|Scientific Name:||Galeus melastomus|
|Species Authority:||Rafinesque, 1810|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Serena, F., Mancusi, C., Ungaro, N., Hareide, N.R., Guallart, J.,Coelho, R. & Crozier, P.|
|Reviewer/s:||Cavanagh, R.D, Valenti, S.V, Dudley, S. & Soldo, A. (Shark Red List Authority)|
This small, common to abundant catshark is widely distributed in the Northeast Atlantic and Mediterranean Seas. Galeus melastomus occurs on continental shelves and upper slopes, mainly at depths of 200–500 m, although it has been recorded between 55–2,000 m. It is taken as bycatch in demersal trawl and longline fisheries and is generally discarded, although it is retained and utilised in some areas. Research surveys indicate that this species is very abundant in some areas, notably the area southwest of Iceland, on the Hatton Bank, northwest of Ireland and in the Alboran Sea in the western Mediterranean. Various research survey and landings data show no evidence of any significant decline, and overall populations appear stable. The recently introduced ban on bottom trawling below 1,000 m depth in the Mediterranean Sea should also offer this species some refuge from fishing pressure at greater depths. At present this species is assessed as Least Concern, but population trends should continue to be monitored.
|Range Description:||Northeast and eastern central Atlantic: from Faeroe Islands and Trondheim, Norway, northern area of the mid-Atlantic Ridge, Reykjanes Ridge, southwest Iceland (Hareide and Garnes 2001), southward to Senegal and Azores (Compagno 1984).
Mediterranean Sea: throughout the Mediterranean Sea excluding the northern Adriatic Sea, the northern Aegean Sea and the Black Sea (Bauchot 1987, Serena 2005).
Native:Albania; Algeria; Belgium; Bosnia and Herzegovina; Croatia; Denmark; Egypt; France; Germany; Greece; Israel; Italy; Libya; Mauritania; Montenegro; Morocco; Netherlands; Norway; Portugal; Senegal; Slovenia; Spain; Sweden; Syrian Arab Republic; Tunisia; Turkey; United Kingdom; 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.|
This species segregates by size and sex, with small, immature sharks generally found at depths of less than 500 m (P. Crozier pers. comm.). Norwegian exploratory fishery surveys found this species between depths of 500–1,000 m, where CPUE peaked at 750 m, with a catch rate of 140 kg/1,000 hooks (N-R. Hareide pers. comm.).
This species was one of the most abundant elasmobranchs recorded in the Norwegian Sea according to fishery-independent Annual Autumn Bottom Trawl Surveys of the north Norwegian Coast, from 1992–2005 (ICES 2007). The total catch during these years was 8,376 individuals, with annual catch fluctuating widely between 26 and 1,883 individuals per year (averaging a catch rate of 644.3 over all years) (ICES 2007).
Data obtained aboard commercial longline vessels operating off southern Portugal (Algarve) from 1997 and 1998 (Erzini et al. 1999) compared to 2003 (Coelho et al|. 2005) show an increase of 151% in CPUE Official fisheries landings statistics for this species in the Algarve show an increase in landings of 48% during the last decade (DGPA 1988–2001). It should be noted this increase refers only to commercial landings and not actual captures. This increase may be due to a reduction in discards of this species, since a decline in stocks of traditional target species has resulted in increased retention of this species. Despite this, off southern Portugal the population appears to be stable currently.
This species is very abundant in the northern area of the Mid-Atlantic Ridge, especially in the Reykjanes Ridge (southwest of Iceland) where the CPUE can be as high as 58.5 kg/1,000 hooks (Hareide and Garnes 2001). It is also very abundant on the Hatton Bank, northwest of Ireland (Hareide unpubl. data).
This species is apparently relatively common in the Mediterranean Sea. It occurred in 1,702 of 6,336 tows during MEDITS research trawl surveys conducted throughout the northern Mediterranean from 1994–1999 (Alboran to the Aegean Sea, at depths of 10–800 m) (Baino et al. 2001).
Data from the MEDITS bottom trawl surveys revealed high occurrence (>5% of the hauls) and abundance (>10 kg/km² or >10% of relative biomass) of G. melastomus (Serena et al. 2005). Abundance was consistently >100 kg/km² in the Gulf of Lions and in Sardinian waters, with a maximum of 1,040 kg/km² recorded from the Alboran Sea. From estimates of the total biomass, 40% of the Mediterranean stock was found to occur in the Alboran Sea (2,600 t). Elsewhere, the only significant stocks (300–400 t) were in the central Tyrrhenian (off Corsica) and the Sicilian Channel (Serena 2005). In the Alboran Sea, maximum indices, obtained in 1997 and 2002, indicated no specific trend in abundance, whereas the biomass showed a slightly decreasing trend from 1994 (Rey et al. 2004).
G. melastomus is very abundant off eastern Spain. CPUE from trawl surveys conducted in the Gulf of Valencia during 1988–1990 captured between 27 and 250 specimens per five hour trawl (Guallart 1990).
Monthly landings data from Viareggio harbour (Italy) from 1990–2001 and trawl surveys (GRUND project) from 1985–2001 (Relini and Piccinetti 1996) suggest a decreasing trend in abundance (expressed as catch in kg/hr), especially over the last three years. However, no robust statistical analysis of the time series was possible due to variability and a lack of data series (Abella and Serena 2005).
Comparable trawl surveys conducted in the Adriatic Sea in 1948 and1998 showed no significant difference in the abundance of this species on the slope (Jukić-Peladić et al. 2001).
MEDITS survey data presented by Bertrand et al. (2000) showed no apparent trend in density indices between the years, although in some parts of the Mediterranean basin (Tyrrhenian Sea) G. melastomus showed a slight increasing trend and some seasonal fluctuations in biomass, with a maximum in winter and a minimum in summer (Baino and Serena 2000).Data from surveys suggests that juveniles occur in shallower waters, and adults at greater depths. For example, specimens captured at depths of 201–500 m in the Alboran Sea were generally all smaller than 20 cm (although they were also recorded at 501–800 m), whereas specimens larger than 20 cm were generally restricted to the 501–800 m range (Rey et al. 2004). Specimens captured by deep trawl nets (>800 m) tend to be of a larger mean size (Ungaro et al. 2001, Massutì and Moranta 2002), similar to results obtained from bottom longline catches (Carasson et al. 1992, Ungaro et al. 1999). High concentrations of juveniles have also been observed in the Alboran Sea, Sardinian waters and southeastern Tyrrhenian Sea (Serena et al. 2005).
|Habitat and Ecology:||
Galeus melastomus occurs on continental shelves and upper slopes, mainly at depths of 200–500 m, although it has been recorded between 55–2,000 m (Stefanescu et al. 1992, Relini et al. 1999, Moranta et al. 1998, Compagno et al. 2005). Found predominantly on slope bottoms (Carasson et al. 1992, Stefanescu et al. 1992, Tursi et al. 1993, Ungaro et al. 1994, Ungaro et al. 2001, Abella and Serena 2005) and is less common in shallower areas such as the Northern Adriatic and Aegean Seas (Baino et al. 2001).
Size at maturity in females is documented as 38–51 cm and males as 34–45 cm in the Mediterranean Sea (Bauchot 1987, Tursi et al. 1993, Ungaro et al. 1994, Rey et al. 2002). The species reaches a maximum size of about 62–67 cm (Rey et al. 2002, Costa et al. 2005), although Compagno et al. (2005) documents 90 cm TL. The species is oviparous, with eggs hatching mainly in the spring and summer. Vitellogenesis occurs at any time during the year (Tursi et al. 1990). Females produce 2–8 eggs per litter (Tortonese 1956, Bini 1967).
G. melastomus feeds mainly on crustaceans, teleost fishes and cephalopods (Ungaro et al. 1994, Wurtz and Vacchi 1981). Analysis of the stomach contents of individuals caught in the northern Tyrrhenian Sea also found galley leftovers (Scali 2003).
This species is taken as bycatch by demersal trawls and longlines throughout large areas of its geographic range. It is generally discarded, but is retained and utilised in some areas.
Although a large portion of the population of G. melastomus avoided most of the commercial fishing pressure associated with the 1970s deepwater trawl fishery for Blue Ling (Molva dypterygia) in the northeast Atlantic at >600 m, it is concerning to note that mature individuals of this species are found at similar depths to the shallowest depth range of this fishery, and that commercial deepwater trawl vessels are now targeting these sharks. The targeting of mature individuals of this species may lead to similar detrimental impacts experienced by other deepwater species in this area (Crozier 2003).
Off the south coast of Portugal (Algarve), this species is captured in high quantities as bycatch of the bottom trawl fishery that targets the Norway Lobster (Nephrops norvegicus), Red Shrimp (Aristeus antennatus) and Deepwater Pink Shrimp (Parapenaeus longirostris), and by the near bottom longline fishery that targets European Hake (Merluccius merluccius), Conger Eels (Conger conger) and Wreck Fish (Polyprion americanus). In both fisheries, most captured specimens are discarded (Coelho et al. 2005). Most specimens are captured and returned to the sea alive, but usually with severe injuries (due to the long trawling periods or hooks) that are likely to impair their survival. However, declines in traditional target species during the last few years mean it is likely that fisherman are now landing larger quantities of “alternative” species, such as this catshark, so it may be increasingly retained and sold.
The species is caught as bycatch by trawl nets and bottom longlines on slope bottoms. The species appears to suffer greater fishing mortality in the Ionian, south Adriatic and Aegean Seas, compared to along the coasts of Morocco, Spain, France and around Crete. Length Frequency Distributions (LFD) show that along the coasts of Morocco, Spain, France and around Crete specimens were mostly larger than 30 cm (78% of the total), while only 23% of the specimens around the coasts of Corsica, Sicily and in the Ionian, South Adriatic and Aegean Seas were over 30 cm (Serena et al. 2005).
It seems that this species suffers relatively moderate effects from fishing pressure in the south Ligurian and northern Tyrrhenian sea, although it is an important bycatch of the Norway lobster Nephrops norvegicus fishery.
G. melastomus constitutes a significant portion of the bycatch of the Viareggio fleet’s fishing efforts, but most of the individuals are discarded due to the limited market demand and low commercial value. Only a fraction of the larger individuals (TL>40 cm) are landed at Viareggio (about 700 kg in 2002) (Abella and Serena 2005). Considering the depths at which G. melastomus is caught (250–800 m) and the observed poor condition of the individuals immediately after their capture, it is likely that only a small fraction of the discarded individuals survive. However, it should be noted that the fishing grounds for the Viareggio fleet coincide only partially with the areas where G. melastomus is known to be abundant, and that higher densities of this species are found in deep waters off northern Corsica, where the fishing pressure is moderate. These areas could therefore act as a refuge for this species (Abella and Serena 2005).
In the Alboran Sea, where this species is very abundant, G. melastomus is the most important bycatch species in the recently developed bottom trawl fishery targeting the Deepwater Shrimp (Aristeus antennatus) (Torres et al. 2001).
The recently developed ban on bottom trawling below depths of 1,000 m in the Mediterranean Sea probably offers this species some refuge from fishing pressure.
No species-specific actions are in place for this species. The General Fisheries Commission for the Mediterranean (GFCM) banned bottom trawling below depths of 1,000 m in the Mediterranean Sea in February 2005 (recommendation GFCM/2005/1 on the management of certain fisheries exploiting demersal and deepwater species) and this came into force in September 2005.
In European Commission waters, a combined TAC is set for a group of deep-water sharks, which includes G. melastomus. In 2007, the Total Allowable Catch (TAC) for deepwater sharks (including this species) in ICES Sub-areas V, VI, VII, VIII and IX was 2,472 t (ICES 2007). In 2008, the TAC for these species in these areas was reduced to 1,646 t. In 2007 and 2008, the TAC for deepwater sharks was set at 20 t annually in Sub-area X, and 99 t in Sub-area XII (ICES 2007).
|Citation:||Serena, F., Mancusi, C., Ungaro, N., Hareide, N.R., Guallart, J.,Coelho, R. & Crozier, P. 2009. Galeus melastomus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 22 May 2013.|
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