Seasonality in the Trans-Atlantic Slave Trade

Stephen D. Behrendt (Victoria University of Wellington), 2008

Provisioning-slaving seasons

Seasonality in Atlantic slaving markets linked closely to food supplies, since merchants, whether African, European, or American, would not purchase large numbers of people they could not keep alive. There were distinct provisioning-slaving seasons in Atlantic regions dependent upon a short rainy season and a staple crop. In more diversified early modern economies, often those with fewer dry months (and hence more evenly distributed rainfall), food production and labor requirements on farms became less seasonal. Provisioning-slaving seasons ebbed during rainy planting months and increased during and after dry season harvests. After crops were harvested and stored, African merchants sold enslaved farmers and provisions to coastal middlemen who, in turn, sold these captives to ship captains.

In Africa, Upper Guinea (from Senegal to the Ivory Coast) and the Bight of Biafra had marked provisioning-slaving seasons. In Senegal and Gambia, millet stocks increased in March-May before the summer rains. May-July was correspondingly the greatest quarter in the Senegambian slave export trade—three times greater than in the September-November quarter. Along the Sierra Leone/Windward Coasts, the rice-slave season began in November and supplies of food and people began to dwindle in late April. In spring 1751, south of Sierra Leone, Liverpool captain John Newton VoyageID 90350, the author of “Amazing Grace,” purchased late-season rice and slaves. He remarked on April 30th in his logbook, held today at the National Maritime Museum (UK), “the season is so far advanced.” Sierra Leone/Windward Coast slave exports from March to May almost doubled totals from June to August. In the Bight of Biafra, the season’s first yams arrived in markets in July and August; the peak harvest occurred in October, and supplies remained until February or March. September-November slave exports doubled those totals from June-August. Fewer dry months along the Gold Coast or Bight of Benin enabled farmers to often double-crop maize and other cereals. Given greater food supplies, slave exports exhibited less of a seasonal trend. Traders also did not identify provisioning-slaving seasons along the West-Central African coast. With few foodstuffs available for export overseas, the link between harvest cycles and slave supplies is weakest in the South Atlantic African slaving markets.

The timing of dry season grain and cash crop harvests regulated the New World demand for enslaved African labor. The sugar producing West Indies and Guianas imported more slaves during the December-May corn and cane harvests. In Brazilian sugar-producing centers, such as Bahia, the provisioning-slaving season centered on the drier November-February quarter. During three months of the harvest season, slave import figures ranged from twenty-nine percent of annual totals (Cuba, Pernambuco, Bahia) to forty-four percent (northwest Jamaica). In the smaller non-sugar-growing regions of North and South America, captains disembarked comparatively large numbers of slaves in-season during rainier months. Chesapeake tobacco planters only demanded new migrant farmers during the April-May spring rains, when men and women transplanted tobacco stalks to the fields, and in June-August, before harvesting and curing. The autumn corn harvest provided food stocks to sustain workers forced to produce the annual tobacco crop. In the rice-growing Carolina/Georgia Lowcountry, Surinam, and Maranhão, planters purchased twice as many workers during the four in-crop months.

Agricultural calendars and labor requirements Slave-trading seasonality: case studies
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