Although New Zealand fur seals are native to Australia, they also occur at several other islands in the Southern Ocean and around the South Island of New Zealand, where they were first described. New Zealand fur seals breed adjacent to the South‐west Marine Region on rocky islands off South Australia and the southern coast of Western Australia.
There are approximately 51 known breeding sites for this species in Australia, mostly in South Australia and Western Australia. Large breeding populations, which account for more than 80 per cent of the national pup production for the species (Goldsworthy, Campbell & McKenzie 2006), are found in South Australian waters at North and South Neptune Islands, Kangaroo Island and Liguanea Island. Colonies in Western Australia are centred on the islands of the Recherche Archipelago;
the westernmost population is found near Cape Leeuwin. Available information suggests that the range of the species is expanding in Western Australia, with greater numbers of animals hauling out and breeding on the south‐west coast (Goldsworthy, Campbell & McKenzie 2006).
Australian Fur Seal
Australian fur seals have been common visitors to the eastern part of the region for many years. They are known to haul out among and near New Zealand fur seal colonies on Kangaroo Island and are sometimes seen around the Neptune Islands. Recently, small numbers of Australian fur seals have bred in the region for example, on North Casuarina Island (off Kangaroo Island), 29 pups were produced in February 2008 (Shaughnessy et al. 2010). Like Australian sea lions, Australian fur seals feed mainly in the waters of the shelf. They are known to dive to at least 164 m to feed. Australian fur seals are generally benthic foragers, which is unusual for a fur seal, and take a wide variety of prey, particularly fish, squid, cuttlefish and octopus (DAFF 2007).
Populations of Australian sea lions, Australian fur seals and New Zealand fur seals were substantially reduced by commercial sealing in the 18th, 19th and early 20th centuries. Fur seal populations have recently shown evidence of recovery since the cessation of commercial sealing, while Australian sea lions appear to have remained stable or have declined. Unlike fur seals, Australian sea lions have failed to recover from the effects of sealing. Population trends for Australian sea lions are difficult to obtain due to the large number and inaccessibility of breeding sites, although the few observations of population trends indicate that most are stable, some are declining and only one is increasing (Goldsworthy et al. 2007; Hamer et al. 2009; Shaughnessy et al. 2011).
The life history characteristics and population structure of Australian sea lions are unusual among seals and sea lions (see above), and make the species vulnerable to the impacts of human activities. These characteristics and the species’ lack of recovery mean that even small levels of human‐induced mortality could have a significant impact on the species.
Sea level rise was assessed as of potential concern for Australian sea lions and New Zealand fur seals. Sea level rise may reduce the usable area of many colonies of Australian sea lions, rendering low‐lying colonies unviable. Many breeding colonies are on highly exposed rocky shores, and breeding and nursing often take place on small ledges. Rising sea levels, accompanied by more intense and frequent severe storms, are likely to affect pup survival rates. Whether sea lions can adapt to these changes is uncertain (DEWHA 2010a). With its similar life history characteristics, New Zealand fur seals are likely to be affected by climate change in a similar way to Australian sea lions. However, this species may be more resilient because its population is increasing.
Global sea levels have risen about 20 cm between 1870 and 2008. They are currently rising at a rate near the upper end of current projections and will continue to rise during the 21st century in response to increasing levels of greenhouse gases in the atmosphere. The Intergovernmental Panel on Climate Change predicts a rise of 18–79 cm by 2095 (since 1990). However, sea levels higher than this projection are possible because of inadequate understanding of the response of the ice sheets to global warming (Church et al. 2009).
Global sea levels have risen about 20 cm between 1870 and 2008. They are currently rising at a rate near the upper end of current projections and will continue to rise during the 21st century in response to increasing levels of greenhouse gases in the atmosphere. The Intergovernmental Panel on Climate Change predicts a rise of 18–79 cm by 2095 (since 1990). However, sea levels higher than this projection are possible because of inadequate understanding of the response of the ice sheets to global warming (Church et al. 2009).
Marine debris is assessed as of concern for Australian sea lions and of potential concern for New Zealand fur seals. A number of studies have shown that entanglement in marine debris is likely to be a significant source of mortality for sea lion populations and may be contributing to their lack of recovery across parts of their range (Page et al. 2004; Shaughnessy et al. 2006). It is estimated that 0.2–1.3 per cent of the population becomes entangled in debris (Page et al.2004; Shaughnessy et al. 2003). The Threat Abatement Plan for the Impacts of Marine Debris on Vertebrate Marine Life (DEWHA 2009) lists Australian sea lions as being adversely affected by ingestion of, or entanglement in, harmful marine debris. Based on a study at Kangaroo Island, Page et al. (2004) estimated that approximately 64 sea lions and 295 New Zealand fur seals die each year in southern Australia from entanglement, mostly in lost or discarded fishing gear. Because of the threat to pinnipeds, the southern rock lobster industry is phasing out the use of bait supplied in packaging that requires strapping.
Noise pollution has been assessed as a pressure of potential concern for the Australian sea lion. Pinnipeds are likely to be susceptible to increased noise levels or increased noise pollution for example, from seismic survey, construction or operational activities. The impacts of noise disturbance on Australian pinnipeds have not been investigated. Studies from elsewhere and on similar species indicate that they may be impacted by seismic surveys and other sources of noise, such as shipping or construction (Gordon et al. 2003). Harbor seals display strong avoidance behaviour (swimming rapidly away from the source) and cessation of feeding in response to air‐gun explosions of the type generated through seismic surveys Similar avoidance responses were documented during trials with grey seals: they changed from making foraging dives and moved away from the source, and some seals hauled out, possibly to avoid the noise. Responses to more powerful commercial arrays may be more extreme and longer lasting, and occur at greater distances. Given the status of the Australian sea lion and in light of likely increases in noise generating activities within or in proximity of Australian sea lion habitats, this pressure is of potential concern.
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