The Atlantic Slave Trade: A Census

10. A Postscript on Mortality

CHAPTER 10 A POSTSCRIPT ON M:ORTALITY The cost of the slave trade in human life was many times the number of slaves landed in the Americas. For every slave landed alive, other people died in warfare, along the bush paths leading to the coast, awaiting shipment, or in the crowded and unsanitary conditions of the middle passage. Once in the New World, still others died on entering a new disease environment. Most of these losses are not measurable. More careful investigation of the slave trade within Africa should produce illuminating samples of the slaves' experience, but these could only be typical for a particular period and a particular place. Mortality rates at sea, however, are measurable, and historians of the trade usually have produced an estimated rate of loss in transit. Among the recent English-language textbooks on African history, Robert Rotberg sets the loss of life during the maritime leg of the journey into slavery at 21> to 33 per cent. J. D. Hargreaves says it was about one-sixth (or half of the rate given by Rotberg) and J. D. Fage says it was "at least" one-sixth.l Donald L. Wiedner is still more precise: "Many of the trading records have been lost or destroyed, but enough has survived to permit at least an estimate of the percentage of slaves who died during the rigorous ocean voyage: about 12 per cent in French ships, contrasted with 17 per cent in Dutch and British ships; 1. Rotberg. Political History, p. 149; Hargreaves, West Africa, p. S6; Fage, West Africa, p. 82. 275 276 THE ATLANTIC SLAVE TRADE Portuguese losses in the early centuries ran about 15 per cent, but when the nineteenth-century abolitionists pressure forced the slave traders to take chances, the casualty rate rose to 25 to 30 per cent,''2 Textbooks customarily cite no sources, and it is not clear where this information came from; but one source of the high estimate for the nineteenth-century slave trade is the Foreign Office report of 1848, which set the rate of loss at about 25 per cent.3 Another source often cited in the literature for the eighteenth century is Rinchon's calculation from his compilation of Nantes shipping-that over the period 1748-82 the number of slaves sold in the Americas was 13 per cent lower than the number purchased in Africa. This figure, for example, was used recently by Basil Davidson as a general indicator of the rate of loss.4 Thus the recent literature on the slave trade tends to put the mortality rate at sea somewhere between 13 per cent and 33 per cent. This wide range is easily explicable: mortality rates varied greatly according to the route, the length of the voyage, the original disease environment of the slaves themselves, the care they received, and the chance occurrence of epidemics. Westergaard 's archival survey of the Danish slave trade, for example, showed that individual voyages between 1698 and 1733 had mortality rates as low as 10 per cent and as high as 55 per cent.1i But some general tendencies are also discernible. One of these is a decreasing rate of loss over the eighteenth and nineteenth 2. Wiedner, History of Africa, p. 67. 8. PP, 1847-48, xxii (628), p. 8. 4. Davidson, Black Mother, p. 87. Davidson's figure of 18 per cent loss between 1748 and 1782 is based on Rinchon's own totals for these years alone. They disagree slightly with the gross loss of 14.88 per cent, found on recomputing the mortality rate from Rinchon's list of ships sailing from Nantes between 1748 and 1792 or with the figure of 15.2 per cent obtained if ships listed as selling more slaves than they had purchased are disregarded. These results may differ from Rinchon's own calculation because they include loss from capture and shipwreck as well as loss from disease. (See Rinchon, Le Trafic negrier, pp. 248--S05, esp. p. 805.) 5. Westergaard, Danish West Indies, p. 144. A Postscript on Mortality TABLE 78 Loss OF SLAVES IN TRANSIT SUSTAINED BY THE SLAVE TRADERS OF NANTES, 1715-75 Mortality Mortality from di,'ease from all Period (%) causes (%) 1715-19 12.2 19.1 1720-24* 19.1 22.4 1727-31 13.5 13.5 1732-36 18.4 18.4 1737-41 19.4 19.6 1742-45...