(Peron, 1816) - Australian sea lion
Distinctive Characteristics
Australian sea lions have a large head and a muzzle that is long and somewhat narrow, tapering slightly to a rounded end in profile. The ear pinnae are small and lie close to the head. The vibrissae are moderate in length, reaching just beyond the area of the ears. In adult males, the head and especially the neck and shoulders are greatly enlarged.
At birth, Australian sea lion pups are dark brown, with a paler crown and a dark facial mask. Pups begin to moult their birth coat at 2 months and change to their juvenile pelage, which is similar to that of adult females. This coat is fawn to silvery grey above and tan to pale yellow below. The demarcation between light and dark zones is high on the neck, but dips downward to the insertion of the flippers. The foreflippers are often darker above. The light coloration sometimes extends to the area around the ears (which are often particularly light and appear highlighted), the eyes, and the muzzle. In some animals there may be little discernable contrast between coloration above and below. Subadult males are coloured like females, but darken as they mature. The first evidence of this appears as dark spotting on the chest and darkening of the muzzle. Adult males have a dark brown coat, a whitish creamy crown and nape, and a slightly paler chest and lower throat area. This accentuates the darker “masked” face, chin, and muzzle. Younger bulls are incompletely marked and have a whitish ring around the eyes.
The dental formula is I 3/2, C 1/1, PC 5/5 (there is some variation in upper post-canine numbers).
Can be confused with
New Zealand and Australian fur seals occur within or very near the present range of Australian sea lions. Australian sea lions can be differentiated from these and all other southern fur seals based on coloration, lack of dense underfur, generally shorter pelage (exclusive of the mane on adult males) and vibrissae, head and muzzle shape, size of the ear pinnae, and size and shape of toes on the hindflippers.
Size
Very little information exists, but males reach lengths of at least 2.5 m and weights of 300 kg. Females reach at least 1.8 m and 105 kg. At birth, pups are approximately 60 to 70 cm and weigh 6.5 to 8 kg.
Geographical Distribution
Australian sea lions are found only around southern and southwestern Australia. They inhabit islands and the mainland coast, ranging over waters of the adjacent continental shelf. Little is known of their distribution at sea.
Biology and Behaviour
Breeding in this polygynous species is unusual for a pinniped, in that pups can be born at many different times of year. Although little information is available on behaviour at sea, Australian sea lions are known to porpoise when traveling rapidly, and also to surf beach waves. These seals are considered to be non-migratory. The greatest distance recorded for a tagged animal is approximately 300 km.
Australian sea lions are known to prey on a wide variety of fishes (including rays and small sharks), squid, cuttlefish, and penguins. They are thought to concentrate their efforts on shallow-water benthic prey. Fishermen complain of sea lions robbing lobster traps and fishing nets.
Exploitation
There is no direct exploitation at present, and Australian sea lions are protected throughout their limited range. Historically these sea lions had a more extensive range in Australia, but they were severely reduced by 19th Century commercial hunting. In some areas sea lions are killed by fishermen, directly when they interfere in operations and indirectly when caught in working nets. Entanglement in net debris, results in necklaced animals and some unknown level of mortality. The population appears to be stable.
IUCN Status
Rare.