Notes on seasonal abundance and spawning of some important offshore linefish in Natal and Transkei waters, southern Africa

Catches of geelbek Atractoscion aequidens, red steenbras Petrus rupestris, seventy-four Polysteganus undulosus, yellowtail Seriola lalandi and blue hottentot Pachymetopon aeneum in Natal and Transkei waters increase noticeably between July and November. Most of the fish caught are sexually mature and in spawning condition, suggesting that they may undertake spawning migrations from Cape waters into the Natal/Transkei region at this time of year. Spawning of A. aequidens and P. undulosus appears to be limited to this region, whereas P. rupestris, S. lalandi and P. aeneum are known to spawn in Cape waters as well. It is postulated that three reproductive strategies are used by pelagic-spawning predatory fish along South Africa's eastern and southern coasts: one involves the migration of the entire breeding stock north-eastwards into warmer waters to spawn, another involves a migration of part of the breeding stock, and the third covers species which do not migrate, but spawn when local conditions are seasonally favourable.