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Endangered sawfishes and river sharks in Western Australia

Morgan, D.L., Whitty, J.M. and Phillips, N. (2009) Endangered sawfishes and river sharks in Western Australia. Murdoch University. Centre for Fish & Fisheries Research, Western Australia.

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    Abstract

    The coastal waters of the northern Pilbara and the western Kimberley are a global hotspot for sawfish (Pristidae) diversity, with four of the world’s seven1 species found there; these four species comprise all of the known Australian species. This unique group of rays is readily identified by the presence of a blade like snout possessing enlarged tooth like denticles known as rostral teeth (Last and Stevens 2009). Globally, almost all sawfishes have undergone major declines in both range and abundance, largely as a result of their vulnerability to entanglement in fishing nets, but also through loss of habitat. It is only recently that information on the distribution, ecology, biology, population demographics and genetics and habitat utilization of the Australian sawfish fauna has started to become available, with much of this information restricted to grey literature or as unpublished work in progress. There is limited (or no) information on the size of the remaining populations, but many of the world’s sawfish populations are thought to survive in small fragmented areas (e.g. Simpfendorfer 2000). The four Australian species are from two genera, and are typically found throughout northern Australia, but accurate distributional descriptions are hindered by a lack of targeted surveying and are based on: limited surveys, from anecdotal reports or from collections of dried rostra. However, the Pilbara coast and west Kimberley are known to represent an important area for the four species, namely Freshwater Sawfish (Pristis microdon), Dwarf Sawfish (Pristis clavata), Green Sawfish (Pristis zijsron) and the Narrow Sawfish (Anoxypristis cuspidata).The first three of these species are listed as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and these form the basis of this review; although all are protected species within Western Australia under the Fish Resource Management Act 1994 (FRMA Act). Pristis zijsron was also listed under Schedule 1 of the Wildlife Conservation Act 1950 in Western Australia in 2006.Woodside Energy Ltd contracted the Centre for Fish & Fisheries Research (Murdoch University) to provide an overview of the current knowledge of the three EPBC Act listed pristids (P. microdon, P. clavata and P. zijsron) and also the Endangered (EPBC Act) Northern River Shark (Glyphis garricki) in Western Australian waters.Glyphis garricki was discovered in Western Australia in 2002 (Thorburn and Morgan 2004) and its formal description is recent (Compagno et al. 2008).Collectively, these species represent 50% of Australia’s elasmobranchs that are listed as Vulnerable or higher under the EPBC Act

    This report presents all known information with regard to their distribution in Western Australia, morphological characteristics, habitat utilization and population structure and genetic diversity in relation to northern Australia populations. The relevance of these data are then discussed in relation to the James Price Point development.

    Publication Type: Report
    Murdoch Affiliation: Centre for Fish and Fisheries Research
    Series Name: Murdoch University Report to Woodside Energy Ltd
    Publisher: Murdoch University. Centre for Fish & Fisheries Research
    Copyright: 2010 Murdoch University. Centre for Fish & Fisheries Research
    URI: http://researchrepository.murdoch.edu.au/id/eprint/6092
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