From the late fifteenth to the early nineteenth century, the duration of Spain's imperial heyday, ocean-going ships provided crucial links between the home country and its colonies around the globe. Trading voyages across the Atlantic and Pacific, as well as within Europe, accounted for an overwhelming majority of the demand for sailors over those three centuries. Military needs added substantially, especially during the frequent wars of the early modern period. Mariners were also needed for Spain's coastal fisheries and for more distant voyages in pursuit of cod and whales. How were these demands matched with the supply of mariners? Or, put another way, to what extent did a labour market for sailors function in Spain during the early modern era?

Any approach to this question involves comparisons among several elements: on one hand, population size and trends, the importance of other occupations (especially agriculture), and the availability of nautical skills in the workforce; on the other, total demand for mariners, given the relative importance of commerce and warfare. Wage levels in agriculture, industry, service, and maritime occupations would let us examine whether remuneration played a dominant role in matching supply with demand. The sources provide surprisingly detailed information about some of these elements, but very little on others. Because government records are far better preserved than private accounts, we know more about crews on royal ships than on private merchantmen. Moreover, historical scholarship has served some regions of early modern Spain better than others, leaving discouraging gaps. For instance, Galicia in northwest Spain, with a long seafaring tradition, has been much better studied than the Basque province of Vizcaya, which had an equally intimate connection with the sea. In the analysis that follows, I will discuss several factors that defined the market for maritime labour in early modern Spain: demographic and economic trends, the number of mariners, the total tonnage of shipping, and the level of maritime wages.