Latin name

Champsocephalus gunnari

Other name

Champsocephalus gunnari

Identification

Champsocephalus: Greek, champso = crocodile, voracious predator + Greek, kephale = head.

The body of the mackerel icefish is low (11-15% of standard body length), pronotal. The rostral spike at the tip of the snout is absent. The tip of the lower jaw is on the same vertical line as the tip of the upper jaw. The head is relatively high, its height slightly greater than the length of the snout. The muzzle is relatively long, 34-48% of the length of the head. The mouth is large, the posterior edge of the upper jaw reaching the level of the anterior third of the orbit. Eye relatively large, orbital diameter 16-26% of head length. Interorbital space of moderate width (16-26% of head length). The outer edges of the frontal bones above the eyes are smooth, without crenulation (not serrated) and not raised. The body has two lateral lines (dorsal and medial) without bony segments. There are 11-20 gill stamens in the lower part of the first gill arch. The total number of vertebrae is 58-64.

Features of fish fins

The first dorsal fin has 7-10 flexible barb rays, the second dorsal fin has 35-41 articulated rays, the anal fin has 35-40 articulated rays, the pectoral fin has 25-28 rays and the caudal fin has 12 branchial rays. Both dorsal fins are relatively low, touching at their bases or barely separated by a very narrow interdorsal space. The pelvic fins are moderately long, the middle rays being the largest (16-20% of standard body length) and not reaching the beginning of the base of the anal fin. Caudal fin notched.

Fish colouring

General body colour silvery-light grey, white on the ventral side of the body. Head and back dark. There are irregular vertical dark stripes on the sides of the body, with the 4 darkest stripes standing out. Dorsal, caudal and anal fins dark or blackish in adults, pale in juveniles.

Distribution

The range of the species is characterised as circum-Antarctic intermittent, mainly restricted to islands near the northern boundary of the Antarctic Convergence. In West Antarctica, it is found near South Georgia Island, at Shag Rocks, near the South Sandwich, South Orkney and South Shetland Islands, on Bouvet Island and near the northern part of the Antarctic Peninsula. In East Antarctica, the range is restricted to the islands and banks of the submarine Kerguelen Ridge - Kerguelen, Shchuchya, Skif, South and Hird and McDonald Islands. 

Habitat

A marine benthopelagic polar species with a habitat depth range of 0 to 700 m, usually 30 to 250 m.

Size

Large fish. The South Georgia population reaches a total length of 66 cm and a mass of 1-1.2 kg. The largest fish recorded from South Georgia was 69.5 cm total length with a mass of 3.2 kg. In the Kerguelen archipelago, the total length of fish does not exceed 45 cm. The mass of market fish ranges from 100 g to 1 kg, with a length of 25-35 cm.

Behavior

It is a gregarious fish that migrates vertically on a daily basis. 

Food and feeding habits

Mackerel icefish feed mainly on krill and shellfish. 

Reproduction

Mackerel icefish reach reproductive maturity at the age of 3-4 years. They spawn synchronously in autumn and winter. Mature males have a much higher dorsal fin than females. This species approaches the shore to spawn. Females lay 10,000 to 20,000 large eggs which remain on the seabed for about 3 months before hatching. The larvae hatch from August to October at South Georgia and in October around the Kerguelen Islands. The larvae have a long pelagic phase. The maximum life span is 15 years.

Fishing

It's a valuable commercial fish.

Relationship with a person

The flesh of this fish is rich in potassium, phosphorus, fluorine and other trace elements. It is dense, tender, lean (2-8 g of fat per 100 g of weight) and low in calories (80-140 kcal per 100 g). Its protein content is around 17%. Virtually boneless: the fish has only the backbone and contains no ribs or small bones. And the backbone itself is soft and practically edible (easy to chew because it contains a small amount of calcium).