According to observers of the late 1500s and early 1600s, there were around 35,000 European Christian slaves held throughout this time on the Barbary Coast – many in Tripoli, Tunis, and various Moroccan towns, but most of all in Algiers. The greatest number were sailors, taken with their ships, but a good many were fishermen and coastal villagers. Out of all these, the British captives were mostly sailors, and although they were numerous there were relatively fewer of them than of people from lands close to Africa, especially Spain and Italy. The unfortunate southerners were sometimes taken by the thousands, by slavers who raided the coasts of Valencia, Andalusia, Calabria and Sicily so often that eventually it was said that ‘there was no one left to capture any longer’.
…There are no records of how many men, women and children were enslaved, but it is possible to calculate roughly the number of fresh captives that would have been needed to keep populations steady and replace those slaves who died, escaped, were ransomed, or converted to Islam. On this basis it is thought that around 8,500 new slaves were needed annually to replenish numbers – about 850,000 captives over the century from 1580 to 1680.
By extension, for the 250 years between 1530 and 1780, the figure could easily have been as high as 1,250,000 – this is only just over a tenth of the Africans taken as slaves to the Americas from 1500 to 1800, but a considerable figure nevertheless.