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Somniosidae (Sleeper sharks)
Etymology: Somniosus: Latin for sleepy, reflecting Lesueur’s surmise that these sharks are slow or sluggish because of their relatively small fins (hence the name sleeper sharks) (See ETYFish); pacificus: -icus (L.), belonging to: the Pacific Ocean (specifically, the North Pacific), where it occurs (also in Arctic Ocean) (See ETYFish).
Environnement : milieu / zone climatique / profondeur / gamme de distribution
Écologie
marin benthopélagique; océanodrome (Ref. 138310); profondeur 0 - 2205 m (Ref. 119696). Boreal; 72°N - 23°N, 121°E - 110°W
North Pacific and Arctic: Taiwan to Japan and Kuril Islands, Sea of Okhotsk, southeastern Kamchatka, Commander and Aleutian Islands, and southern Baja California to Gulf of Alaska, Bering Sea, Chukchi Sea and Beaufort Sea.
Taille / Poids / Âge
Maturité: Lm ? range ? - ? cm
Max length : 440 cm TL mâle / non sexé; (Ref. 247); 430.0 cm TL (female)
Épines dorsales (Total) : 0; Épines anales: 0. Diagnosis: Somniosus pacificus differs from S. antarcticus by the following characters: interdorsal space about 70% of prebranchial length (vs. 80%); height of first dorsal fin about 3.7% of precaudal length (PCL) (vs. 3.0%); height of second dorsal fin about 3.4% of PCL (vs. 2.9%); number of turns in spiral valve 32-37 (mode 33) (vs. 36-41, mode 39); precaudal vertebrae 28-30 (mode 29) (vs. 30-31, mode 30) (Ref. 50224).
Body shape (shape guide): elongated.
Demersal and mesobenthopelagic (Ref. 119696); found on continental shelves and slopes (Ref. 247). At high latitudes, they occasionally occur in littoral and even intertidal areas; in lower latitudes ithey may never come to the surface and down to at least 2,000 m (Ref. 247), reported to about 2,205 m in the Hawaiian Is. as recorded by camera arrays (Ref. 119696). They feed on bottom animals such as fishes, octopi, squids, crabs and tritons; also harbor seals and carrion (Ref. 247). Ovoviviparous (Ref. 205), with 300 pups in a litter (Ref. 247), length at birth about 42 cm or less (Ref. 26346). The flesh contains a type of toxin which, when eaten, produces symptoms of drunkenness (Ref. 583). Possibly reaches lengths greater than 700 cm (Ref. 247). It is of limited importance in fisheries, with older small-scale commercial harvests reported in southern areas; and based on its population dynamics it can be sensitive to overfishing (Ref. 117245).
Cycle de vie et comportement reproducteur
Maturité | Reproduction | Frai | Œufs | Fécondité | Larves
Probably ovoviviparous (Ref. 247). Size at birth 42 cm or less (Ref. 26346). Distinct pairing with embrace (Ref. 205).
Yano, K., J.D. Stevens and L.J.V. Compagno, 2004. A review of the systematics of the sleeper shark genus Somniosus with redescriptions of Somniosus (Somniosus) antarcticus and Somniosus (Rhinoscymnus) longus (Squaliformes: Somniosidae). Ichthyol. Res. 51:360-373. (Ref. 50224)
Statut dans la liste rouge de l'IUCN (Ref. 130435: Version 2025-2 (Global))
Utilisations par l'homme
Pêcheries: sans intérêt
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Estimations basées sur des modèles
Température préférée (Réf.
123201): 0.5 - 4.5, mean 2.3 °C (based on 400 cells).
Indice de diversité phylogénétique (Réf.
82804): PD
50 = 0.5156 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00575 (0.00319 - 0.01039), b=3.09 (2.93 - 3.25), in cm total length, based on LWR estimates for this species & (Sub)family-body (Ref.
93245).
Niveau trophique (Réf.
69278): 4.4 ±0.4 se; based on diet studies.
Résilience (Réf.
120179): Faible, temps minimum de doublement de population : 4,5 à 14 années (Fec=300; assuming tm<=10).
Vulnérabilité de la pêche (Ref.
59153): Very high vulnerability (90 of 100).
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Vulnérabilité climatique (Ref.
125649): Moderate vulnerability (38 of 100).
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