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Polar Cod fish identification, its habitats, characteristics, fishing methods.
The polar cod, Boreogadus saida, also known as the Arctic cod, is a fish of the cod family Gadidae, related to the true cod (genus Gadus). Note that there is another fish with the common name Arctic cod, Arctogadus glacialis, also related to the true cod genus. The polar cod is a cold-loving fish living up to 6-7 years and normally grows to only 6-8 inches (15-20 cm) long, but may grow to 15 inches (38 cm). They occur in coastal habitats during summer and winter and feed on plankton and krill. The polar cod is found further north than any other fish species. They are spanning the Arctic seas off northern Russia, Alaska, Canada, and Greenland. It is in turn the primary food source for narwhals, belugas, ringed seals and seabirds. The polar cod is generally not considered important for human food. They are fished commercially in Russia.
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The polar cod, Boreogadus saida, also known as the Arctic cod, Polar bib, Polartorsk in Denmark, Polardorsch in Germany, Polartorsk in Norway, Сайка or Полярная Трсочкк in Russian, is a fish of the cod family Gadidae, related to the true cod (genus Gadus). They widely distributed in the Arctic Ocean in North Atlantic: White and Barents Seas, off Spitzbergen, Iceland, around Greenland into the Miramichi River, New Brunswick in Canada. Also found North Pacific in the Beaufort and Chulkchi Seas, in Hudson Bay and in the north and northwest Bering Sea to Cape Olyutorski, the Pribilof Islands, and Bristol Bay.
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Description
The polar cod has a slender elongate body, its greatest height at the back of the head, approximately 1/4th - 1/5th of length. They have projecting mouth and a small whisker on its chin, sometimes barely perceptible or absent. The head is pointed and large, 1/4th of a length, large eyes, snout longer than eye, which is equal to interorbital space, and about one-fourth of a head.
Jaws are of about equal length or lower jaw slightly longer. Teeth extremely minute, sharp, those in the outer series are trifle larger, palatine teeth always absent. Three dorsal fins, two anal fins, all separate from each other; first anal fin base short, less than one-half of pre-anal distance and more than half of distance from it up to the beginning of a head; deeply forked caudal, the upper lobe the longer, the height of the slender tail stalk. Pectoral fin is approximately one and a half in head, reaching beyond end of first dorsal fin; pelvic fin with a slightly elongated ray; ventral’s long, 11/3 in head, vent below front of second dorsal. Lateral line interrupted along its entire length, variable in position, only slightly curved with 2 or 3 wavy curves behind middle of second dorsal fin base, caudal fin deeply forked. No lateral line pores on head. Scales are very small, tiny and embedded, not overlapping, also minute bony spinous plates on sides of body, head and fins.
Key characters
Lower jaw is slightly longer than upper jaw. Chin barbel very small or absent. No lateral line pores on head. Scales small and embedded, not overlapping. Color is brownish along the back with many fine points, the fins dusky with pale margins; the sides and belly silvery.
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42-57 Dorsal soft rays (11-15 +12-17 + 17-23)
33 – 44 Anal soft rays (14-20 + 18-24)
49 - 58 Vertebrae
37-46 Gill rakers
Max length: 32 cm, usually 12-16 cm
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The polar cod look a lot like the Pollock, Pollachius virens and is found in the Arctic Ocean from Greenland to Siberia. It may be distinguished from related species by a forked tail and slender body, length of the first anal fin and whitish light slightly curved lateral line.
The color is variable, back and sides brownish, with many fine dark spots, and lighter with violet or yellowish tint above lateral line, silvery-grey below. Top of the head and spin is grayish-brown, fins dusky, dotted with pale margins, the dorsal and pectoral fins almost entirely black, as is the lower half of the anal fins; lateral line pale.
Habitats
The polar cod is most commonly found at the water's surface, at depths of 40 to 400 m, but is also known to travel at depths greater than 1300 m throughout the waters of the Arctic Ocean in all its seas. They occur in coastal habitats during both summer and winter, inshore but mainly offshore, at edge and under drifting ice, salt and brackish water, and known entering brackish lagoons and almost fresh water river mouths. It is a hardy circumpolar fish that survives best at temperatures of 0–4 °C but may tolerate colder temperatures owing to the presence of antifreeze protein compounds in its blood. They group in large schools in ice-free waters, or under the floating ice, often coming to shore, forming massive concentrations in coastal waters and estuaries.
They gregarious usually found in large shoals and make feeding and spawning migrations to near-shore waters in late summer in the Beaufort Sea and winter mass migrations into the White Sea for spawning. Onshore-offshore movements are associated with spawning and movements of the ice.
Polar cod feed mostly on phytoplankton and zooplankton, calanoids, hyperiids, epibenthic, euphausiids, mysids and also on juvenile amphipods and copepods. For those that are under the ice surface in offshore waters, fish is the principal food item during the winter. Although they prefer to eat mysids, young shrimp, fish, mostly Boreogadus saida, small amphipods inhabiting lower surface of drifting ice, rarely calanoids.
Spawning:
Polar cod spawns inshore and offshore, under or near drifting ice, near bottom when temperature below 0° C. They spawn once in its lifetime. Most males become mature at 2 to 3 years old. Females become mature in the 3rd to 5th year of life, reaching a length of 19-20 cm. 74% females in populations are of 3 to 6 years old fish. Its fecundity is 9000 to 35000 pelagic eggs, on average 11900 eggs per females. They spawn in winter from late November to early February in the coastal areas of the Beaufort Sea, from end of December to February under the shore ice of the Barents Sea, and from January to February (sometimes April) under the shore ice of the White Sea. Polar cod is a species with early maturity, rapid growth, production of larger numbers of offspring at a given parental size, small body size, high rates of mortality, and shorter life span. During autumn migrations, the fishes form aggregates.
Fishing Methods:.
Polar cod used to be intensively fished by USSR, Norway, Danish and German vessels using bottom- and mid-water trawls in the Barents and White Seas, and the northwest Atlantic. The fish is pursued from January through May producing massive catches during February.
In Canadian waters, Polar cod has a limited commercial value because it is small and apparently not abundant. The flesh is said to be of low quality. Its major utilization by Norwegians is for fish meal and oil.
Cod Recepies
Cod meat is white in color, is moist and lean, medium- to firm-textured, and delicately flavorful with a mild taste. Tender, thick fillets with large flakes that "gape" (separate) when cooked. It is a good source of low fat protein, phosphorus, niacin, and vitamin B12 with a mild flavor and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of vitamin A, vitamin D, vitamin E and omega-3 fatty acids (EPA and DHA).
Cod is excellent for poaching, broiling, baking, braising, and frying. A popular main ingredient in chowders, which are creamy and binding enough to support the big flakes of meat that fall apart when cooked. Whole cod are often stuffed and baked. Heads and bones make fine soup stock.
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