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The abundance of spawning Cape anchovy (Engraulis capensis) on the South African continental shelf in 1985 and 1986 has been assessed through combined acoustic and egg-production surveys from a single vessel. The two surveys are complementary, and their combination is a natural and efficient means of improving estimates of spawning biomass. Acoustic estimates were obtained by stratified random-sample surveys using a multi-channel digital echo integrator. Egg counts at regular intervals on the acoustic grid, together with estimates of spawning fraction obtained from midwater-trawl identification hauls, allowed the mean daily egg production to be estimated in both years, from which alternative estimates of spawning biomass were derived. Agreement between estimates obtained by the two methods was acceptable in both years. A spawning-biomass estimator based on the acoustic and egg-produc­tion estimates from both the current year and previous years has been developed. The estimator is considered to be less susceptible to bias than one obtained from acoustic and egg-production estimates from the current year only, although it will be less precise. Weighting factors for minimizing the variance in the former estimate are developed and applied to the 1985 and 1986 estimates to give a spawning biomass in 1986 of 1.37 million tonnes, with a coefficient of variation of 27%. All the estimates indicate that the anchovy spawning stock is considerably greater than was previously believed to be the case on the basis of virtual population analysis (VPA) of age data from commercial catches. Application of the survey estimates has led to the anchovy quota being more than doubled since the inception of the survey programme.