|Scientific Name:||Raja asterias|
|Species Authority:||Delaroche, 1809|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Serena, F., Mancusi, C., Ungaro, N., Notarbartolo di Sciara, G. & Tinti, F.|
|Reviewer/s:||Valenti, S.V. & Kulka, D.W. (Shark Red List Authority)|
This moderately productive ray is mainly restricted to the Mediterranean but may propagate to the Atlantic, near the southern coast of Portugal. It is caught as bycatch by bottom trawl fisheries in the Ligurian Sea targeting teleost fish, by modified beam trawl off Tuscany and also by trammel and gill nets. Analyses of CPUE data indicate that this population is currently stable, despite fishing pressure. Furthermore nursery areas are protected by a ban on trawling within three miles of the coast, and fishing pressure in this area has reduced in the last 15 years. It is quick to mature (three years) and has a short life span (10 years) indicating that it is relatively productive and resilient to fishing pressure. Therefore this species is currently assessed as Least Concern, but further information on its status in the southern Mediterranean is needed.
|Range Description:||The species can probably be considered endemic in the Mediterranean sea (Serena 2005).|
Native:Albania; Algeria; Bosnia and Herzegovina; Cyprus; Egypt; France (Corsica); Greece (East Aegean Is., Kriti); Israel; Italy (Sardegna, Sicilia); Lebanon; Libya; Monaco; Montenegro; Morocco; Slovenia; Spain (Baleares); Tunisia; Turkey
|FAO Marine Fishing Areas:||
Present - origin uncertain:
Atlantic – eastern central; Atlantic – northeast; Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species was captured in both the GRUND (Italian waters) and MEDITS (Mediterranean basin) trawl surveys (Relini 1998, Bertrand et al. 1997), which began in 1985 and 1994 respectively. In the south Ligurian and north Tyrrhenian sea this species was captured over muddy bottoms, in restricted coastal areas from 9 to 190 m depth, but mainly concentrated at 100 to 150 m depth. From 1999 to 2004 the Biomass Index is lower than the Density Iindex, which probably indicates a change in the population structure with a predominance of smaller specimens (Serena et al. 2005). The species has a higher relative abundance on the Italian and Corsica continental shelves (Baino and Serena 2000, Serena et al. 2005). Nursery areas are located very close to the coast (at 2 to 15 m depth) (Abella and Serena 2005).|
|Habitat and Ecology:||
R. asterias is found predominantly on the Italian and Corsica continental shelves between shallow waters and 150 m depth (Baino and Serena 2000). In the eastern Ionian sea, the species is found down to depths of 343 m (Mytilineou et al. 2005). Prefers muddy and sandy bottoms, characterised by Crangon crangon, Goneplax rhomboides and Liocarcinus spp. (Vannucci 2005).
Juvenile R. asterias move quickly into shallow waters (5 to 7 m depth) soon after birth and then move into deeper waters progressively with growth. Tag and release studies (Catalano et al. 2003) suggest that hatching probably occurs close to the bottom, at about 30 to 40 m depth. The sex-ratio confirms equal presence of both sexes.
Maximum size is estimated at 72 cm TL for males and of 76 cm TL for females (Bono et al. 2005, Serena and Abella 1999). The growth parameter data obtained using the Von Bertalanffy model were L? = 67.45, K = 0.454, t0 = -0.23 (Bono et al. 2005). Barone et al. (in press.) and Serena et al. (2005) estimate length at maturity at 51.7 cm TL for males and 56.1 cm TL for females, and Serena and Abella (1999) and Bauchot (1987) reported length at maturity at 45 to 54 cm for males and 60 cm for females. Age at maturity is reported at 3 to 4 years for both males and females (Serena and Abella 1999, Bono et al. 2005). Oviparous, the number of egg cases layed (34 to 112) depends on individual size, and egg cases can reach 45 mm in length and 30 mm width (Bauchot 1987). Juveniles are about 8 cm TL when they emerge from the egg cases in January. The sex ratio is about equal (Minervini et al. 1985, Abella et al. 1997).
Recent preliminary tagging experiments (Catalano et al. 2003) suggest a faster growth rate than described in previous literature (Serena and Abella 1999). As this species reaches maturity relatively early (~3 years) and has a short lifespan (~10 years) it is considered to be relatively productive, even though it is only moderately fecund. Therefore it is likely to be resilient to fishing pressure.
Feeds almost exclusively on benthic species, including decapods crustaceans and teleost fishes of the Gobidi family (Gobidae sp., Leserigobius sp., Leserigobius fresii, Gobius niger), Clupeiformes (Engraulis encrasicolus and other species) and Pleuronectiformes (Citharus linguattola, Arnoglossus laterna and others), but occasionally on pelagic species such as the anchovy Engraulis encrasicolus. Juveniles feed mainly on amphipods, and teleost fish become more important in the diet with growth (Cuoco et al. 2005).
Average reproductive age, the annual rate of population increase and natural mortality are unknown.
Starry rays are mainly caught by bottom trawl nets and trammel and gill nets. Near the Corsican coast, in particular, fishing pressure is low because only a few Corsican trawlers, as well as a few Italian vessels, operate in this area (Abella and Serena 2002). A reduced number of trawlers belonging to the La Spezia fleet operate on the same grounds northwards to Viareggio harbour (the most important fishing port of the Northern Tyrrhenian- south Ligurian Sea). The Livorno fleet operating in the same area is also relatively small. Trawlers concentrate their effort mainly on the grounds at depths between 100 and 400 m and therefore there is a little overlap with areas in which the Viareggio fleet operate.
Off Tuscany (Viareggio, Italy) this species is mainly landed as by-catch of beam trawlers, targeting common sole and turbots. It is the most common species caught by a variant of the beam trawl called a rapido, however very few of these operate in this area (Abella and Serena 2002). Most small individuals of R. asterias caught near shore with trammel and gill nets by these artisanal fisheries are landed. However the ban on trawling within three miles of the coast in this area of the Mediterranean affords protection to this species' shallow nursery areas (2 to 15 m) (Abella and Serena 2002). Moreover, a general reduction in fishing effort on the grounds traditionally exploited by the Viareggio fleet occurred during the last 15 years because the number of vessels in operation reduced from 107 in 1985, to 78 in 2000 (Abella and Serena 2002).
Current levels of catch appear to be sustainable among studied stocks (Abella and Serena 2002), however it should be noted that data are lacking throughout the rest of this species' range in the Mediterranean. Further study is needed to accurately assess the status of populations in the rest of its range.
Little information is available on the probability of survival of discarded juveniles. Preliminary experiments performed with individuals caught and successively put into pools of marine water have demonstrated high rates of survival for released individuals of R. asterias caught with bottom trawl nets (Catalano et al. 2003).
Although R. asterias is one of the more exploited species in the Ligurian sea, it is apparently relatively resilient to fishing pressure as a result of its life history characteristics. It is relatively productive due to its early age of first maturity (about three years) and relatively short lifespan (about 10 years), even if it is only moderately fecund (Abella and Serena 2002).
The development and implementation of management plans (national and/or regional e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) are required to facilitate the conservation and sustainable management of all chondrichthyan species in the region.
Further research and monitoring of the population where it is fished is required to prevent declines in the future.
|Citation:||Serena, F., Mancusi, C., Ungaro, N., Notarbartolo di Sciara, G. & Tinti, F. 2007. Raja asterias. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 08 March 2014.|
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