Striped notothen / striped rockcod / green rockcod Trematomus hansoni

Trematomus hansoni is found throughout Antarctica and the Antarctic Peninsula, South Shetland Islands, South Orkney Islands, and South Georgia Island at depths from 0 to 640 meters [1,3,6,8,12]. T. hansoni is colored greenish-grey with large black crossbars; its head is bluish mauve at the lower part [6]. The dorsal and anal fins of T. hansoni have greyish-green rays and black membrane and the caudal fin has dark transverse narrow bands with a clear membrane [6]. The pectoral fins of T. hansoni have light and grey bands with a dark membrane between the four last rays; its pelvic fins are punctuated with black spots on the rays [6]. T. hansoni can reach 42 centimeters in length [1,6,13].

Trematomus hansoni eats juvenile fish, fish eggs, algae, polychaetes (including Harmothoe spinosa, Haploscoloplos kerguelensis, Spiophanes tcherniai, Gyptis sp., Capitella sp.), krill, mysids, isopods (including Austrosignum grande, Antarcturus sp.), amphipods (including Monoculodes scabriculosus, Heterophoxus videns, Hyperiella sp.), tanaid Nototanais dimorphus, shrimp (Chorismus antarcticus, Notocrangon antarcticus), copepods, nemerteans, crinoids, holothurians, anemones (including Edwardsia meridionalis), medusae, pycnogonids, pterobranchs, and gastropods (including Neobuccinum eatoni, Marseniopsis mollis ) [1,3,6,7,10,11,12,13]. T. hansoni tends to take more prey from the water column than other primarily benthic feeding fish like T. pennelli or T. bernacchii [2].

Depending on location, T. hansoni becomes sexually mature and spawning in December - February; eggs probably hatch in winter [1,6,12,13]. Antarctic fish like Trematomus hansoni are well-adapted to the extremely low and stable temperatures of McMurdo Sound where seawater has a nearly constant mean annual temperature of - 1.86 degrees Celsius (28.65 degrees Fahrenheit) and temperature doesn't vary much with depth or season -- 0.2 degrees Celsius (0.36 degrees Fahrenheit) [5]. The flip side is that T. hansoni and some other cold- adapted Antarctic fish die of heat at approximately 6 degrees Celsius (42.8 degrees Fahrenheit) which is the lowest known heat death temperature of any animal [4]. This freezing resistance is accomplished with special antifreeze glycopeptides in its body fluids, that bind to emerging ice crystals and prevent their growth; these antifreeze compounds are being commercially marketed for product development [9,14].

The species name hansoni honors Nicolai Hanson, the biologist of the Southern Cross Expedition.

Taxonomic Note: Sometimes reported with the genus Pagothenia. Some use the genus Pseudotrematomus [1,15,16]

1: Fishes of the Southern Ocean. O Gon and PC Heemstra, eds. Grahamstown, South Africa : JLB Smith Institute of Ichthyology, 1990. pp. 319-321; 2: Polar Biology 13(6):429-431, 1993; 3: Polar Biology 17(1):62-68, 1997; 4: Science 156:257-258, 1967; 5: Antarctic Research Series 5, Biology of the Antarctic Seas II. GA Llano, ed. Washington DC : American Geophysical Union, pp.1-37; 6: FAO Species Identification Sheets for Fishery Purposes : Southern Ocean (Fishing Areas 48, 58 and 88) (CCAMLR Convention Area) / W Fischer & JC Hureau, eds. Rome : Food and Agriculture Organization of the United Nations, 1985; 7: Bulletin de l'Institut Oceanographique 66(1368), 1966; 8: Tethys 6(3):631-653, 1974; 9: www.afprotein.com; 10: Ophelia 24(3):155-175, 1985; 11: Ross Sea Ecology : Italiantartide Expeditions (1987-1995). FM Faranda, L Guglielmo, A Ianora, eds. Berlin : Springer, 2000. pp. 551-561; 12: Antarctic Ecosystems : Models for Wider Ecological Understanding. W Davison, C Howard-Williams, P Broady, eds. Christchurch, NZ : New Zealand Natural Sciences, 2000. pp. 96-100; 13: Ross Sea Ecology : Italiantartide Expeditions (1987-1995). FM Faranda, L Guglielmo, A Ianora, eds. Berlin : Springer, 2000. pp. 457-468; 14: Water and Life : Comparative Analysis of Water Relationships at the Organismic, Cellular, and Molecular Levels. GN Somero, CB Osmond, CL Bolis, eds. New York : Springer-Verlag, 1992. pp. 301-315; 15: History and Atlas of the Fishes of the Antarctic Ocean. RG Miller. Carson City, Nev. : Foresta Institute for Ocean and Mountain Studies, 1993; 16: Biologiia Shel’fovykh zon Mirovogo Okeana : tezisy dokladov Vtoroi vsesoiuznoi konferentsii po morskoi biologii, Vladivostok, sentiabr’ 1982 g. AI Kafanov & TS Veniaminson, eds. Vladivostok : DVNTS AN SSSR, 1982. Volume 2, pp. 9-10

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