Larry was tracked two years ago

South Australia's Sea Lions as Ocean Observers

A project of Fur seal, pelagic shark and seabird tracking.

click map for full-size version For more information about Larry's Australian sea lion friends, please visit www.henrythesealion.com

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Species: Australian Sea Lion
Life Stage: Adult
Gender: Male
Release Date: 2009-03-01 00:00:00
Release Location: Lilliput Island
Last Location: 2009-06-30 00:00:00

Adoptive Parents:
Brian Kauffman
Emma Caniglia

Background

This project stemmed from our need for a detailed understanding of Australian sea lion foraging behaviour. As we began to understand more about their foraging behaviour and movements at sea, Australian sea lions started teaching us about how they interact with their environment. In studying the foraging behaviour of these natural explorers, we began to record information about more than sea lion behaviour, depths, and distances. Through this work we rapidly expanded our understanding of the linkages between the ocean and coastal climate dynamics.

Our most recent undertaking is a truly interdisciplinary project, bringing together the interests of biologists studying living systems and oceanographers studying marine physics. The maritime expeditions of the Australian sea lions are now yielding data that are important to both biologists and oceanographers and refining our understanding of the intimate connections between the mechanics of the Earth’s oceans, and the complex ecosystems which dwell within and upon them.

The primary aim of the project is to use Australian sea lions to carry instruments to obtain "CTD" (conductivity - temperature - depth) profiles at high frequency, and in real-time from remote, relatively inaccessible parts of the South Australian continental shelf. We are using custom-built satellite linked CTDs to provide CTD profiles from the Bonney Upwelling. Previous real-time CTD profiles from Australian sea lions have demonstrated that they can be efficiently used as ocean observers.

This is an extremely cost-effective means of adding to existing global oceanographic data archives. It has the potential to complement existing sampling methods, especially for regions from which data are scarce and where these alternative methods may be difficult or prohibitively expensive to implement. Importanly, this approach provides a mechanism of targeting the collection of physical oceanographic data from regions that are biologically of interest (ie. where high trophic level predators feed), therefore providing greater insights into how physical ocean processes underpin marine ecosystems and commercial fisheries.

The Australian sea lion (Neophoca cinerea) is the only endemic, and least abundant pinniped (seal and sea lions) that breeds in Australia. It is a member of the Otariidae family. Breeding populations of Australian sea lions are currently found from the Abrolhos Islands (Western Australia) to the Pages Islands (South Australia), although their historic range was far more extensive. The species hauls out and breeds on rocks and sandy beaches on the sheltered sides of islands, although there are several small colonies on the Australian mainland.

In 2008 (at the time of preparation) there were 76 known breeding locations for the Australian sea lion, 48 of which occurred in South Australia and 28 in Western Australia. The species is most numerous in South Australia. Based on pup numbers, 86% (3105 pups) of the population is found in South Australia and 14% (503 pups) in Western Australia. The estimated total population of the Australian sea lion is approximately 14700.

Australian sea lions are unique in having large numbers of small breeding colonies, low reproductive rates, a non-annual and asynchronous breeding season, high site fidelity and poor dispersal. Genetic investigation into the population structure of Australian sea lions using both mitochondrial and nuclear microsatellite DNA markers has found evidence of strong sex-biased dispersal, indicated primarily in extreme female natal site fidelity (or philopatry), which is unparalleled among other pinnipeds. Although genetic research to date has largely focused on colonies in Western Australia, it indicates extreme philopatry in females and suggests limited geographic dispersal of males between those colonies. Male dispersal between colonies appears to be limited to approximately 200km. These findings indicate that at least some Australian sea lions are genetically isolated, and that re-colonisation may not occur readily if colonies are extirpated.

Also unlike most pinnipeds that were harvested in Australia during the late 18th, 19th and early 20th centuries, Australian sea lion populations have not yet recovered, and at some localities there is recent evidence of population decline.

The species was listed as threatened (vulnerable) under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) on 14 February 2005.