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Potamotrygon scobina

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES POTAMOTRYGONIDAE

Scientific Name: Potamotrygon scobina
Species Authority: Garman, 1913
Common Name(s):
English Arraia, Raspy River Stingray
Taxonomic Notes: This species shows a wide range of color variation within juvenile and adult specimens (adults may present up to four completely different color patterns) (Almeida 2003). Misidentifications occur with several other freshwater stingray species, but especially with P. motoro (Rosa 1985), P. castexi and P. signata (Almeida 2003, author's pers. obs.).

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2004
Date Assessed: 2004-04-30
Assessor(s): De Almeida, M.P. & Charvet-Almeida, P.
Reviewer(s): Kyne, P.M. & Cavanagh, R.D. (Shark Red List Authority)
Justification:
A medium to large-sized, moderately common endemic freshwater stingray, widely distributed in the mid-lower Amazon basin (main area of distribution is the lower Amazon basin). This species presents one of the highest chromatic variations and highest fecundity (up to 16 young per litter) among the potamotrygonid rays. Although it is known that this species is taken for food and ornamental purposes in some regions, only sparse life history and population data are available. Further studies and a new assessment are highly recommended in the near future, due to the existence of a number of identified and potential threats, including habitat degradation, persecution, pollution, ornamental trade and fishery impacts.

Geographic Range [top]

Range Description: Northern Brazil, in the mid and lower Amazon drainage, from Manaus to Belém (Rosa 1985, Carvalho et al. 2003); also found in the lower Tocantins River drainage (type locality Cametá; Garman 1913); Pará and Trombetas River (Carvalho et al. 2003) and possibly in the lower drainage of other Amazonas tributaries (author's pers. obs.).

Reproduction and nursery areas have been observed for this species, more specifically inshore off some islands located in the Marajó Bay region (State of Pará, Brazil) (Almeida 2003, Charvet-Almeida, pers. obs).
Countries:
Native:
Brazil
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There are no further data on range and population available.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: The distribution of this species in the Amazon estuary region is influenced by seasonal salinity variations (Almeida 2003, Charvet-Almeida, pers. obs.).

Sexual dimorphism has been recorded for P. scobina (Almeida 2003). Maximum size measured corresponded to a female specimen of 69.1 cm disc width (DW) and 132.5 cm total length (TL) (Almeida 2003).

Preliminary reproductive data has been observed in the Amazon estuary indicating sexual maturity at 35 cm DW (males) and 40 cm DW (females); ovarian fecundity of 1 to 13; litter size 1 to 16 embryos (Charvet-Almeida et al. in press). Evidence of sexual and ontogenetic segregation has been noted (author's unpubl. data).

Food items include mainly isopods (Sphaeromatidae) and shrimps (Paleomonidae) (Bragança 2002).

Population trends and dynamics have never been estimated for this species. Further life history studies of this species are currently underway.
Systems: Freshwater

Use and Trade [top]

Use and Trade: aquarium trade

Threats [top]

Major Threat(s): This species is used as a human food source in some regions but is also subject to bycatch (hooking and netting) impacts from other fisheries. Juveniles are occasionally illegally caught and exported for the ornamental fish trade.

Its habitat is threatened by mining activities and agricultural impacts, including water pollution by agricultural chemical wastes. The development of infrastructure, tourism and recreational activities may lead to habitat disturbances, persecution and impacts on reproductive and nursery grounds. Oil spills and the construction of dams are additional potential threats for this species.

Conservation Actions [top]

Conservation Actions: Several conservation measures need to be implemented for P. scobina and very few are in progress.

Research is currently underway for this species: on taxonomy, biology, ecology, habitat status, cultural relevance and population trends/monitoring studies. While these studies are broad at the present, they are providing significant baseline information for the family Potamotrygonidae, a group for which there is limited information available. No other conservation measures are underway at the present time.

Fishery management-plans, legislation, regional community management and implementation of sustainable use principles are required for P. scobina. The establishment of a quota system for the ornamental fish trade should also be considered. Habitat conservation and protection, especially of important breeding and nursery areas are needed.

All these measures depend on education and public awareness in order to become locally understood, adopted and effectively implemented and managed.

Citation: De Almeida, M.P. & Charvet-Almeida, P. 2004. Potamotrygon scobina. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 30 August 2014.
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