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Biological Profiles




PORTUGUESE SHARK
Order - Squaliformes
Family - Somniosidae
Genus - Centroscymnus
Species - coelolepis
Portuguese Shark



Taxonomy

The Portuguese shark was originally described as Centroscymnus coelolepis by Barbosa du Bocage and Brito Capello in 1864. This name is still accepted as scientifically valid. Scymnodon melas is a synonym that has occurred in past scientific literature to refer to this species. The genus name, Centroscymnus, is derived from the Greek "kentron" which means sting and from the Greek "skymnos" which means puppy.


Common Names

English language common names of Centroscymnus coelolepis include Portuguese shark, Portuguese dogfish and siki shark. Common names in other languages are centroscimno (Italian), glíggjháur (Faroese), gljáháfur (Icelandic), kalb (Arabic), kentroskymnos (Greek), marubara-yumezame (Japanese), ostroun portugalský (Czech), pailona (Spanish), pailona commun (French), pailonahaj (Swedish), palluda (Spanish), Portugese ijshaai (Dutch), Portugiesenhai (German), Portugisisk fløjlshaj (Danish), rasqueta (Spanish), syvänne-piikkihai (Finnish), tiburón portugués (Spanish), tubarão português (Portuguese) and xara preta (Portuguese).


Geographical Distribution

The range of the Portuguese shark is from Grand Banks, Newfoundland to Virginia in the western Atlantic Ocean. In the eastern Atlantic Ocean, this species is found from Iceland southward to Sierra Leone, including the Mediterranean, also from Namibia to Quoin Point, South Africa. The Portuguese shark is also found in the western central Pacific Ocean.

Distribution Map of the Portuguese shark
World distribution map for the Portuguese shark

Habitat

Portuguese sharks are benthic and live in deepwater, captured most frequently at depths of greater than 1,300 feet (400m). They have been taken from waters ranging from 886-12,000 feet (270-3,675 m) deep, at temperatures of 41-55 °F (5-13 °C). Females tend to inhabit deeper waters than males.


Biology


Portuguese shark
source: FAO Sharks of the World
· Distinctive Features
The body of the Portuguese shark is moderately stout with a short, blunt snout. The gill arches are short. The mouth of this shark is slightly arched with thick lips and the presence of the upper and lower labial furrows. There is a very short, grooved spine barely protruding from the origin of each of the two equally small dorsal fins. The first dorsal fin origin is posterior to the broadly rounded pectoral fins. The second dorsal and pelvic fins are located far posteriorly with the second dorsal fin originating over the midpelvic base. This shark lacks an anal fin. The upper caudal lob is much longer than the lower with a deep subterminal notch. There are no lateral keels or precaudal pits present.


Portuguese shark: ventral side of head
source: FAO Sharks of the World


This shark may be confused with the Greenland shark (Somniosus microcephalus) or the kitefin shark (Dalatias licha), however both of these species lack dorsal spines.


· Coloration
Adult Portuguese sharks are uniformly blackish brown, without any obvious black markings above the pelvic fins, ventrally on the caudal peduncle, or laterally on the upper caudal lobe. Young individuals tend to be bluish black in color while juveniles are more black than brown.



Portuguese shark: ventral side of head
source: FAO Sharks of the World


· Dentition
The upper and lower teeth are markedly different in shape. The upper teeth are awl-shaped, erect and thin with one lanceolate cusp and no cusplets. The lower teeth are very short with oblique cusps and large with overlapping bases, forming a cutting edge. The teeth of the upper jaw number 43-68 while there are 29-41 teeth in the lower jaw.


· Dermal Denticles
Denticles along the trunk of mature Portuguese sharks are large and closely overlap. Each denticle is concave and crown-shaped when viewed laterally. Young specimens have widely spaced three-pointed, leaflike denticles.


· Size, Age & Growth
The average adult length is 27-39 inches (70-100 cm) with a maximum reported size of about 47 inches (120 cm). Males are smaller than females, reaching a maximum length of just over 35 inches (90 cm).


· Food Habits
Benthic fishes, squids, octopods, and gastropods are among the prey items included in the diet of the Portuguese shark. They actively scavenge as well, as evidenced by marine mammals remains found in stomachs of this shark. They feed primarily at night.


· Reproduction
Portuguese sharks are ovoviviparous. Males reach sexual maturity at 27-30 inches (70-75 cm) total length (TL); mature females have been reported at 35-39 inches (90-100 cm) TL. Females ovulate mature ova measuring 50-60 mm in diameter. Embryos are nourished by the yolk; there is no placental attachment with the mother during development. The largest observed embryo with an external yolk sac measured 130 mm TL. Females give birth to 13-17 young, which are born at 11-12 inches (27-30 cm) in length.


· Predators
Potential predators include large fish and sharks residing in the same habitats and depths as the Portuguese shark.


Importance to Humans

Portuguese sharks are occasionally captured on halibut lines and infrequently in deepwater trawls. They derive their name from their importance in the deepwater fishery off Portugal. They are not of commercial importance off the coast of New England in the U.S., however they are the object of fishing pressure in other parts of the world. This is primarily for the squalene in their liver oil, but also for human consumption and reduction into fish meal.


Danger to Humans

The Portuguese shark poses no danger to humans due to its small size and deepwater habitat.


Conservation

Considered "Near Threatened" by the World Conservation Union (IUCN), the Portuguese shark has been commercially exploited in some regions of the world for squalene. The productivity of this species is likely to be low (although age estimates and annual fecundity are currently unknown) and further increases in catches should be a reason for concern. Conservation measures include regulations set forth by the South East Trawl Fishery in Australia (2002) which prohibits the landings of livers unless the accompanying carcass is also landed.

Prepared by:

George Burgess and Cathy Bester