Biology, fishery and management of sardines (Sardinops sagax) in southern African waters

Abstract

Sardines have been a major contributor to the pelagic fishery off southern Africa for several decades. The South African and Namibian stocks are separate, and seasonal hydrology, in conjunction with age-related behaviour, produces the observed size-distribution patterns. Sardines are relatively fast- growing and spawn repeatedly over the spring and summer months. Eggs and larvae are transported from the Agulhas Bank to the west coast by the north-flowing jet current at the shelf edge. Sardines are omnivorous, microphagist filter-feeders and are important prey for many piscivorous fishes, birds and mammals. There have been major fluctuations in sardine population biomass in southern Africa which have been associated with environment, regime shifts, recruitment and fishing. South African and Namibian sardine catches peaked in the 1960s, declining dramatically thereafter, and the pelagic fishing industry switched to anchovy. During the 1990s, sardine biomass increased but, although South African catches rose, the Namibian stock collapsed again. The annual South African total allowable catch is set through an operational management procedure that takes into account biomass estimates from comprehensive hydroacoustic surveys and the sardine by-catch in the anchovy fishery.