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Atlantoraja castelnaui

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES ARHYNCHOBATIDAE

Scientific Name: Atlantoraja castelnaui
Species Authority: (Miranda Ribeiro, 1907)
Common Name(s):
English Spotback Skate
Spanish Raya A Lunares, Raia-jereba, Raia-chita, Raya Chita, Raya Pintada
Synonym(s):
Raja castelnaui Miranda Ribeiro, 1907

Assessment Information [top]

Red List Category & Criteria: Endangered A2bd+3bd+4bd ver 3.1
Year Published: 2004
Date Assessed: 2004-04-30
Assessor(s): Hozbor, N., Massa, A & Vooren, C.M.
Reviewer(s): Walker, T.I., Kyne, P.M., Cavanagh, R.D. & Fowler, S.L. (Shark Red List Authority)
Justification:
A large skate, endemic to the Southwest Atlantic (southern Brazil, Uruguay and Argentina) continental shelf, which is subject to heavy fishing pressure. The vulnerability of similar large skates to overexploitation and subsequent population depletion is well documented. In south Brazil, the species has been commercially landed since at least 1986 and was frequently observed in trawler landings in 2002 and 2003. In Argentina, the species has been landed since 1994. Landing statistics are not available because all species of batoids are recorded as "unidentified rays and skates". Due to its large body size, the species has a high commercial value. Trawl fishing in the habitat of the species is intense. Off Argentina and Uruguay, biomass measured by research trawling decreased by 75% in the years from 1994-1999 and it is highly probable that in Brazil the species has declined by a similar amount.

Geographic Range [top]

Range Description: The depth distribution of the species appears to be much wider in south Brazil, where the species occurs across most of the continental shelf (20 to 220 m), than in Argentina, where the species is reported from the inner shelf only (40 to 60 m).
Countries:
Native:
Argentina; Brazil (Rio de Janeiro); Uruguay
FAO Marine Fishing Areas:
Native:
Atlantic – southwest
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Southern Brazil may be the stronghold of the species in terms of its abundance.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: In south Brazil, the species occurs all year round across most of the continental shelf, at 20 to 220 m, and at bottom temperatures of 9.5 to 22°C without preference for temperatures within this wide range (Vooren 1997, Vooren, unpubl. data). In Argentina, the species occurs at depths of 40 to 60 m and at bottom temperatures of 9.6 to 13.5°C (Menni and Stehmann 2000). Perhaps in Argentina depths greater than 60 m have bottom temperatures below 9.5°C, which is the minimum limit of the species. This would explain the wider depth distribution of the species in south Brazil where a wider range of temperatures greater than 9.5°C is available.

In south Brazil, in trawl surveys of the entire shelf in the years 1980 to 1986 (Vooren and Lamónaca, unpubl. data), disc width (DW) was as follows:
- Total range 20 cm to 103 cm (1 to 18 kg).
- Most abundant size classes 40 to 90 cm (1.5 to 12.5 kg).
- Females maximum size 103 cm, maximum total weight 18 kg.
- Males maximum size 90 cm, total weight 13 kg.

In Argentina, maximum total length (TL) is 140 cm and the species feeds on fish, squid and crustaceans (Cousseau and Perrotta 2000).

Oviparous, egg-laying occurs from January to October (assessors, pers. obs).
Systems: Marine

Threats [top]

Major Threat(s): In south Brazil the species has been fished by bottom trawling from at least 1986 and was frequently observed in trawler landings in 2002 and 2003 (Vooren and Lamónaca, unpubl. data). In Argentina, the species has been landed since 1994. Trawl fishing in the habitat of the species is intense. In Argentina and Uruguay, biomass measured by research trawling decreased by 75% in the years from 1994 to 1999 (Hozbor and Massa, unpubl. data) and it is highly probable that in Brazil the species is threatened by fishing at a similar level.

Furthermore, the vulnerability of large skates to overexploitation and subsequent population depletion is well documented (Dulvy and Reynolds 2002).

Conservation Actions [top]

Conservation Actions: No conservation measures exist in Brazil. In Argentina, the species is included in the annual catch quota of the fishery for coastal skates. Fishery landing statistics should be improved, by listing A. castelnaui specifically and not under "unidentified rays and skates". Management measures for this and other elasmobranch species should be reached bilaterally between Argentina and Uruguay in the first instance due to the common zone of fishing shared between them.

Citation: Hozbor, N., Massa, A & Vooren, C.M. 2004. Atlantoraja castelnaui. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 21 August 2014.
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