Overview

Comprehensive Description

Galeus melastomus ZBK Rafinesque, 1810

Sea of Marmara : 400-15 (3 spc.), 20.05.1989 , Offshore of Yesilkoey, 142 m , N. Meriç ; 400-8 (1 spa), 08.06.1991 , Offshore of Mimarsinan , trammel net , 162 m, N. Meriç ; 400-526 (1 spc.), 20.05.1989 , Offshore of Yesilkoey, 142 m , N. Meriç ; 400-16 (2 spa), 05.07.1991 , Offshore of Guerpinar , trammel net , 250 m, N. Meriç .

  • Nurettin Meriç, Lütfiye Eryilmaz, Müfit Özulug (2007): A catalogue of the fishes held in the Istanbul University, Science Faculty, Hydrobiology Museum. Zootaxa 1472, 29-54: 31-31, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:428F3980-C1B8-45FF-812E-0F4847AF6786
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Biology

Depth range is reported at 55m-1200m in Ref. 9996. Found on the outer continental shelves and upper slopes. Feeds mainly on bottom invertebrates, including shrimps and cephalopods, but also on small pelagic bony fishes (lanternfishes) and other small elasmobranchs. Oviparous, with up to 13 eggs present in the oviducts at one time. Individuals from the Ionian Sea apparently reproduces from end of February to September and eggs are laid between 200 and 600 meters (Ref. 87978). Utilized fresh and dried-salted for human consumption, and for leather.
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Distribution

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).
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Northeast Atlantic: Faeroe Islands and Trondheim, Norway southward to Senegal. Mediterranean Sea.
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Baltic Sea, North Sea, Mediterranean Sea, Eastern North Atlantic: Faeroe Islands and Norway to Senegal.
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Physical Description

Size

Maximum size: 610 mm TL
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Max. size

75.0 cm TL (male/unsexed; (Ref. 40637)); 90 cm TL (female); max. published weight: 1,370 g (Ref. 40637)
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Ecology

Habitat

Habitat and Ecology

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).

Systems
  • Marine
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Environment

demersal; marine; depth range 55 - 1873 m (Ref. 55744), usually 150 - 1200 m (Ref. 35388)
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Depth range based on 3758 specimens in 1 taxon.
Water temperature and chemistry ranges based on 1652 samples.

Environmental ranges
  Depth range (m): -9 - 1484
  Temperature range (°C): 7.273 - 14.269
  Nitrate (umol/L): 4.282 - 29.720
  Salinity (PPS): 35.068 - 38.649
  Oxygen (ml/l): 1.840 - 6.341
  Phosphate (umol/l): 0.263 - 1.749
  Silicate (umol/l): 1.843 - 12.952

Graphical representation

Depth range (m): -9 - 1484

Temperature range (°C): 7.273 - 14.269

Nitrate (umol/L): 4.282 - 29.720

Salinity (PPS): 35.068 - 38.649

Oxygen (ml/l): 1.840 - 6.341

Phosphate (umol/l): 0.263 - 1.749

Silicate (umol/l): 1.843 - 12.952
 
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Depth: 55 - 1000m.
From 55 to 1000 meters.

Habitat: bathydemersal. Found on the outer continental shelves and upper slopes. Feeds mainly on bottom invertebrates, including shrimps and cephalopods, but also on small pelagic bony fishes (lanternfishes) and other small elasmobranchs. Oviparous, with up to 13 eggs present in the oviducts at one time. Utilized fresh and dried-salted for human consumption, and for leather.
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Trophic Strategy

Most abundant demersal shark on the upper and middle slope in the western Mediterranean from 1000 m to as deep as 1400 m (Ref. 40720).
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Life History and Behavior

Life Cycle

Oviparous, embryos feed solely on yolk (Ref. 50449).
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Galeus melastomus

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 6
Specimens with Barcodes: 49
Species With Barcodes: 1
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Barcode data: Galeus melastomus

The following is a representative barcode sequence, the centroid of all available sequences for this species.


No available public DNA sequences.

Download FASTA File
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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
2009

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)

Contributor/s

Justification
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.
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Population

Population
Northeast Atlantic
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).

Mediterranean
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).

Population Trend
Stable
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Threats

Major Threats
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.

Northeast Atlantic
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.

Mediterranean
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.
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Least Concern (LC)
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Management

Conservation Actions

Conservation Actions
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).
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Relevance to Humans and Ecosystems

Benefits

Importance

fisheries: minor commercial; price category: high; price reliability: reliable: based on ex-vessel price for this species
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Wikipedia

Blackmouth catshark

The blackmouth catshark (Galeus melastomus) is a species of catshark, and part of the family Scyliorhinidae, common in the northeastern Atlantic Ocean from Iceland to Senegal, including the Mediterranean Sea. It is typically found over the continental slope at depths of 150–1,400 m (490–4,590 ft), on or near muddy bottoms. The youngest sharks generally inhabit shallower water than the older juveniles and adults. This slim-bodied species is characterized by the black interior of its mouth, a marbled pattern of pale-edged brownish saddles or blotches along its back and tail, and a prominent saw-toothed crest of enlarged dermal denticles along the upper edge of its caudal fin. It reaches lengths of 50–79 cm (20–31 in), with sharks in the Atlantic growing larger than those in the Mediterranean.

Slow-swimming but active, the blackmouth catshark is a generalist that preys on a wide variety of crustaceans, cephalopods, and fishes. Its visual and electroreceptive systems are adept at tracking moving, bioluminescent prey. This species is oviparous, with females producing batches of up to 13 egg cases throughout the year. Because of its abundance, the blackmouth catshark forms a substantial part of the bycatch of deepwater commercial fisheries across much of its range. It has low economic value and is usually discarded, though the largest sharks may be marketed for meat and leather. The International Union for Conservation of Nature (IUCN) has listed this species under Least Concern, as there is no indication that its numbers have declined despite fishing pressure.

Taxonomy and phylogeny[edit]

Constantine Samuel Rafinesque briefly described the blackmouth catshark in his 1810 Caratteri di alcuni nuovi generi e nuove specie di animali e piante della Sicilia: con varie osservazioni sopra i medesimi, wherein he referenced the distinctive black interior of its mouth (from which the specific epithet melastomus is derived). No type specimen was designated.[2] This species may also be called the black-mouthed dogfish.[3] A 2005 phylogenetic analysis that included five Galeus species, based on mitochondrial and nuclear DNA, found that G. melastomus forms a clade with G. murinus, apart from the clade of G. eastmani, G. gracilis, and G. sauteri.[4] The oldest documented blackmouth catshark fossils come from the northern Apennines and date to the Lower Pliocene (5.3–3.6 Ma).[5]

Distribution and habitat[edit]

The blackmouth catshark is widely distributed in the northeastern Atlantic Ocean, from southwestern Iceland and Trondheim, Norway southward to Senegal, including the Faroe Islands, the British Isles, the Azores, and the northern portion of the Mid-Atlantic Ridge. It occurs throughout the Mediterranean Sea, save for the northern waters of the Adriatic and Aegean Seas, and is absent from the Black Sea.[1] This species primarily inhabits the continental slope, at depths of 150–1,400 m (490–4,590 ft). However, it has been documented from water as shallow as 50–60 m (160–200 ft) off southern France, and as deep as 2,300–3,850 m (7,550–12,630 ft) in the eastern Mediterranean.[6] The depths at which it is most common vary between regions, for example 300–500 m (980–1,640 ft) in the Bay of Biscay,[7] 400–800 m (1,300–2,600 ft) off Portugal,[8] 500–800 m (1,600–2,600 ft) in the Strait of Sicily,[6] 1,000–1,400 m (3,300–4,600 ft) in the Catalan Sea,[9] and 1,500–1,830 m (4,920–6,000 ft) in the eastern Mediterranean.[10] Water temperature does not appear to be an important factor in determining the distribution of this species.[6]

Found on or near the bottom, the blackmouth catshark favors a muddy habitat.[11] There is little evidence for segregation by sex.[8][12] A number of studies in the northern and western Mediterranean have reported that adults occur deeper than juveniles.[9][11][12][13] Other studies though have found no such pattern. It is possible that areas such as the waters off southern France offer a habitat suitable for sharks of all ages.[14] Another explanation with some scientific support is that adults are most common at intermediate depths, while young sharks are restricted to shallower water and both adults and juveniles are found in deeper water. If true, the age-depth inconsistencies observed from previous research could have resulted from incomplete depth sampling.[6]

Description[edit]

Early illustration of a blackmouth catshark, showing its ornate dorsal color pattern.

The reported maximum lengths attained by the blackmouth catshark varies from 67 to 79 cm (26 to 31 in) for Atlantic sharks and 50 to 64 cm (20 to 25 in) for Mediterranean sharks; a length record of 90 cm (35 in) may be dubious. Females attain a larger ultimate size than males.[6][14] The maximum weight on record is 1.4 kg (3.1 lb).[3] This species has a slender, firm body with a rather long, pointed snout comprising roughly 6–9% of the total length. The anterior rim of each nostril bears a large triangular flap, which divides the nostril into incurrent and excurrent openings. The eyes are horizontally oval and equipped with rudimentary nictitating membranes (protective third eyelids). Beneath each eye is a subtle ridge, and behind is a small spiracle. The mouth forms a short, wide arch, and bears moderately long furrows around the corners. The upper and lower jaws contain around 69 and 79 tooth rows respectively. Each tooth is small, with a narrow central cusp flanked by one or two smaller cusplets on either side. There are five pairs of gill slits, with the fifth pair over the pectoral fin bases.[15][16][17]

The two dorsal fins are roughly equal in size and placed far back on the body: the first originates behind the midpoint of the pelvic fin bases and the second behind the midpoint of the anal fin base. The pectoral fins are large, while the pelvic fins are small and low, with angular margins. The anal fin is much larger than either dorsal fin; its base measures 13–18% of the total length and greatly exceeds the distance between the pelvic and anal fins, or between the dorsal fins. The caudal peduncle is laterally compressed, with the end of the anal fin very close to the caudal fin. The caudal fin comprises around a quarter of the total length; the upper lobe is low with a ventral notch near the tip, while the lower lobe is indistinct. The skin is very thick and covered by well-calcified dermal denticles. There is a prominent row of enlarged denticles, resembling saw teeth, along the upper edge of the caudal fin.[15] The body is grayish-brown above, with 15–18 dark, rounded saddles, blotches, and/or spots that run onto the tail; each marking is highlighted by a paler border. The underside is white, as are the tips of the dorsal and caudal fins. The inside of the mouth is black.[16][18]

Biology and ecology[edit]

Within its range, the blackmouth catshark is one of the most abundant sharks over the upper and middle continental slope.[9] It is nomadic in nature and may be found alone or in groups. Relatively slow, this shark swims with strong eel-like (anguilliform) undulations of its body. It often cruises just above the sea floor, perhaps taking advantage of the ground effect (a reduction in the drag on a wing when close to the ground) to save energy. It has also been seen resting motionless on the bottom.[6][12][19][20] Known predators of the blackmouth catshark include the kitefin shark (Dalatias licha) and the European flying squid (Todarodes sagittatus).[21][22] Parasites that have been documented from this species include the tapeworm Ditrachybothridium macrocephalum and the protist Eimeria palavensis.[23][24]

Feeding[edit]

The blackmouth catshark has well-developed eyes and ampullae of Lorenzini for finding prey.

The blackmouth catshark is an active, generalist predator that feeds on both bottom-dwelling and free-swimming organisms.[6][25] Its diet is dominated by decapods, krill, bony fishes (including lanternfishes, bristlemouths, dragonfishes, and moras), and cephalopods. The most significant prey species generally reflect what is most available in the environment, for example the shrimps Calocaris macandreae and Pasiphaea multidentata off southern France and the prawns Sergestes arcticus and Sergia robusta off the Iberian Peninsula. Juveniles consume a greater amount and variety of crustaceans than adults, including smaller types such as mysids and hyperiid amphipods. Adults favor relatively large fish prey and have been known to take other sharks and rays and smaller members of the same species. The importance of cephalopod prey across ages differs between regions.[7][9][26] The stomachs of some blackmouth catsharks have found to contain pieces of animals too large for a single shark to overwhelm, suggesting that it may sometimes attack in groups. Scavenging has been infrequently documented, including of human refuse.[1][9]

When foraging, the blackmouth catshark swings its head from side to side to employ its senses more effectively. It likely relies mainly on vision and electroreception to find food, and less on smell. As in most sharks, its visual acuity is greatest along the median horizontal plane. The lens and cone cells of its eyes are large, allowing smaller or farther objects to be discerned from the background. The rod cells of its eyes are most sensitive to the wavelengths emitted by bioluminescence, which is exhibited by most of the organisms it hunts. For electroreception, the blackmouth catshark has a high number of ampullae of Lorenzini that are evenly arranged, which enhances spatial resolution and is best suited for localizing fast-moving prey.[27][28]

Life history[edit]

Unlike most members of its genus, the blackmouth catshark exhibits multiple oviparity, in which more than one egg can mature within each oviduct simultaneously. Females may contain up to 13 developing eggs, though 1–4 per oviduct is typical.[6][15] The number of eggs laid annually per female has been estimated at between 60 to 100, increasing with female size.[12] Only the right ovary is functional in mature females. The egg case is vase-shaped and bears a slight flange along the lateral margins; the anterior end is squared off, with a pair of stubby, coiled horns at the corners, while the posterior end is rounded. The surface of the case is somewhat translucent, smooth, and glossy. The case is a golden brown color when first laid, and becomes dark brown in sea water.[4] Egg cases produced by Atlantic sharks measure 3.5–6.5 cm (1.4–2.6 in) long and 1.4–3.0 cm (0.55–1.18 in) across. Those produced by Mediterranean sharks tend to be smaller at 4.2–5.5 cm (1.7–2.2 in) long and 1.7–2.5 cm (0.67–0.98 in) across. Larger females produce slightly larger egg cases.[8]

Mating and egg-laying proceeds year-round; reproductive activity is highest in winter and summer, though not all studies have found such a seasonal pattern.[8][12][13] The eggs are deposited on muddy substrates in relatively shallow water.[6][29] Maturation size varies between geographical regions, and is generally larger in the Atlantic than in the Mediterranean. Lengths at maturity for males and females have been variously reported from 48 to 79 cm (19 to 31 in) and 56 to 79 cm (22 to 31 in) respectively in the Atlantic,[8][12] and from 42 to 55 cm (17 to 22 in) and 39 to 61 cm (15 to 24 in) respectively in the Mediterranean.[12][14]

Human interactions[edit]

Harmless to humans and of little economic value,[3] the blackmouth catshark is caught incidentally in large numbers by commercial bottom trawl and longline fisheries. In particular, it is among the most commonly bycaught sharks in trawls targeting deepwater lobsters and shrimps (Nephrops norvegicus, Parapenaeus longirostris, Aristeus antennatus, and Aristaeomorpha folicea), operating off Portugal and in the Mediterranean. Most captured sharks are discarded, probably with heavy mortality. Some fisheries, such as those off Portugal and Italy, retain and utilize a small subset of the largest individuals for human consumption fresh or dried and salted, and for leather; the fishing fleet of Viareggio, Tuscany reported landing 700 kg (1,500 lb) in 2005. In the northeastern Atlantic, this shark is being increasingly targeted by fishers following the decline of other deepwater shark species.[1][8][11][13]

Off Corsica, Sicily, and southern Portugal, and in the Ionian, southern Adriatic, and Aegean Seas, most of the blackmouth catsharks captured are immature, suggesting there has been a negative impact of fishing pressure.[1][30] However, the species remains extremely abundant in a number of areas, and survey and fishery data have not shown any evidence of overall population decline. The wide range of depths it occupies likely afford it some protection against fishing, particularly given a 2005 ban on trawling deeper than 1,000 m (3,300 ft) in the Mediterranean.[1][6] Therefore, the International Union for Conservation of Nature (IUCN) has listed the blackmouth catshark under Least Concern. In the waters of the European Commission, fishing for this species is managed as part of the Total Allowable Catch (TAC) for deepwater sharks.[1]

References[edit]

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