Types of seals
Recovering from the slaughter
Threats to seals
What you can do to help
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.
A number of species occasionally visit our shores, however, only two species breed in Tasmanian waters.
The seals that breed in Tasmania are the:
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.
Four species of seal once bred in Tasmania's Bass Strait, the Australian fur seal, New Zealand 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 New Zealand 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 New Zealand fur seal is now classified as a threatened species in Tasmania. The New Zealand fur seal breeds in South Australia and Western Australia and has a total population of approximately 58,000.
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!
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.
Historically, branding and tagging have helped us to identify individual seals and to learn how long they live and how far they range. Branding and tagging was conducted at Bass Strait breeding colonies and the Maatsuyker Island group from 1990 to 1997. Australian fur seals branded and/or tagged at Bass Strait colonies are often observed at haul-outs on islands south of Tasmania. No branding is conducted as part of current research, and only relocated animals are tagged using newly developed short-term tags. A New Zealand fur seal tagged as a pup on Maatsuyker in 1994 (tag no. 239) was observed 13 months later on Macquarie Island - half way to Antarctica.
Tracking seals has uncovered some surprising facts - for example, using dive recorders, a male Australian fur seal, captured at Port Arthur and released at the north of Tasmania was tracked over ten days, covering more than 500 km and diving nearly 500 times each day. The deepest dive was 102 metres, and the longest lasted seven minutes.
Six Australian fur seal cows from Tenth Island have been equipped with satellite-linked time-depth recorders and results show that cow seals forage mostly within 200 km of the breeding colony. Dive information from one of these seals revealed that her dives, mostly at night, lasted about three minutes each and took her to depths below 45 metres.
Research is presently being carried out on Australian fur seals from Victorian breeding colonies. This research shows that this species travels across great distances, and frequently forages in Tasmanian waters.
Research like this tells us more about seal behaviour, and helps us to better understand their place in the marine environment.
Sightings of any seal, whether healthy, sick or dead, should be reported. The Wildlife and Marine Conservation Branch 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:
Contact: Biodiversity Monitoring SectionRosemary Gales
Section Head - Biodiversity Monitoring
134 Macquarie Street HOBART TAS 7000
Phone: 03 6233 3865
Fax: 03 6233 3477
See also Seal Conservation Society - www.pinnipeds.org - British-based website with information on species of seals and conservation issues.
Tasmania Online | Service Tasmania
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