Marine Protected Areas
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The Australian sea lion is Australia's only endemic sea lion with over 80% of the population found in South Australia. Sea lions were harvested in the late 1700s and early 1800s with their populations reduced to very low numbers. It is estimated that there are currently between 10 000 and 12 000 animals. This small population makes these mammals a threatened species in all of its range. It is listed as 'rare' under South Australian legislation and has 'special protected species' status in Western Australia. Nationally, it is listed as a threatened species (vulnerable) under the Environment Protection and Biodiversity Conservation Act. A recovery plan for the Australian sea lion is currently in preparation. The Great Australian Bight Marine Park has a critical role in protecting this species.
Example of temporal asynchrony in the timing of the breeding (shaded bars) across nine Australian sea lion colonies in South Australia (Figure 2 in Shaughnessy et al. 2005). (Light shading denotes the beginning and end of the breeding, darkest shading represents the mid-point of the breeding season).
Unique is a word that understates the charismatic value of these mammals. Australian sea lions do not have an annual breeding cycle like any other mammal. They breed every 17½ months (spread over a 5 month period), so one year they're breeding in summer and the following breeding period will be winter. Sea lion colonies also have an asynchronous breeding cycle, meaning that various colonies are breeding at different times of the year. Therefore, sea lion colonies are all breeding at different times, for example one colony may be at the peak of its breeding cycle while another has no breeding activity. In comparison, New Zealand fur seals breed for a 1 month period every November.
Satellite tracker on the back of female Australian sea-lion. Photo: Bradley Page SARDI
The Great Australian Bight Marine Park contributes to the protection of the Australian sea lion via a one nautical mile Sanctuary Zone and Conservation Zone adjacent to the cliffs in State waters and a Marine Mammal Protection Zone in Commonwealth Waters. Access to the Sanctuary Zone is not permitted and the Conservation Zone and Marine Mammal Protection Zone are closed seasonally.
The Department of the Environment, Water, Heritage and the Arts is working cooperatively with the South Australian Department for Environment and Heritage and South Australian Research and Development Institute (SARDI) to determine the foraging range and behaviour of the Australian sea lion. This will help determine the level of interaction with industries, such as commercial fishing, that may pose a risk to sea lion welfare. SARDI are currently undertaking satellite tracking of seals in other locations within South Australia.
The aim of this project was to place trackers on the back of female sea lions that inhabit colonies at the base of the Bunda Cliffs in the Marine Park. Females are considered important, as they are the breeders. The project required the assistance of the local SES Vertical Rescue Crew and volunteers. This crew played a critical role in the exercise by deploying and retrieving the SARDI scientists and park manager over the two-day operation.
After two days the team successfully deployed 5 tracking devices. The trackers record the positions of the animals as they forage for food on the seafloor. Data is transmitted to a satellite system each time the animal breaks the surface of the water which is downloaded by SARDI as required. The trackers, which will fall off with the next moult, cause no harm to the sea lions. The operation was undertaken with animal ethics approval.
Information collected to date has shown the five females foraging in different areas in a south to south west direction from the colony. Three have moved up to 180 km away from where they were caught, with another remaining relatively close to the colony. They appear to be feeding in different locations and have not gone any further than the 100m depth contour.
SES volunteer climbing up the cliff. Photo:(SADEH)
The information gathered will be used to contribute towards future sea lion management strategies. It will be used to develop a risk assessment process to determine the level of threatening processes that occur in the region and eventually assist with the effective management of the Marine Park.
References:
McKenzie J, Goldsworthy SD, Shaughnessy PD, McIntosh R (2005). Understanding the impediments to the growth of Australian sea lion populations. South Australian Research and Development Institute (Aquatic Sciences), Adelaide, 107pp. SARDI Publication Number RD04/0171.
Shaughnessy, PD, Dennis, TE. and Seager, P.G. (2005). Status of Australian sea lions, Neophoca cinerea, and New Zealand fur seals, Arctocephalus forsteri, on Eyre Peninsula and the Far West Coast of South Australia. Wildlife Research, 32: 85-101.
