the Legacy continues…………………….
Gregory R. Mann, Ph.D. {ret.}

Australian Sea Lion

“Neophoca Cinerea”

Australian Sea Lions are listed as “Endangered” by the International Union for the Conservation of Nature (IUCN). They have been afforded legal protection in Western Australia as a “Special Protected Species” from as early as 1892 and have received full protection from the Australian Government since 1964. Under the National Parks & Wildlife Act of 1972, it is illegal to harm or kill an Australian Sea Lion. They suffer from entanglement in shark nets as well as general marine debris and commercial fisheries nets. Loss of habitat, human interference and high pup mortality rates all work towards their continued demise. Although illegal shootings do occur, they are less frequent than most other species. Australian Sea Lions are found both on the Western & Southern coasts of Australia. They are very social creatures and they form very large colonies on the land, they also have sub groups that are more intimate. They average 10 to 15 per sub-group and they can move from one to another as their needs change over the course of their lives. Australian Sea Lions prefer to haul out on small off-shore islands to breed. The breeding season is usually quite long, around 5 months. Males are unable to protect their territories for the entire period and so will spend up to 4 weeks at a time maintaining a small harem. They become very aggressive towards other males during this time. Australian Sea Lions are unique in that they have a 17 month breeding cycle. Pupping alternates according to summer or winter and different breeding colonies will have different pupping seasons. Females usually give birth 1-2 days after coming on shore and will mate roughly 1 week after. Pups weigh in at approximately 7 kilograms and measure around 65 centimeters in length. Male pups tend to be slightly larger. The female will remain with her newborn for the initial 10 days before hunger forces her to go off foraging. She will abandon the pup for a period of 2 days while she feeds before returning to nurse and suckle for a day or two. This cycle continues until the pup is fully weaned at around 18 months, though extended weaning has been known to occur as long as 23 months. Pup mortality in this species tends to be relatively high (40-50%). This is mostly due to the extreme aggression displayed by both males & females. Females reach sexual maturity when they are between 4-6 years of age. The reproduction process for the Australian Sea Lion is very different from that of other Sea Lions. They have an 18 month cycle rather than 12 months in length. However, the Australian Sea Lion has an open window of up to 9 months.

Another difference is that the males can mate with 5 different females in turn. Adult females weigh in at between 65 kilograms and 110 kilograms measuring on average 1.5 meters in length. Males take longer to reach sexual maturity, usually between the ages of 8-9 years. They show an aggressively fight for the right to mate with any female around that is in estrus. This will occur about 10 days after she gives birth to a pup. She will only be in estrus for about 24 hours. The males will also kill her young pup she has just given birth with to show aggression and to get her to mate. It is believed that the females will have a pattern of returning to the same location again & again to give birth to their pups. That is why it is vital that conservation efforts are in place to protect their natural habitat. Females may stop mating if they can no longer access that location for giving birth. It is believed there is a mortality high rate of the pups which means that it is hard to get the population up. The males tend to be much heavier & longer, weighing up to 300 kilograms and measuring just over 2 meters in length. Australian Sea Lions live for around 25 years. Australian Sea Lions are one of the most endangered of the pinniped species. Population estimates put them at between 3-5 thousand animals. Their biggest natural predators are sharks, particularly White Pointer (Great White) Sharks and Killer Whales. Males & females tend to vary in color. Males are almost always a dark brown, while females tend to be more silvery-gray in color with a lighter underbelly. Although this species may travel great distances to find food with a diet of lobster, squid, fish, crustaceans, octopus and sea birds, they are non-migratory and will always return to their home turf. They swallow small prey and tear larger prey into sizable chunks. They also have back teeth that can be used to crack shells if needed to get to meat. They have been known to consume small penguins if necessary to survive. 80% of the population lives in South Australia with the remaining 20% living in Western Australia. Of the 73 known breeding sites, only 5 produce in excess of 100 pups each year. Unlike many pinniped species that have recovered from commercial exploitation during the 18th, 19th and 20th centuries, the Australian Sea Lion numbers have not stabilized. Populations are currently at an all-time low and numbers continue to dwindle. Pups will often congregate in shallow rock pools. These areas serve as nurseries and are important places for the animals to learn and develop their hunting skills while still remaining in relative safety.

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