The brown catshark (''Apristurus brunneus'') is commonly found in the Pacific Ocean, ranging from the northern Pacific waters off the coast of British Columbia and south to the Baja California peninsula in Mexico. They may live as far south as Ecuador and Peru. Brown catsharks are deep-water sharks that live on the outer

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

and the upper slope. They have been known to live at depths ranging from 30 to 650 m and live on the bottom, usually in muddy or sandy areas. The brown catshark, when originally described, was called ''Catulus brunneus''.

Description

Brown catsharks have long, slender bodies with broad, bell-shaped snouts. They are dark brown with light-colored markings on the posterior margins of their fins. Their bodies are soft and flabby, with a weak skin that can easily be harmed. Brown catsharks' two dorsal fins are the same size and do not have spines. The first dorsal fin originates to the front of the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

and the second dorsal fin is located in front of the

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

's insertion. They typically reach a maximum size of 68 cm in total length, but they average between 30 and 60 cm.

Behavior

Very little is known about the behavior of brown catsharks; they are believed to be solitary,

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

creatures. They are thought to be migratory, but most of the year near the edge of the continental shelf. Communication specific to brown catsharks is unknown. However, as with most other sharks, including other members of the family Scyliorhinidae, they are believed to have a well-developed sense of smell, and are

electroreceptive Electroreception and electrogenesis are the closely-related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes to stu ...

, which allows them to detect electricity emitted by other animals, and may also allow them to detect magnetic fields, which aides in navigation.

Food habits and predation

Brown catsharks feed on many

bottom-dwelling The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning ...

species, including small

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

, euphausiids,

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...

, and small fish. It is unknown whether brown catsharks are important predators within their ecosystem.

Reproduction

Reproduction in brown catsharks is

oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...

, with a single egg at a time per oviduct. Egg cases are usually about 5 cm long and 2.5 cm wide. The egg cases are transparent and have long tendrils that are probably used to attach them to hard structures. The incubation period is possibly a year. In Canadian waters, females carry egg cases from February to August; however, the carrying time for warmer waters is unknown.

Conservation status and economic impact

Brown catsharks are not listed as endangered on the IUCN Red List or the CITES list. They are not known to be a

vulnerable Vulnerable may refer to: General * Vulnerability * Vulnerability (computing) * Vulnerable adult * Vulnerable species Music Albums * ''Vulnerable'' (Marvin Gaye album), 1997 * ''Vulnerable'' (Tricky album), 2003 * ''Vulnerable'' (The Used album) ...

or threatened species. They are, however, listed on the IUCN list as needing to be reclassified. The only known negative impact that brown catsharks have on humans is the frequent

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

of deep-water

fishing trawlers A fishing trawler is a commercial fishing vessel designed to operate fishing trawls. Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing nets tha ...

, which while not economically significant, can cause damage to nets, as well as time lost in removing the bycatch from the viable catch.

References

Sources

* Compagno, L.J.V., 1984. FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 2 - Carcharhiniformes.. FAO Fish. Synop. 125(4/2):251-655. * Shark Foundation. 2006. "Brown catshark (Apristurus brunneus)" (On-line). Accessed April 6, 2006 at http://www.shark.ch/Database/Search/species.html?sh_id=1189 {{Taxonbar, from=Q1956595

brown catshark The brown catshark (''Apristurus brunneus'') is commonly found in the Pacific Ocean, ranging from the northern Pacific waters off the coast of British Columbia and south to the Baja California peninsula in Mexico. They may live as far south as Ecu ...

Western North American coastal fauna Taxa named by Charles Henry Gilbert