|Scientific Name:||Raja undulata|
|Species Authority:||Lacepède, 1802|
|Red List Category & Criteria:||Endangered A2bd+3d+4bd ver 3.1|
|Assessor/s:||Coelho, R., Bertozzi, M.,Ungaro. N. & Ellis, J.|
|Reviewer/s:||Kulka, D.W., Valenti, S.V. & Fowler, S.L. (Shark Red List Authority)|
The Undulate Ray (Raja undulata) is a medium-sized, inshore skate that has a patchy distribution in the northeast and eastern central Atlantic, with discrete areas where it may be locally common (southwestern Ireland, eastern English Channel, southern Portugal). It also occurs in the Mediterranean Sea, where it appears to be uncommon. The Undulate Ray occurs in shelf waters down to about 200 m depth, although it is more common in shallow waters. This species is taken as utilised bycatch by trawl, trammel net and other demersal fisheries. Its patchy distribution means that populations are widely separated, possibly with little exchange. In the areas where it is known to be locally common, available data suggest declines have occurred. Time series catch data from Tralee Bay, southwestern Ireland (where this species forms a discreet subpopulation) show that catches of this species have declined by 60?80% since 1981, although they fluctuate each year. The species has also traditionally been observed in English beam trawl surveys in the eastern English Channel, but has been absent in recent years. French landings of this species from the Celtic Seas have declined steeply during the past decade. Another major area of occurrence is southern Portugal, where it is the most common skate captured by the mixed species trammel net fisheries. Species-specific landings data are not collected, but overall landings of Raja species have decreased by 29% between 1988 and 2004 in this area. This medium-bodied skate has limiting life-history characteristics that make it more vulnerable to exploitation than smaller skate species (three year generation period of ~45 years). Given the Undulate Ray's life-history characteristics, documented species-specific declines in some areas and the declines in aggregate catch data, significant declines are also inferred to have occusrred off southern Portugal. Although no specific data are available from western Africa, intensive artisanal and demersal trawl fisheries operate throughout its inshore range there. Due to the patchy distribution of this inshore species, and that it is thought to have declined in major areas of its range, it is assessed as Endangered.
|Range Description:||This species has a patchy distribution in the eastern Atlantic, including the Mediterranean Sea, with discrete areas where it may be locally common (southwestern Ireland, eastern English Channel, southern Portugal).
Northeast and eastern central Atlantic: occurs from southern Ireland and southwestern England to the Gulf of Guinea, including the Canary Islands (Coelho and Erzini 2006).
Mediterranean Sea: western Mediterranean, a few records along the coasts of Israel and Turkey (Serena 2005). It has been recorded in the Ria Formosa coastal lagoon on the south coast of Portugal (Coelho et al. 2002), an important nursery ground for many bony fishes (Erzini et al. 2002). Smaller specimens of R. undulata have been reported in this coastal lagoon which may suggest that this species also uses these sheltered areas as nursery grounds (Coelho et al. 2002).
Native:Algeria; Benin; Cameroon; Côte d'Ivoire; Egypt (Egypt (African part)); Equatorial Guinea (Equatorial Guinea (mainland)); France (France (mainland)); Gambia; Ghana; Greece (Greece (mainland), Kriti); Guinea; Guinea-Bissau; Israel; Italy (Italy (mainland), Sardegna, Sicilia); Lebanon; Liberia; Libya; Mauritania; Morocco; Portugal (Portugal (mainland)); Senegal; Sierra Leone; Spain (Baleares, Canary Is., Spain (mainland)); Syrian Arab Republic; Togo; Tunisia; Turkey (Turkey-in-Asia); United Kingdom (Great Britain); Western Sahara
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – northeast; Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
There appears to be a discrete population of Raja undulata in Tralee Bay (ICES 2007). Angling records from Tralee Bay (Ireland) indicate a peak in records of undulate ray in 1981?1982, with lower (but stable) catches since then (ICES 2007). Undulate ray have traditionally been observed in English beam trawl surveys in the eastern English Channel, but have been absent for the most recent two years (ICES 2008). It is uncommon in the Bay of Biscay (ICES 2007). Determining accurate stock trends in surveys is problematic due to the patchy distribution of the species.
The species is also common off southern Portugal (Coelho and Erzini 2006), where it forms a separate population to that on the Portuguese west coast (Moura et al. 2007). Raja undulata appears to be uncommon in the Mediterranean Sea, with only occasional records (Bertozzi et al. 2003, Baino et al. 2001).
|Habitat and Ecology:||
This skate occurs in shelf waters to about 200 m depth, on sandy and muddy substrates and appears to be more common in shallow waters (Stehmann and Bürkel 1984, Coelho and Erzini 2006). Smaller specimens have been reported in coastal lagoons (specifically in the Ria Formosa coastal lagoon on the South coast of Portugal), which suggests that this species may use these sheltered habitats as nursery areas (Coelho et al. 2002). Like other skates, reproduction is oviparous. Estimated asymptotic maximum size is110 cm total length (TL) (Coelho and Erzini 2002). Significant regional differences have been observed in size at first maturity of this species: In Portugal, females mature (50% maturity) at 76.2 cm TL in the Algarve (southern) region and at 83.8 cm TL in the Peniche (western) region, while males mature (50% maturity) at 73.6 cm TL in the Algarve and at 78.1 cm TL in Peniche. Age at first maturity for the Algarve population has been estimated to occur at 8.98 years in females and 7.66 years in males (Coelho and Erzini 2006). An annual reproductive cycle has been observed, but differences occur between the different populations: In southern Portugal this species breeds mainly during the winter (Coelho and Erzini 2006), while in the Portuguese west coast it breeds during the winter and the spring (Moura et al. 2007). These differences seem to be related to water temperature, with reproduction restricted to periods of colder water. The maximum observed age for this species is 13 years old (Coelho and Erzini 2002) but longevity has been estimated at 21?23 years (Coelho et al. 2002). The population on the South Portuguese coast has a very slow growth rate (k=0.11) (Coelho and Erzini 2002). Natural mortality for this population has been estimated to be 0.20?0.219 year-1 (Coelho et al. 2002).
Generation period for this species varies from 14.9?15.9 years in females and from 14.3?15.3 in males. Generation period was estimated using the following formula: average reproductive age = age at maturity + 0.5* (longevity - age at maturity).
R. undulata shows a dietary ontogenetic shift within three major length groups: 20?55 cm TL; 55?75 cm TL and 75?100 cm TL. This shift goes from small semi-pelagic to larger and benthic prey and from a generalised to a specialised diet. Shrimps and mysids are especially important in the diet of smaller specimens, while in larger specimens brachyuran crabs have an increased importance (Moura et al. 2008).
This species is a bycatch of trawl, trammel net and other demersal fisheries operating within its range. Raja undulata has a patchy distribution and declines have been documented in areas where is it was formerly considered locally abundant. Catch records are available from two charter-angling vessels in Tralee Bay (southwestern Island), where this species forms a discreet population. These data show that catches of this species declined from a high of 80?100 fish per year in 1981 to 20?30 fish per year in the mid 1990s (a decline of 60?70%), before increasing to 40?60 per year in 2001?2003. Catches now appear to be declining again, with less than 20 fish recorded in 2005, although they fluctuate each year (ICES 2007). R. undulata has traditionally been observed in English beam trawl surveys in the eastern English Channel, but has been absent for the most recent two years (ICES 2008). ICES advice (2008) is now for no target fishing in the North Sea, English Channel and Celtic Seas (ICES 2008).
Raja undulata is captured in large quantities as bycatch in the mixed species trammel net fishery that operates off the southern coast of Portugal (Coelho et al. 2002). The species is retained and marketed for human consumption. It is mainly captured in shallow waters, with CPUE values in this fishery decreasing from 1.91 specimens/1000m net at 10-30m depth to 0.03 specimens /1,000 m net at more than 90 m depth (Coelho et al. 2005). Portuguese official fisheries statistics for landings of Raja spp. in the Algarve have decreased 29.1% between 1988 and 2004 (DGPA 1988-2004). Raja undulata is the most common skate species in this area and its size makes it more vulnerable to depletion than smaller skate species, and these declines may under-reflect changes in the population of this species (Erzini et al. 2001, Coelho et al. 2005).
It is also a known bycatch of the Spanish demersal trawl fleet operating in the Cantabrian Sea, southern Bay of Biscay, which targets a mixture of gadoids and flatfish at depths of 100?300 m over the continental shelf (ICES 2007). Species-specific French landings data for the Celtic Seas report 12 t of R. undulata in 1995, 6 in 1996, 10 in 1997, after which landings fell to 2 t in 1998, 1 t in 1999, to 0 t in 2000?2001 (ICES 2007).
This species? preference for shallow waters places it within the range of intensive artisanal coastal fisheries operating along the western coast of Africa (Walker et al. 2005). Although no specific details are currently available on catches, this species is presumably a utilised bycatch of these, and demersal trawl fisheries operating in this area. Exploitation of the continental shelf is also high in the Mediterranean Sea (Massuti and Moranta 2003).
Like many other larger skates, this species possesses life history characteristics that may increase vulnerability to exploitation, reduce rate of recovery and increase the risk of extinction: including delayed age at maturity, long generation time (14?15 years), low fecundity, and consequently slow population growth (Dulvy et al. 2000).
There is no species-specific management in place for Raja undulata. Tralee Bay is voluntarily closed to commercial fishing to protect regionally important elasmobranchs such as R. undulata and angel shark, which are only found in localised populations on the Irish West coast (ICES 2007). Recreational fishing continues in this area.
The most recent ICES advice (2008) is for no target fishing in the North Sea, English Channel and Celtic Seas. Species-specific monitoring of catches and landings is required to determine the proportion of Raja undulata taken.
|Citation:||Coelho, R., Bertozzi, M.,Ungaro. N. & Ellis, J. 2009. Raja undulata. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 21 May 2013.|
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