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Psammobatis extenta

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES ARHYNCHOBATIDAE

Scientific Name: Psammobatis extenta
Species Authority: (Garman, 1913)
Common Name(s):
English Zipper Sandskate
Spanish Rayita Con Orlas
Synonym(s):
Psammobatis glansdissimilis McEachran, 1983
Taxonomic Notes: Carvalho and de Figueiredo (1994) considered Psammobatis glansdissimilis McEachran, 1983 a junior synonym of P. extenta.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2004
Date Assessed: 2004-04-30
Assessor(s): Chiaramonte, G.E.
Reviewer(s): Musick, J.A., Kyne, P.M., Cavanagh, R.D. & Fowler, S.L. (Shark Red List Authority)
Justification:
Endemic to the Southwest Atlantic from Cabo Frío, Brazil (22°56'S) to Patagonia, Argentina (45°S), this small skate is abundant in coastal waters off Uruguay and Argentina. This species is commonly caught and discarded by the coastal bottom trawlers operating in Buenos Aires Province (Argentina). While the conspecific Psammobatis bergi has recently become a target species in this fishery, the smaller (up to 31.3 cm total length (TL)), P. extenta is still discarded. The mass of P. extenta discarded by the coastal fishery from Puerto Quequén (Argentina), was low in relation to other batoid species, but it was the second most important batoid species discarded by number. The catch per unit effort (CPUE) of the total batoid catches did not change over the three year study period. However, species-specific trends are not available, and this, combined with the short time frame of the study prevents any clear changes in P. extenta abundance from being documented. This species is also taken as bycatch and discarded in other fisheries off Argentina, including those for hake and shrimp, and Patagonian bottom trawl fisheries. Females appear to be able to breed all year round. Due to its apparent abundance and probable high reproductive output (for a chondrichthyan) the species is assessed as Least Concern. However, given increasing fisheries pressure across its range careful monitoring needs to be undertaken. Further information is required from Brazil.

Geographic Range [top]

Range Description: Endemic to the Southwest Atlantic from Cabo Frío, Brazil (22°56'S) to Patagonia, Argentina (45°S) (Norman, 1937).
Countries:
Native:
Argentina; Brazil; Uruguay
FAO Marine Fishing Areas:
Native:
Atlantic – southwest
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: It is an abundant small skate in Uruguayan and Argentinean coastal waters.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: Off Puerto Quequén area (Argentina) this species occurs at 36 to 56 m depth, is present all year with a peak in summer, does not show sexual differences in size frequency distribution and also does not show any pattern of sexual segregation by depth. Only half of the sample (49.5%) was mature (Tamini et al. 2006).

Braccini and Chiaramonte (2002) report a neonate of 6.0 cm total length (TL), and a size at 50% maturity of 24.9 cm TL (86 g) (females) and 26.2 cm TL (93 g) (males), which represented 80% and 84% of the largest females and males measured (31.3 cm TL), respectively. These authors also concluded that the evidence suggested a continuous reproductive cycle during the year, with a maximum number of females carrying eggcases in summer. The number of eggs produced per year and the hatching time remains unknown.

This skate feeds mainly on Penoidea and Gammaridea with a narrow niche width B = 0.0975 (San Martín et al. 2003).
Systems: Marine

Threats [top]

Major Threat(s): This skate is commonly caught and discarded by the bottom trawlers operating in Buenos Aires Province (Argentina) (Tamini 2001). While the conspecific P. bergi has recently become a target species in this fishery, the smaller P. extenta is still discarded. In a study of batoids discarded by the coastal fishery from Puerto Quequén (Argentina), Tamini et al. (2006) found that the discarded mass of Psammobatis extenta was inconsiderable in relation with other batoid species, but was the second most important batoid species discarded by number. These authors also found that the CPUE of the total batoid catches did not change over the three year study period. Thus, no clear changes of P. extenta abundance could be noted. This species is also taken as bycatch and discarded in other fisheries off Argentina, including those for hake and shrimp, and Patagonian bottom trawl fisheries.

The growth of fishing pressure along the entire range of P. extenta along with the environmental loss of reproductive areas due to the disturbance and destruction of the seabed made by the coastal fleets of bottom trawlers could be pushing the species towards the Near Threatened category in the next 5-10 years.

Conservation Actions [top]

Conservation Actions: Since 1995, there has been a Permitted Maximum Catch (PMC) for coastal skates and rays in Argentina with a peak of 12,000 tonnes in 1997 and a drop to 4,000 tonnes in 2001 and 2002 (Massa et al. 2003). However, as this species is always discarded, the PMC is not an accurate tool for the conservation of this and other small skates.

Citation: Chiaramonte, G.E. 2004. Psammobatis extenta. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 29 July 2014.
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