Bathyraja scaphiops

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:

Bathyraja scaphiops

Species Authority:

(Norman, 1937)

Common Name/s:

English	–	Cuphead Skate
Spanish	–	Raya Nariguda Manchada, Raya Picuda

Assessment Information [top]

Red List Category & Criteria:	Near Threatened ver 3.1
Year Assessed:	2007
Assessor/s:	McCormack, C., 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 111 cm TL) recorded off Argentina and the Falkland/Malvinas Islands in the Southwest Atlantic. Known from depths of 109 to 509 m. Reportedly taken as bycatch in deeper water benthic trawl and longline teleost target fisheries as well as in target longline skate fishing from off Mar del Plata, Argentina. The latter fishery primarily targets Dipturus chilensis, but has been observed to process small quantities (<5% of the catch) of B. scaphiops (Colonello et al. 2002). The quantity of discarded catch is unknown. There is little species-specific bycatch or catch information available for trawl fisheries off Argentina, however, fishing pressure 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 decline in the biomass of B. scaphiops 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. B. scaphiops is also taken in the targeted multispecies skate fishery around the Falkland/Malvinas Islands. This fishery experienced declines in the early 1990s especially in the area south of the Islands which is now closed to the rajid trawl fleet. There is little species-specific information on population trends for B. scaphiops, however, an assessment of the northern ray population did not indicate any significant trends in CPUE for the species over the period from 1992 to 2001. Bathyraja scaphiops is a large species with a large size at maturity rendering it susceptible to overfishing. Generally, more information is required on population trends, however, heavy fishing pressure has occurred in the past and is continuing throughout the species' range and it is likely that declines have occurred. The relatively restricted distribution of this large skate, endemic to Argentina and the Falkland/Malvinas Islands, may render it more vulnerable to decline than other more widely ranging species. It is therefore assessed as Near Threatened on the basis of suspected past and future declines. There is concern that the species may be close to meeting criteria for VU A4d.

Geographic Range [top]

Range Description:	Occurs in the Southwest Atlantic off Argentina and around the Falkland/Malvinas Islands. Reported from 45°30'S to 51°30'S and to 59°35'W (Menni and Stehmann 2000).
Countries:	Native: Argentina; Falkland Islands (Malvinas)
FAO Marine Fishing Areas:	Native: Atlantic – southwest
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Moderately common species of the Magellanic fauna, but population size unknown.
Population Trend:	Unknown

Habitat and Ecology [top]

Habitat and Ecology:	Known from depths of 109 to 509 m at bottom temperatures ranging from 4.3 to 7.6°C (Menni and Stehmann 2000). Most abundant about the centre of the shelf, from 104 to 159 m at bottom temperatures of 4.5 to 6°C (Menni and Stehmann 2000). Shows a strict stenothermic-stenohaline behaviour in relation to water masses (Figueroa et al. 1999). Size at maturity has been estimated around 74.2 cm TL for male specimens and maximum size has been estimated at 111 cm TL (Stehmann et al. unpubl. data). The smallest known specimen is 21 cm TL (Stehmann et al. unpubl. data). Like other skates, B. scaphiops 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:

Known from depths of 109 to 509 m at bottom temperatures ranging from 4.3 to 7.6°C (Menni and Stehmann 2000). Most abundant about the centre of the shelf, from 104 to 159 m at bottom temperatures of 4.5 to 6°C (Menni and Stehmann 2000). Shows a strict stenothermic-stenohaline behaviour in relation to water masses (Figueroa et al. 1999). Size at maturity has been estimated around 74.2 cm TL for male specimens and maximum size has been estimated at 111 cm TL (Stehmann et al. unpubl. data). The smallest known specimen is 21 cm TL (Stehmann et al. unpubl. data). Like other skates, B. scaphiops 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):	The term rajid refers to skates of both the families Rajidae and Arhynchobatidae. Argentina Skate landings 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). Bathyraja scaphiops is a regular bycatch in bottom trawl fisheries for bony fishes. It has been captured during fishery-independent investigations for hake Merluccius hubbsi and other species (García de la Rosa et al. 2000). García de la Rosa et al. (2000) reported a 74% decline in the biomass of B. scaphiops 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 (García de la Rosa et al. 2000). 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 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 low proportions of B. scaphiops (<5%) (Colonello et al. 2002). Falkland/Malvinas Islands Bathyraja scaphiops is taken in the multi-species skate trawl fishery around the Falkland/Malvinas Islands which has been operating since 1989. The 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. In 1996, following declines in CPUE, the southern area (south of 52°S) was closed to the fleet and the fishery now operates north of the Islands. An assessment of the northern ray population (Wakeford et al. 2004) indicated that there was no significant increasing or decreasing trend in the CPUE for B. scaphiops over the period from 1992 to 2001. The Falkland/Malvinas Islands have in place a precautionary management system for the skate fishery (see Conservation Actions), and together with the recovery of biomass (Agnew et al. 2000), what this means is that the fishery will continue into the future, because overall stocks are stable or recovering. There have been no studies to determine the abundance of this species in the southern area since the rajid fishery closure. However, this species may also be caught as bycatch by finfish trawlers operating around the Falkland/Malvinas Islands and within the southern rajid closure. While vessels fishing under general finfish licenses are prohibited from targeting rajids, a small bycatch (below 10%) is allowed and rajids to the south of the Islands are continuing to face bycatch fishing pressure.

Major Threat(s):

The term rajid refers to skates of both the families Rajidae and Arhynchobatidae.

Argentina
Skate landings 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).

Bathyraja scaphiops is a regular bycatch in bottom trawl fisheries for bony fishes. It has been captured during fishery-independent investigations for hake Merluccius hubbsi and other species (García de la Rosa et al. 2000). García de la Rosa et al. (2000) reported a 74% decline in the biomass of B. scaphiops 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 (García de la Rosa et al. 2000). 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 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 low proportions of B. scaphiops (<5%) (Colonello et al. 2002).

Falkland/Malvinas Islands
Bathyraja scaphiops is taken in the multi-species skate trawl fishery around the Falkland/Malvinas Islands which has been operating since 1989. The 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. In 1996, following declines in CPUE, the southern area (south of 52°S) was closed to the fleet and the fishery now operates north of the Islands. An assessment of the northern ray population (Wakeford et al. 2004) indicated that there was no significant increasing or decreasing trend in the CPUE for B. scaphiops over the period from 1992 to 2001. The Falkland/Malvinas Islands have in place a precautionary management system for the skate fishery (see Conservation Actions), and together with the recovery of biomass (Agnew et al. 2000), what this means is that the fishery will continue into the future, because overall stocks are stable or recovering. There have been no studies to determine the abundance of this species in the southern area since the rajid fishery closure. However, this species may also be caught as bycatch by finfish trawlers operating around the Falkland/Malvinas Islands and within the southern rajid closure. While vessels fishing under general finfish licenses are prohibited from targeting rajids, a small bycatch (below 10%) is allowed and rajids to the south of the Islands are continuing to face bycatch fishing pressure.

Conservation Actions [top]

Conservation Actions:	In Argentina, 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 skate 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:

In Argentina, 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 skate 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., San Martín, M.J. & Stehmann, M.F.W. 2007. Bathyraja scaphiops. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 04 February 2012.
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