|Scientific Name:||Leucoraja melitensis|
|Species Authority:||(Clark, 1926)|
|Taxonomic Notes:||The subgenus Leucoraja was elevated to genus rank by McEachran and Dunn (1998).|
|Red List Category & Criteria:||Critically Endangered A2bcd+3bcd+4bcd ver 3.1|
|Assessor/s:||Ungaro, N., Serena, F., Dulvy, N.K., Tinti, F., Bertozzi, M., Pasolini, P., Mancusi, C., Notarbartolo di Sciara, G. & participants of the Shark Specialist Group Mediterranean workshop|
|Reviewer/s:||Cavanagh, R.D., Kyne, P.M. & Heenan, A. (Shark Red List Authority)|
Leucoraja melitensis is one of only four skate species endemic to the Mediterranean where it was previously found over a relatively narrow area (about ¼ of the total area) in the depth range where trawl fisheries routinely operate. Historically, this species was moderately common off Tunisia, not considered rare around Malta but rare off Algeria and Italy was recorded once (Stehmann and Burkel 1984). However, it is now extremely rare, recorded in only 20 out of 6,336 hauls of the western central Mediterranean (the coasts of Thyrrenia, Corsica, Sardinia and Sicily) during the Mediterranean International Trawl Surveys (MEDITS) of 1994 to 1999 (Baino et al. 2001). Its main range now appears to be restricted to the Sicilian channel. It is now rare off Malta (Schembri et al. 2003) and rare or absent off Tunisia (Bradai 2000). The species was historically reported to be present in the Gulf of Lions but was apparently not found in surveys carried out in the 1990s (Aldebert 1997). Scientific data on the exploitation and demographic features on this species are lacking but given the small range of the remaining population the potential detrimental impact of trawl fisheries may be significant. This species is assessed as Critically Endangered based on its endemism, inferred population reductions off the Maltese, Tunisian and French coasts and inferred reduction in the area of occupancy. This species now appears to be found in only one small location of the Mediterranean, the Sicilian channel around Malta island, which is subject to heavy trawling activity. More research is needed on its exploitation, distribution, biology and ecology as well as abundance.
|Range Description:||This species main range now appears to be restricted to the Sicilian channel, as discussed in the threats section below.|
Native:Algeria; Italy; Malta; Tunisia
|FAO Marine Fishing Areas:||
Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No information available.|
|Habitat and Ecology:||
This benthic skate is endemic to the Mediterranean and can now only be found within the Strait of Sicily, distributed over sandy and sandy-muddy bottoms from a few meters to over 800 m in depth. It has been recorded at depths of 60 to 800 m, but is more commonly found between 400 to 800 m. The size range of the specimens caught in this area from 1985 to 2001 was 9 to 42 cm (Ragonese et al. 2003). The species was reported for this area also by Ragonese et al. 2000, Cannavò et al. 1999, Relini 1995, Pipitone et al. 1992).
Breeding occurs throughout the year; however, ovulating females were observed mainly in spring and autumn (Stehmann and Burkel 1984, Serena 2005) and produce 10 to 56 eggs/year (Bauchot 1987). Both males and females have an average size at maturity of 40 cm (Bauchot 1987, Notarbartolo and Bianchi 1998), the maximum reported size is ~50 cm (TL) (Stehmann and Burkel 1984). Age at maturity, longevity, size at birth, reproductive age, gestation time, fecundity, rate of population increase and mortality are not known.
This species (one of only four skate species endemic to the Mediterranean) has undergone a serious decline throughout its geographic range. Leucoraja melitensis was previously found over a relatively narrow area (about ¼ of the total area of the Mediterranean) in the depth range where trawl fisheries routinely operate. Historically, this species was moderately common off Tunisia, common around Malta but rare off Algeria and Italy (where it was recorded once) (Stehmann and Burkel 1984). However, it is now considered to be quite rare off Malta (Schembri et al. 2003) and rare or absent off Tunisia (Bradai 2000). This species was rarely recorded (in only 20 out of 6,336 hauls) in the Western Central Mediterranean (Thyrrenian, Corsica, Sardinia and Sicilian coasts, with the easternmost record in the Aegean Sea) during the International MEDITS trawl surveys from 1994?1999 (Baino et al. 2001, Bertrand et al. 2000). In this area, the standing stock biomass of this species was 705 t. If we assume the average weight of an individual is 2 kg, then the estimated population size in the MEDITS survey area was approximately 35,200 individuals (note: that this does not include any remaining population around Malta and North Africa).
Its main range now appears to be restricted to the Sicilian channel, in the national GRUND (National Group for Demersal Resource Evaluation) trawl survey covering all Italian Seas from 1985 to 2000 this species was recorded only in the Sicilian channel (in 59% of hauls operating in this area (Relini et al. 2000)). In this area the species was caught with a frequency of 87% referred to 23 surveys performed from 1985 to 2001 by IRMA-CNR (Ragonese et al. 2003).
The species was historically reported to be present in the Gulf of Lions (northwestern Mediterranean, France) in the years 1957?60 (shelf) and 1980?84 (slope), but the species was not found in further comparable surveys carried out in 1992?95 (Aldebert 1997). However, caution should be taken with this latter statement because the species could be confused with L. naevus which is widespread in the western part of the Mediterranean.
Within the Mediterranean, benthic trawling effort over the continental shelf and slope area has increased both with respect to numerical (effort) and technological advances over the last 50 years. This species is only rarely present in fish markets, however it is believed that while it is only the large individuals that are landed for consumption, most size classes for this species are likely to be taken as bycatch in fishing nets as the legal mesh size used in much of the Mediterranean region is approximately 20 mm. Along the Tunisian coast, this species was caught as bycatch in the following gear types; bottom trawl, gillnet and bottom long line (Bauchot 1987), however it now extremely rare or considered absent off the coasts of Tunisia. In the remainder of this species range within the Mediterranean (the Sicilian channel around Malta), it?s depth distribution coincides with that of intensive trawling activity. The strait of Sicily is the highest exploited region of the Italian coast. It ranks first, with respect to the number of trawl boats and the total number of fishing vessels of all kind, compared to other sectors of the basin. Most of the fleet is composed by multipurpose artisanal vessels using bottom long liners, gill-netters and trammel netters, gear types likely to catch this species. Trawl fishing vessels constitute 11% of the fleet (Relini et al. 1999). For these fisheries skates are bycatch and are in large part discarded (Ragonese et al. 2003). The Tunisian and Maltese fisheries operating in the strait use the same gear types as those employed by the Italian fishing fleet. However, their fishing pressure, given by the number of operating fishing vessels, is smaller than the Italian fishery. The Tunisian fisheries are coastal and likely to operate outwith the area of occupancy of the Maltese skate, which in the Gulf of Gabes occurs in grounds deeper than 200 meters (Samira 2002). Bottom long line and bottom trawl fishing can affect the Maltese skate in Malta since these are the only two fishing gear that can go deeper than 200 meters (de Leiva et al. 1998). The other fisheries operating in the Sicilian channel are coastal, thus have little effect of the population of Maltese skate.
Avoid as much is possible fishery activities below 500 m depths (Ungaro pers. comm). Given the low commercial value of skate and the full retention in the cod-end of the currently used gears, that remain unchanged up to unproposeable (for the Mediterranean fisheries) mesh size >60 mm opening (Ragonese et al. 2001), the only management measure aimed at their sustainable use may be to define the suitable not-trawlable areas and enlarge these ?closed? spots in order to protect a fraction of the population and likely the eggs (often found in the trawl cod-end) (Ragonese et al. 2003).
The global increase of fishing effort and the ensuing depletion of population have been the subject of the debate by the international bodies charged with the management and conservation of marine resources. Relevant is the formulation by FAO of the ?International Plan of Action on the management and conservation of cartilaginous fishes? (IPOA-Sharks). According to the Plan, all the states that capture sharks, rays or chimaeras, either as target species or as bycatch, shall implement a national action plans to ensure suitable use, conservation and recovery of threatened species (Vacchi and Notarbartolo 2000). In this context the FAO SAC Subcommittee on the Environment and Ecosystem proposed a recommendation to activate the necessary tools and regional agreements towards the formulation of a Mediterranean Action Plan for the Management and Conservation of Cartilaginous Fishes. A project for record data proceeding from all Mediterranean basin and regarding large elasmobranchs (MEDLEM) has been discussed and adopted at the last SAC meeting held in Rome (FAO 2005). Also the EC prepared a draft proposal for the European Community Plan of Action that encourages research programs aimed at the assessment of the conservation status of cartilaginous fishes in the Mediterranean Sea (Serena et al. 2002). Italy must act urgently to establish a plan of action for the conservation and management of its chondrichthyan fauna, in tight coordination with other Mediterranean riparian countries. The Italian National Action Plan (PAN-SHARKS) draft was formulated by a scientific committee coordinated by ICRAM (Central Institute for the Marine Research) and was conceived in order to provide Italy with the necessary tools for the ratification of the SPA protocol, in the respect of the guidelines formulated within the EC Draft Action Plan and the FAO IPOA-Sharks recommendation (Serena et al. 2000, Vacchi and Notarbartolo 2000).
|Citation:||Ungaro, N., Serena, F., Dulvy, N.K., Tinti, F., Bertozzi, M., Pasolini, P., Mancusi, C., Notarbartolo di Sciara, G. & participants of the Shark Specialist Group Mediterranean workshop 2006. Leucoraja melitensis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 22 May 2013.|
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