|Scientific Name:||Himantura toshi|
|Species Authority:||Whitley, 1939|
There have been recent taxonomic name changes within the genus Himantura due to access to more specimens (Last et al. 2008). The Brown Whipray (Himantura toshi) had previously been confused with the Blackspotted Whipray (H. astra) and the two forms had been considered to be a single species, however they are now known to be two morphologically distinct species. Himantura sp. A (sensu Last & Stevens, 1994) has been named H. toshi (Last and Stevens 2009) and Himantura toshi (sensu Last & Stevens, 1994) has been renamed H. astra (Last and Stevens 2009).
The two species differ in dorsal colouration, adult tail colouration and squamation: the Brown Whipray is plain brownish when young while adults often have white spots on the disc; the Blackspotted Whipray has a strong colour pattern of black spots in both juveniles and adults. The post-sting tail of the Brown Whipray has blackish dorsal and ventral surfaces whereas in the Blackspotted Whipray it is black and white banded dorsally and pale ventrally (Last et al. 2008)
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Rigby, C. & Pierce, S.J.|
|Reviewer/s:||Kyne, P.M. & Ebert, D.A.|
The Brown Whipray (Himantura toshi) is a medium-sized whipray endemic to subtropical and tropical northern and eastern Australia. Its current known distribution ranges from northern New South Wales to the Northern Territory and possibly extends to Western Australia. The species appears to mainly occur in shallow inshore habitats, and is most commonly reported from mangrove flats and muddy substrates. In eastern Australia its preferred habitats have been considerably degraded in urban areas, which are mostly restricted to the southern part of its east coast range, i.e. south-east Queensland and northern New South Wales (NSW). There is concern that this habitat degradation and their capture as bycatch in net and trawl fishes are threatening processes, particularly as the species has not been recently collected from NSW. Populations of two sympatric batoid species, the Estuary Stingray (Dasyatis fluviorum) and Green Sawfish (Pristis zijsron), have significantly declined in the same habitat. The Brown Whipray, however, remains common in the urbanised Moreton Bay area of south-east Queensland and the majority of its habitat across eastern and northern Australia is not heavily urbanised. Accordingly, the Brown Whipray is currently assessed as Least Concern, though the lack of knowledge of both its population status and its distribution in tropical waters (which needs to be clarified), together with the potential for increases in urbanisation over parts of its range, are of concern.
The Brown Whipray is endemic to inshore waters of eastern and northern Australia from Darwin (Northern Territory) in the north to the Clarence River (New South Wales) in the south. However, its distribution across northern Australia is not well defined and requires clarification and it possibly extends to waters off north-western Australia south to Shark Bay (Western Australia) (Vaudo and Heithaus 2009). In recent years it has not been recorded from its most south-eastern limits (Last and Stevens 2009).
Native:Australia (New South Wales, Northern Territory, Queensland)
|FAO Marine Fishing Areas:||
Indian Ocean – eastern; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
The Brown Whipray is common near the coast over muddy substrates and mangrove flats (Last and Stevens 2009). It has been recorded as common in intertidal sandflat habitats in Moreton Bay, Queensland (Pierce et al. 2011). There is no other information on its population sizes or trends.
|Habitat and Ecology:||The Brown Whipray is most common in shallow inshore waters from 0 to 10 m, but has been recorded to 41 m (based on museum collection records and field observations; S. Pierce unpubl. data 2011). Little is known of its biology. It attains at least 74 cm disc width (DW) (Last and Stevens 2009). Male maturity occurs at approximately 53 cm DW in Moreton Bay, Queensland (Pierce et al. 2011). Tagging studies in Moreton Bay have shown that some individuals show high short-term site fidelity to intertidal sandflat habitats, with small (<30 cm DW) juveniles particularly common within these environments (Pierce at al. 2011).|
The Brown Whipray is most common in shallow inshore environments. These habitats have been subject to substantial modification and degradation on the highly urbanised eastern coast of Australia. Populations of some sympatric elasmobranch species utilising these habitats, such as the Green Sawfish (Pristis zijsron) and the Estuary Stingray (Dasyatis fluviorum), have been substantially reduced. The Brown Whipray is likely to be affected by many of the same threats as these species.
Specific assessment of the threats affecting the Brown Whipray is hampered by the recent re-description of the species, as much of the existing literature appears to pertain to the related species now known as the Blackspotted Whipray. Habitat modification of mangrove-fringed sandflats is likely to have reduced the carrying capacity of preferred habitat in some areas, and the Brown Whipray is regularly caught as a bycatch of inshore net and prawn-trawl fisheries in south-eastern Queensland. Most large rivers in New South Wales are utilised by estuarine prawn-trawl fisheries and the Brown Whipray is a likely bycatch of these fisheries. The Brown Whipray is caught in the Northern Prawn Fishery (NPF), a fishery that operates in the Gulf of Carpentaria and across northern Australia. Among the NPF elasmobranch bycatch, the population of this species was considered to have a moderate sustainability to the impacts of trawling (Stobutzki et al. 2002). The introduction of Turtle Exclusion Devices (TEDs) in 2000 and other bycatch reduction devices has significantly reduced the bycatch of rays, though more so for large individuals greater than 1 m DW and to a lesser degree for animals smaller than this, such as the Brown Whipray (Brewer et al. 2004).
|Conservation Actions:||There are no conservation actions currently in place for this species. It is a bycatch species, and research is required to improve knowledge of its population size, life history characteristics and to confirm its distribution.|
|Citation:||Rigby, C. & Pierce, S.J. 2012. Himantura toshi. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 18 May 2013.|
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