Data from recent trawl surveys in the vicinity of Heard Island and McDonald Islands (Division 58.5.2), reveal an unusual cohort structure in the mackerel icefish (Champsocephalus gunnari) population

Surveys of mackerel icefish, Champsocephalus gunnari, was undertaken in Division 58.5.2 in the vicinity of Heard Island during September 2010 and April 2011, to provide information on the population dynamics of this species, and to provide a basis for an assessment of short-term annual yield in the 2011/2012 CCAMLR season. This paper provides a preliminary assessment of yield for the area of Division 58.5.2 to the west of 79o 20’ E using standard CCAMLR methods. A predicted in 2010, the strong 4+ cohort that dominated the population declined rapidly in late 2010. Two new cohorts are present in the population, leading to a situation that is unusual for this region, with four or five successive year classes all present simultaneously. A catch limit of 103 t is recommended for the 2011/12 season.