Inter-annual variation in the gonad cycle of the mackerel icefish

Spawning by Antarctic fish is generally considered to be seasonal and restr icted to a brief period during the autumn and winter. Arising from this it has been assumed that the gonadal maturation cycle is also closely associat ed with the time of year. The gonad maturation cycle of the mackerel icefis h Champsocephalus gunnari was investigated using data collected during rese arch surveys and from sampling the commercial fishery. Spawning appears to occur at the same time each year, but the timing of gonadal development is subject to a considerable inter-annual variation. The implications of this variation are discussed with respect to feeding conditions. (C) 2000 The Fi sheries Society of the British Isles.