How can you tell a male from a female sea lion?

A full-grown, male sea lion (a bull) has brown hair, a blonde mane and can weigh up to 350kg. Females and juve­niles are ash grey on top with cream under­bel­lies. A full-grown female will weigh up to 100kg.

How long do they live?

Aus­tralian sea lions have a life span of between 17 and 25 years.

Males mature between eight and nine years of age, and females from three years. The long peri­od between birth and reach­ing matu­ri­ty is one of the rea­sons for the slow pop­u­la­tion growth of the Aus­tralian sea lion.


Aus­tralian sea lions are quite agile on land, they use their front flip­pers to prop them­selves up. Their back flip­pers help them to walk’ on land. In the water the back flip­pers act as a rud­der to steer. They are very social ani­mals and when not feed­ing out at sea, they spend time rest­ing and sun­bak­ing on sandy beach­es and rocks.

What do they eat?

The Aus­tralian sea lion feeds along the con­ti­nen­tal shelf, most in depths of 20 – 100m. They feed from the sea floor, catch­ing crea­tures such as octo­pus, cut­tle­fish, small rays, sharks and rock lobster.

Do they eat penguins?

As oppor­tunis­tic feed­ers, sea lions have been known to eat seabirds, but they hunt main­ly on the sea floor rather than catch­ing sur­face-dwelling ani­mals such as penguins.

Do they com­pete with fur seals for food?

No, fur seals and sea lions are not in direct com­pe­ti­tion for food. Fur seals most­ly feed from the mid­dle of the ocean where they take fast mov­ing fish. Sea lions are bot­tom feed­ers and eat cut­tle­fish, mul­let and small rays.

Where do they feed?

When feed­ing, male sea lions will trav­el up to 100km and females up to 70km from their breed­ing colony. These trips aver­age about 3 days and in that time a sea lion will dive 900‑1200 times.

Where are Aus­tralian sea lions found?

Sea lions are unique to South Aus­tralia and West­ern Aus­tralia. Their total pop­u­la­tion is less than 12 000, with 85 per­cent in South Aus­tralia and the oth­er 15 per­cent in West­ern Australia.

Large colonies exist at Dan­ger­ous Reef in the Spencer Gulf, Seal Bay on Kan­ga­roo Island and The Pages. There are small­er colonies on the West Coast and in the Great Aus­tralian Bight.

In South Aus­tralia, there are 39 breed­ing colonies. Most are very small and some of these are at risk of becom­ing extinct because each breed­ing colony is a closed pop­u­la­tion. Female sea lions prac­tice what is called philopa­try’, mean­ing they return to the same breed­ing colony through­out their lives, and their pups do the same. There­fore Aus­tralian sea lion colonies don’t tend to mix – mak­ing each breed­ing site a closed population.

This makes the Aus­tralian sea lion unlike­ly to expand its range or recolonise breed­ing sites that have already become extinct.

Breed­ing and rais­ing their young

Dur­ing the breed­ing sea­son, mature bulls fight for access to females. They become aggres­sive and ter­ri­to­r­i­al, defend­ing females from oth­er males.

Tim­ing of the birth of pups is not the same at each colony. Females can fall preg­nant from the age of three and ges­ta­tion time is 17.6 months – the longest of any seal species.

Are their num­bers decreasing?

Aus­tralian sea lions were hunt­ed heav­i­ly dur­ing the 19th cen­tu­ry for their leather and oil. The pop­u­la­tion has nev­er returned to its pre-hunt­ing levels.

The colony at Seal Bay is declin­ing, though it still has more than 800 ani­mals. The Pages colony is sta­ble. Dan­ger­ous Reef is the only sea lion colony that is increas­ing in size.

There are reg­u­lar sur­veys of sea lion pop­u­la­tions. The sur­veys are invalu­able as a com­par­i­son between sea­sons and a barom­e­ter of how the pop­u­la­tions are faring.

What are the biggest threats to Aus­tralian sea lions?

Entan­gle­ment in marine debris and fish­ing gear pose the main threat to sea lions. Up to 80 per­cent of this debris comes from the land, includ­ing rub­bish dumped by beach visitors.

Oth­er threats include big sharks (such as great white sharks), being struck by boats, human dis­tur­bance, pol­lu­tion, and over­fish­ing which reduces access to prey. 

The major caus­es of death in sea lion pups are acci­den­tal crush­ing by adults (par­tic­u­lar­ly fight­ing juve­nile males), and delib­er­ate attacks by sub-adult males. It is nor­mal for one third of sea lion pups to die before weaning.

What is the con­ser­va­tion sta­tus of the Aus­tralian sea lion?

The Aus­tralian sea lion is list­ed as threat­ened (vul­ner­a­ble) nation­al­ly (Envi­ron­ment Pro­tec­tion and Bio­di­ver­si­ty Con­ser­va­tion Act 1999) and in South Aus­tralia (Nation­al Parks and Wildlife Act 1972).

In West­ern Aus­tralia it is list­ed as spe­cial­ly pro­tect­ed fau­na (Wildlife Con­ser­va­tion – Spe­cial­ly Pro­tect­ed Fau­na – Notice 2003)