Latin name

Pleuragramma antarctica

Other name

Antarctic herring

Identification

The body of the Antarctic silverfish is pronounced, strongly compressed at the sides, herring-shaped, with rather jelly-like and elastic lateral muscles, covered with large, very thin, easily falling cycloid scales. The gill covers and cheeks are also covered with scales, the top of the head is bare. The snout is pointed, the mouth is upper, with the lower jaw protruding forward and an oblique mouth slit. The teeth on the jaws are small, bristle-like, arranged in up to 3 rows at the symphysis of the upper jaw. The middle part of the lower jaw has 3-4 enlarged teeth each. On the sides of the body there are three lateral lines represented by punctate scales, on the surface of each of which there are 3 free neuromasts, grouped in a compact group in the form of a short vertical line. The total number of stamens on the first gill arch is 29-35, of which 20-26 are in the lower part and 8-12 gill stamens in the upper part. Total number of stamens is 52-56.

Features of fish fins

The first dorsal fin has 6-8 flexible barb rays, the second dorsal fin has 35-38 articulated rays, the anal fin has 36-39 articulated rays, the pectoral fin has 19-21 rays and the caudal fin has 12 branchial rays. The caudal fin is deeply emarginated.

Fish colouring

The overall body colouration is typically pelagic, with a dark back and silvery white sides and underside. When alive, the sides of the body have a characteristic iridescent pinkish glow. All fins are pale with a transparent fin fold. After death the body becomes silvery with a darker back. 

Distribution

Antarctic silverfish are circumpolar in the Antarctic marginal seas and off the Antarctic Peninsula, South Shetland Islands and South Orkney Islands. 

Habitat

Marine pelagic-oceanic polar species. Depth range from 0 to 1000 m. Inhabits the water column in a wide bathymetric range - from the surface to 970-1000 metres. Favourable conditions for the formation of dense aggregations of this species are waters with temperature within -1.5-1.85 °C and salinity 33.57-34.20 ‰. It is considered to be the only truly pelagic fish in Antarctic waters. Larvae and post-larvae are found from 0 to 135 m, juveniles from 50 to 400 m and adults below 400 m. The larval pelagic phase is long.

Size

Females reach a total length of 305 mm (274 mm standard length) and weigh 239 g. Males are slightly smaller, reaching a total length of 250 mm (221 mm standard length) and weighing 124 g. The average size of fish has been observed to increase with increasing fishing depth. The largest fish are found in the Indo-Pacific sector of the Southern Ocean. Maximum age reported: 20 years.

Behavior

In summer it forms large and dense feeding aggregations, usually confined to the outer shelf and upper part of the continental slope. The most stable aggregations have been observed in Prydz Bay in the Commonwealth Sea. The densest aggregations, characterised as fisheries, are associated with a zone of increased horizontal water temperature gradients. 

Food and feeding habits

Postlarvae feed mainly on eggs and larvae of paddlefish; juveniles feed mainly on crustaceans, but also on eggs and larvae of euphausiids, polychaetes and cheetognaths. Larger individuals are eaten as they increase in size. 

Reproduction

Mature females can spawn for the first time at around 7-9 years of age.

Fishing

Antarctic silverfish has a minor commercial interest in fisheries.

Relationship with a person

Harmless.