|Scientific Name:||Myliobatis hamlyni|
|Species Authority:||Ogilby, 1911|
|Taxonomic Source(s):||White, W.T. and Naylor, G.J.P. 2016. Resurrection of the family Aetobatidae (Myliobatiformes) for the pelagic eagle rays, genus Aetobatus. Zootaxa 4139(3): 435-438.|
|Taxonomic Notes:||Previously considered to be restricted to Australia. A recent taxonomic study by White et al. (2015) provided a redescription of the Purple Eagle Ray and the Japanese Eagle Ray (M. tobijei). The results of that study showed that previous records of the Japanese Eagle Ray from Indonesia, the Philippines, Taiwan and Okinawa in Japan actually refer to the Purple Eagle Ray. The Japanese Eagle Ray if confined to the western North Pacific, primarily in Japan. Thus, the Purple Eagle Ray's distribution is now extended from Australia north to Taiwan and southern Japan.|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||White, W.T., Kyne, P.M. & Last, P.R.|
|Reviewer(s):||Dulvy, N.K. & Lawson, J.|
|Facilitator/Compiler(s):||Kyne, P.M. & Walls, R.H.L.|
The Purple Eagle Ray (Myliobatis hamlyni) previously was considered to be an eastern Australian endemic species, but a recent taxonomic study revealed that it is more widespread, occurring also in Indonesia, the Philippines, Taiwan, southern Japan and Western Australia.
The Purple Eagle Ray attains at least 114 cm disc width. It occurs on a narrow band of the outer continental shelf and upper continental slope at depths of 117-330 m (based on Australian records). The deeper water nature of this species is unique amongst Myliobatis species, which are generally inshore species. The small number of records of this species throughout much of its range suggests that this is a naturally rare species (or not regularly exposed to fishing gear).
Fishing pressure is high in some areas of its range, e.g. eastern Australia, and Taiwan (possibly also the Philippines), but overall the level of exploitation is not thought to be excessive throughout its known range. However, given that this species is likely naturally rare, its common occurrence in Taiwanese trawl landings may suggest that the catch of this species is unsustainable in this country and this requires investigation. The Purple Eagle Ray is assessed as Near Threatened globally based on an inferred population reduction of <30% over the last 47 years (three generations) due to locally high mortality for a naturally rare species in Taiwan and eastern Australia, nested within a larger geographic range where there are lower levels of mortality.
|Previously published Red List assessments:|
|Range Description:||The Purple Eagle Ray has a patchy distribution in the East Indo-West Pacific (White et al. 2015). In Australia, the Purple Eagle Ray is known from patchy records. Off eastern Australia, it has been recorded from Swain Reefs and the type locality, Cape Moreton, in Queensland, and off Swansea and Coffs Harbour in New South Wales. Off Western Australia, it has been recorded off Forestier Island and Shark Bay. In Indonesia, it has been recorded in the landings at the Tanjung Luar fishing port in eastern Lombok and the Kedonganan fish market in southern Bali. The capture locations for these records is in local waters close to the respective landing sites. In the Philippines, it has been recorded from the Pasil fish market in Cebu City and Palapala fishing port in Cadiz City (Compagno et al. 2005). Recorded in the South China Sea by Randall and Lim (2000), but specimens are needed to confirm their identity. It has been recorded from the Da-xi (=Tashi) fish market in Yilan, Taiwan, and a single Purple Eagle Ray specimen was taken from off Okinawa, Japan. Records from Ryukyu Islands and Okinawa Trough (Okamura and Kitajima 1984, Yano 1999) possibly refer to this species but this requires verification. Specimens recorded off the Tokyo Submarine Canyon by Obara et al. (2009), as Myliobatis sp., between 150 and 500 m depth may also refer to this species, but this needs to be confirmed.|
Native:Australia (New South Wales, Queensland, Western Australia); Indonesia; Japan; Philippines; Taiwan, Province of China (Taiwan, Province of China (main island))
|FAO Marine Fishing Areas:|
Indian Ocean – eastern; Pacific – southwest; Pacific – western central; Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||There is no information on the population size of the Purple Eagle Ray, but it has a patchy distribution and appears to be naturally rare where it occurs. It has a deeper water habit compared to its congeners and there are no records of it forming aggregations as in some other species of eagle rays.|
Given the historical high levels of fishing on the New South Wales outer shelf and upper slope and off southern Queensland, it is possible that this species was affected early on by fishing activities and now we are seeing only a depleted population in eastern Australia. However, this is speculation and given it appears to be rare throughout its patchy distribution, it is more likely that it is just a naturally rare species. Of 13 specimens taken by the New South Wales Fisheries research vessel Kapala, nine were collected at the beginning of surveying (1976 to 1979) while four were collected in the later years of surveying (up until 1997) (K. Graham, pers. comm., 2006).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||The Purple Eagle Ray is benthic on the outer continental shelf and upper slope, recorded from depths of 117-330 m in Australian waters (museum records and K. Graham, pers. comm., 2006) with information on depth ranges lacking from outside of Australia. This species attains at least 114 cm disc width (DW) (White et al. 2015). Two males of 48 cm DW were adolescent, and males between 56 and 80 cm DW were mature (White et al. 2015). Female size at maturity, size at birth and litter size unknown.|
|Generation Length (years):||15.8|
|Use and Trade:||Landed in Asia and utilized for its meat.|
The Purple Eagle Ray is considered to be a naturally rare species (as indicated by the low catches throughout most of its range), and despite many decades of survey work along the east coast of Australia, it is rarely observed there. The Cape Moreton area (where the holotype is from) receives relatively significant levels of trawling for eastern king prawn by the Queensland East Coast Trawl Fishery (ECTF). The Swain Reefs (Coral Sea) specimen was collected from champagne lobster trawl bycatch; this area is subject to only low fishing pressure. Its area of occurrence off New South Wales has been subject to heavy trawling activity for a considerable number of years (Graham et al. 2001). Fishing pressure is very low at the locations and habitat where the Purple Eagle Ray has been recorded from in Western Australia (Marton and Mazur 2014a, 2014b).
In Indonesia, the distribution of this species is mainly on the the outer shelf or upper slope (based on species composition of catches). No trawling occurs at those depths in these areas so although fishing pressure is very high in Indonesia in general, fishing pressure specifically on the Purple Eagle Ray appears to be relatively low. In the Philippines, seven juvenile and adult specimens were recorded from several fish markets in 1999 and 2000 (Compagno et al. 2005), but information on the fishing gear, habitats fished and ongoing threats in not known. In Taiwan, there is intensive trawling on the outer shelf and upper slope which represents a threat to this species in those waters and it is regularly seen in the landings (Ebert et al. 2013).
|Conservation Actions:||Throughout the range of the Purple Eagle Rays, more information is required on this species to obtain more detailed information on its exploitation, habitat use and distribution. Due to the low number of records of the Purple Eagle Ray in Australian waters, any captures of this rare species should be documented. Education for safe release of the species after recording of basic information (location, depth, size, sex, maturity) should be considered due to its naturally low abundance. The use of turtle exclusion devices in the Queensland East Coast Trawl Fishery may assist in limiting catches in that part of the species' range.|
|Citation:||White, W.T., Kyne, P.M. & Last, P.R. 2016. Myliobatis hamlyni. The IUCN Red List of Threatened Species 2016: e.T60124A68634957.Downloaded on 23 May 2017.|
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