|Scientific Name:||Himantura toshi|
|Species Authority:||Whitley, 1939|
|Taxonomic Source(s):||Last, P.R. and Stevens, J.D. 2009. Sharks and Rays of Australia. Second Edition. CSIRO Publishing, Collingwood, Australia.|
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):||Walls, R.H.L. & Kyne, P.M.|
|Facilitator/Compiler(s):||Kyne, P.M. & Walls, R.H.L.|
The Brown Whipray (Himantura toshi) is a medium-sized whipray endemic to subtropical and tropical northern and eastern Australia. The species' preferred habitats are mangrove flats and muddy substrates, which, in eastern Australia have been considerably degraded in urban areas that are mostly restricted to the southern part of its east coast range. There is concern that this habitat degradation and their capture as bycatch in net and trawl fisheries are threatening processes, particularly as the species has not been recently collected from New South Wales. Populations of two sympatric batoid species, the Estuary Stingray (Dasyatis fluviorum) and the Green Sawfish (Pristis zijsron), have significantly declined in the same habitat. The Brown Whipray, however, remains common in the urbanised Moreton Bay area of southeast Queensland and the majority of its habitat across eastern and northern Australia is not heavily urbanised. Accordingly, this ray is currently assessed as Least Concern, though the lack of knowledge of both its population status and its range in tropical waters, an absence of recent records from the southern limits of its range, together with the potential for increases in urbanisation over parts of its range, are of concern.
|Previously published Red List assessments:||
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 range across northern Australia is not well defined and requires clarification. It possibly extends to waters off northwest Australia south to Shark Bay in Western Australia (Vaudo and Heithaus 2009). In recent years it has not been recorded from its most southeast 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
|Lower depth limit (metres):||41|
|Range Map:||Click here to open the map viewer and explore range.|
This whipray is common within its preferred habitat, for example, in intertidal sandflat habitats in Moreton Bay, Queensland (Pierce et al. 2011). However, there is no other information on its population size or trend. In recent years it has not been recorded from its most southeast limits (Last and Stevens 2009).
|Current Population Trend:||Unknown|
|Habitat and Ecology:||The Brown Whipray is most abundant in shallow inshore waters in 0–10 m depth, but has been recorded to 41 m depth (based on museum collection records and field observations; S. Pierce, unpubl. data, 2011). It is found mostly over muddy substrates and mangrove flats (Last and Stevens 2009). 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 this habitat (Pierce at al. 2011).|
|Use and Trade:||This species is not known to be used or traded commercially.|
This ray is most common in shallow inshore habitats, which have been subject to substantial modification and degradation on the highly urbanised eastern coast of Australia. Populations of some sympatric elasmobranch species using 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 this ray 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 (H. astra). 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 Queensland. For example, it is a regular bycatch in the Queensland East Coast Trawl Fishery, including in Hervey Bay, and central and north Queensland (Kyne 2008). Most large rivers in New South Wales are used by estuarine prawn-trawl fisheries and this species is a likely bycatch of these fisheries. It 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, this species was considered to have a moderate sustainability to the effects of trawling (Stobutzki et al. 2002). Bycatch rays caught in the East Coast Trawl Fishery and the Northern Prawn Fishery are discarded, but post-release survivorship is not well understood.
|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 range. The use of turtle exclusion devices (TEDs) and other bycatch reduction devices has significantly reduced the bycatch of rays, though more so for large individuals with >100 cm disc width and to a lesser degree for animals smaller than this, such as the Brown Whipray (Brewer et al. 2004). The species occurs in several marine protected areas, such as Moreton Bay Marine Park, Great Sandy Marine Park and the Great Barrier Reef Marine Park.|
|Citation:||Rigby, C. & Pierce, S.J. 2015. Himantura toshi. The IUCN Red List of Threatened Species 2015: e.T161505A68628968. . Downloaded on 29 May 2016.|