|Scientific Name:||Eusphyra blochii|
|Species Authority:||(Cuvier, 1816)|
Zygaena blochii Cuvier, 1816
|Taxonomic Source(s):||Cuvier, G. 1816. Le Règne Animal distribué d'après son organisation pour servir de base à l'histoire naturelle des animaux et d'introduction à l'anatomie comparée. Les reptiles, les poissons, les mollusques et les annélides.|
|Taxonomic Notes:||Synonyms = Zygaena latycephala van Hasselt, 1823; Zygaena laticeps Cantor, 1837. The name Sphyrna blochii has also been used recently for this species.|
|Red List Category & Criteria:||Endangered A2d+3d ver 3.1|
|Assessor(s):||Smart, J.J. & Simpfendorfer, C.|
|Reviewer(s):||Lawson, J., Dulvy, N.K. & Kyne, P.M.|
|Contributor(s):||Sherman, C.S., White, W.T., Dulvy, N.K. & Johnson, G.J.|
|Facilitator/Compiler(s):||Kyne, P.M., Walls, R.H.L., Simpfendorfer, C. & Chin, A.|
The Winghead Shark (Eusphyra blochii) is a highly distinctive Indo-West Pacific continental shelf species that is fished throughout its range. It is a slow growing species which reaches a maximum size of 186 cm total length, a maximum age of 21 years and has a generation length of 14 years. These life history parameters along with its apparent patchy localised distribution increases its susceptibility to depletion due to heavy fishing effort. Furthermore, its morphology makes it extremely susceptible to entanglement in a wide variety of nets.
Throughout the majority of its range, in particular Asia, fishing effort is concentrated in coastal regions, is intense and is generally unregulated; the Winghead Shark is inferred to have been heavily exploited. This species is now rarely encountered in both India and Indonesia where it has previously been reported, and the absence of the species from fish market and landing surveys in these countries is likely to accurately reflect the situation more broadly across the majority of its range. While there are no species-scientific data on its status, the population is inferred to have declined by at least 50% within the equivalent of three generations (42 years) and hence it is assessed as Endangered globally based on heavy exploitation levels. As fishing practices across most of its range are expected to remain unchanged in terms of intense pressure in nearshore waters, it is inferred that the global population will continue to decline at a similar rate over the next three generations. In Australia, the Winghead Shark is only a small component of commercial catches, therefore the population is considered to be relatively healthy and is regionally assessed as Least Concern.
|Previously published Red List assessments:|
|Range Description:||The Winghead Shark occurs on and near continental shelf waters of the Indo-West Pacific from the Arabian/Persian Gulf through south Asia to northern Australia and Papua New Guinea (Last and Stevens 2009).|
Native:Australia (Northern Territory, Queensland, Western Australia); Bangladesh; Brunei Darussalam; Cambodia; China; India; Indonesia; Iran, Islamic Republic of; Kuwait; Malaysia; Myanmar; Oman; Pakistan; Papua New Guinea; Philippines; Saudi Arabia; Sri Lanka; Taiwan, Province of China; Thailand; United Arab Emirates; Viet Nam
|FAO Marine Fishing Areas:|
Indian Ocean – eastern; Indian Ocean – western; Pacific – northwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||There are no species-specific data available on population numbers, and how they have changed over time, for any part of the range. Globally, however, 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) 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).|
While species-specific data on long-term declines in elasmobranchs in the Southeast Asian region are lacking, declines in the Winghead Shark in Southeast Asia and elsewhere in the Indo-West Pacific 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). In Australian waters, this species makes up a very small proportion of catches in tropical gillnet fisheries (Harry et al. 2011) and its population is not believed to have declined substantially.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||The Winghead Shark occurs on the continental shelves and is mainly found in coastal nearshore waters. In eastern Australia, this species is mainly encountered in concentrated areas of less than 50 km² (J. Smart, pers. obs. 2015). This species is familiar to local fishers within these concentrated areas and is seldom encountered by fishers further away, thereby suggesting a patchy localised distribution. This is however, based on local ecological knowledge as there is little additional survey data. One tag recapture has been confirmed from northern Australia with this individual re-caught within 21 km of the original capture location after 12 months (Stevens et al. 2000).|
Young are born at approximately 45 cm total length (TL), maturity occurs at around 120 cm TL for females and 108 cm TL for males, and they reach a maximum size of 186 cm TL (Stevens and Lyle 1989). Mature females produce litters of 6–25 (mean = 11) every year after a gestation period of 8 to 11 months (Compagno 1984, Stevens and Lyle 1989). This is a slow growing species that reaches maturity at 7.2 years for females and 5.5 years for males. The oldest documented maximum age is 21 years according to vertebral analysis (Stevens and Lyle 1989, Smart et al. 2013). Generation length is estimated to be 14 years.
|Generation Length (years):||14.1|
|Use and Trade:||The Winghead Shark has been heavily exploited for fins and meat across the vast majority of its range, with the exception of Australia, where, while still utilized, exploitation rates are much lower.|
The Winghead Shark is heavily exploited in many parts of its range, for example the Gulf of Thailand, India and Indonesia (Simpfendorfer 2003). Only one individual was seen in market surveys in Indonesia during which approximately 20,000 sharks were recorded. It is therefore suspected to be severely overfished in this country as most of Indonesia's fishing effort is focused on coastal nearshore areas where it would be suspected to inhabit (W. White, CSIRO, pers. comm. 2015). Recent catch data from India identifies sharks to species level and has no mention of the Winghead Shark as a bycatch or byproduct species (e.g. Varghese et al. 2013). Severe population declines are therefore also suspected as they have previously been recorded there. This pattern is expected throughout the species' Asian range where fishing pressure on nearshore regions is intense and generally unregulated.
Within Australia, the Winghead Shark is lightly exploited in several net fisheries. Its elongated hammer-shaped head makes it susceptible to a wide range of mesh sizes and therefore it is predominantly caught in gillnets and trawls. However, it is only caught in low numbers in the Queensland East Coast Finfish Fishery (0.4% of total catch; Harry et. al 2011), Gulf of Carpentaria Inshore Finfish Fishery (<0.3% of total catch; DAFF 2012), Northern Prawn Fishery (0.02% of total catch; Stobutzki et al. 2002) and the Pilbara Trawl Fishery (Western Australia Department of Fisheries 2010).
The greatest catches of the Winghead Shark in Australia are taken in the Northern Territory Offshore Net and Line Fishery and has ranged between 10.942 t and 21.356 t between 2007 and 2012. Due to operational changes in the fishery, however, this catch has decreased to 12.786 t in 2012 and this trend is likely to continue (Grant Johnson, NT Fisheries, pers. comm., 2015).
|Conservation Actions:||There are currently no species-specific management measures in place for the Winghead Shark. Northern Australian fisheries are generally well-managed.|
|Citation:||Smart, J.J. & Simpfendorfer, C. 2016. Eusphyra blochii. The IUCN Red List of Threatened Species 2016: e.T41810A68623209.Downloaded on 22 August 2017.|