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An intricately patterned species. Reddish-brown above with a row
of 15-18 rounded brown blotches circled in white along flank. Fins may have
bluish dark tips and white trailing edges. Ventrum off white.
Pectoral fins large. Pelvic fins low but
long. Anal fin extremely long - extending to caudal fin origin or beyond.
Enlarged denticals present on upper margin of caudal fin.
Eyes large. Mouth cavity pigment dark - hence common name. Teeth tricuspid -
lateral cusps much smaller than central cusp.
maximum (female). 61cm (male).
Rocky, sandy or muddy substrates on outer continental shelf. Usually remains on bottom
or close to it. Mostly found between 200-500m. Listed as occurring between
55-1000m but regularly encountered in certain Norwegian fiords between 25-40m
even when no chum is used.
The blackmouth Catsharks is present in the Northeast
Atlantic Ocean and Mediterranean Sea. From
the Faroe ISlands and Southern Norway southward to the Azores and
Often rests on the substrate.
Diet: Hunts for bottom dwelling
invertebrates (shrimps, cephalopods, etc) and lanternfish.
Oviparous, laying up
to 13 egg cases.
Conservation Status: The IUCN lists the Blackmouth Catshark as
LEAST CONCERN. However, 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.
most of the commercial fishing pressure associated with the 1970s
deepwater trawl fishery for Blue Ling (Molva
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
Red Shrimp (Aristeus
and Deepwater Pink Shrimp (Parapenaeus
and by the near bottom longline fishery that targets European Hake (Merluccius
Conger Eels (Conger
and Wreck Fish (Polyprion
In both fisheries, most captured specimens are discarded (Coelho et
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
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
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.
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
the most important bycatch species in the recently developed bottom
trawl fishery targeting the Deepwater Shrimp (Aristeus
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.
Namsen and Trondheim
Fiords in Western Norway.
The only other catshark with similar
markings and an overlapping range is the African Sawtail Catshark - Galeus
polli. This species has large greyish blotches, less intricate markings
overall and is shorter and relatively more robust. Its range overlaps with the
blackmouth Catshark in Northwest Africa.
Reaction to divers:
This species rests on the bottom for long
periods of time.
Easy to get close to
after a slow, non-threatening approach.
logistics: Although normally found in water too deep
for recreational diving, in certain Norwegian fiords e.g. Namsen Fiord and
Trondheim Fiord, run-off at the surface creates a layer of silty water that
significantly lowers the light level in the water below it.
In these areas, blackmouth catsharks and other
deepwater species, come much closer to the surface than elsewhere.
Blackmouth Catsharks can often be seen when exploring certain reefs
within these fiords but they are even easier to see and approach
when bait is introduced.
Big Fish Expeditions offers yearly
Safaris in Norway. Usually in October.
Serena, F., Mancusi, C., Ungaro, N., Hareide, N.R.,
Guallart, J.,Coelho, R. & Crozier, P. 2009. Galeus
IUCN Red List of Threatened Species 2009: e.T161398A5414850. http://dx.doi.org/10.2305/IUCN.UK.2009-2.RLTS.T161398A5414850.en. Downloaded
on 12 December 2018.