Chub mackerelScomber japonicusin the South-East Atlantic – its seasonal distribution and evidence of a powerful 1977 year-class

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Abstract
Until 1975 catches of chub mackerel in the South-East Atlantic were mainly made by purse-seine vessels off the Western Cape, South Africa, but subsequently by midwater or demersal trawlers fishing primarily off South West Africa (Namibia). Chub mackerel were most abundant in the northern Benguela Current region during the austral spring and summer, appeared to migrate through the central region in autumn, and were caught on the southern fishing grounds from winter through mid-spring. These movements can plausibly be related to seasonal patterns of prey availability. An exceptionally powerful year-class appears to have been formed in 1977 and to have been largely responsible for the peak catch of about 200 000 tons in 1978. As with powerful year-classes produced in the mid 1960s, the 1977 year-class arose after a period of unusually poor upwelling, but when a forage species was plentiful. Mortality inflicted by chub mackerel and other predators on anchovy Engraulis capensis off the Western Cape appears to have been low immediately prior to a large increase in the anchovy stock in this area. A total annual catch of chub mackerel from the South-East Atlantic not exceeding the mean value for the period 1971—1982, i.e. about 70 000 t, is provisionally suggested.

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