber layer which provides most of the animal's insulation.
Foraging
While at sea, seals alternate between resting on the surface and foraging for food. Although the diet varies between species, seals generally eat fish, squid, octopus and crustaceans such as krill. When foraging, seals can leave haul-out sites for days, weeks or in the case of elephant seals, several months. They may also travel vast distances and swim to great depths in search of prey. Southern elephant seals, which feed in the cold sub-Antarctic waters, can dive to 1800 m for half an hour or more! Marine mammals have many adaptations which enable them to dive to such depths and to avoid the 'bends' when resurfacing after dives.
Reproduction
Seals are pregnant for nine months, however, they delay the development of the embryo for approximately three months. This creates an annual cycle which facilitates mating success and allows the female to recover from the demands of nursing her previous pup. The exception is the Australian sea lion which has an 18 month breeding cycle. The males congregate at breeding colonies and maintain a territory or harem prior to the females arrival. Upon, arrival, females typically give birth to a single pup, but twins can occur. This process is well synchronised with the majority of pups born within a few days of one another. The female then begins feeding the pup and is mated within a short period of time after giving birth.
Recovering from the slaughter
In Australia the commercial harvest of seals for the fur trade began in 1798. The industry had collapsed by the 1830s, and although it was still legal to hunt seals until 1923, this rarely occurred.
Four species of seal once bred in Tasmania's Bass Strait, the Australian fur seal, long-nosed fur seal, Australian sea lion, and the Southern Elephant seal.
Three of these species were totally eradicated and only the Australian fur seal now remains in Bass Strait. Approximately 17,000 pups are born each year at both Tasmanian and Victorian breeding colonies and the total Australian fur seal population is estimated to be 60,000 to 80,000. Prior to the exploitation of the sealing industry there was an estimated three-quarters of a million seals in Bass Strait.
The long-nosed fur seal is now restricted to breeding on a small group of islands off the South coast of Tasmania, the Maatsuyker Island group, where approximately 100 pups are born each year. The long-nosed fur seal is now classified as a threatened species in Tasmania. The long-nosed fur seal breeds in South Australia and Western Australia and has a total population of approximately 58,000.
Threats to seals
The greatest threat to seals comes not from their natural predators, white pointer sharks and killer whales, but from humans.
Seals also suffer horrific deaths due to marine pollution, such as entanglement in marine debris. This plastic, non-biodegradable debris includes free-drifting trawl net, packaging straps and monofilament gill net. Such debris causes 1-2% of Tasmania's seals to suffer a slow strangulation.
Seals are among the most inquisitive of creatures and often end up with rope, fishing net or packaging strap wrapped around their necks. As the seal grows, this material gradually strangles the animal. Before the seal dies it may suffer from starvation due to the entanglement restricting movement or preventing the swallowing of food. Entanglements cutting through the skin, blubber and muscle to reveal the oesophagus have been observed in Tasmanian waters. Ultimately, death is slow and very painful!
Beached seals
Seals do not 'strand' in the true sense of the word as they are adapted to spending some time on land and are quite capable of movement on land. Seals are regularly found lying or 'hauled out' on the Tasmanian coastline. All species found in Tasmania engage in this behaviour.
Sick or injured seals, however, also may be found on the beach.
Consequently, it is not unusual for people to come across seals. Should you be fortunate enough to come across a seal, it is very important for both the seal's sake and your own safety not to disturb the animal in any way. See our pages on
observing seals in the wild for further details or call 0427 942 537.
All seals are wholly protected throughout Australian waters.
Research
Tasmanian seal and cetacean research is largely funded by the legacy of Hobart born woman, Pauline Curran, who in 1926 married Prince Maximilian Melikoff of the exiled Russian royal family. Princess Melikoff died in 1988, and in her will, bequeathed a trust to help save our seals and dolphins.
What you can do to help
The following information is sought by researchers to help our understanding and management of seals in Tasmania. Any information should be passed on to the Department's Marine Conservation Program.
Sightings of any seal, whether healthy, sick or dead, should be reported. The Marine Conservation Program is collating data on all seal sightings in Tasmania. Whether you think we'd be interested or not, give us a call anyway!
The Department is also keen to receive sightings of:
- Entangled seals. It would be of great benefit if the type and colour of the material is recorded.
- Shark bites. Seals are often seen with shark bites and information is needed on the position of the bite, approximate size and whether it is fresh or a scar etc.