Operation Jeedara: Spotlight on Endangered Australian Sea Lions
Saturday, Apr 07, 2018
An endangered Australian Sea Lion underwater in the Great Australian Bight. Photo Credit: Sea Shepherd / Eliza Muirhead.
One of the world’s rarest sea lions
The Australian sea lion (Neophoca cinerea) is one of the world’s rarest sea lions. It’s an endemic species meaning it is unique to Australia and therefore as Australians, we have a global responsibility to look after it.
Thousands of Australian sea lions were taken during the sealing era of the 19th century, however their pelt, being made up of coarse hairs was not as desirable as those of fur seals, hence were not as impacted as other species. Australian sea lions have been historically targeted by fishermen as competition for their resource, and shooting seals was accepted practice until the mid-1970’s with many colonies significantly reduced or wiped out.
According to the International Union for the Conservation of Nature (IUCN), Australian sea Lions are a red listed Endangered species, whose numbers are still declining, with their entire population estimated to be less than 12,000. Of these, 85 percent live in South Australia and the other 15 percent in Western Australia. They are listed as Vulnerable under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, and are protected under the National Parks and Wildlife Act 1972.
Australian sea lions (Neophoca cinerea) are part of a group known as ‘eared’ seals. They use their front flippers to prop themselves up and their back flippers to help them to ‘walk’ on land, while in the water their back flippers act as a rudder. The Australian sea lion differs from earless or ‘true’ seals, such as leopard, weddell or harp seals, which have no external ear flaps and can’t use their hind legs when on land. The breeding cycle of the Australian sea lion is around an 18-month cycle and is 'not' synchronised between colonies. The duration of the breeding season can range from five to seven months and has been recorded for up to nine months at places like Seal Bay on Kangaroo Island.
A Male (Bull) Australian Sea Lion on Pearson Isles. Photo Credit: Sea Shepherd / Simon Ager.
Male sea lions
Male sea lions (bulls) do not have fixed territories during the breeding season. The males fight other males from a very young age to establish their individual positions in the male hierarchy and during the breeding season, dominant males will guard females for the right to breed with her when she comes into oestrus (season). A female comes into season for about 24 hours within 7 to 10 days after she has given birth to her new pup, hence why bulls will hang around when females are pupping. The mother will only look after the new pup and generally fights off the previous season's pup if it attempts to continue to suckle from her. Tragically, male Australian sea lions are also known to kill young as an act of defence of territory. Australian sea lions also practice something called alloparental care, in which an adult may adopt the pup or pups of another. This might take place if the original parents die or are for some reason separated from them.
Female sea lions
Given females only breed once every 18 months it’s going to take a long time for the Australian sea lions to recover, even if we had the best protections in place as many threats still remain. Threats such as large sharks, especially great white sharks, will attack and eat sea lions (a good reason not to swim near sea lion breeding islands). Other risks include becoming entangled in fishing nets, struck by boats, human disturbance, pollution and prey depletion caused by overfishing.
In more recent times, the sea lion exclusion devices (known as a SLED) have been developed to stop sea lion pups entering commercial craypots and drowning. Australian sea lions head out to sea to hunt for squid, octopus, cuttlefish, fish, small sharks and rock lobsters. They hunt close to the seafloor and adult males can feed in depths of up to 150 metres!
Endangered Australian Sea Lions on Pearson Isles. Photo Credit: Sea Shepherd / Eliza Muirhead.
Current threats to Australian sea lions
One of the biggest threats now days to sea lions is the gill net shark fisheries off South Australia and Western Australia. The reason being is that the distribution of Australian sea lion colonies and foraging overlaps with a fishery managed by the Australian Fisheries Management Authority (AFMA). The fishery uses gillnets to target gummy sharks (aka flake in fish and chip shops), however, gillnets are invisible, thin mesh nets that are suspended in the water column close to the benthos where sea lions predominantly forage, and gummy sharks and other fish get snagged in the mesh.
But tragically so do Australian sea lions and they drown. With the death rate soaring with by-catch in the nets and the species chances of recovery slim, after pressure from the environment sector, including AMCS, HSI and the public, AFMA agreed to reduce the ‘trigger limit’ of sea lions that could be killed in the fishery for South Australia. Spatial closures excluding gill net fishing, of between 4 – 10 nautical miles have also been implemented around most sea lion colonies in the state.
An endangered Australian Sea Lion on the beach at Pearson Isles. Photo Credit: Sea Shepherd / Eliza Muirhead.
As it stands, the fishing area is split into seven different zones, in which a number of animals can be killed before the zone is closed to fishing. A total of 15 Australian sea lion deaths is now considered an acceptable toll. Following indications that fishers were also not reporting sea lion interactions, AFMA implemented electronic monitoring on every single boat that worked within the region of the sea lion colonies. However there are ways to avoid the camera monitoring in terms of how the net is brought alongside if a sea lion is snared.
Often when a female is killed, its can often be the life of the pup on land and the foetus inside that is lost, having a devastating blow on the recovery of the species.
It is important to note that these monitoring programs are only in place in South Australia and much more needs to be done for the protection of the Australian sea lions in Western Australia, where sea lion populations and gill net fisheries overlap. There is even discrepancies with the allowable distance the public can approach sea lions with 30 metres in South Australian and only 5 metres in Western Australia. This distance in WA needs to be increased as it is critical that when sea lions are at haul out areas that they are allowed to rest and recovered from many hours of hunting. We all know how much we humans need a good night’s sleep, well just like us, our endangered Australian sea lions too need their rest. Please keep this in mind next time you see one of our little Aussie battlers having a rest on the beach/island.
Why sanctuary zones like Pearson Isles are important for Australian Sea Lions
Female sea lions tend to stay close to where they were born and will return to pup also where they were born. These characteristics mean each of the small populations is genetically distinct from its neighbour locations, and the unnatural death of even a single female can have a large impact on a colony’s survival.
A young Australian sea lion pup. Photo Credit: Sea Shepherd / Eliza Muirhead.
The smaller the population, the higher the impact a death is. So a place like Pearson would have had thousands of years of generations of sea lions there, coming to shore to rest and recover, to mate and to give birth. Given Australian sea lions only reproduce every two to three years and they are already severely struggling as a species, these sanctuary zones like Pearson are critical to maintain safe haven for the survival of this iconic, wonderful and playful species, both in the water and on land.
What can you do to protect the Australian sea lion?
Admire sea lions from a safe distance of 30 metres on land and in the water. During the breeding season the females defend their pups vigorously and will attack people if they approach, so keep off islands where they are breeding. Do not feed sea lions as it is important that they get their own food and don't become dependent on handouts.
Take your rubbish home with you - each year some sea lions die a terrible slow death from entanglement and from ingesting plastic and other rubbish. Go slow for those below when you're in a boat, and look out for these playful and charismatic creatures.
Beneath the waves: Endangered Australian sea lions. Photo Credit: Sea Shepherd / Eliza Muirhead.