Pelagic eggs of marine fishes from Park Rynie, KwaZulu-Natal, South Africa: seasonal spawning patterns of the three most common species

Abstract

For the period 1987 to 1998, pelagic eggs of marine fishes were collected from shelf waters at Park Rynie on the KwaZulu-Natal south coast. The three most numerous eggs collected were those of the mackerel Scomber japonicus, the sardine Sardinops sagax and the East coast roundherring Etrumeus teres. Together they comprised 67 % of all eggs collected. At times single-species egg densities were high, the highest accurately recorded was 850 eggs/cubic metre for S. sagax. All three species were predominantly winter to spring spawners. The seasonal pattern of sardine eggs at Park Rynie suggests that after entering KwaZulu-Natal waters in June, sardines remain until November or December of each year before returning south to eastern Cape waters. Spawning in the East coast roundherring began in June, peaked in October to November, and tailed off in January. The mackerel showed a similar pattern of spawning, beginning in June and ending in December.

Key words: Mackerel, sardine, East coast roundherring, western Indian Ocean, spawning intensity.