|Scientific Name:||Zearaja maugeana|
|Species Authority:||Last & Gledhill, 2007|
Dipturus sp. L
Raja sp. L subspecies
|Red List Category & Criteria:||Endangered B1ab(iii) ver 3.1|
|Assessor(s):||Gledhill, D. & Last, P.|
|Reviewer(s):||Musick, J.A. & Fowler, S.L. (Shark Red List Authority)|
This assessment is based on the information published in the 2005 shark status survey (Fowler et al. 2005).
Very little is known of this primitive skate, which was discovered just over a decade ago. It is only recorded from Bathurst and Macquarie Harbours on the Tasmanian west coast, which may contain two distinct populations. Its range in these estuary systems is not known, but is likely to be small, appearing to favour the shallow upper regions. There are no scientific data relating to the biology, distribution or the environmental requirements of this animal.
|Range Description:||A temperate Australian species, confined to two large estuary systems in western Tasmania, Bathurst and Macquarie Harbours. Its range within these systems is unknown but appears to be mainly in the upper estuary. The total available habitat is no more than a few tens of km² and initial surveys suggest the population is likely be small (less than 1,000 individuals; pers. obs.).|
|FAO Marine Fishing Areas:||
Indian Ocean – eastern
|Range Map:||Click here to open the map viewer and explore range.|
|Habitat and Ecology:||
A medium-sized ray (to at least 77 cm total length (TL)), this species is unique among skates in that it is found only in brackish water. The estuarine systems in which it lives are high in tannin content, with low light penetration and silty bottoms, resulting in the encroachment of several deepwater invertebrate species into relatively shallow depths. The morphology of this skate resembles that of Dipturus species found on the continental slope (Last and Stevens 1994).
Little is known of the biological or ecological requirements of this recently discovered and unnamed species. The estuaries are well separated and, given that this skate has never been taken in the sea, may form genetically distinct populations. Specimens have been caught in a broad range of brackish salinities to almost fresh water (pers. obs.).
|Major Threat(s):||Both populations of this skate, which are likely to be small, are in scenic and important recreational areas facing increasing pressure from ecotourism. They are probably also caught occasionally by recreational gillnetting. The isolation of Bathurst Harbour in the World Heritage area of south-western Tasmania affords some habitat protection for this species. However, the other population is in an estuary heavily polluted by prolonged mining operations.|
|Conservation Actions:||There are currently no conservation or management initiatives in place for this species, excepting those indirectly afforded by the inclusion of Bathurst Harbour in the World Heritage area of south-western Tasmania.|
|Citation:||Gledhill, D. & Last, P. 2005. Zearaja maugeana. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 31 July 2015.|
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