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Pavoraja arenaria

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES ARHYNCHOBATIDAE

Scientific Name: Pavoraja arenaria
Species Authority: Last, Mallick & Yearsley, 2008
Common Name(s):
English Sandy Skate, Yellow Skate
Taxonomic Notes:

The Sandy Skate (Pavoraja arenaria) was previously referred to as Pavoraja sp. C by Last and Stevens (1994).

Most of the Australian species of softnose skates were only discovered in the past 25 years and have been described recently (Last and Stevens 2009). A number of batoid taxonomists have considered this group to be a sub-family of the family Rajidae (Last and Stevens 2009). There is still work to be done to resolve their classification as debate still exists in regard to the softnose skate classification (Last and Stevens 2009).

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2011
Date Assessed: 2010-11-17
Assessor(s): Heaven, C. & Huveneers, C.
Reviewer(s): Ebert, D.A. & Kyne, P.M.
Justification:
The Sandy Skate (Pavoraja arenaria) is a small softnose skate, endemic to the waters of southern Australia. It is a demersal species which ranges from Cape Leeuwin (Western Australia) to Portland (Victoria), in depths of 190–710 m, although it is mostly found at 300–400 m. Maximum size is at least 34 cm total length but little is known about its biology as it has only recently (2008) been described. The Sandy Skate is taken as bycatch from demersal trawl fisheries due to the depth and distribution ranges of this species overlapping with trawling ranges. Unfortunately, species-specific catch data is lacking within many of these fisheries and it is therefore difficult to assess the vulnerability of this species to fishing pressure. Like many deepwater skates, there is little information available to undertake an accurate assessment of its conservation status; however, the Sandy Skate has been identified as being directly impacted by commercial trawling, due to having a narrow distribution range and fisheries across the majority of their range. Given the vulnerability of skates to overfishing, and a general lack of data on many skate species, bycatch levels need monitoring and research is required on distribution and ecology of this species. Currently there is insufficient information on the population size/structure, trend or range for this species to be assessed beyond Data Deficient.

Geographic Range [top]

Range Description:

The Sandy Skate is known from the Great Australian Bight between Cape Leeuwin in Western Australia (34°59’S, 114°53’E) and Portland, Victoria (34°42’S, 141°20’E) (Last and Stevens 2009).

The Sandy Skate belongs to the Southern marine biogeographic province of Australia (IMCRA Technical Group 1998) where it is mainly found in the upper slope biome (Last et al. 2005).

Countries:
Native:
Australia (South Australia, Victoria, Western Australia)
FAO Marine Fishing Areas:
Native:
Indian Ocean – eastern
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There are no details of population size, structure, or trends within the current literature on the Sandy Skate.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: The Sandy Skate is a demersal species occurring on the outer continental shelf and upper slope at depths of 190–710 m, although it is mostly found between depths of 300–400 m (Last and Stevens 2009). However, no specific information regarding the habitat of this species is currently available. The Sandy Skate reaches at least 34.3 cm total length (TL) and approximately 18 cm disc width (Last et al. 2008). Males mature at around 29–33 cm TL (Last and Stevens 2009). Like other skates, this species is assumed to be oviparous, yet little is known about reproductive output, seasonality, or other aspects of the biology of this species (Last and Stevens 2009).
Systems: Marine

Use and Trade [top]

Use and Trade:

The Sandy Skate is not known to be traded or marketed for human use or consumption, because generally, the flesh of skates is not highly regarded for human consumption (Bester 2010).

Threats [top]

Major Threat(s):

Other than natural predators, trawling and demersal longline fishing are most likely to be the main threats to the Sandy Skate (AFMA 2008). The Sandy Skate, along with seven other skate species have been identified as being directly impacted by commercial trawling, due to having narrow distribution ranges and fisheries across the majority of their ranges (WWF 2008). The main fisheries that could pose a threat to this species are the Commonwealth-managed Great Australian Bight Trawl Sector (GABTS) which is part of the Southern and Eastern Scalefish and Shark Fishery (SESSF), the Western Deepwater Trawl Fishery (WDTF) and the Western Australian (WA) managed Demersal Gillnet and Longline Fishery (Wilson et al. 2009).

The GABTS is primarily a demersal trawl fishery, but provision exists for mid-water trawling. The GABTS is based on demersal catches from three distinct depth regions: the shelf/upper slope sub-fishery, the deepwater slope sub-fishery (Orange Roughy (Hoplostethus atlanticus)), and the developing slope sub-fishery (Blue Grenadier, gemfish etc.) (AFMA 2008). The GABTS shelf sub-fishery extends approximately out to the 250 m depth, the upper continental slope sub-fishery operates in waters 300–750 m depth, whereas the deepwater slope sub-fishery operates in waters from 750–1,000 m. However, waters deeper than 750 m are currently closed to protect stocks of Orange Roughy. Therefore, the deepwater sub-fishery is no longer a threat to the Sandy Skate, yet they may still be threatened by the shelf/upper slope and developing slope sub-fisheries (AFMA 2008). Considering that the depth range of the Sandy Skate overlaps with the upper slope sub-fishery, it is possible that this species is a component of the bycatch of this fishery. Although post-release survival rate of the species is unknown, 100% of the skates and rays caught within the SESSF are reported to be discarded (Bergh et al. 2009).

The 2008 report from the WA Demersal Gillnet and Longline Fishery states that the total catch of sharks and rays from 2005-06 was 1,357 tonnes (McAuley 2008). Direct information on bycatch in the fishery is limited, however the WA Status of the Fisheries Report 2003-2004 states that ‘there is some discarded bycatch of unsaleable species of sharks, rays, and scalefish.’

The report further states that in the Ecological Risk Assessment carried out for the fishery in 2002, all impacts on bycatch species are considered to be low (McAuley and Simpfendorfer 2003). Additionally, in WA State waters, all sharks and rays were listed as commercially protected species since November 2006. This regulation essentially restricts the possession of sharks and rays by commercial fishers to four target fisheries in which shark catches are well understood and pose little risk to stock sustainability (McAuley 2008). As a result, reported shark and ray catches by vessels operating in non-target fisheries between North West Cape and the South Australian border declined to 5 tonnes in 2006/07 and 3.4 tonnes in 2007/08 (McAuley 2008). Despite the commercial protection, 47 tonnes of sharks were taken by vessels using ‘wetline’ methods in the region during 2006/07, although this declined to 3.8 tonnes in 2007/08 (McAuley 2008). While some of the fisheries bycatch reports mention that rays and skates are caught as bycatch, yet they do not record the species name or how much (tonnes) of these animals are actually being caught.

Conservation Actions [top]

Conservation Actions:

No conservation actions are currently in place for the Sandy Skate. It is difficult to implement management strategies for a specific species if there is no accurate, detailed information on catch, trend and population.

The WA Demersal Gillnet and Longline Fishery is managed via input controls in the form of time/gear effort units, restricted mesh/hook sizes, net height and maximum net length restrictions. The impact on stocks of bycatch from this fishery is determined to be low (McAuley 2008).

A better understanding of the biology, life histories and population dynamics of skate species in general is required so that each individual species can be properly managed. Conservation measures are essential to protect the future of chondrichthyan species such as the Sandy Skate. The following is a list of recommended actions that could be implemented to mitigate major threats to this species (DAFF 2004):

  • Improve the reporting of discarded bycatch and the associated mortality rates in trawl and demersal longline fisheries through improved data collection and species identification by fisheries observers, as well as through compulsory reporting of all bycatch for the commercial and recreational fishing industry;
  • Raise awareness among commercial and recreational fishers and other resource users about the status and threats of chondrichthyan species and encourage conservation-based release practices to decrease discard mortality;
  • Evaluate existing practices in all commercial and recreational fisheries and implement, where practicable, new regulations or technologies with the potential to decrease both the bycatch of chondrichthyans and associated mortality; and,
  • Increase the level of support and funding for research in order to obtain critical information about chondrichthyan species which are either threatened or data deficient. Data that is required about individual species includes: spatial distribution, critical habitats, fecundity, growth rates, age and population dynamics.

Citation: Heaven, C. & Huveneers, C. 2011. Pavoraja arenaria. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 29 August 2014.
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