Insentiraja subtilispinosa 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Chondrichthyes Rajiformes Arhynchobatidae

Scientific Name: Insentiraja subtilispinosa
Species Authority: (Stehmann, 1989)
Common Name(s):
English Western Looseskin Skate, Velvet Skate
Notoraja subtilispinosa Stehmann, 1989
Taxonomic Notes: Shape differences are evident between populations across its range and need further investigation (Last and Compagno 1998). There is a need to ascertain if this species is conspecific with the population in the type locality (i.e., the Philippines).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2015-05-09
Assessor(s): Huveneers, C., Stehmann, M.F.W. & Last, P.R.
Reviewer(s): Walls, R.H.L. & Kyne, P.M.
Facilitator/Compiler(s): Kyne, P.M. & Walls, R.H.L.
The Western Looseskin Skate (Insentiraja subtilispinosa) is a small, moderately common, deepwater skate found at depths of 320–1,460 m on the continental slope of the Eastern Indian Ocean and Western Central Pacific, off northwest Australia, Indonesia, and the Philippines. The species is common in some areas but its distribution is probably patchy. Possibly the most abundant skate at depths of 900–1,100 m throughout its known range, yet its biology is virtually unknown. It is taken as bycatch by deepwater trawlers and could be of minor commercial value but is currently discarded. Trawl fishing effort is currently low in the species' Australian range, and it likely receives refuge at depths beyond those fished. It is therefore currently assessed as Least Concern. Monitoring of deepwater fisheries operating within its range and catches is required, and if the level of deepwater fishing pressure increases this assessment may need to be revisited.
Previously published Red List assessments:
2009 Least Concern (LC)

Geographic Range [top]

Range Description: The Western Looseskin Skate occurs in the Eastern Indian Ocean and Western Central Pacific. Its range is not well defined, but it is known to occur off Western Australia, Indonesia, and the northern Philippines (Last and Stevens 2009). It is likely to be more widely distributed through the Indo-Malay Archipelago than presently known (Last and Compagno 1998).
Countries occurrence:
Australia (Western Australia); Indonesia; Philippines
FAO Marine Fishing Areas:
Indian Ocean – eastern; Pacific – western central
Lower depth limit (metres): 1460
Upper depth limit (metres): 320
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Common in some areas but its range is probably patchy. Possibly the most abundant skate at depths of 900–1,100 m throughout its known range (Last and Compagno 1998). Nothing is known of the overall population size or structure.
Current Population Trend: Unknown
Additional data:
Population severely fragmented: No

Habitat and Ecology [top]

Habitat and Ecology: A small, moderately common, deepwater skate inhabiting soft substrates on the mid continental slope at depths of 320–1,460 m, but most abundant at depths of 900–1,100 m (Last and Compagno 1998, Last and Stevens 2009). This species attains at least 57 cm total length (TL) and males are mature at 50 cm TL (Last and Compagno 1998, Last and Stevens 2009). Females are mature at about 40–45 cm TL (Stehmann and Last, pers. obs.). Like other skates this species is oviparous. Its biology is little known.
Systems: Marine

Use and Trade [top]

Use and Trade: This species is not known to be utilized or traded.

Threats [top]

Major Threat(s): This species is frequently taken as bycatch by deep trawlers on the continental slope in Australian waters and could be of minor commercial value but is currently discarded (Last and Compagno 1998, Last and Stevens 2009). Both the Western Deepwater Trawl Fishery and the Northwest Slope Trawl Fishery operate within the range of this species, however current effort and catch is low with only a very small number of active vessels in these fisheries (Marton and Mazur 2014a, 2014b). There is no catch information available from Indonesia or the Philippines. There is no information available on post-discard survival rate.

Conservation Actions [top]

Conservation Actions: There are no species-specific conservation measures in place. Trawl fishing effort within its Australian range is currently low, but careful monitoring of fishing effort throughout the extent of occurrence would be beneficial.

Citation: Huveneers, C., Stehmann, M.F.W. & Last, P.R. 2015. Insentiraja subtilispinosa. The IUCN Red List of Threatened Species 2015: e.T161553A68630712. . Downloaded on 02 December 2015.
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