Rhinoraja magellanica

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	CHONDRICHTHYES	RAJIFORMES	ARHYNCHOBATIDAE

Scientific Name:

Rhinoraja magellanica

Species Authority:

(Philippi, 1902)

Common Name/s:

English	–	Magellan Skate
Spanish	–	Raya Atigrada

Synonym/s:

Bathyraja magellanica (Philippi, 1902)

Raja magellanica Philippi, 1902

Taxonomic Notes:

Compagno (1999, 2005) reallocated this species from Bathyraja to the genus Rhinoraja but the validity of this move remains unconfirmed. Both are currently in use, until a definitive systematic revision of these genera is conducted.

Assessment Information [top]

Red List Category & Criteria:	Data Deficient ver 3.1
Year Assessed:	2007
Assessor/s:	McCormack, C., Lamilla, J., San Martín, M.J. & Stehmann, M.F.W.
Reviewer/s:	Kyne, P.M. & Valenti, S.V. (Shark Red List Authority)
Justification: A poorly known large skate (to 105 cm TL) from the Southwest Atlantic off Argentina, the Falkland/Malvinas Islands and the Burdwood Bank. Also known from the Southeast Pacific off southern Chile. Known from depths of 51 to 600 m. Reportedly taken as bycatch in deeper water benthic trawl and longline teleost target fisheries (for Merluccius hubbsi, M. australis and Dissostichus eleginoides). There is no species-specific bycatch information available, however, fishing pressure off Argentina has increased substantially over the past decade and in 1999, there was a decrease in the captures of rays by the deep sea fishing fleet of around 15% with regard to 1998. There was a reported a decline in the biomass of B. magellanica captured during fishery-independent investigations at 45° to 55°S off Argentina from 1998 to 1999, however the second phase of investigations employed gear which likely reduced the capture of rays. The species is also taken by one longline vessel targeting skates from Mar del Plata where it has been observed to comprise very little to around 8% of the catch. It is also occasionally taken in the Falkland/Malvinas Islands multispecies skate fishery although in this region it is prevalent mainly outside fishing depths (i.e., generally in depths <70 m). There may be some refuge for the species there as there are no artisanal fisheries or other trawlers operating at these shallow depths. Globally this species is assessed as Data Deficient and further information on its distribution and trends in catches off Chile and Argentina are required. Bathyraja magellanica is a larger species and could therefore be vulnerable to overfishing. There is an urgent need to collect species-specific bycatch data for trawl fisheries operating off Argentina to make a full assessment of the conservation status of this species.

Geographic Range [top]

Range Description:	Has a more restricted distribution than other Magellanic species (Menni and Stehmann 2000). Present off Argentina, the Falkland/Malvinas Islands and on the Burdwook bank in the Southwest Atlantic. Also reported in the Southwest Pacific off southern Chile.
Countries:	Native: Argentina; Chile; Falkland Islands (Malvinas)
FAO Marine Fishing Areas:	Native: Atlantic – southwest; Pacific – southeast
Range Map:	(click map to view full version)

Population [top]

Population:	Population size unknown. In the Falkland/Malvinas Islands, the species is only caught very occasionally, and there has previously been uncertainty as to whether these were strays from the South America mainland, or actually breeding there. Since then, there has been one experimental fishing trip with longlines in depths of about 50 to 60 m, and during this trip quite a few adult specimens were caught, thereby showing that a population exists. Subsequently, since 1998 occasional fishing from a research vessel in shallower waters has found local 'hotspots' of this species (J. Pompert pers. comm. 2006).
Population Trend:	Unknown

Population:

Population size unknown. In the Falkland/Malvinas Islands, the species is only caught very occasionally, and there has previously been uncertainty as to whether these were strays from the South America mainland, or actually breeding there. Since then, there has been one experimental fishing trip with longlines in depths of about 50 to 60 m, and during this trip quite a few adult specimens were caught, thereby showing that a population exists. Subsequently, since 1998 occasional fishing from a research vessel in shallower waters has found local 'hotspots' of this species (J. Pompert pers. comm. 2006).

Population Trend:

Unknown

Habitat and Ecology [top]

Habitat and Ecology:	Benthic species known from off Argentina at depths of 51 to 600 m in bottom temperatures ranging from 3.5°C to 11.0°C (Menni and Stehmann 2000). Around the Falkland/Malvinas Islands, it is prevalent mainly in depths of <70 m (J. Pompert pers. comm). Size at maturity has been estimated around 58 cm TL (Stehmann et al. unpubl. data). This species has been reported from a minimum of 14 cm TL (Norman 1937) to a maximum of 105 cm TL (Stehmann et al. unpubl. data). Feeds primarily (around 75%) on crustaceans, but also polychaetes and fishes (Sánchez and Mabragaña 2002). Like other skate species, B. magellanica is oviparous. Further information on the life history of the species may become available in the near future as the ECORAYA project is finalised (M. Stehmann pers. comm. 2006).
Systems:	Marine

Habitat and Ecology:

Benthic species known from off Argentina at depths of 51 to 600 m in bottom temperatures ranging from 3.5°C to 11.0°C (Menni and Stehmann 2000). Around the Falkland/Malvinas Islands, it is prevalent mainly in depths of <70 m (J. Pompert pers. comm). Size at maturity has been estimated around 58 cm TL (Stehmann et al. unpubl. data). This species has been reported from a minimum of 14 cm TL (Norman 1937) to a maximum of 105 cm TL (Stehmann et al. unpubl. data). Feeds primarily (around 75%) on crustaceans, but also polychaetes and fishes (Sánchez and Mabragaña 2002). Like other skate species, B. magellanica is oviparous. Further information on the life history of the species may become available in the near future as the ECORAYA project is finalised (M. Stehmann pers. comm. 2006).

Systems:

Marine

Threats [top]

Major Threat(s):	Throughout this section the term rajid refers to skates of both the families Rajidae and Arhynchobatidae. Argentina Skate landing have been increasing considerably in Argentina due to international demand. Prior to 1994, skate captures were less than 1,000 t, however, since that year skate landings increased considerably, reaching >15,000 t in 2001 and 17,465 t in 2003 (Massa et al. 2004). B. magellanica is a regular bycatch in bottom trawl fisheries for bony fishes. It was captured during fishing investigations for hake Merluccius hubbsi and other species (García de la Rosa et al. 2000). García de la Rosa et al. (2000) reported a 41% decline in the biomass of B. magellanica captured from 45° to 55°S during the summer investigations of 1999 compared to 1998, however, it was acknowledged that during the second phase of the investigations, new gear was employed which likely reduced the capture of rays. During 1999, there was a decrease in the captures of rays by the deep sea fishing fleet of around 15% with regard to 1998 (García de la Rosa et al. 2000). The species is also taken in the Dipturus chilensis directed skate fishery off Argentina which currently comprises a single vessel. Onboard observation of the fishing operation in 2000 and 2001 indicated that the vessel fished from 37° to 44°S on the off Argentina in two regions; around 50 m of depth and along the 100 m isobath. At greater depths, the processed catch composition varied between trips and comprised very few or up to around 8% of B. magellanica (Colonello et al. 2002). Species-specific bycatch data are not generally collected for this fishery, however, and remain a priority for this and the trawl fishery. Falkland/Malvinas Islands Since 1989, rajids have been targeted by a Korean fleet utilizing demersal trawls around the Falkland/Malvinas Islands. Bathyraja magellanica comprises a very small proportion of the catch of in this fishery compared with other species of rays (Wakeford et al. 2004) most likely because this species is prevalent mainly outside the main fishing areas (i.e., generally in depths <70 m), and hence biomass is largely unknown. There are no other fisheries operating at these shallow depths in the area (J. Pompert pers. comm.) and the species may be afforded some refuge there. The multispecies skate fishery initially operated over two main areas, one located on the shelf edge to the north of the Islands, and the other to the south of the Islands. Following declines in CPUE in the early 1990's, the southern area was closed to the ray fleet in 1996 and the fishery now concentrates in the northern area. An assessment of the northern ray population, utilizing observer data, has shown little indication of an increasing or decreasing trend in CPUE for this species (Wakeford et al. 2004). Chile There is no information on the bycatch of this species in Chilean fisheries.

Major Threat(s):

Throughout this section the term rajid refers to skates of both the families Rajidae and Arhynchobatidae.

Argentina
Skate landing have been increasing considerably in Argentina due to international demand. Prior to 1994, skate captures were less than 1,000 t, however, since that year skate landings increased considerably, reaching >15,000 t in 2001 and 17,465 t in 2003 (Massa et al. 2004).

B. magellanica is a regular bycatch in bottom trawl fisheries for bony fishes. It was captured during fishing investigations for hake Merluccius hubbsi and other species (García de la Rosa et al. 2000). García de la Rosa et al. (2000) reported a 41% decline in the biomass of B. magellanica captured from 45° to 55°S during the summer investigations of 1999 compared to 1998, however, it was acknowledged that during the second phase of the investigations, new gear was employed which likely reduced the capture of rays. During 1999, there was a decrease in the captures of rays by the deep sea fishing fleet of around 15% with regard to 1998 (García de la Rosa et al. 2000). The species is also taken in the Dipturus chilensis directed skate fishery off Argentina which currently comprises a single vessel. Onboard observation of the fishing operation in 2000 and 2001 indicated that the vessel fished from 37° to 44°S on the off Argentina in two regions; around 50 m of depth and along the 100 m isobath. At greater depths, the processed catch composition varied between trips and comprised very few or up to around 8% of B. magellanica (Colonello et al. 2002). Species-specific bycatch data are not generally collected for this fishery, however, and remain a priority for this and the trawl fishery.

Falkland/Malvinas Islands
Since 1989, rajids have been targeted by a Korean fleet utilizing demersal trawls around the Falkland/Malvinas Islands. Bathyraja magellanica comprises a very small proportion of the catch of in this fishery compared with other species of rays (Wakeford et al. 2004) most likely because this species is prevalent mainly outside the main fishing areas (i.e., generally in depths <70 m), and hence biomass is largely unknown. There are no other fisheries operating at these shallow depths in the area (J. Pompert pers. comm.) and the species may be afforded some refuge there. The multispecies skate fishery initially operated over two main areas, one located on the shelf edge to the north of the Islands, and the other to the south of the Islands. Following declines in CPUE in the early 1990's, the southern area was closed to the ray fleet in 1996 and the fishery now concentrates in the northern area. An assessment of the northern ray population, utilizing observer data, has shown little indication of an increasing or decreasing trend in CPUE for this species (Wakeford et al. 2004).

Chile
There is no information on the bycatch of this species in Chilean fisheries.

Conservation Actions [top]

Conservation Actions:	Argentina There are theoretically TACs, minimum sizes and overall annual quotas for quite a number of elasmobranch species in Argentina, however, little attention is paid to these and there is no regular monitoring by authorities (M. Stehmann pers. obs. 2006). Species-specific assessments of direct and indirect catches are a priority. Falkland/Malvinas Islands The following information is taken from Agnew et al. (1999, 2000) unless otherwise specified. The Falkland/Malvinas Islands multispecies skate fishery is managed by limiting fishing effort. The effort that each vessel is likely to exert is calculated (based on size, duration of license and past fishing history) and since 1994 only a limited number of licenses are granted to ensure that the total allowable effort (determined from assessments of stock status) is not exceeded. Stock status assessments are not, however, species-specific and a sustainable total allowable effort for the entire stock may not translate to sustainable levels of effort for individual species. Following declines in CPUE in the early 1990s, in 1996, the southern area (below 52°S) was closed to rajid fishing and the fishery is now restricted to the area north of the Islands. This closure is extended to 50°30´S (between 56°30W and 58°W) during the second season of each year to exclude the skate fishing fleet from Loligo gahi fishing grounds. All licensed vessels are required to provide daily catch and effort details, including discards of commercial and non-commercial species to the Falkland Island Fisheries Department. There is, however, no requirement to report species-specific information. Scientific observers are deployed onboard vessels in order to quantify the catch composition by species and to obtain detailed biological data on individual species. Vessels fishing under general finfish licenses are prohibited from targeting rajids, although a small bycatch (below 10%) is allowed.

Conservation Actions:

Argentina
There are theoretically TACs, minimum sizes and overall annual quotas for quite a number of elasmobranch species in Argentina, however, little attention is paid to these and there is no regular monitoring by authorities (M. Stehmann pers. obs. 2006). Species-specific assessments of direct and indirect catches are a priority.

Falkland/Malvinas Islands
The following information is taken from Agnew et al. (1999, 2000) unless otherwise specified.
The Falkland/Malvinas Islands multispecies skate fishery is managed by limiting fishing effort. The effort that each vessel is likely to exert is calculated (based on size, duration of license and past fishing history) and since 1994 only a limited number of licenses are granted to ensure that the total allowable effort (determined from assessments of stock status) is not exceeded. Stock status assessments are not, however, species-specific and a sustainable total allowable effort for the entire stock may not translate to sustainable levels of effort for individual species. Following declines in CPUE in the early 1990s, in 1996, the southern area (below 52°S) was closed to rajid fishing and the fishery is now restricted to the area north of the Islands. This closure is extended to 50°30´S (between 56°30W and 58°W) during the second season of each year to exclude the skate fishing fleet from Loligo gahi fishing grounds. All licensed vessels are required to provide daily catch and effort details, including discards of commercial and non-commercial species to the Falkland Island Fisheries Department. There is, however, no requirement to report species-specific information. Scientific observers are deployed onboard vessels in order to quantify the catch composition by species and to obtain detailed biological data on individual species. Vessels fishing under general finfish licenses are prohibited from targeting rajids, although a small bycatch (below 10%) is allowed.

Citation:	McCormack, C., Lamilla, J., San Martín, M.J. & Stehmann, M.F.W. 2007. Rhinoraja magellanica. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 04 February 2012.
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