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Brochiraja aenigma

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES ARHYNCHOBATIDAE

Scientific Name: Brochiraja aenigma
Species Authority: Last & McEachran, 2006
Taxonomic Notes: Brochiraja aenigma remains poorly defined. A recent trawl survey to the type locality provided no additional specimens. Hence, its generic placement is provisional because features of adult males are unknown, and the only known female lacks a rostral thorn and is in a poor state of preservation. Within the southwest Pacific it is unique in appearance having a rounded disc covered in very fine granular denticles, a very long tail, and high meristic values (Last and McEachran 2006).

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2009
Date Assessed: 2008-12-01
Assessor(s): Stevens, J.D.
Reviewer(s): Francis, M. & Valenti, S.V. (Shark Red List Authority)
Justification:
This recently described species is only known from a single specimen from the Wanganella Bank on the Norfolk Ridge (south of Norfolk Island) at 422-437 m depth. Brochiraja aenigma attains at least 44 cm TL. The Wanganella Bank is rarely fished at depths shallower than 500 m so the bycatch of B. aenigma may be low; however the impact of fishing cannot be determined until information is available on the full geographic and depth range of the species. No information on the population of Brochiraja species in the area is available as catches are not reported. Subsequent research surveys in the type locality have aimed to collect further specimens, but have failed to record it again. There is concern that the species may be very rare with a limited range, making it potentially vulnerable to population depletion. However, given that the species was only recently described from an area that is not heavily fished there is insufficient information to assess it beyond Data Deficient at present. Future surveys should attempt to record this species and it may warrant a threatened category in the future.

Geographic Range [top]

Range Description: Southwest Pacific: known from a single specimen from the Wanganela Bank on the Norfolk Ridge (south of Norfolk Island) (Last and McEachran 2006).
Countries:
Native:
Norfolk Island
FAO Marine Fishing Areas:
Native:
Pacific – southwest
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Rare. This species is only known from a single specimen. Further surveys conducted in the type locality aimed to collect it again, but failed to record more specimens (P. Last and J. Stevens pers. obs. 2007).
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: The biology of Brochiraja aenigma is virtually unknown. The only known specimen was collected from 422-437 m depth and was 44 cm total length (TL) (Last and McEachran 2006). It is presumably oviparous and deposits eggs in quadrangular egg cases, like other skates.
Systems: Marine

Threats [top]

Major Threat(s): The Wanganella Bank is rarely fished at depths shallower than 500 m (S. Baird, NIWA, unpublished data), so bycatch of Brochiraja aenigma may be low; however the impact of fishing cannot be determined until information is available on the full geographic and depth range of the species. When caught, these skates are probably not retained (unless converted to fish meal) but are probably all dead on return to the sea. Catches are not reported, and the species is uncommon, making it impossible to estimate relative biomass using trawl surveys. Taxonomic confusion with other New Zealand species of Brochiraja has exacerbated these problems until recently.

Conservation Actions [top]

Conservation Actions: None in place. Future surveys should attempt to record this species to determine its full distribution, as well as information on its population and biology.

Citation: Stevens, J.D. 2009. Brochiraja aenigma. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 21 September 2014.
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