Aspects of the biology ofArgyrosomus hololepidotusandAtractoscion aequidens(Osteichthyes: Sciaenidae) in waters of the south-eastern Cape, South Africa

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Argyrosomus hololepiclotus (kob) is an important component of the line fishery of the south-eastern Cape. Specimens were sampled between 1978 and 1981, and they ranged in size between 226 and 1 701 mm total length. Largest line catches were recorded between spring (August) and late summer (March) in inshore areas (<40 m depth). Trawl catches of kob made in deeper water (54—117 m) peaked in winter and summer. Long-term trends in the trawl fishery suggest that the stock size decreased greatly after the mid-1960s. Estimates of mortality of line-caught kob were high, with Z values of 1,52 between ages 2 and 5, and 0,50 between ages 5 and 11. An overall sex ratio of 1 male to 1,8 females was recorded. Sexual maturity is attained by 250 mm total length, and evidence of spawning was found throughout the year, with a major peak from July to December. Atractoscion aequidens (geelbek) of 283—992 mm fork length were also caught by the line fishery, but sporadically throughout the year. A sex ratio of 1 male to 1,2 f...