The Yaqui Valley is located on the northwest coast of mainland Mexico in the state of Sonora (Plate 9). Situated on a coastal strip along the Gulf of California, the valley consists of an intensively managed agricultural region amidst a desert scrub forest and is bordered by estuarine ecosystems that provide critical habitat for migratory and resident water birds, marine mammals, fish, and shellfish populations (Flores-Verdugo, Gonzalez-Farias, and Zaragoza-Araujo, 1992). These coastal waters have long been an important center for both subsistence and the export fishing industry. The Yaqui Valley region is of vital economic importance to Mexico both in terms of its agricultural production and fish production. Today the Yaqui Valley consists of 225,000 hectares (ha) of irrigated wheat-based agriculture, and it is one of the country’s most productive breadbaskets (Naylor, Falcon, and Puente-González, 2001). Using a combination of irrigation, high fertilizer rates, and modern cultivars (Matson, Naylor, and Ortiz-Monasterio, 1998), valley farmers produce some of the highest wheat yields in the world (Food and Agriculture Organization, 1997). The region also maintains the most productive fisheries in Mexico, with sardines and shrimp among the most important species (CONAPESCA, 2002). In recent years the region has also developed the second-largest shrimp aquaculture industries in Mexico (CONAPESCA, 2002). However, in a world of globalized markets, reduced subsidies and price supports, drought, hurricanes, and other forces, many farmers and fishers in the region are concerned about maintaining production and household incomes.

Like many developing regions, the Yaqui Valley is undergoing rapid socioeconomic and ecological changes. Population growth, urbanization, agricultural intensification, expanded livestock operations, and coastal aquaculture development are just some of the major developments in the area.

In the early 1900s the land in the Yaqui Valley was primarily under the control of large landholders (Lewis, 2002). However, the land tenure in the region began to change in the aftermath of the 1910 Mexican Revolution, when Article 27 of the Mexican Constitution established the ejido land reform program and declared all land ultimately the property of the nation. While private property was allowed in principle under the new system, Article 27 established a legal limit on private landholdings of 100 irrigated hectares or the “non-irrigated equivalent.”¹ Furthermore, Article 27 man-