The little sleeper shark (''Somniosus rostratus'') is a small

sleeper shark The Somniosidae are a family of sharks in the order Squaliformes, commonly known as sleeper sharks. The common name "''sleeper shark''" comes from their slow swimming, low activity level, and perceived non-aggressive nature. Distribution and hab ...

of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Somniosidae The Somniosidae are a family of sharks in the order Squaliformes, commonly known as sleeper sharks. The common name "''sleeper shark''" comes from their slow swimming, low activity level, and perceived non-aggressive nature. Distribution and hab ...

found in the northeast

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, western

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

, and western

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

around

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(though these records may be of another species), at depths between 200 and 1,000 m. Its length is up to 1.43 m.

Distribution

This species is rarely encountered. It has in the northeast Atlantic and western Mediterranean. It has also been found in Israel and Cuba.

Habitat

Although currently the species has been found in water at depths of 180–2200m, it is possible that it may range deeper. It is a bathydemersal species found above sandy mud substrate on the outer continental shelves and on the upper slopes.

Ecology

Reproduction and Growth

''S. rostratus'' reaches a maximum size of 140 cm. Males mature at 71 cm. Females mature at 80 cm and are aplacental viviparous, giving birth to 8–17 pups per litter. Much about the reproduction of this species is still unknown.

Diet

This species feeds on cephalopods such as those of the genus '' Histioteuthis'' and ''

Todarodes sagittatus The European flying squid (''Todarodes sagittatus'') is a species of squid from the continental slope and oceanic waters of the eastern Atlantic Ocean and the Mediterranean Sea. It is the type species of the genus ''Todarodes'', the type genus o ...

''. Although the species is often caught using fishing gears for bottom-dwelling fish, the presence of these fast-moving prey items in stomach contents suggests that this organism moves throughout the deeper areas of the water column. This may partially explain the lower than expected rates of capture in deep demersal fisheries.

Threats

''S. rostratus'' is occasionally taken on longlines and in bottom trawls in the eastern Atlantic. It is often recorded under the category "sleeper sharks" or "sharks". It is often discarded at sea when caught on the Mediterranean coast of Spain and not landed. Post-discard survival is likely very rare, though. The fish has also been historically fished for off the coast of Portugal, however by 1996 this industry had all but ended. This animal is also caught as bycatch of general demersal and black scabbardfish fisheries in the Azores. These threats are compounded by the fact that, like other Squaloid sharks, the Little Sleeper shark is likely to be slow to mature, and the relatively small range of the fish.

Conservation

Although no species-specific conservation measures are in place, the General Fisheries Commission for the Mediterranean has banned bottom trawling below depths of 1000m. More information is needed on the species before detailed protection can be brought in to action.

References

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IUCN Redlist
{{DEFAULTSORT:Little sleeper shark Somniosus Fish described in 1827 Fish of the Mediterranean Sea