Overview

Comprehensive Description

Biology

Found mainly on soft bottoms (Ref. 3167). Feed mainly on crustaceans and bony fishes depending on the sex, size and also partly with the season (Ref. 3167). Oviparous. Distinct pairing with embrace. Young may tend to follow large objects, such as their mother (Ref. 205). Eggs are oblong capsules with stiff pointed horns at the corners deposited in sandy or muddy flats (Ref. 205). About 20-62 eggs are laid by an individual in a year (Ref. 41314).
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Distribution

Range Description

Speckled Skate (Raja polystigma) is moderately common, endemic species throughout the Mediterranean Sea (Serena 2005), particularly in the western (Morocco, Spain and France) and western central areas (Tyrrhenia, Corsica, Sardinia and Sicily) (Baino et al. 2001, Ragonese et al. 2003, Florio et al. 2003, Follesa et al. 2003, Spedicato et al. 2003, Serena 2005, Mancusi et al. 2005), along northern African coasts (Stehmann and Brkel 1984), and eastern Algerian coasts (Bertozzi et al. 2003). The species also exists in the southern Ligurian Sea (Vannucci et al. 2006) and around Asinara Island, northwest Sardinia (Catalano et al. 2007). It is rare in the Ionian Seas (Notarbartolo di Sciara and Bianchi 1998, Mytilineou et al. 2005). In the Adriatic Sea, it is rarely captured.

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Northeast Atlantic: known only from the western Mediterranean, more common along the African coasts.
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Mediterranean Sea endemic.
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Physical Description

Size

Maximum size: 600 mm TL
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Max. size

60.0 cm TL (male/unsexed; (Ref. 3167))
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
The species is benthic, and it inhabits mainly soft bottoms from 100-400 m (Serena 2005), but with a wide depth range from 20-633 m. Both males and females are estimated to mature at 40-53 cm total length (TL) with a maximum recorded size of 60 cm TL (Tortonese 1956, Bini 1967, Bauchot 1987, Stehmann and Burkel 1984, Notarbartolo di Sciara and Bianchi 1998, Serena 2005). It is common at sizes of 30-40 cm TL (Bauchot 1987). Like other skates, this species is egg laying. Reproduction takes place in winter and 20-62 egg cases (depending on size) are laid per year (Bauchot 1987, Stehmann and Burkel 1984, Serena 2005). The egg-cases measure 46 by 35 mm excluding horns (Stehmann and Burkel 1984, Serena 2005).

Systems
  • Marine
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Environment

demersal; marine; depth range 100 - 400 m (Ref. 3167)
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Depth: 100 - 400m.
From 100 to 400 meters.

Habitat: demersal.
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Trophic Strategy

Found mainly on soft bottoms. Feeds mainly on crustaceans and bony fishes depending on the sex, size and also partly with the season.
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Life History and Behavior

Life Cycle

Oviparous, paired eggs are laid. Embryos feed solely on yolk (Ref. 50449). Ripe females occurring mostly in the winter and deposit 20 to 62 egg-cases per year depending on size (Ref. 3167). Distinct pairing with embrace. Y oung may tend to follow large objects, such as their mother (Ref. 205).
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Raja polystigma

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 21
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2015

Assessor/s
Ungaro, N., Dulvy, N.K., Tinti, F., Bertozzi, M., Notarbartolo di Sciara, G., Serena, F., Abella, A. & Walls, R.H.L.

Reviewer/s
Mancusi, C.

Contributor/s

Justification

Speckled Skate (Raja polystigma) is endemic to the Mediterranean Sea. This relatively small skate (up to 60 cm total length) mainly inhabits soft bottoms on the continental shelf at depths of 100-400 m. It shows a wide geographic range in the Mediterranean Sea (mostly western and western central areas) where it is moderately common. It is part of the bycatch in fisheries using bottom trawl nets, but is also fished with gillnets, longlines and handlines in artisanal fisheries. Although little is known of the effect of fisheries on population size, its entire range overlaps intensively trawled regions. Given its small-body size, it is likely to be able to withstand moderate levels of fishing pressure. Speckled Skate is therefore assessed as Least Concern, although the status of this endemic species should be monitored.


History
  • 2009
    Near Threatened (NT)
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Population

Population

The species is found predominantly on the shelf and has been caught in the MEDITS program at depths up to 500 m (Baino et al. 2001). It is the third most abundant skate species captured in trawl surveys performed in the south Ligurian and north Tyrrhenian Sea from 1985-2004 after Thornback Skate (R. clavata) and Brown Skate (R. miraletus). In this area it occupies a very wide depth range (20-633 m) but is more concentrated between 300 and 400 m. Important catches of juveniles were recorded occasionally. Most of the collected specimens measured between 12 and 49 cm in length (Serena et al. 2005).

A study of commercial bottom trawl catch from 1995 to 2006 in the Aegean Sea caught a total of 203 specimens, with a mean catch per unit effort (CPUE) of 2.07 kilograms per hour, or 6.33 individuals per hour (Damalas and Vassilopoulou 2011). Of this catch, the majority was discarded (77.72% in weight; 93.60% in number) and the remaining fraction marketed (22.28% in weight; 6.40% in number). The same authors reported that fishery-dependent mean nominal CPUE of Speckled Skate in the central Aegean Sea has increased by 98.69% from a mean value of 0.01 individuals per hour (< 0.01 kg/h) between 1995 and 2000 to 0.71 individuals per hour (0.23 kg/h) between 2003 and 2006.

Due to the high degree of morphological similarity with Spotted Skate (Raja montagui), in the past many Speckled Skate captured in the scientific surveys have been incorrectly identified as Spotted Skate (Cannas et al. 2008).


Population Trend
Unknown
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Threats

Major Threats

The species is caught as bycatch in demersal trawl fisheries but is also fished with gillnets, longlines and handlines in artisanal fisheries (Bauchot 1987). There is a high level of exploitation over the continental shelf and upper slope, up to a depth of 800 m in the Mediterranean Sea (Massuti and Moranta 2003). Benthic trawl effort has increased both numerically and in technological terms in the shelf and slope area of the Mediterranean Sea over the past 50 years, even though a small decline occurred in recent years. For example, the Gulf of Lions area resources were initially exploited by small-scale benthic trawl fisheries comprising 27 small low powered boats (total nominal horse power of 2,700 hp), more recently effort has increased to a total nominal horse power of 19,940 hp (1974-1987) (Aldebert 1997).

It is known to be retained and marketed along the African coasts of the Mediterranean Sea, where both trawl and artisanal fisheries operate (Bauchot 1987). This species is rarely landed separately from other rays in Italian Seas and it is not possible to monitor catches. An increase in CPUE and decrease in discards is reported in the central Aegean Sea (Damalas and Vassilopoulou 2011).
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Near Threatened (NT)
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Management

Conservation Actions

Conservation Actions
There are no specific measures for the management or conservation of this species in the Mediterranean Sea. Landings are allowed without any minimum legal landing size nor catch limits. Fisheries regulations in the Mediterranean Sea are based on effort control (some measures of effort reduction have been implemented) and technical adjustments, such as minimum mesh size for bottom trawl, which are too small to enable escapement of even the smallest Speckled Skate individuals. Further research should be conducted on the population size and trend of the species.
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