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The bald notothen (''Pagothenia borchgrevinki''), also known as the bald rockcod, is a species of marine ray-finned fish belonging to the family Nototheniidae, the notothens or cod icefishes. It is native to the Southern Ocean.


Taxonomy

The bald notothen was first formally described in 1907 as ''Trematomus borchgrevinki'' by the Belgian-born British ichthyologist George Albert Boulenger with the type localities given as at the surface at Duke of York Island and at
Cape Adare Cape Adare is a prominent cape of black basalt forming the northern tip of the Adare Peninsula and the north-easternmost extremity of Victoria Land, East Antarctica. Description Marking the north end of Borchgrevink Coast and the west e ...
. The specific name honours
Carsten Egeberg Borchgrevink Carsten Egeberg Borchgrevink (1 December 186421 April 1934) was an Anglo-Norwegian polar explorer and a pioneer of Antarctic travel. He inspired Sir Robert Falcon Scott, Sir Ernest Shackleton, Roald Amundsen, and others associated with the Her ...
who commanded the British Southern Cross Antarctic Expedition (1898–1900), during which types were collected.


Description

The bald notothen attains a maximum
total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...
around , it is yellow with dark spots and irregular crossbars. Its
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...
and
caudal 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 s ...
s may occasionally also be spotted.


Distribution, habitat and biology

The bald notothen is found in the Southern Ocean where it has been recorded from the Weddell Sea, the Ross Sea, the
Davis Sea Davis Sea is an area of the sea along the coast of East Antarctica between West Ice Shelf in the west and the Shackleton Ice Shelf in the east, or between 82° and 96°E. The name "Davis Sea" appears in most leading geographically authoritat ...
, in
Vincennes Bay Vincennes Bay is a large V-shaped bay, 105 km (65 mi) wide at its entrance between Cape Nutt and Cape Folger in Antarctica, marked by several large, steep glaciers near its head, lying along Knox and Budd Coasts. It was photographed ...
, and around the
Budd Coast Budd Coast (), part of Wilkes Land, is that portion of the coast of Antarctica lying between the Hatch Islands, at 109°16'E, and Cape Waldron, at 115°33'E. It was discovered in February 1840 by the U.S. Exploring Expedition (1838–42) unde ...
, the
Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctic ...
,
South Orkneys The South Orkney Islands are a group of islands in the Southern Ocean, about north-east of the tip of the Antarctic PeninsulaSouth Shetland Islands. It can be found at depths from the surface to , though it is much rarer below . This species is cryopelagic and is often found along the under surfaces of ice foraging for prey such as
sympagic A sympagic environment is one where water exists mostly as a solid, ice, such as a polar ice cap or glacier. Solid sea ice is permeated with channels filled with salty brine. These briny channels and the sea ice itself have its ecology, referred t ...
copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...
s and
krill Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian word ', meaning "small fry of fish", which is also often attributed to species of fish. Krill are cons ...
. In turn, it is known to be preyed upon by the
ploughfish The ploughfish (''Gymnodraco acuticeps'') is a species of Antarctic dragonfish native to the Southern Ocean around Antarctica. It is found at depths of from over the Antarctic continental shelf. This species is the only known member of its gen ...
(''Gymnodraco acuticeps'') and the
Antarctic toothfish The Antarctic toothfish (''Dissostichus mawsoni'') is a large, black or brown fish found in very cold (subzero) waters of the Southern Ocean near Antarctica. It is the largest fish in the Southern Ocean, feeding on shrimp and smaller fish, and pr ...
(''Dissostichus mawsoni'').
Antifreeze protein Antifreeze proteins (AFPs) or ice structuring proteins refer to a class of polypeptides produced by certain animals, plants, fungi and bacteria that permit their survival in temperatures below the freezing point of water. AFPs bind to small ...
s in its blood prevent it freezing in the subzero water temperatures of
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
. The bald notothen is adapted to life in the water column as the shape and flatness of the trunk may streamline the fish and reduce drag. the pelvic and
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 s ...
s do not have the adaptations for substrate contact borne by related benthic species. There are silvery reflective layers, called ''strata argentea'' below the skin and in the this provides camouflage when the fish is seen against the background of platelet ice. The retina had numerous
cones A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines con ...
suggesting that the eye is able to function during the day and at night. Sexually mature individuals of this species spawn once a year. The larvae have a long pelagic phase.


Fisheries

The bald notothen is of no interest to
commercial fisheries Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often ...
.


References

{{Taxonbar, from=Q924372
Bald notothen The bald notothen (''Pagothenia borchgrevinki''), also known as the bald rockcod, is a species of marine ray-finned fish belonging to the family Nototheniidae, the notothens or cod icefishes. It is native to the Southern Ocean. Taxonomy The bald ...
Fish of the Southern Ocean Fish of Antarctica Fish described in 1902 Taxa named by George Albert Boulenger