The biology of the spiny icefish (Chaenodraco wilsoni Regan, 1914)

The most abundant icefish species observed in catches off the northern tip of the Antarctic Peninsula in the last 25 - 30 years has been the spiny icefish Chaenodraco wilsoni Regan 1914. C. wilsoni has been exploited on a commercial scale from the late 1970’s to the end of the 1980’s off Joinville – D’Urville Islands (CCAMLR Statistical Subarea 48.1) and in the Cosmonauts and Cooperation Seas and Prydz Bay in the Indian Ocean sector (CCAMLR Statistical Division 58.4.2). This paper presents new information on biological features and life history characteristics of C. wilsoni, based on research survey collections along the northern Antarctic Peninsula in 2006 and 2007 and samples taken in the commercial fishery in 1987. Length frequency compositions from the research surveys demonstrated that fish 21 – 34 cm long predominated in the catches. Sexual maturity is attained at 24 – 25 cm. Absolute fecundity and relative fecundity is low (1000 – 2500 eggs; 6 – 12 eggs). Oocyte diameter varied from 4.3 to 4.8 mm very close to spawning. Spawning at the tip of the Antarctic Peninsula is likely to occur in October-November. Remotely Operated Vehicle deployments in the northern Weddell Sea demonstrated that C. wilsoni exhibit parental nest guarding where males protect the eggs. The incubation period is likely to be 8 months long. Fish feed primarily on Antarctic krill (Euphausia superba) in the Antarctic Peninsula region and in the Cosmonauts and Cooperation Seas while fish take ice krill (E. crystallorophias), Pleuragramma antarcticum and myctophids to some extent in other areas. Age determination still awaits validation. Preliminary ageing attempts suggested a maximum age of about 8 – 10 years.