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Raja texana

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES RAJIDAE

Scientific Name: Raja texana
Species Authority: Chandler, 1921
Common Name(s):
English Roundel Skate, Rondel Skate, Texas Clearnose Skate

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2009
Date Assessed: 2008-12-01
Assessor(s): Bethea, D.M., Carlson, J. & Sulikowski, J.
Reviewer(s): Valenti, S.V. & Musick, J.A. (Shark Red List Authority)
Justification:
The Roundel Skate (Raja texana) occurs in marine waters nearshore and offshore up to 183 m. It is distributed off the southeastern coast of Florida, USA, Gulf of Mexico, and Yucatan Bank, Mexico and is a potential bycatch in demersal trawls throughout this range. While a trend in abundance for a 30 year trawl data set in the Gulf of Mexico indicate that this species may be slightly increasing in abundance, which might warrant a status of Least Concern, this abundance trend is only from one series. Moreover, the overall productivity of this species is still unknown. Therefore this species is assessed as Data Deficient until further information is available to conduct a full evaluation of the impact of fisheries on the population.

Geographic Range [top]

Range Description: Western central Atlantic: from off the southeastern coast of Florida, USA, Gulf of Mexico, and Yucatan Bank, Mexico (McEachran and Fechhelm 1998).
Countries:
Native:
Mexico; United States (Alabama, Florida, Louisiana, Mississippi, Texas)
FAO Marine Fishing Areas:
Native:
Atlantic – western central
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Unknown.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This species occurs in marine waters nearshore and offshore up to 183 m and temperatures between 14–28°C (Smith, 1997); however, it most commonly occurs at 15–110 m at temperatures of 16–25°C (McEachran and Fechhelm, 1998). Young occur in shallow bays whereas adults tend to live offshore (Smith 1997); however, all sizes have been collected in bottom and pelagic trawls in NOAA fishery independent surveys in the US Gulf of Mexico (unpublished data NOAA Mississippi Labs, A. DeBose and A. Hamilton).

This species is oviparous with a distinct sexual dimorphism between males and females. The ovaries of the female are functional on both sides. Once the eggs are mature, they are released from the ovaries, fertilized in the upper part of the shell gland, are enclosed with yolk and albumen in a capsule formed by the lower shell gland. These capsules vary widely in size and are believed to be associated with parental body size. The capsules are light brown and have the characteristic horns on the four corners. Typically, there is only one fertilized egg found in a single capsule. These capsules are flat on one side and convex on the other. The female will often deposit eggs in sandy or muddy flats. When the young hatch from the capsules, they are fully formed and are similar in appearance to adults (unpublished data, J. Sulikowski).

Analysis of stomach contents from 222 immature (195 non-empty; mean DW = 23.5 cm) and 191 mature animals (167 non-empty; mean DW = 32.2 cm) in the northern Gulf of Mexico indicate shrimp (mostly euphasiids) make up 91% IRI of immature skate diet. Fish make up the remainder of immature skate diet. Mature skate diet was also predominantly shrimp (65 %IRI); however, fishes made up a much larger percentage (25 %IRI). Crabs were also relatively important in the diet of mature animals (4 %IRI). This suggests that roundel skate exhibit ontogenetic changes in diet with size and maturity (Bethea et al. In prep).
Systems: Marine

Threats [top]

Major Threat(s): The species is potentially caught as bycatch in demersal trawls that occur off the southeastern coast of Florida, USA, and in the Gulf of Mexico and probably discarded. It is also taken as bycatch in the butterfish fishery.

Conservation Actions [top]

Conservation Actions: None.

Citation: Bethea, D.M., Carlson, J. & Sulikowski, J. 2009. Raja texana. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 25 October 2014.
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