|Scientific Name:||Himantura leoparda Manjaji-Matsumoto & Last, 2008|
Trygon russellii Gray, 1834
|Taxonomic Source(s):||Last, P., White, W., de Carvalho, M., Séret, B., Stehmann, M. and Naylor, G. 2016. Rays of the World. CSIRO Publishing, Clayton.|
|Taxonomic Notes:||The Leopard Whipray (Himantura leoparda) is a recently described (2008) species of whipray closely related and similar in shape and dorsal disc pattern to the Reticulate Whipray (H. uarnak) and Honeycomb Whipray (H. undulata). These three species are from the ‘uarnak’ species-complex, a subgroup of mainly reticulated, ocellated or spotted whiprays. The Leopard Whipray can be distinguished by its unique arrangement of midscapular denticles and the leopard-like markings on the dorsal surface of adults and large specimens. Juveniles of the three species are born at different sizes and vary slightly in colour patterns and denticle shapes (Manjaji-Matsumoto and Last 2008; Last and Stevens 2009). Taxonomic work is currently ongoing to more clearly define the sister species relationships (Peter Last, pers. comm. 2010).
Previously this species has been misidentified as Dasyatis uarnak: Wallace 1967; Himantura fava: Compagno and Roberts 1982; Himantura sp. 1: Gloerfelt-Tarp and Kailola 1984; Himantura uarnak: Compagno 1986, Compagno et al. 1989; and Himantura undulata: Last and Stevens 1994, Last and Compagno 1999, White et al. 2006.
|Red List Category & Criteria:||Vulnerable A2bd ver 3.1|
|Assessor(s):||Rigby, C., Moore, A. & Rowat, D.|
|Reviewer(s):||Walls, R.H.L. & Bigman, J.S.|
The Leopard Whipray (Himantura leoparda) is possibly widely distributed in the Indo-West Pacific in mainly coastal inshore waters. It is currently known to range from Southeast Asia to the Japanese Archipelago and south to northern Australia, however there are ongoing taxonomic issues that are being investigated, the outcomes of which may affect the known range.
Its biology is poorly known, partly due to confusion with other members of the ‘uarnak’ species-complex. This species is commercially valuable throughout Southeast Asia where it is taken as utilised bycatch in a range of commercial and artisanal fisheries including demersal trawl and tangle/gill nets, dropline and longline fisheries, and Danish seine fisheries. In recent decades, demersal fishing pressure has increased in both capacity and effort and is intense throughout this species’ inshore range in Southeast Asia. Fishing pressure is also very heavy in the Arafura Sea region; previously more than 600 trawlers operated and although the numbers of currently active trawlers is unclear, there are still high levels of Indonesian trawl fishing in the area. This level of exploitation is of great concern to the sustainability of Leopard Whipray populations in the Arafura Sea outside the Australian Fishing Zone.
This species’ preference for inshore coastal waters means it is also threatened by extensive habitat degradation and destructive fishing practices throughout a large part of its range. Although species-specific data are not available, given the species’ high levels of exploitation, extensive habitat degradation and its large size, significant population declines are inferred to have occurred and are likely to be ongoing in Southeast Asia. Conversely, this species has refuge from fishing pressure in northern Australia, where fishing pressure is light, bycatch mitigation measures are in place and it is not commercially utilised and consequently is considered at low risk.
Given the continuation of high levels of exploitation throughout its range in Southeast Asia where the species is caught in multiple types of fisheries, along with evidence for declines in catches of rays, the level of decline (>30% over the last three generations) and exploitation can be inferred from overall declines in fish catches in the region, as well as from habitat loss. The Leopard Whipray is assessed as Vulnerable globally based on inferred levels of decline and exploitation across a large part of its range, but is considered to be Least Concern in Australia.
|Previously published Red List assessments:|
The Leopard Whipray is possibly widespread in the Indo-West Pacific. Its range is based on current knowledge, however there are ongoing taxonomic issues that are being investigated and the outcomes of these may affect the known range. It is currently known from Southeast Asia to the Japanese Archipelago and south to northern Australia, where it occurs from Coral Bay, Western Australia to the Torres Strait, Queensland (Manjaji-Matsumoto and Last 2008, Last and Stevens 2009). It is currently considered absent from the Western Indian Ocean.
Native:Australia (Northern Territory, Queensland, Western Australia); Cambodia; China; Indonesia; Japan; Malaysia; Papua New Guinea (Papua New Guinea (main island group)); Taiwan, Province of China; Thailand; Viet Nam
|FAO Marine Fishing Areas:|
Indian Ocean – eastern; Pacific – western central; Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
Globally, shark and ray landings have declined by at least 20% since 2003, but the Indo-Pacific is amongst the regions where this decline has been more severe (Dulvy et al. 2014). Catches of sharks and rays in Southeast Asia are very high but are declining and fishers are travelling much further from port in order to increase catches (Chen 1996). Net and trawl fisheries in Indonesia (especially the Java Sea) and elsewhere are very extensive and as a result, many shark and ray species are highly exploited and stocks of most species have declined by at least an order of magnitude (Blaber et al. 2009). Batoids are heavily exploited (White and Dharmadi 2007) and datasets from as early as 1963–1972 show the considerable decline in batoids in the Gulf of Thailand (Pauly 1979). Trawl and gill net fisheries are also moving further afield. For example, in Jakarta the gillnet fishery at Muara Baru travels to waters around Kalimantan due to the decline in local populations (W.T. White, unpubl. data). While species-specific data on long-term declines in elasmobranchs in the Southeast Asian region are lacking, declines of the Leopard Whipray in Southeast Asia are inferred given the widespread historical and continuing declines of demersal fisheries in this region (Stobutzki et al. 2006). Furthermore, the extensive loss and degradation of habitats such as coastal mangroves are another key threat to coastal and inshore species; Southeast Asia has seen an estimated 30% reduction in mangrove area since 1980 (FAO 2007, Polidoro et al. 2010).
It is not possible to estimate the proportion of the global population occurring within the Australian region as there is little information on the population structure of this species, however an estimated 15% of the Leopard Whipray’s known distributional range is in the Australian region.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||The Leopard Whipray is demersal on soft substrates and is mainly inshore and coastal though it also occurs on the continental shelf to at least 70 m depth (White et al. 2006, Manjaji-Matsumoto and Last 2008). The biology of this species is poorly known, partly due to confusion with other species of the ‘uarnak’ species-complex, especially the Reticulate Whipray (H. uarnak) and the Honeycomb Whipray (H. undulata) (Last and Stevens 2009). It attains about 140 cm disc width (DW); born at about 20 cm DW; males mature at 70–94 cm DW (White and Dharmadi 2007, Last and Stevens 2009). Reproduction is viviparous (White et al. 2006).|
As there is no information on this species’ maximum age and age at maturity, generation length was inferred as 20 years based on data for the congener, the Blackspotted Whipray (Himantura astra). Female Blackspotted Whiprays are reported to have a maximum age of 29 years and an age at maturity of nine years (Jacobsen and Bennett 2011). These were used to calculate a generation length of 19 years based on the equation: generation length = 9+((29-9)/2). The maximum size of the Leopard Whipray is considerably larger (~140 cm DW) than that of the Blackspotted Whipray (80 cm DW) so it is possible the generation length of the Leopard Whipray could be greater than 20 years.
|Generation Length (years):||19|
|Use and Trade:||
In large parts of its range outside of Australia (i.e., Southeast Asia) this species is used for its cartilage, meat and its highly-valued skin (White et al. 2006).
The threats to the Leopard Whipray are many of those faced by other Himantura species within its range. However, the Leopard Whipray may be more vulnerable than some of its congeners due to its large size at maturity and maximum size and its preference for inshore coastal waters that are heavily fished and degraded in many parts of its range outside Australian waters (Manjaji and White 2004).
In Indonesia and across large parts of its distribution, the Leopard Whipray is caught by demersal trawl and tangle/gill nets, dropline and longline fishing, Danish seine fishing gear, and coastal artisanal fisheries (Manjaji and White 2004, White et al. 2006). In Southeast Asia, this species is commercially valuable, with most specimens caught as bycatch landed and sold. The Leopard Whipray is important in the gill and tangle net fisheries in Indonesian waters, which likely also includes adjacent waters. These fisheries, along with trawl fishing are particularly intensive in the Arafura Sea region (W. White pers. comm. 2010). In 2004, it was reported that more than 600 trawlers operated in the Arafura Sea and that catches in inshore waters had declined with vessels travelling further south to maintain catches (Manjaji and White 2004). Although the numbers of trawlers currently operating is unclear, this intensive fishing pressure still continues; high levels of Indonesian trawl fishing in the Arafura Sea adjacent to the Australian Fishing Zone have recently been reported (Heazle and Butcher 2007, Northern Territory Government 2009) and thus the level of exploitation of this species could be extremely high.
In recent decades, demersal fishing pressure has increased in both capacity and effort in many areas of this species’ inshore range. For example, demersal resources in the Gulf of Thailand went from being lightly exploited to severely over-exploited between 1973 and 1994 (Pauly et al. 2005). On standardized trawl surveys conducted over this 20 year period in the Gulf of Thailand, the abundance (biomass) of the major trawl bycatch groups was recorded. The group ‘rays’ showed a large reduction in biomass over this period and an ecosystem model fitted to the bycatch data indicated that ‘rays’ were one of the groups most severely impacted by the initial increase in fishing pressure (Pauly et al. 2005). Species-specific catch data are not available, but Indonesian landings of ‘Rays, stingrays, mantas, nei’ (nei = not elsewhere included) increased from ~10,000 t in 1975 to 58,000 t in 2004 (FAO 2009).
This species’ preference for inshore coastal waters means it is also threatened by extensive habitat degradation, including pollution and clearing, and destructive fishing practices. Large coastal areas, in particular mangroves, have been lost in Indonesia and Malaysia through land conversion for urban development, shrimp farms and agriculture. Across Indonesia and Malaysia from 1980 to 2005, the area of mangroves was reduced by >30% (FAO 2007).
Although data are available mostly only for grouped ‘rays’ and not specifically for the Leopard Whipray and/or other Himantura species, given that the Leopard Whipray is a large species with a preference for shallow waters where threats from coastal fisheries and habitat degradation are highest, significant declines are suspected to have occurred in Southeast Asia.
Conversely, this species has refuge from fishing pressure across its range in northern Australia where there is much less fishing pressure and bycatch mitigation measures are enacted. Large specimens were previously occasionally caught as bycatch in the Australian Northern Prawn Fishery (NPF), a trawl fishery across northern Australia, but the introduction of turtle exclusion devices (TEDs) in 2000 significantly reduced the bycatch of this species, particularly those individuals >1 m DW (Brewer et al. 2004). In the NPF, this species was considered to have a moderate to high sustainability to the impacts of trawling (Stobutzki et al. 2002, Zhou and Griffiths 2008). It has also been recorded as a minor component of the bycatch in the banana prawn and scallop sectors of the Queensland East Coast Otter Trawl Fishery (Stobutzki et al. 2001, Courtney et al. 2007), but again the use of TEDs in this fishery should limit bycatch (particularly of larger specimens).
|Conservation Actions:||Research is required to assess catches of the Leopard Whipray throughout its range, and to examine its habitat, ecology and life history parameters including confirmation of its distributional range. Except in Australian waters, the fisheries that capture this species are largely unregulated (licenses are issued but catches and landings are not properly monitored), and presently there are no specific conservation actions in place to help address this problem. In Australia, management measures have been introduced over the last decade that have significantly reduced the threat to this species and it is now considered at low risk from fishing pressures in northern Australian waters.|
|Citation:||Rigby, C., Moore, A. & Rowat, D. 2016. Himantura leoparda. The IUCN Red List of Threatened Species 2016: e.T195456A68628645.Downloaded on 21 September 2017.|